Title of Invention	APPARATUS FOR ELECTROPHORESIS
Abstract	Apparatus for electrophoresis comprising a suitable housing (100), (200) accommodating a first gel matrix (38), (238) adapted for performing an electrophoretic process on at least one sample of interest therein in a first direction, characterized in comprising at least a first trap (90) comprising a second gel matrix (48), (248) having at least one suitable absorption material capable of trapping and retaining therein at least one target substance migrating thereto from the first gel matrix (38), (238) in an opposite direction to said first direction when an electrophoretic process is performed in said first matrix (38), (238) in said first direction, wherein said first gel matrix (38), (238) is in ionic communication with said second gel matrix (48), (248), and wherein said target substance is different from said at least one sample of interest.

Title of Invention

APPARATUS FOR ELECTROPHORESIS

Abstract

Apparatus for electrophoresis comprising a suitable housing (100), (200) accommodating a first gel matrix (38), (238) adapted for performing an electrophoretic process on at least one sample of interest therein in a first direction, characterized in comprising at least a first trap (90) comprising a second gel matrix (48), (248) having at least one suitable absorption material capable of trapping and retaining therein at least one target substance migrating thereto from the first gel matrix (38), (238) in an opposite direction to said first direction when an electrophoretic process is performed in said first matrix (38), (238) in said first direction, wherein said first gel matrix (38), (238) is in ionic communication with said second gel matrix (48), (248), and wherein said target substance is different from said at least one sample of interest.

Full Text	APPARATUS FOR ELECTROPHORESIS Technical Field The present invention relates to an apparatus for electrophoresis , in particular to such devices or apparatus adapted for the safe handling and disposal of agarose-type gels containing dyeing compounds used therewith. Background Gel electrophoresis, a commonly used method on, molecular biology research, is a technique designed to separate, identify and purify DNA, RNA and protein molecules based on their weight, size and shape. This technique, which is simple and rapid to perform, is carried out by first preparing a gel. When the gel is ready it is placed in a gel box, immersed in a buffer solution, and connected to a power source. Once stimulated by the electric field that is set up in the gel, the molecules move through the gel matrix at different rates. The migration rate for each species of molecule is dependent upon the electrical charge, the size and shape of the molecules, as well as on the composition of the gel. Most commonly, the smaller molecules will move through the matrix at a quicker pace than those of a larger size. Sufficient quantity of buffer (typically TAE, TBE or protein running buffer) is generally used to ensure that the electric field is set up in the gel, and that the gel is covered with it and thus prevent the gel from drying out during electrophoresis. When loading a sample containing the molecule species of interest into the gel, a loading dye is typically used. The loading dye normally allows easy visualization of the solution during the loading process, as well as enabling the density of the sample to be increased to ensure that the sample is fully and evenly accommodated in a corresponding well in the gel, and further allows visualisation of the migration during electrophoresis. The most commonly used gels are prepared with either agarose or acrylarnide, either one of which can be provided in varying shapes, sizes and thicknesses. The deciding factor as to which particular gel and its physical attributes is generally related to the size of molecule being separated and the desired experiment to be performed by the user. Acrylarnide is usually chosen for relatively small molecules such as proteins, while agarose is used for larger molecules such as DNA or RNA. and agarose is the preferred choice for horizontal gel electrophoresis, typically cast in open trays by users. Typically, it is desirable to visualize and to document the results of the electrophoresis separation test. In electrophoresis separation of DNA or RNA molecules, this may be accomplished by immersing the gel slab after the electrophoretic separation has been completed in a solution of a fluorescent compound which emits visible light when exposed to a ultraviolet (UV) light. Other methods of staining the gel are also known, for example by adding a suitable dye to the gel while casting the same. A widely used fluorescent compound is ethidmm bromide. However, many types of such fiuorescervt compounds, including ethidium bromide, Acrydine Orange, SYBR Green I, and SYBR Green II, as well as acrlyamide and also some components used together with some agarose gels, are toxic and/or carcinogenic, and contact with users must be strictly avoided, particularly when disposing of the gels after use. It is therefore an aim of the present invention to provide a device and method which overcomes the limitations of prior art electrophoresis devices and methods. It is another aim of the present invention to provide a device for enabling safe handling and disposal of gels which may contain harmful substances. It is another aim of the present invention to provide such a device that is simple to use. It is another aim of the present invention to provide such a device that is relatively simple mechanically and thus economic to produce. It is another aim of the present invention to provide such a device that is adapted for use with regular horizontal electrophoresis equipment. These and other aims are accomplished in the present invention by providing a precast cassette for horizontal electrophoresis, in particular a disposable and closed cassette for horizontal electrophoresis. In particular, the cassette comprises preferably a pair of traps, one at each longitudinal end of the cassette, each trap comprising an absorption material for preventing toxic material from migrating out of the cassette. This is an important safety feature, particularly in view of the handling of the horizontal electrophoresis apparatus and of the cassette during use thereof, and more so in view-ofthe disposability of the cassette, which thus minimises the risk of human contact with toxic substances comprised in the cassette. In the preferred embodiment, the cassette comprises a box-like construction, having a bottom flat base and four vertical walls joined thereto about its periphe^, and an upper cover mountable onto the vertical walls to define a gel chamber into which gel may be precast. The cassette also comprises openings at two opposite ends of the bottom base to enable ionic communication between the gel and an electrolytic solution in which the cassette may be partially immersed. The openings ai'e preferably comprised in downwardly extending hollow leg members running the transverse length of the cassette at two longitudinal ends thereof, the leg members comprising gel in ionic communication with the main body of gel within the cassette. This design is particularly adapted for using the cassette with standard ion exchange chambers. Activated carbon or the like is provided in the legs and also in a second trapping chamber to absorb dangerous materials such as the dyeing compounds. US 3,888,759 discloses a gel cassette having a substantially box-like construction, having a downwardly depending transversely extending hollow leg at each longitudinal end of the cassette. The device appears to be reusable, providing the user with different options, and it appears intended for the user to cast the gel each time, rather than providing a precast package. There is no disclosure or suggestion of a trap for toxic materials, and in fact teaches away from this concept. US 5,443,704 discloses a substantially box-like container assembly for packaging prefabricated gels, containing more than one precast gel in a stacked arrangement. No trap for harmful substances is disclosed therein. US 5,064,769 discloses a gel for immunoassay of a single protein species in which the horizontal gel comprises a first part made from acrylamide gel having a proportion of agarpse (0.7%) and a second part made from agarose gel. No trap for harmful substances is disclosed therein. In US 3,930,983 an arrangement and process are disclosed for determining antigens, in which a support plate is coated with an agar or agarose as a matrix in successive gel strips. No trap for harmful substances is disclosed therein. US 5,582,702 is directed to a self-contained electrophoresis apparatus comprising a housing having a gel body accommodated therein together with ion exchange matrices and electrodes, which are electrically connectable to an external power source. The apparatus is thus not generally compatible with existing ion exchange chambers currently used for horizontal electrophoresis. While it is presented as optionally "disposable", the apparatus is nonetheless complex, and does not appear inexpensive in comparison with simple precast gels, such as those described in US 5,443,704, for example. Moreover, the apparatus contains elements which are not normally considered disposable, notably the electrodes and ion exchange matrices. In fact by being fully closed, in particular regarding the lower side thereof, the apparatus cannot be used with standard ion exchange apparatuses, and thus needs a dedicated stand having electrical connection points for the electrodes. Optionany, ethidium cations may be released into the gel by one of the ion exchange matrices within the housing, which may be simply disposed after use. However, and as stated earlier, the complexity of the apparatus renders this a rather expensive solution for the disposal of the contaminated gel. Furthermore, no traps are actually provided for retaining the contaminants therein - therefore, if any openings were to be made, for example, at the lower part of the cassette, for example as in the present invention, the contaminants could flow out, in contrast thereto. EP 471949 discloses a capillary tube for performing capillary zone electrophoresis.' The tube is modified by including a polystyrene frit that divides the tube into a downstream free zone, and an upstream zone which can comprise a polyacrylamide stacking gel. The gel plug functions as a filter to pre-treat the samples that are to be analysed in the free zone of the tube. This is in contrast to the present invention, wherein the traps are placed downstream to treat the contaminants in the gel during and at the end of the electrophoretic process, and not prior to the beginning thereof. In fact, the samples in the present invention do not generally require pretreatment as described in this patent. Furthermore, the present invention uses agarose gel with an absorption material for retaining therein a target substance. On the other hand, in EP 471949 uses polyacrylamide, which is also toxic and use thereof would be detrimental in the present invention as a trapping gel, and in fact counterproductive for this purpose. Thus, this publication teaches away from the present invention. W092/17259 describes a method for identifying a solute of interest in an effluent stream. A sample containing the mixture to be separated is passed through a first system capable of partitioning the components of the mixture, and a detector provides a first output that describes the temporal and/or spatial sequence of components exiting the first system. The effluent stream is then passed through a second system capable of extracting a solute of interest from the effluent, and a detector provides a second output that describes the temporal and/or spatial sequence of components exiting the second system, which, no longer includes the solute of interest. The solute of interest can then be identified in the first output by comparing this to the second output. This method is thus directed at identifying a substance in a first separating system by employing a parallel second separating system, and is thus very different to the present invention, in which only a single electrophoresis process is employed, the target substance being removed during that process. WO 92/17259 does not address the problem of, nor does it provide a solution for, the trapping of toxic substances in an electrophoresis process, less so in the manner of the present invention. WO 95/20155 relates to a sample holder in the form of a well, into which a sample and a first molten gel is introduced. When the first gel/sample mixture has solidified, the sample holder is applied against one end of a second gel slab, such as to bring the first gel/sample solidified mixture in ionic contact with the second gel. At no time is the first gel in solidified form brought into contact with the second gel prior to introducing the sample. WO 99/30145 relates to a slotted electrophoresis gel composition and methods for use, for providing a multilayered gel for vertical gel electrophoresis. It does not address, nor provide a solution for, the problem of forming stable sample wells for horizontal electrophoresis in an acrylamide gel. These publications do not address the problem of, nor do they provide a solution for, the trapping of toxic substances in an electrophoresis process, less so in the manner of the present invention Other publications of background relevance to the present invention include WO 98/10277, US 5228971, US 5827418, US 3873433, EP 971229, WO 95/14921, DE 3232685, EP 199470 and US 3S03020. Summary of Invention The present invention relates to an apparatus for electrophoresis comprising a first gel matrix in communication with a second gel matrix, said first gel matrix and said second gel matrix accommodated within a statable housing, said housing comprising at least one first opening and at least one said second opening, said at least one first opening being adapted to permit ionic communication between said first gel matrix and an external ionic buffer solution, and said at least one second opening being adapted to permit ionic communication between said second gel matrix and an external ionic buffer solution, wherein said first gel matrix adapted for performing an electrophoretic process therein, and wherein said second gel comprises at least one suitable absorption material capable of retaining therein at least one target substance capable of migrating thereto at least from the said first gel matrix when an electrophoretic process is performed in said first matrix. Typically, electrophoresis of a sample is conducted in said first gel matrix in a direction substantially away from said second gel matrix, and the said first gel matrix may comprise suitable wells adapted for introducing therein samples of interest to be eleetrophoresed. The first gel matrix is accommodated in a first chamber within said housing and said second gel matrix is accommodated in a second chamber within said housing, said first chamber being in communication with said second chamber. Optionally, the apparatus further comprises a third gel matrix accommodated in said housing and in communication at least with said first gel matrix, wherein ionic communication between said first gel matrix and an external ionic buffer solution is via said third gel matrix and via said at least one first opening, and wherein said third gel matrix comprises a suitable absorption material capable of retaining therein a target substance capable of migrating thereto at least from the said first gel matrix when an electrophoretic process is performed therein in a direction substantially towards said second gel matrix. In the preferred embodiment, the housing further comprises a first substantially hollow leg member extending downwardly from said at least one first opening, said first leg member adapted for providing communication between said first gel matrix and an outside of said housing. Similarly, the housing further comprises a second substantially hollow leg member extending downwardly from said at least one second opening, said second leg member adapted for providing communication between said second gel matrix and an outside of said housing. The said first leg member typically comprises said third gel matrix, and a fourth gel matrix may be accommodated in said second leg member and in communication at least with said second gel matrix, wherein ionic communication between said second gel matrix and an external ionic btrffer solution is via said fourth gel matrix and said at least one second opening, and wherein said fourth gel comprises a suitable absorption material capable of retaining therein a target substance capable of migrating thereto at least from the said first gel matrix when an electrophoretic process is performed therein in a direction substantially towards said second gel matrix. The target substance is typically a suitable dyeing compound; the first gel matrix is made primarily from agarose; the second gel matrix is made primary from agarose mixed with said absorption compound; the third gel matrix is made primary from agarose mixed with said absorption compound; and the fourth gel matrix is made primary from agarose mixed with said absorption compound, typically activated carbon. The present invention also relates to an apparatus for performing electrophoresis therein, comprising;- a housing comprising a first chamber adapted for accommodating therein a first gel for use in an electrophoretic process; and a second chamber adapted for trapping therein at least one target substance capable of migrating thereto at least from said first chamber, said first chamber being in communication with said second chamber; said housing further comprising at least one first opening and at least one said second opening, said at least one first opening being adapted to permit ionic communication between a gel accommodated in said first chamber and an external ionic buffer solution, and said at least one second opening being adapted to permit ionic communication between a gel accommodated in said second chamber and an external ionic buffer solution. In. the preferred embodiment, the housing comprises at least a first base and peripherally joined walls defining said first chamber having a first longitudinal end and a second longitudinal -end. -The- housing may also comprise at least a second base and peripherally joined walls defining said second chamber having a third longitudinal end and a fourth longitudinal end. The first chamber is partially superposed over said second chamber to define an area of horizontal overlap between said first chamber and said second chamber, and communication between said first chamber and said second chamber is via a suitable opening comprised in said area of horizontal overlap. The housing is adapted for performing electrophoresis of a sample within said first chamber in a direction substantially away from said second chamber, and further comprises a suitable first gel matrix accommodated in said first chamber arranged such that migration occurs in a direction from said second end to said first end when said apparatus is used in an electrophoretic process. Typically, the first gel matrix comprises suitable wells adapted for introducing therein samples of interest to be electrophoresed. The first gel matrix typically comprises a suitable dyeing compound, and the target substance may be such a dyeing compound, which may be harmful to humans. The second chamber is adapted for trapping said target substance by accommodating therein a suitable second gel matrix, said second gel matrix characterised in comprising at least one suitable absorption material capable of retaining therein at least said target substance. A second gel matrix is accommodated in said second chamber within said housing, and a third gel matrix accommodated in said housing and in communication at least with said first gel matrix, wherein ionic communication between said first gel matrix and an external ionic buffer solution is via said third gel matrix and said at least one first opening, and wherein said third gel comprises a suitable absorption material capable of retaining therein a target substance capable of migrating thereto at least from the said first gel matrix when an electrophoretic process is performed therein in a direction substantially towards said second gel matrix. In the preferred embodiment, the housing further comprises a first substantially hollow leg member extending downwardly from said at least one first opening, said first leg member adapted for providing communication between said first chamber and an outside of said housing. Similarly, the housing further comprises a second substantially hollow leg member extending downwardly from said at least one second opening, said second leg member adapted for providing communication between said second chamber and an outside of said housing. In this embodiment, the first leg member comprises said third gel matrix, and a fourth gel matrix is accommodated in said second leg member and in communication at least with said second gel matrix, wherein ionic communication between said second chamber and an outside of the housing is via said fourth gel matrix and said at least one second opening, and wherein said fourth gel comprises a suitable absorption material capable of retaining therein a target substance capable of migrating thereto at least from the said first gel matrix when an electrophoretic process is performed therein in a direction substantially towards said second gel matrix. The target substance is typically a suitable dyeing compound; the first gel matrix is made primarily from agarose; the second gel matrix is made primary from agarose mixed with, said absorption, compound; the third gel matrix is made primary from agarose mixed with said absorption compound; the fourth gel matrix is made primary from agarose mixed with said absorption compound, typically comprising activated carbon. The apparatus preferably further comprises a cover for releasably closing said first chamber. A suitable comb for forming wells in a gel may be accommodated in said first chamber, said cover comprising at least one suitable aperture for enabling said comb to penetrate into said first chamber. Optionally, the cover comprises a tab in registry with and spaced from a platform comprised at said first longitudinal end of said device. Advantageously, suitable adhesive strips are provided for reversibly sealing said bottom ends of said first and second leg members, respectively. At least in the preferred embodiment, the housing is adapted to enable said apparatus to be used with standard electrophoresis devices having a pair of parallel juxtaposed buffer-containing toughs separated by an elevated platform for supporting said base of said housing, said first and second leg members extending sufficiently into corresponding said troughs to provide ionic communication at least between said third gel portion and buffer contained in one trough, and between said fourth gel portion and buffer contained in the other trough. Description of Figures Figure 1 shows in exploded perspective view the main elements of a preferred embodiment of the present invention. Figure 2 shows in side view the embodiment of Figure 1 assembled. Figure 3 shows in top view the embodiment of Figure 2. Figure 4 shows in side elevational cross-sectional view, the embodiment of Figure 3 taken along E-E. Figure 5 shows in side elevational cross-sectional view, a second embodiment of the present invention. Figure 6 shows in side elevational cross-sectional view, a third embodiment of the present invention. Disclosure of Invention The present invention is defined by the claims, the contents of which are to be read as included within the disclosure of the specification, and will now be described by way of example with reference to the accompanying Figures. The present invention relates to a device for horizontal electrophoresis which may be provided with any required macromolecule-separating compounds and any buffer compositions that are used for running macrouaolecules, as well as any required labelling compounds, characterised in comprising at least one suitable trap for trapping and retaining at least one of any such compounds therein, thereby minimising contamination hazard to the external environment including users of the device. Such an apparatus or device is preferably disposable, but may also be re- usable for a host of applications. The term "disposable" in the present application means that the devices are designed (in corresponding embodiments) to be thrown away or otherwise disposed off after one use with only negligible economic loss. Such negligible economic loss may be comparable, for example, to the economic loss incurred in disposing of plastic pipettes for handling liquids or eppendorf tubes. While these items may be used more than once, they are nonetheless typically thrown away after a single use, this being more cost effective than cleaning and/or sterilising the same for subsequent use. Referring to the Figures, Figures 1 to 4 illustrate a preferred embodiment of the present invention. The apparatus or cassette, designated by the numeral (1), comprises a housing (100) of a box-like construction, a suitable gel (38) for electrophoresis, accommodated in a first chamber (30), and a second suitable gel for trapping dangerous substances therein, accommodated in a second chamber (40). The cassette (1) comprises a stepped bottom base (10) having a flat upper part (11) and a flat but shorter lower part (13) joined longitudinally one to the other by a first intermediate vertical wall (15). Two side walls (12), (14) run the longitudinal length of the cassette (1) and are preferably integrally joined to the base (10). and to end walls (16) and (18) at opposite longitudinalends of the cassette (1). A second intermediate wall (19) is joined to side walls (12) and (14) at a longitudinal location between first intermediate wall (15) at the end wall (IS) closest thereto. The second intermediate wall (19) substantially divides each side wall (12) and (14) longitudinally into longer portions (12') and (14'), respectively, extending between the end wall (16) and intermediate wall (19), and shorter portions (12") and (14"), respectively, extending between the intermediate wall (19) and the other end wall (18). The upper edge of the second intermediate wall (19) is substantially coplanar with the upper edge of end wall (16) and with the upper edges of at least the longer side wall portions (12') and (14').. and thus enable an upper cover (50) to be releasably and sealingly mounted thereonto. Upper cover (50) may comprise optionally closable apertures (51) and (53) longitudinally spaced one from the other along the mid-line of the cover (50). These apertures (51), (53) facilitate pouring of gel into the cassette (1) when the cover (50) is in place, described in greater detail hereinbelow. Thus, the second intermediate wall (19), end wall (16) and the longer side wall portions (12') and (14'), together with upper cover (50) and the upper part (11) of the base (10) define the first chamber (30) of the cassette (1). The second chamber (40) of the cassette is correspondingly defined by the second intermediate wall (19), end wall (18) and the shorter side wall portions (12") and (14"), together with upper wall (55) and the lower part (13) of the base (10). Upper wall (55) may optionally be joined typically integrally with the second intermediate wall (19), end wall (18) and the shorter side wall portions (12") and (14"). Preferably, though, and as illustrated in Figures 1 and 4, upper wall (55) is integrally joined to the upper cover (50) and is releasably and sealingly mountable onto the upper edges of the second intermediate wall (19), end wall (18) and the shorter side wall portions (12") and (14"). The lower edge of the second intermediate wall (19), however, does not extend as far as the lower part (13) of the base (10), and thus communication between the first chamber (30) and second chamber (40) is provided by virtue of the longitudinal gap between the first and second intermediate walls, (15) and (19), respectively. Thus, in the preferred embodiment, the first chamber (30) is partially superposed over the second chamber (40), defining an area (31) where the two chambers overlap horizontally. At least a portion of this area (31) has an opening, or preferably is open, providing communication between the first chamber (30) and the second chamber (40). Preferably, the cassette (1) or other embodiments thereof is provided with a suitable first gel matrix (38) accommodated in the first chamber (30) and a suitable second gel portion (48) is accommodated in the second chamber (40). Alternatively, the cassette (1) or other embodiments thereof may be provided without one or both these gels, which can be cast as and when needed. In any case, the first gel matrix (38) is adapted for performing electrophoresis therein, and typically comprises at least one dyeing compound. The term dyeing compound is taken herein to include any type of labelling substance that may be used to identify the molecules of interest in the sample being electrophoresed in the first gel matrix (38). The second gel matrix (48) is adapted for trapping and retaining therein at least one target substance capable of migrating thereto at least from the first gel (38) during electrophoresis, and dyeing compounds are typically such target substances. The second gel matrix is typically adapted for trapping by comprising an absorbent material mixed therewith and which prevents the target substance from exiting the second gel (48). Top cover (50), and preferably the rest of housing (100) is made from any- suitable ultraviolet-transparent material. Preferably, the whole of the cassette (1), in particular the housing (100), is made from an economically disposable material. Optionally, a tab (57) is provided at one end of the cover (50), and a corresponding platform (58) is provided at end (16), preferably integrally joined thereto, such that the tab (57) is in registry with platform (58) and mutually spaced by space (59) when the cover (50) is in place over chamber (30), By placing a suitable flattened tool such as a screwdriver or key (not shown), for example, within space (59) and rotating it by 90°, say, the cover (50) may be snapped open and thus removed from the chamber (30). Having an openable cover (50) is important in applications, for example, where it is required to remove some of the first gel portion (38) for further processing such as electroelution or transfer of molecules from the first gel portion (38) to a membrane (western blot or northern blot). The cassette (1) also comprises openings at two opposite ends of the bottom base (10) to enable ionic communication between the gel that is accommodated in the cassette (1) and an electrolytic solution in which the cassette (1) may be partially immersed. Thus, transverse opening (32) at longitudinal end of the upper part (11) of the base (10) near end wall (16) provides communication between the first chamber (30) and the outside of the cassette (1). Similarly, transverse opening (42) at longitudinal end of the lower part (11) of the base (10) near end wall (18) provides communication between the second chamber (40) and the outside of the cassette (1). Openings (32) and (42) serve to provide ionic communication between the gels accommodated within the cassette (1) and external ionic solutions, and thus enable electrophoresis to be conducted within the cassette (1) with the provision of a suitable electric field. Preferably, though, the openings at the bottom base (10) are in the form of substantially hollow leg members running the transverse length of the cassette (1) at two longitudinal ends thereof, the leg members also being capable of accommodating gel in ionic communication with the main body of gel accommodated within the cassette (1). This inverted- U design is particularly adapted for using the cassette (1) with standard ion exchange chambers, which are generally in the form of two juxtaposed buffer- containing troughs separated by an elevated platform which is ideal for supporting the base (10) of cassette (1). One leg member is extends into one trough, and the other leg member into the second trough to provide ionic communication at least between the gel contained in the legs and the corresponding buffer solutions in the troughs. One trough has a cathode and the other trough has an anode. Thus, the cassette (1) optionally, and preferably, comprises hollow legs (60) and (70) provided at opposite longitudinal ends thereof. At one end of the cassette (1), leg (60) is denned by a downwards extension of end wall (16), together with downwardly extending tab-like projections (62) at the end of longer side wall portions (12") and (14"), respectively, and a fourth wall (65) projecting downwards from the upper part (11) of base (10). Similarly, leg (70) at the other longitudinal end of the cassette (1) is defined by a downwards extension of end wall (18), together with downwardly extending tab-like projections (72) at the end of shorter side wall portions (12') and (14'), respectively, and a corresponding fourth wall (75) projecting downwards from the lower part (13) of base (10). Each leg (60), (70) are open at the corresponding bottom ends (66), (76) thereof, which may be temporarily closed (at least prior to use of the cassette (1)) by means of suitable removable adhesive strips (not shown) adhered thereto. The bottom ends (66), (76) are in communication with the first chamber (30) and second chamber (40), respectively, via the transverse openings (32) and (42), respectively. The first chamber (30) is thus adapted to accommodate a suitable gel matrix (38) adapted for electrophoresis, preferably comprising a plurality of wells (39) for accepting samples that are to undergo an electrophoretic process. The gel matrix (38) typically comprises an agarose gel, though alternatively it may comprise other types of gels, included multilayered gels, which comprise strips of different gels or gel compositions juxtaposed one with another sequentially. Alternatively, the gel matrix (38) may comprise a hybrid gel matrix having a substantially solidified first gel portion juxtaposed with at least a substantially solidified second gel portion, wherein the first gel portion is capable of accommodating therein at least one sample for electrophoresis after said first gel portion is in solidified form, and is generally made from or contains sufficient agarsose to provide a stable well structure for accommodating samples, and the second gel portion is adapted for enabling an electrophoresis processto be applied to such a sample that may be accommodated in said first gel portion, the second gel portion comprising an acrylamide gel. Such hybrid gels are disclosed in co-pending Israel Patent Application No. 139446, filed by Applicants. The wells (39) may be formed by a comb (80), for example, having teeth (84) that are typically inserted into the first gel portion (37) via corresponding apertures (52) comprised in the cover (50). Alternatively, a common slit may be provided in. the cover (50) in place of the individual apertures (52). Typically, the comb (SO) is kept in place engaged with respect to the cover (50) until the cassette (1) is used, whereupon samples may be introduced into one or more wells (39) via corresponding apertures (52). After use, and before disposing of the cassette (1), the apertures (52) are preferably again closed by means of the comb (BO), The agarose gel (38) is preferably provided precast in the first chamber (30), though may be alternatively cast by users in some applications. In any case, the gel may be poured into the first chamber (30) having first removed the cover (50). Another method of casting the gel is by turning the cassette (1) vertically such that the end wall (18) is uppermost Gel is then poured into tie chamber (30) up to the required height (which corresponds to the end wall (16) when the cassette (1) is returned to its horizontal position). With this method, the gel may be poured into the chamber (30) via aperture (53). Other ways of casting the gel are also possible. Wells (39) may be formed in the normal manner using, for example, a comb (80). However, the step of casting the first gel matrix (38) is usually performed after the second gel matrix (48) is cast, as described hereinbelow. According to the present invention, at least one trap, and preferably two traps are provided for preventing release of dangerous substances from the cassette (1) to the external environment. Many labelling. compounds, as well as acrylamide gels, may be toxic and/or carcinogenic and therefore potentially harmful, to the cassette operator and to the environment. Thus, a first trap (90) is provided in the form of the second chamber (40) for trapping and thus retaining' labelling compounds and the like, and thus preventing the same from exiting the cassette (1). Second chamber (40) -which is in open communication with first chamber (30), and at least in ionic communication therewith when both chambers are accommodating gels - is provided with a suitable second gel matrix (48), typically agarose gel having active carbon, silica gel (at a special pH condition), for example, or any other suitable absorption material, mixed therewith. The term absorption material is taken herein to include any type of material capable of retaining therein at least one target substance, such a target substance being typically capable of migrating in an electrophoretic process. Particularly when the cassette (1) is used with precast agarose gels, the dye compounds which are used originally for visualising the molecules being separated, are provided mixed with the agarose gel in the first chamber (30), thereby removing the hazard associated with handling of these compounds prior to use of the cassette (1). Under electrophoresis, molecules of interest contained in samples provided at the wells (39) migrate from the wells (39) towards the end wall (16). At the same time, dyeing compounds such as ethidium bromide comprised in the gel migrate in the opposite direction, i.e., towards end wall (18), thereby arriving at the second chamber (40), and are prevented from leaving the second chamber (40) as well as leg (70) by virtue of the activated carbon particles or other suitable absorbent material comprised therein. Typically, electrostatic interactions build up between activated carbon particles and ethidium bromide leading to absorption of the latter within the appropriate gel matrix. A second trap (95) is provided at the other longitudinal end of the cassette (1) to absorb the dye compounds as the dye, when the user mistakenly runs the gel in an inverted configuration. In the latter situation, migration occurs from end (16) towards end (18), rather than the vice versa, and dye compounds are absorbed by the trap (95). The second trap (95) also prevents unwanted migration of dye compounds by diffusion forces when the cassette is not being used. This enables the cassette to have a relatively long shelf life, perhaps a year or more, for "example." The second "trap(95) is" economically provided by The hollow leg (60), which comprises an third gel matrix (69) comprising an agarose gel having a quantity of activated carbon, silica gel (at a special pH condition), for example; and/or any other suitable absorption material mixed therein. Thus, even if openings (76) and (66) in legs (70) and (60), respectively, remain unsealed, the dyeing compounds will not run out due to their adherence to the absorption materials. The traps (90), (95) are generally prepared before casting the gel in the first, electrophoresis, chamber (30). With the cover (50), including portion (55) off, and with the bottom ends of the legs (60) and (70) sealed with suitable adhesive peel-off tape, agarose gel (79), containing mixed therein a suitable proportion of activated carbon is poured into leg (70) and chamber (40), up to the level of the upper part (11) of base (10). Then, agarose gel (69), also containing mixed therein a suitable proportion of activated carbon or other suitable absorption material is poured into leg (60) and preferably also the second chamber (40), i.e. up to the level of the upper part (11) of base (10). When the gels (79) and (69) are set the first gel matrix (38) may be poured arid set in the first chamber (30) as hereinbefore described. While trap (90) has been described as being in the form of a second chamber (40) at a level below the first chamber (30), this need not generally be so. Minimally, the trap (90) needs only to be adapted to provide ionic communication between the absorbent material comprised therein and the gel comprised in the first chamber (30), and situated with respect to the first chamber such as to be substantially downstream of the migration path of the dye compounds. Any configuration of trap (90) meeting these criteria are generally suitable. Thus, in a more simplified cassette, for example, a single chamber is provided, in which one end is provided with agarose gel containing absorption material, and this is juxtaposed with and in communication with a second body of gel within the chamber for electrophoresis. While the cassette (1) preferably comprises both the traps (90), (95), the second trap (95) is generally not required. Thus, optionally, a simpler cassette (1) may be provided without the he second trap (95), if it is so desired Further optionally, the cassette (1) may be provided without the said hollow legs (60) and (70), leading to a simplified structure. Thus communication between said first chamber (30) and external ionic solutions is via opening (32) in the base (10), and communication between said second chamber (40) and external ionic solutions is via opening (42) in the base (10). Thus, referring to Figure 5, a second embodiment of the present invention comprises a housing (200) having a base (210) and peripheral walls joined thereto at a lower end thereof, to define a chamber (234). A first gel matrix (238), similar to the first gel matrix (38) of the first embodiment, mutatis mutandis, and a second gel matrix (248) similar to the second gel matrix (48) of the first embodiment, mutatis mutandis, juxtaposed and in ionic contact with one another, are accommodated in the chamber (234). Thus, the first gel matrix (238) is adapted for performing electrophoresis, and may thus comprise dyeing substances and the like, while the second gel matrix (248) is adapted for trapping therein dangerous target substances such as these dyeing compounds, for example. The chamber (234) comprises openings (232) and (242) at longitudinal ends of the base (210) for providing ionic communication between the first gel matrix (238) and an external buffer solution, and between the second gel matrix (248) and an external buffer solution. Wells (239) are provided in the first gel matrix (238) for introducing samples to be electrophoresed. Optionally, a cover plate (250) may be provided, having suitable openings (252) for a comb (280) to be inserted therein to form wells (239). A third embodiment of the present invention comprises all the components of the second embodiment as described above, mutatis mutandis, and is illustrated in Figure 6. In addition, though, the chamber- (234) further comprises a third gel matrix (269) juxtaposed and in ionic communication with the first gel matrix (238), but located at the opposed longitudinal end of the housing (200) with relation to the second gel matrix (248). The third gel matrix (269) serves as a precautionary second trap, and is thus similar to the third gel matrix (69) of the first embodiment, mutatis mutandis. While in the foregoing description describes in detail only a few specific embodiments of the invention, it will be understood by those skilled in the art that the invention is not limited thereto and that other variations in form and details may be possible without departing from the scope and spirit of the invention herein disclosed. WE CLAIM : 1. Apparatus for electrophoresis comprising a suitable housing (100), (200) accommodating a first gel matrix (38), (238) adapted for performing an electrophoretic process on at least one sample of interest therein in a first direction, characterized in comprising at least a first trap (90) comprising a second gel matrix (48), (248) having at least one suitable absorption material capable of trapping and retaining therein at least one target substance migrating thereto from the first gel matrix (38), (238) in an opposite direction to said first direction when an electrophoretic process is performed in said first matrix (38), (238) in said first direction, wherein said first gel matrix (38), (238) is in ionic communication with said second gel matrix (48), (248), and wherein said target substance is different from said at least one sample of interest. 2. Apparatus as claimed in claim 1, wherein said housing (100), (200) comprises at least one first opening (32), (232) and at least one said second opening (42), (242), said at least one first opening (32), (232) being adapted to permit ionic communication between said first gel matrix (38), (238) and an external ionic buffer solution, and said at least one second opening (42), (242) being adapted to permit ionic communication between said second gel matrix (48), (248) and an external ionic buffer solution. 3. Apparatus as claimed in claim 2, wherein said first gel matrix (38), (238) comprises suitable wells (39), (239) adapted for introducing therein said samples of interest to be electrophoresed. 4. Apparatus as claimed in claim 2, wherein said first gel matrix (38), (238) is accommodated in a first chamber (30) within said housing (100), (200) and said second gel matrix (48), (248) is accommodated in a second chamber (40) within said housing (100), (200), said first chamber (30) being in communication with said second chamber (40). 5. Apparatus as claimed in claim 2, comprising a second trap (95) comprising a third gel matrix (69), (269) having at least one suitable absorption material capable of trapping and retaining therein at least one harmful target substance migrating thereto from the first gel matrix (38), (238) in said first direction when an electrophoretic process is performed in said first matrix in said first direction, wherein said first gel matrix (38), (238) is in ionic communication with said third gel matrix (69), (269). 6. Apparatus as claimed in claim 2, wherein said housing (100), (200) comprises a first substantially hollow leg member (60) extending downwardly from said at least one first opening (32), (232), said first leg member (60) adapted for providing communication between said first gel matrix (38), (238) and an outside of said housing (100), (200). 7. Apparatus as claimed in claim 2, wherein said housing comprises a second substantially hollow leg member (70) extending downwardly from said at least one second opening (42), (242), said second leg member (70) adapted for providing communication between said second gel matrix (48), (248) and an outside of said housing (100), (200). 8. Apparatus as claimed in claim 6, wherein said first leg member (60) comprises said third gel matrix (69), (269). 9. Apparatus as claimed in claim 7, comprising a fourth gel matrix accommodated in said second leg member (70) and in communication at least with said second gel matrix (48), (248), wherein ionic communication between said second gel matrix (48), (248) and an external ionic buffer solution is via said fourth gel matrix and said at least one second opening (42), (242), and wherein said fourth gel comprises a suitable absorption material capable of retaining therein a target substance capable of migrating thereto at least from the said first gel matrix (38), (238) when an electrophoretic process is performed therein in a direction substantially towards said second gel matrix (48), (248). 10. Apparatus as claimed in claim 1, wherein said target substance is a suitable dyeing compound. 11. Apparatus as claimed in claim 1, wherein said first gel matrix (38), (238) is made primarily from agarose. 12. Apparatus as claimed in claim 1, wherein said second gel matrix (48), (248) is made primary from agarose mixed with said absorption compound. 13. Apparatus as claimed in claim 5, wherein said third gel matrix is made primary from agarose mixed with said absorption compound. 14. Apparatus as claimed in claim 9, wherein said fourth gel matrix is made primary from agarose mixed with said absorption compound. 15. Apparatus as claimed in any one of claims 1 to 14, wherein said at least one absorption material comprises activated carbon. 16. Apparatus for performing electrophoresis therein, comprising:- a housing (100), (200) comprising a first chamber (30) adapted for accommodating therein a first gel (38),(238) for performing an electrophoretic process on at least one sample of interest in a first direction; and a second chamber (40) adapted for trapping therein at least one target substance capable of migrating thereto at least from said first chamber (30) in a direction opposed to said first direction, said first chamber (30) being in communication with said second chamber (40); said housing (100), (200) comprising at least one first opening (32), (232) and at least one said second opening (42), (242), said at least one first opening (32), (232) being adapted to permit ionic communication between a gel that may be accommodated in said first chamber (30) an external ionic buffer solution, and said at least one second opening (42), (242) being adapted to permit ionic communication between a gel that may be accommodated in said second chamber (40) and an external ionic buffer solution. 17. Apparatus as claimed in claim 16, wherein said housing (100), (200) comprises at least a first base (10) and peripherally joined walls (12'), (14'), 16), (19) defining said first chamber (30) having a first longitudinal end and a second longitudinal end. 18. Apparatus as claimed in claim 16, wherein said housing comprises at least a second base and peripherally joined walls (12"), (14"), (18), (19) defining said second chamber (40) having a third longitudinal end and a fourth longitudinal end. 19. Apparatus as claimed in claim 18, wherein said first chamber (30) is partially superposed over said second chamber (40) to define an area of horizontal overlap between said first chamber (30) and said second chamber (40). 20. Apparatus as claimed in claim 19, and wherein communication between said first chamber (30) and said second chamber (40) is via a suitable opening comprised in said area of horizontal overlap. 21. Apparatus as claimed in claim 17, comprising a suitable first gel matrix (38), (238) accommodated in said first chamber (30) arranged such that migration occurs in a direction towards said first end when said apparatus is used in an electrophoretic process, and when said second chamber (48), (248) is located at said second end. 22. Apparatus as claimed in claim 21, wherein said first gel matrix (38), (238) comprises suitable wells (39), (239) adapted for introducing therein samples of interest to be electrophoresed, said wells (39), (239) being located at a longitudinal end of said first gel (38), (238) closer to said second chamber (40) than to said first end. 23. Apparatus as claimed in claim 21, said first gel matrix (38), (238) comprising a suitable dyeing compound. 24. Apparatus as claimed in claim 16, wherein said target substance is a dyeing compound. 25. Apparatus as claimed in claim 24, wherein said dyeing compound is harmful to humans. 26. Apparatus as claimed in claim 16, wherein said second chamber (40) is adapted for trapping said target substance by accommodating therein a suitable second gel matrix (48), (248), said second gel matrix (48), (248) characterised in comprising at least one suitable absorption material capable of retaining therein at least said target substance. 27. Apparatus as claimed in claim 16, wherein a second gel matrix (48), (248) is accommodated in said second chamber (40) within said housing (100), (200). 28. Apparatus as claimed in claim 16, comprising a third gel matrix (69), (269) accommodated in said housing (100), (200) and in communication at least with said first gel matrix (38), (238), wherein ionic communication between said first gel matrix (38), (238) and an external ionic buffer solution is via said third gel matrix (69), (269) and said at least one first opening (32), (232), and wherein said third gel (69), (269) comprises a suitable absorption material capable of retaining therein a target substance capable of migrating thereto at least from the said first gel matrix (38), (238) when an electrophoretic process is performed therein in a direction substantially towards said second gel matrix (48), (248). 29. Apparatus as claimed in claim 16, wherein said housing (100), (200) comprises a first substantially hollow leg member (60) extending downwardly from said at least one first opening (32), (232), said first leg member (60) adapted for providing communication between said first chamber (30) and an outside of said housing (100), (200). 30. Apparatus as claimed in claim 16, wherein said housing (100), (200) comprises a second substantially hollow leg member (70) extending downwardly from said at least one second opening (42), (242), said second leg member (70) adapted for providing communication between said second chamber (40) and an outside of said housing (100), (200). 31. Apparatus as claimed in claim 30, wherein said first leg member (60) comprises said third gel matrix (69), (269). 32. Apparatus as claimed in claim 31, comprising a fourth gel matrix accommodated in said second leg member (70) and in communication at least with said second gel matrix (48), (248), wherein ionic communication between said second chamber (40) and an outside of the housing (100), (200) is via said fourth gel matrix and said at least one second opening (42), (242), and wherein said fourth gel comprises a suitable absorption material capable of retaining therein a target substance capable of migrating thereto at least from the said first gel matrix (38), (238) when an electrophoretic process is performed therein in a direction substantially towards said second gel matrix (48), (248). 33. Apparatus as claimed in claim 16, wherein said target substance is a suitable dyeing compound. 34. Apparatus as claimed in claim 21, wherein said first gel matrix (38), (238) is made primarily from agarose. 35. Apparatus as claimed in claim 23, wherein said second gel matrix (48), (248) is made primary from agarose mixed with said absorption compound. 36. Apparatus as claimed in claim 24, wherein said third gel matrix (69), (269) is made primary from agarose mixed with said absorption compound. 37. Apparatus as claimed in claim 28, wherein said fourth gel matrix is made primary from agarose mixed with said absorption compound. 38. Apparatus as claimed in claim 26, wherein said absorption material comprises activated carbon. 39. Apparatus as claimed in any one of claims 16 to 38, comprising a cover (50) for releasably closing said first chamber (30). 40. Apparatus as claimed in claim 39, comprising a suitable comb (80) for forming wells (39), (239) in a gel accommodated in said first chamber (30), said cover (50) comprising at least one suitable aperture for enabling said comb to penetrate into said first chamber (30). 41. Apparatus as claimed in claim 39, wherein said cover (50) comprises a tab (57) in registry with and spaced from a platform comprised at said first longitudinal end of said device. 42. Apparatus as claimed in claim 30, comprising suitable adhesive strips for reversibly sealing said bottom ends of said first (60) and second (70) leg members, respectively. 43. Apparatus as claimed in claim 30, wherein said housing (100), (200) is adapted to enable said apparatus to be used with standard electrophoresis devices having a pair of parallel juxtaposed buffer-containing toughs separated by an elevated platform for supporting said base of said housing, (100), (200) said first (60) and second (70) leg members extending sufficiently into corresponding said troughs to provide ionic communication at least between said third gel portion (69), (269) and buffer contained in one trough, and between said fourth gel portion and buffer contained in the other trough. Apparatus for electrophoresis comprising a suitable housing (100), (200) accommodating a first gel matrix (38), (238) adapted for performing an electrophoretic process on at least one sample of interest therein in a first direction, characterized in comprising at least a first trap (90) comprising a second gel matrix (48), (248) having at least one suitable absorption material capable of trapping and retaining therein at least one target substance migrating thereto from the first gel matrix (38), (238) in an opposite direction to said first direction when an electrophoretic process is performed in said first matrix (38), (238) in said first direction, wherein said first gel matrix (38), (238) is in ionic communication with said second gel matrix (48), (248), and wherein said target substance is different from said at least one sample of interest.

Full Text

APPARATUS FOR ELECTROPHORESIS
Technical Field
The present invention relates to an apparatus for electrophoresis , in particular to
such devices or apparatus adapted for the safe handling and disposal of agarose-type
gels containing dyeing compounds used therewith.
Background
Gel electrophoresis, a commonly used method on, molecular biology research, is
a technique designed to separate, identify and purify DNA, RNA and protein
molecules based on their weight, size and shape. This technique, which is
simple and rapid to perform, is carried out by first preparing a gel. When the
gel is ready it is placed in a gel box, immersed in a buffer solution, and
connected to a power source. Once stimulated by the electric field that is set up
in the gel, the molecules move through the gel matrix at different rates. The
migration rate for each species of molecule is dependent upon the electrical
charge, the size and shape of the molecules, as well as on the composition of
the gel. Most commonly, the smaller molecules will move through the matrix
at a quicker pace than those of a larger size. Sufficient quantity of buffer
(typically TAE, TBE or protein running buffer) is generally used to ensure that
the electric field is set up in the gel, and that the gel is covered with it and
thus prevent the gel from drying out during electrophoresis. When loading a
sample containing the molecule species of interest into the gel, a loading dye is
typically used. The loading dye normally allows easy visualization of the
solution during the loading process, as well as enabling the density of the
sample to be increased to ensure that the sample is fully and evenly
accommodated in a corresponding well in the gel, and further allows
visualisation of the migration during electrophoresis.

The most commonly used gels are prepared with either agarose or acrylarnide,
either one of which can be provided in varying shapes, sizes and thicknesses.
The deciding factor as to which particular gel and its physical attributes is
generally related to the size of molecule being separated and the desired
experiment to be performed by the user.
Acrylarnide is usually chosen for relatively small molecules such as proteins,
while agarose is used for larger molecules such as DNA or RNA. and agarose is
the preferred choice for horizontal gel electrophoresis, typically cast in open
trays by users.
Typically, it is desirable to visualize and to document the results of the
electrophoresis separation test. In electrophoresis separation of DNA or RNA
molecules, this may be accomplished by immersing the gel slab after the
electrophoretic separation has been completed in a solution of a fluorescent
compound which emits visible light when exposed to a ultraviolet (UV) light.
Other methods of staining the gel are also known, for example by adding a
suitable dye to the gel while casting the same. A widely used fluorescent
compound is ethidmm bromide. However, many types of such fiuorescervt
compounds, including ethidium bromide, Acrydine Orange, SYBR Green I, and
SYBR Green II, as well as acrlyamide and also some components used together
with some agarose gels, are toxic and/or carcinogenic, and contact with users
must be strictly avoided, particularly when disposing of the gels after use.
It is therefore an aim of the present invention to provide a device and method
which overcomes the limitations of prior art electrophoresis devices and
methods.
It is another aim of the present invention to provide a device for enabling safe
handling and disposal of gels which may contain harmful substances.
It is another aim of the present invention to provide such a device that is
simple to use.

It is another aim of the present invention to provide such a device that is
relatively simple mechanically and thus economic to produce.
It is another aim of the present invention to provide such a device that is
adapted for use with regular horizontal electrophoresis equipment.
These and other aims are accomplished in the present invention by providing a
precast cassette for horizontal electrophoresis, in particular a disposable and
closed cassette for horizontal electrophoresis. In particular, the cassette
comprises preferably a pair of traps, one at each longitudinal end of the
cassette, each trap comprising an absorption material for preventing toxic
material from migrating out of the cassette. This is an important safety
feature, particularly in view of the handling of the horizontal electrophoresis
apparatus and of the cassette during use thereof, and more so in view-ofthe
disposability of the cassette, which thus minimises the risk of human contact
with toxic substances comprised in the cassette.
In the preferred embodiment, the cassette comprises a box-like construction,
having a bottom flat base and four vertical walls joined thereto about its
periphe^, and an upper cover mountable onto the vertical walls to define a gel
chamber into which gel may be precast. The cassette also comprises openings
at two opposite ends of the bottom base to enable ionic communication between
the gel and an electrolytic solution in which the cassette may be partially
immersed. The openings ai'e preferably comprised in downwardly extending
hollow leg members running the transverse length of the cassette at two
longitudinal ends thereof, the leg members comprising gel in ionic
communication with the main body of gel within the cassette. This design is
particularly adapted for using the cassette with standard ion exchange
chambers. Activated carbon or the like is provided in the legs and also in a
second trapping chamber to absorb dangerous materials such as the dyeing
compounds.

US 3,888,759 discloses a gel cassette having a substantially box-like
construction, having a downwardly depending transversely extending hollow
leg at each longitudinal end of the cassette. The device appears to be reusable,
providing the user with different options, and it appears intended for the user
to cast the gel each time, rather than providing a precast package. There is no
disclosure or suggestion of a trap for toxic materials, and in fact teaches away
from this concept.
US 5,443,704 discloses a substantially box-like container assembly for
packaging prefabricated gels, containing more than one precast gel in a
stacked arrangement. No trap for harmful substances is disclosed therein.
US 5,064,769 discloses a gel for immunoassay of a single protein species in
which the horizontal gel comprises a first part made from acrylamide gel
having a proportion of agarpse (0.7%) and a second part made from agarose
gel. No trap for harmful substances is disclosed therein.
In US 3,930,983 an arrangement and process are disclosed for determining
antigens, in which a support plate is coated with an agar or agarose as a
matrix in successive gel strips. No trap for harmful substances is disclosed
therein.
US 5,582,702 is directed to a self-contained electrophoresis apparatus
comprising a housing having a gel body accommodated therein together with
ion exchange matrices and electrodes, which are electrically connectable to an
external power source. The apparatus is thus not generally compatible with
existing ion exchange chambers currently used for horizontal electrophoresis.
While it is presented as optionally "disposable", the apparatus is nonetheless
complex, and does not appear inexpensive in comparison with simple precast
gels, such as those described in US 5,443,704, for example. Moreover, the
apparatus contains elements which are not normally considered disposable,
notably the electrodes and ion exchange matrices. In fact by being fully closed,
in particular regarding the lower side thereof, the apparatus cannot be used
with standard ion exchange apparatuses, and thus needs a dedicated stand
having electrical connection points for the electrodes. Optionany, ethidium

cations may be released into the gel by one of the ion exchange matrices within
the housing, which may be simply disposed after use. However, and as stated
earlier, the complexity of the apparatus renders this a rather expensive
solution for the disposal of the contaminated gel. Furthermore, no traps are
actually provided for retaining the contaminants therein - therefore, if any
openings were to be made, for example, at the lower part of the cassette, for
example as in the present invention, the contaminants could flow out, in
contrast thereto.
EP 471949 discloses a capillary tube for performing capillary zone
electrophoresis.' The tube is modified by including a polystyrene frit that
divides the tube into a downstream free zone, and an upstream zone which can
comprise a polyacrylamide stacking gel. The gel plug functions as a filter to
pre-treat the samples that are to be analysed in the free zone of the tube. This
is in contrast to the present invention, wherein the traps are placed
downstream to treat the contaminants in the gel during and at the end of the
electrophoretic process, and not prior to the beginning thereof. In fact, the
samples in the present invention do not generally require pretreatment as
described in this patent. Furthermore, the present invention uses agarose gel
with an absorption material for retaining therein a target substance. On the
other hand, in EP 471949 uses polyacrylamide, which is also toxic and use
thereof would be detrimental in the present invention as a trapping gel, and in
fact counterproductive for this purpose. Thus, this publication teaches away
from the present invention.
W092/17259 describes a method for identifying a solute of interest in an
effluent stream. A sample containing the mixture to be separated is passed
through a first system capable of partitioning the components of the mixture,
and a detector provides a first output that describes the temporal and/or
spatial sequence of components exiting the first system. The effluent stream is
then passed through a second system capable of extracting a solute of interest
from the effluent, and a detector provides a second output that describes the
temporal and/or spatial sequence of components exiting the second system,

which, no longer includes the solute of interest. The solute of interest can then
be identified in the first output by comparing this to the second output. This
method is thus directed at identifying a substance in a first separating system
by employing a parallel second separating system, and is thus very different to
the present invention, in which only a single electrophoresis process is
employed, the target substance being removed during that process. WO
92/17259 does not address the problem of, nor does it provide a solution for,
the trapping of toxic substances in an electrophoresis process, less so in the
manner of the present invention.
WO 95/20155 relates to a sample holder in the form of a well, into which a
sample and a first molten gel is introduced. When the first gel/sample mixture
has solidified, the sample holder is applied against one end of a second gel
slab, such as to bring the first gel/sample solidified mixture in ionic contact
with the second gel. At no time is the first gel in solidified form brought into
contact with the second gel prior to introducing the sample. WO 99/30145
relates to a slotted electrophoresis gel composition and methods for use, for
providing a multilayered gel for vertical gel electrophoresis. It does not
address, nor provide a solution for, the problem of forming stable sample wells
for horizontal electrophoresis in an acrylamide gel. These publications do not
address the problem of, nor do they provide a solution for, the trapping of toxic
substances in an electrophoresis process, less so in the manner of the present
invention
Other publications of background relevance to the present invention include
WO 98/10277, US 5228971, US 5827418, US 3873433, EP 971229,
WO 95/14921, DE 3232685, EP 199470 and US 3S03020.

Summary of Invention
The present invention relates to an apparatus for electrophoresis comprising a
first gel matrix in communication with a second gel matrix, said first gel
matrix and said second gel matrix accommodated within a statable housing,
said housing comprising at least one first opening and at least one said second
opening, said at least one first opening being adapted to permit ionic
communication between said first gel matrix and an external ionic buffer
solution, and said at least one second opening being adapted to permit ionic
communication between said second gel matrix and an external ionic buffer
solution, wherein said first gel matrix adapted for performing an
electrophoretic process therein, and wherein said second gel comprises at least
one suitable absorption material capable of retaining therein at least one
target substance capable of migrating thereto at least from the said first gel
matrix when an electrophoretic process is performed in said first matrix.
Typically, electrophoresis of a sample is conducted in said first gel matrix in a
direction substantially away from said second gel matrix, and the said first gel
matrix may comprise suitable wells adapted for introducing therein samples of
interest to be eleetrophoresed. The first gel matrix is accommodated in a first
chamber within said housing and said second gel matrix is accommodated in a
second chamber within said housing, said first chamber being in
communication with said second chamber.
Optionally, the apparatus further comprises a third gel matrix accommodated
in said housing and in communication at least with said first gel matrix,
wherein ionic communication between said first gel matrix and an external
ionic buffer solution is via said third gel matrix and via said at least one first
opening, and wherein said third gel matrix comprises a suitable absorption
material capable of retaining therein a target substance capable of migrating
thereto at least from the said first gel matrix when an electrophoretic process
is performed therein in a direction substantially towards said second gel
matrix.

In the preferred embodiment, the housing further comprises a first
substantially hollow leg member extending downwardly from said at least one
first opening, said first leg member adapted for providing communication
between said first gel matrix and an outside of said housing. Similarly, the
housing further comprises a second substantially hollow leg member extending
downwardly from said at least one second opening, said second leg member
adapted for providing communication between said second gel matrix and an
outside of said housing. The said first leg member typically comprises said
third gel matrix, and a fourth gel matrix may be accommodated in said second
leg member and in communication at least with said second gel matrix,
wherein ionic communication between said second gel matrix and an external
ionic btrffer solution is via said fourth gel matrix and said at least one second
opening, and wherein said fourth gel comprises a suitable absorption material
capable of retaining therein a target substance capable of migrating thereto at
least from the said first gel matrix when an electrophoretic process is
performed therein in a direction substantially towards said second gel matrix.
The target substance is typically a suitable dyeing compound; the first gel
matrix is made primarily from agarose; the second gel matrix is made primary
from agarose mixed with said absorption compound; the third gel matrix is
made primary from agarose mixed with said absorption compound; and the
fourth gel matrix is made primary from agarose mixed with said absorption
compound, typically activated carbon.
The present invention also relates to an apparatus for performing
electrophoresis therein, comprising;-
a housing comprising
a first chamber adapted for accommodating therein a first gel for use in an
electrophoretic process; and

a second chamber adapted for trapping therein at least one target substance
capable of migrating thereto at least from said first chamber, said first
chamber being in communication with said second chamber;
said housing further comprising at least one first opening and at least one said
second opening, said at least one first opening being adapted to permit ionic
communication between a gel accommodated in said first chamber and an
external ionic buffer solution, and said at least one second opening being
adapted to permit ionic communication between a gel accommodated in said
second chamber and an external ionic buffer solution.
In. the preferred embodiment, the housing comprises at least a first base and
peripherally joined walls defining said first chamber having a first
longitudinal end and a second longitudinal -end. -The- housing may also
comprise at least a second base and peripherally joined walls defining said
second chamber having a third longitudinal end and a fourth longitudinal end.
The first chamber is partially superposed over said second chamber to define
an area of horizontal overlap between said first chamber and said second
chamber, and communication between said first chamber and said second
chamber is via a suitable opening comprised in said area of horizontal overlap.
The housing is adapted for performing electrophoresis of a sample within said
first chamber in a direction substantially away from said second chamber, and
further comprises a suitable first gel matrix accommodated in said first
chamber arranged such that migration occurs in a direction from said second
end to said first end when said apparatus is used in an electrophoretic process.
Typically, the first gel matrix comprises suitable wells adapted for introducing
therein samples of interest to be electrophoresed.
The first gel matrix typically comprises a suitable dyeing compound, and the
target substance may be such a dyeing compound, which may be harmful to
humans.

The second chamber is adapted for trapping said target substance by
accommodating therein a suitable second gel matrix, said second gel matrix
characterised in comprising at least one suitable absorption material capable
of retaining therein at least said target substance. A second gel matrix is
accommodated in said second chamber within said housing, and a third gel
matrix accommodated in said housing and in communication at least with said
first gel matrix, wherein ionic communication between said first gel matrix
and an external ionic buffer solution is via said third gel matrix and said at
least one first opening, and wherein said third gel comprises a suitable
absorption material capable of retaining therein a target substance capable of
migrating thereto at least from the said first gel matrix when an
electrophoretic process is performed therein in a direction substantially
towards said second gel matrix.
In the preferred embodiment, the housing further comprises a first
substantially hollow leg member extending downwardly from said at least one
first opening, said first leg member adapted for providing communication
between said first chamber and an outside of said housing. Similarly, the
housing further comprises a second substantially hollow leg member extending
downwardly from said at least one second opening, said second leg member
adapted for providing communication between said second chamber and an
outside of said housing. In this embodiment, the first leg member comprises
said third gel matrix, and a fourth gel matrix is accommodated in said second
leg member and in communication at least with said second gel matrix,
wherein ionic communication between said second chamber and an outside of
the housing is via said fourth gel matrix and said at least one second opening,
and wherein said fourth gel comprises a suitable absorption material capable
of retaining therein a target substance capable of migrating thereto at least
from the said first gel matrix when an electrophoretic process is performed
therein in a direction substantially towards said second gel matrix.
The target substance is typically a suitable dyeing compound; the first gel
matrix is made primarily from agarose; the second gel matrix is made primary

from agarose mixed with, said absorption, compound; the third gel matrix is
made primary from agarose mixed with said absorption compound; the fourth
gel matrix is made primary from agarose mixed with said absorption
compound, typically comprising activated carbon.
The apparatus preferably further comprises a cover for releasably closing said
first chamber. A suitable comb for forming wells in a gel may be
accommodated in said first chamber, said cover comprising at least one
suitable aperture for enabling said comb to penetrate into said first chamber.
Optionally, the cover comprises a tab in registry with and spaced from a
platform comprised at said first longitudinal end of said device.
Advantageously, suitable adhesive strips are provided for reversibly sealing
said bottom ends of said first and second leg members, respectively.
At least in the preferred embodiment, the housing is adapted to enable said
apparatus to be used with standard electrophoresis devices having a pair of
parallel juxtaposed buffer-containing toughs separated by an elevated
platform for supporting said base of said housing, said first and second leg
members extending sufficiently into corresponding said troughs to provide
ionic communication at least between said third gel portion and buffer
contained in one trough, and between said fourth gel portion and buffer
contained in the other trough.
Description of Figures
Figure 1 shows in exploded perspective view the main elements of a preferred
embodiment of the present invention.
Figure 2 shows in side view the embodiment of Figure 1 assembled.
Figure 3 shows in top view the embodiment of Figure 2.

Figure 4 shows in side elevational cross-sectional view, the embodiment
of Figure 3 taken along E-E.
Figure 5 shows in side elevational cross-sectional view, a second embodiment
of the present invention.
Figure 6 shows in side elevational cross-sectional view, a third embodiment of
the present invention.
Disclosure of Invention
The present invention is defined by the claims, the contents of which are to be
read as included within the disclosure of the specification, and will now be
described by way of example with reference to the accompanying Figures.
The present invention relates to a device for horizontal electrophoresis which
may be provided with any required macromolecule-separating compounds and
any buffer compositions that are used for running macrouaolecules, as well as
any required labelling compounds, characterised in comprising at least one
suitable trap for trapping and retaining at least one of any such compounds
therein, thereby minimising contamination hazard to the external
environment including users of the device.
Such an apparatus or device is preferably disposable, but may also be re-
usable for a host of applications. The term "disposable" in the present
application means that the devices are designed (in corresponding
embodiments) to be thrown away or otherwise disposed off after one use with
only negligible economic loss. Such negligible economic loss may be
comparable, for example, to the economic loss incurred in disposing of plastic
pipettes for handling liquids or eppendorf tubes. While these items may be
used more than once, they are nonetheless typically thrown away after a

single use, this being more cost effective than cleaning and/or sterilising the
same for subsequent use.
Referring to the Figures, Figures 1 to 4 illustrate a preferred embodiment of
the present invention. The apparatus or cassette, designated by the numeral
(1), comprises a housing (100) of a box-like construction, a suitable gel (38) for
electrophoresis, accommodated in a first chamber (30), and a second suitable
gel for trapping dangerous substances therein, accommodated in a second
chamber (40).
The cassette (1) comprises a stepped bottom base (10) having a flat upper part
(11) and a flat but shorter lower part (13) joined longitudinally one to the other
by a first intermediate vertical wall (15). Two side walls (12), (14) run the
longitudinal length of the cassette (1) and are preferably integrally joined to
the base (10). and to end walls (16) and (18) at opposite longitudinalends of the
cassette (1). A second intermediate wall (19) is joined to side walls (12) and
(14) at a longitudinal location between first intermediate wall (15) at the end
wall (IS) closest thereto. The second intermediate wall (19) substantially
divides each side wall (12) and (14) longitudinally into longer portions (12')
and (14'), respectively, extending between the end wall (16) and intermediate
wall (19), and shorter portions (12") and (14"), respectively, extending between
the intermediate wall (19) and the other end wall (18). The upper edge of the
second intermediate wall (19) is substantially coplanar with the upper edge of
end wall (16) and with the upper edges of at least the longer side wall portions
(12') and (14').. and thus enable an upper cover (50) to be releasably and
sealingly mounted thereonto. Upper cover (50) may comprise optionally
closable apertures (51) and (53) longitudinally spaced one from the other along
the mid-line of the cover (50). These apertures (51), (53) facilitate pouring of
gel into the cassette (1) when the cover (50) is in place, described in greater
detail hereinbelow. Thus, the second intermediate wall (19), end wall (16) and
the longer side wall portions (12') and (14'), together with upper cover (50) and
the upper part (11) of the base (10) define the first chamber (30) of the cassette
(1). The second chamber (40) of the cassette is correspondingly defined by the

second intermediate wall (19), end wall (18) and the shorter side wall portions
(12") and (14"), together with upper wall (55) and the lower part (13) of the
base (10). Upper wall (55) may optionally be joined typically integrally with
the second intermediate wall (19), end wall (18) and the shorter side wall
portions (12") and (14"). Preferably, though, and as illustrated in Figures 1 and
4, upper wall (55) is integrally joined to the upper cover (50) and is releasably
and sealingly mountable onto the upper edges of the second intermediate wall
(19), end wall (18) and the shorter side wall portions (12") and (14"). The lower
edge of the second intermediate wall (19), however, does not extend as far as
the lower part (13) of the base (10), and thus communication between the first
chamber (30) and second chamber (40) is provided by virtue of the longitudinal
gap between the first and second intermediate walls, (15) and (19),
respectively.
Thus, in the preferred embodiment, the first chamber (30) is partially
superposed over the second chamber (40), defining an area (31) where the two
chambers overlap horizontally. At least a portion of this area (31) has an
opening, or preferably is open, providing communication between the first
chamber (30) and the second chamber (40).
Preferably, the cassette (1) or other embodiments thereof is provided with a
suitable first gel matrix (38) accommodated in the first chamber (30) and a
suitable second gel portion (48) is accommodated in the second chamber (40).
Alternatively, the cassette (1) or other embodiments thereof may be provided
without one or both these gels, which can be cast as and when needed. In any
case, the first gel matrix (38) is adapted for performing electrophoresis therein,
and typically comprises at least one dyeing compound. The term dyeing
compound is taken herein to include any type of labelling substance that may
be used to identify the molecules of interest in the sample being
electrophoresed in the first gel matrix (38). The second gel matrix (48) is
adapted for trapping and retaining therein at least one target substance
capable of migrating thereto at least from the first gel (38) during
electrophoresis, and dyeing compounds are typically such target substances.

The second gel matrix is typically adapted for trapping by comprising an
absorbent material mixed therewith and which prevents the target substance
from exiting the second gel (48).
Top cover (50), and preferably the rest of housing (100) is made from any-
suitable ultraviolet-transparent material. Preferably, the whole of the cassette
(1), in particular the housing (100), is made from an economically disposable
material.
Optionally, a tab (57) is provided at one end of the cover (50), and a
corresponding platform (58) is provided at end (16), preferably integrally
joined thereto, such that the tab (57) is in registry with platform (58) and
mutually spaced by space (59) when the cover (50) is in place over chamber
(30), By placing a suitable flattened tool such as a screwdriver or key (not
shown), for example, within space (59) and rotating it by 90°, say, the cover
(50) may be snapped open and thus removed from the chamber (30).
Having an openable cover (50) is important in applications, for example, where
it is required to remove some of the first gel portion (38) for further processing
such as electroelution or transfer of molecules from the first gel portion (38) to
a membrane (western blot or northern blot).
The cassette (1) also comprises openings at two opposite ends of the bottom
base (10) to enable ionic communication between the gel that is accommodated
in the cassette (1) and an electrolytic solution in which the cassette (1) may be
partially immersed. Thus, transverse opening (32) at longitudinal end of the
upper part (11) of the base (10) near end wall (16) provides communication
between the first chamber (30) and the outside of the cassette (1). Similarly,
transverse opening (42) at longitudinal end of the lower part (11) of the base
(10) near end wall (18) provides communication between the second chamber
(40) and the outside of the cassette (1).
Openings (32) and (42) serve to provide ionic communication between the gels
accommodated within the cassette (1) and external ionic solutions, and thus

enable electrophoresis to be conducted within the cassette (1) with the
provision of a suitable electric field. Preferably, though, the openings at the
bottom base (10) are in the form of substantially hollow leg members running
the transverse length of the cassette (1) at two longitudinal ends thereof, the
leg members also being capable of accommodating gel in ionic communication
with the main body of gel accommodated within the cassette (1). This inverted-
U design is particularly adapted for using the cassette (1) with standard ion
exchange chambers, which are generally in the form of two juxtaposed buffer-
containing troughs separated by an elevated platform which is ideal for
supporting the base (10) of cassette (1). One leg member is extends into one
trough, and the other leg member into the second trough to provide ionic
communication at least between the gel contained in the legs and the
corresponding buffer solutions in the troughs. One trough has a cathode and
the other trough has an anode.
Thus, the cassette (1) optionally, and preferably, comprises hollow legs (60)
and (70) provided at opposite longitudinal ends thereof. At one end of the
cassette (1), leg (60) is denned by a downwards extension of end wall (16),
together with downwardly extending tab-like projections (62) at the end of
longer side wall portions (12") and (14"), respectively, and a fourth wall (65)
projecting downwards from the upper part (11) of base (10). Similarly, leg (70)
at the other longitudinal end of the cassette (1) is defined by a downwards
extension of end wall (18), together with downwardly extending tab-like
projections (72) at the end of shorter side wall portions (12') and (14'),
respectively, and a corresponding fourth wall (75) projecting downwards from
the lower part (13) of base (10). Each leg (60), (70) are open at the
corresponding bottom ends (66), (76) thereof, which may be temporarily closed
(at least prior to use of the cassette (1)) by means of suitable removable
adhesive strips (not shown) adhered thereto. The bottom ends (66), (76) are in
communication with the first chamber (30) and second chamber (40),
respectively, via the transverse openings (32) and (42), respectively.

The first chamber (30) is thus adapted to accommodate a suitable gel matrix
(38) adapted for electrophoresis, preferably comprising a plurality of wells (39)
for accepting samples that are to undergo an electrophoretic process. The gel
matrix (38) typically comprises an agarose gel, though alternatively it may
comprise other types of gels, included multilayered gels, which comprise strips
of different gels or gel compositions juxtaposed one with another sequentially.
Alternatively, the gel matrix (38) may comprise a hybrid gel matrix having a
substantially solidified first gel portion juxtaposed with at least a
substantially solidified second gel portion, wherein the first gel portion is
capable of accommodating therein at least one sample for electrophoresis after
said first gel portion is in solidified form, and is generally made from or
contains sufficient agarsose to provide a stable well structure for
accommodating samples, and the second gel portion is adapted for enabling an
electrophoresis processto be applied to such a sample that may be
accommodated in said first gel portion, the second gel portion comprising an
acrylamide gel. Such hybrid gels are disclosed in co-pending Israel Patent
Application No. 139446, filed by Applicants.
The wells (39) may be formed by a comb (80), for example, having teeth (84)
that are typically inserted into the first gel portion (37) via corresponding
apertures (52) comprised in the cover (50). Alternatively, a common slit may be
provided in. the cover (50) in place of the individual apertures (52). Typically,
the comb (SO) is kept in place engaged with respect to the cover (50) until the
cassette (1) is used, whereupon samples may be introduced into one or more
wells (39) via corresponding apertures (52). After use, and before disposing of
the cassette (1), the apertures (52) are preferably again closed by means of the
comb (BO),
The agarose gel (38) is preferably provided precast in the first chamber (30),
though may be alternatively cast by users in some applications. In any case,
the gel may be poured into the first chamber (30) having first removed the
cover (50). Another method of casting the gel is by turning the cassette (1)
vertically such that the end wall (18) is uppermost Gel is then poured into tie

chamber (30) up to the required height (which corresponds to the end wall (16)
when the cassette (1) is returned to its horizontal position). With this method,
the gel may be poured into the chamber (30) via aperture (53). Other ways of
casting the gel are also possible. Wells (39) may be formed in the normal
manner using, for example, a comb (80). However, the step of casting the first
gel matrix (38) is usually performed after the second gel matrix (48) is cast, as
described hereinbelow.
According to the present invention, at least one trap, and preferably two traps
are provided for preventing release of dangerous substances from the cassette
(1) to the external environment. Many labelling. compounds, as well as
acrylamide gels, may be toxic and/or carcinogenic and therefore potentially
harmful, to the cassette operator and to the environment. Thus, a first trap (90)
is provided in the form of the second chamber (40) for trapping and thus
retaining' labelling compounds and the like, and thus preventing the same
from exiting the cassette (1). Second chamber (40) -which is in open
communication with first chamber (30), and at least in ionic communication
therewith when both chambers are accommodating gels - is provided with a
suitable second gel matrix (48), typically agarose gel having active carbon,
silica gel (at a special pH condition), for example, or any other suitable
absorption material, mixed therewith. The term absorption material is taken
herein to include any type of material capable of retaining therein at least one
target substance, such a target substance being typically capable of migrating
in an electrophoretic process. Particularly when the cassette (1) is used with
precast agarose gels, the dye compounds which are used originally for
visualising the molecules being separated, are provided mixed with the
agarose gel in the first chamber (30), thereby removing the hazard associated
with handling of these compounds prior to use of the cassette (1). Under
electrophoresis, molecules of interest contained in samples provided at the
wells (39) migrate from the wells (39) towards the end wall (16). At the same
time, dyeing compounds such as ethidium bromide comprised in the gel

migrate in the opposite direction, i.e., towards end wall (18), thereby arriving
at the second chamber (40), and are prevented from leaving the second
chamber (40) as well as leg (70) by virtue of the activated carbon particles or
other suitable absorbent material comprised therein. Typically, electrostatic
interactions build up between activated carbon particles and ethidium bromide
leading to absorption of the latter within the appropriate gel matrix. A second
trap (95) is provided at the other longitudinal end of the cassette (1) to absorb
the dye compounds as the dye, when the user mistakenly runs the gel in an
inverted configuration. In the latter situation, migration occurs from end (16)
towards end (18), rather than the vice versa, and dye compounds are absorbed
by the trap (95). The second trap (95) also prevents unwanted migration of dye
compounds by diffusion forces when the cassette is not being used. This
enables the cassette to have a relatively long shelf life, perhaps a year or more,
for "example." The second "trap(95) is" economically provided by The hollow leg
(60), which comprises an third gel matrix (69) comprising an agarose gel
having a quantity of activated carbon, silica gel (at a special pH condition), for
example; and/or any other suitable absorption material mixed therein. Thus,
even if openings (76) and (66) in legs (70) and (60), respectively, remain
unsealed, the dyeing compounds will not run out due to their adherence to the
absorption materials.
The traps (90), (95) are generally prepared before casting the gel in the first,
electrophoresis, chamber (30). With the cover (50), including portion (55) off,
and with the bottom ends of the legs (60) and (70) sealed with suitable
adhesive peel-off tape, agarose gel (79), containing mixed therein a suitable
proportion of activated carbon is poured into leg (70) and chamber (40), up to
the level of the upper part (11) of base (10). Then, agarose gel (69), also
containing mixed therein a suitable proportion of activated carbon or other
suitable absorption material is poured into leg (60) and preferably also the
second chamber (40), i.e. up to the level of the upper part (11) of base (10).
When the gels (79) and (69) are set the first gel matrix (38) may be poured
arid set in the first chamber (30) as hereinbefore described.

While trap (90) has been described as being in the form of a second chamber
(40) at a level below the first chamber (30), this need not generally be so.
Minimally, the trap (90) needs only to be adapted to provide ionic
communication between the absorbent material comprised therein and the gel
comprised in the first chamber (30), and situated with respect to the first
chamber such as to be substantially downstream of the migration path of the
dye compounds. Any configuration of trap (90) meeting these criteria are
generally suitable. Thus, in a more simplified cassette, for example, a single
chamber is provided, in which one end is provided with agarose gel containing
absorption material, and this is juxtaposed with and in communication with a
second body of gel within the chamber for electrophoresis.
While the cassette (1) preferably comprises both the traps (90), (95), the second
trap (95) is generally not required. Thus, optionally, a simpler cassette (1) may
be provided without the he second trap (95), if it is so desired
Further optionally, the cassette (1) may be provided without the said hollow
legs (60) and (70), leading to a simplified structure. Thus communication
between said first chamber (30) and external ionic solutions is via opening (32)
in the base (10), and communication between said second chamber (40) and
external ionic solutions is via opening (42) in the base (10).
Thus, referring to Figure 5, a second embodiment of the present invention
comprises a housing (200) having a base (210) and peripheral walls joined
thereto at a lower end thereof, to define a chamber (234). A first gel matrix
(238), similar to the first gel matrix (38) of the first embodiment, mutatis
mutandis, and a second gel matrix (248) similar to the second gel matrix (48)
of the first embodiment, mutatis mutandis, juxtaposed and in ionic contact
with one another, are accommodated in the chamber (234). Thus, the first gel
matrix (238) is adapted for performing electrophoresis, and may thus comprise
dyeing substances and the like, while the second gel matrix (248) is adapted

for trapping therein dangerous target substances such as these dyeing
compounds, for example. The chamber (234) comprises openings (232) and
(242) at longitudinal ends of the base (210) for providing ionic communication
between the first gel matrix (238) and an external buffer solution, and between
the second gel matrix (248) and an external buffer solution. Wells (239) are
provided in the first gel matrix (238) for introducing samples to be
electrophoresed. Optionally, a cover plate (250) may be provided, having
suitable openings (252) for a comb (280) to be inserted therein to form wells
(239).
A third embodiment of the present invention comprises all the components of
the second embodiment as described above, mutatis mutandis, and is
illustrated in Figure 6. In addition, though, the chamber- (234) further
comprises a third gel matrix (269) juxtaposed and in ionic communication with
the first gel matrix (238), but located at the opposed longitudinal end of the
housing (200) with relation to the second gel matrix (248). The third gel matrix
(269) serves as a precautionary second trap, and is thus similar to the third gel
matrix (69) of the first embodiment, mutatis mutandis.
While in the foregoing description describes in detail only a few specific
embodiments of the invention, it will be understood by those skilled in the art
that the invention is not limited thereto and that other variations in form and
details may be possible without departing from the scope and spirit of the
invention herein disclosed.

WE CLAIM :
1. Apparatus for electrophoresis comprising a suitable housing (100), (200)
accommodating a first gel matrix (38), (238) adapted for performing an
electrophoretic process on at least one sample of interest therein in a first
direction, characterized in comprising at least a first trap (90) comprising a
second gel matrix (48), (248) having at least one suitable absorption material
capable of trapping and retaining therein at least one target substance migrating
thereto from the first gel matrix (38), (238) in an opposite direction to said first
direction when an electrophoretic process is performed in said first matrix (38),
(238) in said first direction, wherein said first gel matrix (38), (238) is in ionic
communication with said second gel matrix (48), (248), and wherein said target
substance is different from said at least one sample of interest.
2. Apparatus as claimed in claim 1, wherein said housing (100), (200) comprises at
least one first opening (32), (232) and at least one said second opening (42),
(242), said at least one first opening (32), (232) being adapted to permit ionic
communication between said first gel matrix (38), (238) and an external ionic
buffer solution, and said at least one second opening (42), (242) being adapted
to permit ionic communication between said second gel matrix (48), (248) and an
external ionic buffer solution.
3. Apparatus as claimed in claim 2, wherein said first gel matrix (38), (238)
comprises suitable wells (39), (239) adapted for introducing therein said samples
of interest to be electrophoresed.
4. Apparatus as claimed in claim 2, wherein said first gel matrix (38), (238) is
accommodated in a first chamber (30) within said housing (100), (200) and said
second gel matrix (48), (248) is accommodated in a second chamber (40) within
said housing (100), (200), said first chamber (30) being in communication with
said second chamber (40).

5. Apparatus as claimed in claim 2, comprising a second trap (95) comprising a
third gel matrix (69), (269) having at least one suitable absorption material
capable of trapping and retaining therein at least one harmful target substance
migrating thereto from the first gel matrix (38), (238) in said first direction when
an electrophoretic process is performed in said first matrix in said first direction,
wherein said first gel matrix (38), (238) is in ionic communication with said third
gel matrix (69), (269).
6. Apparatus as claimed in claim 2, wherein said housing (100), (200) comprises a
first substantially hollow leg member (60) extending downwardly from said at
least one first opening (32), (232), said first leg member (60) adapted for
providing communication between said first gel matrix (38), (238) and an outside
of said housing (100), (200).
7. Apparatus as claimed in claim 2, wherein said housing comprises a second
substantially hollow leg member (70) extending downwardly from said at least
one second opening (42), (242), said second leg member (70) adapted for
providing communication between said second gel matrix (48), (248) and an
outside of said housing (100), (200).
8. Apparatus as claimed in claim 6, wherein said first leg member (60) comprises
said third gel matrix (69), (269).
9. Apparatus as claimed in claim 7, comprising a fourth gel matrix accommodated in
said second leg member (70) and in communication at least with said second gel
matrix (48), (248), wherein ionic communication between said second gel matrix
(48), (248) and an external ionic buffer solution is via said fourth gel matrix and
said at least one second opening (42), (242), and wherein said fourth gel
comprises a suitable absorption material capable of retaining therein a target
substance capable of migrating thereto at least from the said first gel matrix (38),
(238) when an electrophoretic process is performed therein in a direction
substantially towards said second gel matrix (48), (248).

10. Apparatus as claimed in claim 1, wherein said target substance is a suitable
dyeing compound.
11. Apparatus as claimed in claim 1, wherein said first gel matrix (38), (238) is made
primarily from agarose.
12. Apparatus as claimed in claim 1, wherein said second gel matrix (48), (248) is
made primary from agarose mixed with said absorption compound.
13. Apparatus as claimed in claim 5, wherein said third gel matrix is made primary
from agarose mixed with said absorption compound.
14. Apparatus as claimed in claim 9, wherein said fourth gel matrix is made primary
from agarose mixed with said absorption compound.
15. Apparatus as claimed in any one of claims 1 to 14, wherein said at least one
absorption material comprises activated carbon.
16. Apparatus for performing electrophoresis therein, comprising:-
a housing (100), (200) comprising
a first chamber (30) adapted for accommodating therein a first gel (38),(238) for
performing an electrophoretic process on at least one sample of interest in a first
direction; and
a second chamber (40) adapted for trapping therein at least one target substance
capable of migrating thereto at least from said first chamber (30) in a direction opposed
to said first direction, said first chamber (30) being in communication with said second
chamber (40);
said housing (100), (200) comprising at least one first opening (32), (232) and at least
one said second opening (42), (242), said at least one first opening (32), (232) being
adapted to permit ionic communication between a gel that may be accommodated in
said first chamber (30) an external ionic buffer solution, and said at least one second

opening (42), (242) being adapted to permit ionic communication between a gel that
may be accommodated in said second chamber (40) and an external ionic buffer
solution.
17. Apparatus as claimed in claim 16, wherein said housing (100), (200) comprises
at least a first base (10) and peripherally joined walls (12'), (14'), 16), (19)
defining said first chamber (30) having a first longitudinal end and a second
longitudinal end.
18. Apparatus as claimed in claim 16, wherein said housing comprises at least a
second base and peripherally joined walls (12"), (14"), (18), (19) defining said
second chamber (40) having a third longitudinal end and a fourth longitudinal
end.
19. Apparatus as claimed in claim 18, wherein said first chamber (30) is partially
superposed over said second chamber (40) to define an area of horizontal
overlap between said first chamber (30) and said second chamber (40).
20. Apparatus as claimed in claim 19, and wherein communication between said first
chamber (30) and said second chamber (40) is via a suitable opening comprised
in said area of horizontal overlap.
21. Apparatus as claimed in claim 17, comprising a suitable first gel matrix (38),
(238) accommodated in said first chamber (30) arranged such that migration
occurs in a direction towards said first end when said apparatus is used in an
electrophoretic process, and when said second chamber (48), (248) is located at
said second end.
22. Apparatus as claimed in claim 21, wherein said first gel matrix (38), (238)
comprises suitable wells (39), (239) adapted for introducing therein samples of
interest to be electrophoresed, said wells (39), (239) being located at a
longitudinal end of said first gel (38), (238) closer to said second chamber (40)
than to said first end.

23. Apparatus as claimed in claim 21, said first gel matrix (38), (238) comprising a
suitable dyeing compound.
24. Apparatus as claimed in claim 16, wherein said target substance is a dyeing
compound.
25. Apparatus as claimed in claim 24, wherein said dyeing compound is harmful to
humans.
26. Apparatus as claimed in claim 16, wherein said second chamber (40) is adapted
for trapping said target substance by accommodating therein a suitable second
gel matrix (48), (248), said second gel matrix (48), (248) characterised in
comprising at least one suitable absorption material capable of retaining therein
at least said target substance.
27. Apparatus as claimed in claim 16, wherein a second gel matrix (48), (248) is
accommodated in said second chamber (40) within said housing (100), (200).
28. Apparatus as claimed in claim 16, comprising a third gel matrix (69), (269)
accommodated in said housing (100), (200) and in communication at least with
said first gel matrix (38), (238), wherein ionic communication between said first
gel matrix (38), (238) and an external ionic buffer solution is via said third gel
matrix (69), (269) and said at least one first opening (32), (232), and wherein said
third gel (69), (269) comprises a suitable absorption material capable of retaining
therein a target substance capable of migrating thereto at least from the said first
gel matrix (38), (238) when an electrophoretic process is performed therein in a
direction substantially towards said second gel matrix (48), (248).
29. Apparatus as claimed in claim 16, wherein said housing (100), (200) comprises a
first substantially hollow leg member (60) extending downwardly from said at
least one first opening (32), (232), said first leg member (60) adapted for
providing communication between said first chamber (30) and an outside of said
housing (100), (200).

30. Apparatus as claimed in claim 16, wherein said housing (100), (200) comprises a
second substantially hollow leg member (70) extending downwardly from said at
least one second opening (42), (242), said second leg member (70) adapted for
providing communication between said second chamber (40) and an outside of
said housing (100), (200).
31. Apparatus as claimed in claim 30, wherein said first leg member (60) comprises
said third gel matrix (69), (269).
32. Apparatus as claimed in claim 31, comprising a fourth gel matrix accommodated
in said second leg member (70) and in communication at least with said second
gel matrix (48), (248), wherein ionic communication between said second
chamber (40) and an outside of the housing (100), (200) is via said fourth gel
matrix and said at least one second opening (42), (242), and wherein said fourth
gel comprises a suitable absorption material capable of retaining therein a target
substance capable of migrating thereto at least from the said first gel matrix (38),
(238) when an electrophoretic process is performed therein in a direction
substantially towards said second gel matrix (48), (248).
33. Apparatus as claimed in claim 16, wherein said target substance is a suitable
dyeing compound.
34. Apparatus as claimed in claim 21, wherein said first gel matrix (38), (238) is
made primarily from agarose.
35. Apparatus as claimed in claim 23, wherein said second gel matrix (48), (248) is
made primary from agarose mixed with said absorption compound.
36. Apparatus as claimed in claim 24, wherein said third gel matrix (69), (269) is
made primary from agarose mixed with said absorption compound.

37. Apparatus as claimed in claim 28, wherein said fourth gel matrix is made primary
from agarose mixed with said absorption compound.
38. Apparatus as claimed in claim 26, wherein said absorption material comprises
activated carbon.
39. Apparatus as claimed in any one of claims 16 to 38, comprising a cover (50) for
releasably closing said first chamber (30).
40. Apparatus as claimed in claim 39, comprising a suitable comb (80) for forming
wells (39), (239) in a gel accommodated in said first chamber (30), said cover
(50) comprising at least one suitable aperture for enabling said comb to
penetrate into said first chamber (30).
41. Apparatus as claimed in claim 39, wherein said cover (50) comprises a tab (57)
in registry with and spaced from a platform comprised at said first longitudinal
end of said device.
42. Apparatus as claimed in claim 30, comprising suitable adhesive strips for
reversibly sealing said bottom ends of said first (60) and second (70) leg
members, respectively.
43. Apparatus as claimed in claim 30, wherein said housing (100), (200) is adapted
to enable said apparatus to be used with standard electrophoresis devices
having a pair of parallel juxtaposed buffer-containing toughs separated by an
elevated platform for supporting said base of said housing, (100), (200) said first
(60) and second (70) leg members extending sufficiently into corresponding said
troughs to provide ionic communication at least between said third gel portion
(69), (269) and buffer contained in one trough, and between said fourth gel
portion and buffer contained in the other trough.

Apparatus for electrophoresis comprising a suitable housing (100), (200)
accommodating a first gel matrix (38), (238) adapted for performing an
electrophoretic process on at least one sample of interest therein in a first direction,
characterized in comprising at least a first trap (90) comprising a second gel matrix
(48), (248) having at least one suitable absorption material capable of trapping and
retaining therein at least one target substance migrating thereto from the first gel
matrix (38), (238) in an opposite direction to said first direction when an
electrophoretic process is performed in said first matrix (38), (238) in said first
direction, wherein said first gel matrix (38), (238) is in ionic communication with said
second gel matrix (48), (248), and wherein said target substance is different from
said at least one sample of interest.

Documents:

539-kolnp-2003-granted-abstract.pdf

539-kolnp-2003-granted-assignment.pdf

539-kolnp-2003-granted-claims.pdf

539-kolnp-2003-granted-correspondence.pdf

539-kolnp-2003-granted-description (complete).pdf

539-kolnp-2003-granted-drawings.pdf

539-kolnp-2003-granted-examination report.pdf

539-kolnp-2003-granted-form 1.pdf

539-kolnp-2003-granted-form 2.pdf

539-kolnp-2003-granted-form 3.pdf

539-kolnp-2003-granted-form 5.pdf

539-kolnp-2003-granted-gpa.pdf

539-kolnp-2003-granted-reply to examination report.pdf

539-kolnp-2003-granted-specification.pdf

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Patent Number

227621

Indian Patent Application Number

539/KOLNP/2003

PG Journal Number

03/2009

Publication Date

16-Jan-2009

Grant Date

14-Jan-2009

Date of Filing

29-Apr-2003

Name of Patentee

GENE BIO-APPLICATION LTD.

Applicant Address

P.O. BOX 206, 76875 KFAR HANAGID

Inventors:

#	Inventor's Name	Inventor's Address
1	BEN-ASOULI YITZHAK	P.O. BOX 206, 76875 KFAR HANAGID
2	OSMAN FARHAT	P.O. BOX 1763, 20173 SACHNIN

PCT International Classification Number

G01N 27/447

PCT International Application Number

PCT/IL2001/01000

PCT International Filing date

2001-10-29

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	139446	2000-11-02	Israel
2	139447	2000-11-02	Israel