Abstract:
In the present vertical slab-gel electrophoresis instrument, all the vertical slab gel cassettes comprise un-notched rectangular sidewalls and flanged spacer strips, but still can form a U-notched upper opening with an even rim for each cassette; one type of cassette can undergo gel casting with an electrophoresis cell, while another two types of cassettes can be used to form a multiple-cassette electrophoresis cell. The present invention can also incorporate a swing-frame chosen for urging a cassette to join an upper buffer chamber, provides an improved cooling device such that there is no need for the use of exogenous coolant, and also provides simple methods to enable cassettes to be tightly enclosed within membrane pouches for gel casting.

Description:
BACKGROUND 
     1. Field of Invention 
     This invention relates to electrophoresis equipment and method, and specifically to improved vertical slab gel electrophoresis equipment and related methods. 
     2. Prior Art and Comment 
     Ferdinand Ruess, a Russian physicist, watched the migration of clay colloidal particles between two electrodes in 1897. About 50 years later, Arne Tiselius, a Swedish chemist, studied the migration of protein molecules in electric field, demonstrated the complex nature of serum proteins by using a prototype that he termed as a free electrophoresis apparatus. Whereby he won the Nobel Prize for chemistry of 1948. Electrophoresis has now become a versatile and powerful technique in biomedical and related research areas. It can be employed to fractionalize almost any charged particle, from ionizable small molecules to whole cells. When an electrophoresis carries out in a gel matrix, it terms as gel electrophoresis. Gel electrophoresis has very high resolution, is mainly employed to fractionate biomacromolecular species, such as DNA, RNA or proteins. That is because the network of the gel matrix acts as a molecular sieve to retard the migration of the macromolecular species according to their size and shape. Besides, the gel matrix can also stabilize the boundaries of the separated species both during and after the electrophoresis, so as to facilitate the subsequent analyses. The widely employed gel matrixes are agarose gel and polyacrylamide gel. The latter can be cast into a vertical cavity due to it can adhere better to the cavity walls. By successfully exploited the high fractionation ability of vertical slab polyacrylamide gel electrophoresis for determination the base sequences of DNA, Frederick Sanger, a British biochemist, and his American colleague Walter Gilbert were awarded the Nobel Prize for chemistry of 1980. 
     In vertical slab gel electrophoresis (abbreviated as VSGE hereafter), the electrophoretic vector travels vertically within a slab shaped gel matrix uprightly arranged between an upper and a lower pH buffer solution chambers charged with opposite electrodes. Usually the gel slab is only 0.2 to 2.0 mm in thickness. None such a gel slab can stand uprightly by itself unless it is held in a cassette; none such a gel slab can be properly held in a cassette unless it is directly cast and formed in it. Therefore, and obviously, there are three basic problems regarding the design of any VSGE cell: (i) how to construct a vertical slab gel casting cassette (abbreviated as VSGC cassette, gel casting cassette, or cassette hereafter) having sealed left and right edges but opened up and low ends; (ii) how to insure a gel matrix to be cast into the cassette without leakage; and (iii) how to urge the cassette to water-tightly join the upper buffer chamber (abbreviated as UBC hereafter) with the upper opening of the cassette exposes into the formed cassette/UBC complex. As long as the cassette/UBC complex forms, just sets it into a lower buffer chamber (abbreviated as LBC thereafter), thereupon a VSGE cell is accomplished. As for how to arrange the electrodes in the UBC and LBC, and how to make a lid for the VSGE cell, those are foolproof. 
     About the size: Typically there were three different sized VSGE cells. The 36×30 cm slab gels were usually used for DNA sequencing electrophoresis. But it has been replaced by some automatic capillary gel electrophoresis instruments in the developed countries, referring to U.S. Pat. No. 5,374,527 (1994), etc. The 18×16 cm slab gels were widely used for protein fractionation in the early years. However nowadays, more than 95% chance is to run the mini gel, which casts in 8×10, or 10×10 cm cassettes, due to its shorter running time and easer to manipulate. 
     About the structure style: There were several different styled VSGE cells, referring to U.S. Pat. No. 3,719,580 (1973), U.S. Pat. No. 4,224,134 (1980) and U.S. Pat. No. 4,574,040 (1986), etc. However, the most popular styled VSGE cell is a kind of dual gel cell, which was initiated by Madjar et al (1) in 1977. Thereafter various VSGE cells were patented, but most of them wore still belong to the most popular styled dual gel cell as mentioned above, referring to U.S. Pat. No. 4,574,040 (1986), U.S. Pat. No. 5,632,877 (1997), U.S. Pat. Nos. 5,888,369 and 6,001,233 (1999), etc. Their common structure style is that; on one hand, making the UBC to have two opposite U-shaped side openings; on the other hand, making each cassette to have a U-notched upper opening; and then using an urging mechanism to force those two cassettes to sandwich that UBC between them. Certainly, U-shaped rubber sealing-gaskets are always employed for sealing up the interfaces between the cassettes and UBC. As a result, a water-tightly joined cassettes/UBC complex is formed with the two U-notched upper openings naturally expose into the formed complex. However, their common weakness is that when only one gel runs in such a dual gel cell, the other side opening of the UBC has to be blocked up. It is inconvenient, because more than 50% chance is to run one gel a time. In CN Pat. 88106198.0 (1982), the inventor developed a modular VSGE cell, which allows numerous slab gels to run in it parallel. 
     About the cassette: compare with any kind plastic, glass plate is a better material to wall VSGC cassettes, due to it has much higher rigidity, much higher chemical inertness, much higher thermal conductivity; and especially due to the gel matrix can adhere it better. Ceramic, such as aluminum oxide plate, is even better than glass, but it is not transparent and cannot be as cheap as glass plate. Unfavorably, both of them are typical bad machining-able materials, so that to make glass and/or ceramic walled cassettes can never be as easy as to make them by plastics. Nevertheless, any reusable cassette is had better to be glass and/or ceramic walled by the reason as mentioned above. The simplest glass walled cassettes was formed by two identical rectangular glass plates and a pair of flat plastic spacer strip, as reported by Herbert Tichy (2) in 1966. However, this kind cassette is not easy to join the UBC, and its sample loading area is not easy to access, referring to U.S. Pat. No. 4,224,134 (1980). Afterward, one of the two rectangular glass plates was replaced by a U-notched glass plate, so as to make the cassette having a U-notched upper opening, referring to the report of F. W. Studier (3) in 1973. However, the U-notched glass or ceramic plates are much more costly and much more fragile than rectangular plates. Subsequently, the U-notched glass wall was replaced back by a shorter rectangular glass wall, as in U.S. Pat. No. 4,574,040. Although the shorter glass wall along with two flat plastic spacer strips also can form a U-notched upper opening for the cassette, but this way formed U-notched upper opening does not have an even rim. As a result, the leakage of the upper pH buffer solution becomes the major problem if this kind cassette is employed in any VSGE cell, referring to the Tech Note (4). Cross section T-shaped spacer strips were used to form a cassette in U.S. Pat. No. 4,560,459 (1985), but that cassette still had to use a U-notched sidewall. A three-element cassette was disclosed in U.S. Pat. No. 4,954,236 (1990), but its abutting face has no even margin to insure a leak-free abutting. 
     Besides, a fact was examined in the prior art. That is under appropriate pressure, the left and right margins of those glass walled VSGE cassettes could achieve leak-free, provided the employed two plastic spacer strips are wide and smooth enough, therefore makes no need using grease or glue to seal up the left and right margins. 
     About the urging mechanism: An urging mechanism is always required for forcing the cassette and the UBC to rest on each other tightly. Most employed urging mechanisms were too complex and lax, so that large LBC were always required, refereeing to U.S. Pat. No. 4,574,040 (1986), U.S. Pat. No. 5,632,877 (1997) and U.S. Pat. Nos. 5,888,369, 6,001,233 (1999), etc. A compact clamp urging mechanism was disclosed recently in U.S. Pat. No. 6,436,262 (2002), but it looks short of compatibility. 
     About the gel casting: Essentially the process of gel casting is same to the process of the Plexiglas plate manufacturing, as disclosed in U.S. Pat. No. 2,154,639 (1939) of Rohm et al. However, herein the formed polymer is a hydrophilic gel matrix, is not supposed to be moved out off the mold for any other use, but is for stay in situ as a matrix for an electrophoresis to take place therein. Most ordinary VSGC cassettes can be arranged in face to face, put into a gel-casting box to perform gel casting. The first gel casting box, and the method of gradient slab gel casting was reported by Margolis et al (5) in 1968. Different size, different improved gel casting boxes are commercially available nowadays. However, their common defect is lacking of flexibility. G. P. Magnant patented a casting method for forming a gel matrix in U.S. Pat. No. 5,188,790 (1993). However since several thousand years ago, our human being already knew how to form objects by casting. The chemical mechanism of the polyacrylamide gel formation for electrophoresis was published by Leonard Ornstein (6) in 1964. Of course, any kind of casting needs a mold. If Magnant patented apparatuses is a three-element assembled mold, it had been disclosed by Rohm et al 54 years ago before him. Even though, the problem is how to carry out an electrophoresis in such a three-element mold, which has no lower opening. Overlooking of all other problems, and if there is no misunderstood to us, then the patented method of Magnate seems nothing more than putting a ordinary cassette into a ordinary loose plastic membrane bag, and then using four objects from four sides to push the loose bag towards the cassette for gel casting. If so, Magnant patented method looks neither convenient nor flexible than using those gel casting boxes. Several different methods were designed to seal up the lower openings of VSGC cassettes for gel casting, referring to U.S. Pat. No. 4,224,134 (1980), U.S. Pat. No. 5,192,408 (1993), U.S. Pat. No. 5,520,790 (1996), U.S. Pat. Nos. 6,110,340 and 6,162,342 (2000), etc. But most of them have no compatibility, some are not dependable, some are inconvenient. 
     About the heat absorbing device: Joule-heating generates in the gel matrix during electrophoresis. A heat-absorbing device is required in a VSGE cell when the samples need to run in native state. However in most cases, such as in DNA sequencing gel electrophoresis or SDS protein gel electrophoresis, the samples need to run in denatured state, therefore making no heat-absorbing device is required. All heat-absorbing devices in the prior art need to use exogenous coolant, referring to U.S. Pat. No. 4,224,134 (1980) and U.S. Pat. No. 4,574,040 (1986), etc. 
     SUMMARY 
     According to the present innovates, almost all aspects of VSGE cell and the related method have been improved; wherein 6 embodiments embodied 3 different mechanisms for urging the cassette to abut to the UBC, each of them has its merit; a dual gel cell allows not to block up the other side opening when a single gel runs in it; all cassettes are formed by rectangular sidewalls and fringed spacer strips, but still can form a U-notched upper opening with even rim for every cassette; two kind cassettes can undergo the gel casting within the VSGE cell, other two kind cassettes can form an unlimited cassette/UBC complex, which is ideal for the 2-D electrophoresis; a cooling device needs not exogenous coolant; improved rubber sealing-gasket has higher elasticity and higher compatibility to thickness different cassettes; disclosed four convenient methods can snugly encase almost all kind cassettes into membrane pouch for performing homogeneous or gradient gel casting. 
     OBJECTS AND ADVANTAGES 
     Accordingly, the objects and advantages of the present invention are:
         (a) planting a septum wall or a cooling chamber into a UBC, raising up the altitude of the electrodes in it, and using a shallower LBC, so as to allow unnecessary blocking up the other side opening when a single gel runs in such a dual gel cell;   (b) equipping a swing-frame aside each U-shaped side opening of the UBC; swung-open it allowing a cassette to insert therebetween; swing-close it can urge the cassette to abut the UBC tightly; this mechanism is novel, compact, flexible and easy to operate;   (c) arranging a UBC along with two cassettes into a right angle trapezoidal apron, thus a V-shaped gap is formed therebetween; to push a cylinder-beam into the V-shaped gap can urge the cassette(s) to abut the UBC tightly; this mechanism is also novel, compact, flexible and easy to operate;   (d) holding a cam-beam aside a cassette, which faces a U-shaped side opening of the UBC; turn-close the cam-beam also can urge the cassette to abut the UBC tightly; this mechanism his nothing to do with the LBC;   (e) persisting in using glass and/or ceramic plates to wall the VSGC cassettes, so as to make the formed cassettes has higher rigidity, better heat dissipation, and allows the gel matrix to adhere better to the cassette walls;   (f) using non-notched side walls and flanged spacer strips to form all cassettes, but still can form a U-notched upper opening with even rim for every cassette, so as to insure a leak-free abutting to the UBC, and can significantly reduce the cost and the fragility of the cassettes;   (g) two kind cassettes can undergo the gel casting within the VSGE cell, so that nothing else is required;   (h) other two kind cassettes can form an infinite cassette/UBC complex, which is ideal for the 2-D electrophoresis running;   (i) improved rubber sealing gasket has an 8-shaped cross section, so as to have much higher compressibility and elasticity, to be compatible with thickness different cassettes;   (j) an improved heat-absorbing device does not need exogenous coolant, so that is very convenient to use; and   (k) four disclosed convenient methods can snugly encase almost all kind VSGC cassettes into membrane pouches for both homogeneous and the gradient gel casting without leakage.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the improved VSGE cell  1 . 
         FIG. 2  is an exploded perspective view showing the structure of the improved VSGE cell  2 . 
         FIG. 3  is a set of perspective view illustrating the structure of the improved VSGE cell  3 . 
         FIG. 4  is an exploded perspective view showing the structure of the improved VSGE cell  4 . 
         FIG. 5  is a set of perspective view illustrating the structure of the improved VSGE cell  5 . 
         FIG. 6  is a set of exploded perspective view showing the structure of the improved VSGC cassettes  6 -A,  6 -B and  6 -C. 
         FIG. 7  is a set of fragmentary perspective view showing the structure of the improved VSGC cassette  7 -A and  7 -B. 
         FIG. 8  is a set of front view showing the position relationship of the U-shaped rubber sealing-gasket versus the cassette  7 -A or  7 -B during gel casting or electrophoresis running respectively. 
         FIG. 9  is an exploded fragmentary perspective view showing the structure of the improved VSGC cassettes  9 . 
         FIG. 10  is an exploded perspective view of the improved VSGC cassette  10 . 
         FIG. 11  is an exploded perspective view of the improved VSGC cassette  11 . 
         FIG. 12  is an exploded fragmentary perspective view showing a way to modify an ordinary UBC as well as an ordinary U-shaped rubber sealing-gasket, so as to enable the cassette  7 -A or  7 -B to undergo the gel casting in situ exactly at their electrophoresis running position. 
         FIG. 13  is a perspective view of a segment of the multiple cassette/UBC complex  13 . 
         FIG. 14  is a set of front view showing a method for snugly encasing the VSGC cassettes into a lower softening point plastic membrane pouch for gel casting. 
         FIG. 15  is a set of front view showing a method for snugly encasing the VSGC cassettes into an elastic membrane pouch for gel casting. 
         FIG. 16  is a set of perspective view showing a method for snugly encasing two VSGC cassettes into an ordinary plastic membrane pouch for gel casting. 
         FIG. 17  is a set of perspective view showing a method for snugly encasing the VSGC cassettes into an ordinary plastic membrane pouch for gel casting. 
         FIG. 18  is a set of front view showing the structure of the membrane pouch  18 -A and  18 -B. 
         FIG. 19  is a perspective view of the splint pair  19  employed for gel casting. 
         FIG. 20  is a perspective view illustrating the method of sandwich those pouch snugly encased cassettes between the splint pair  19  for gel casting. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a perspective view of the improved VSGE cell  1 . Wherein UBC  22   a  has a flat cooling-chamber  24 , which divides the UBC  22   a  into two compartments, each of them has an upper electrode  26  and a U-shaped side opening with a U-shaped groove  28  alongside it for a rubber sealing-gasket  30  to inlay in. Ceramic sheets  32   a  and  32   b  are the sidewalls, which are glued on the grids and the frame of the cooling-chamber  24 . Banana plug  34   a  is for the upper electrode  26   a , while  34   b  is for the lower electrode  62 , which is hanged under the UBC  22   a . One rubber sealing-gasket  30   b  has been pulled out off the U-shaped groove  28  in this drawing. In many embodiments of the present invention, the employed rubber sealing-gasket is formed by a rubber tubule that has an 8-shaped cross section as the  30   b  shown on the bottom of  FIG. 1 . This way formed rubber sealing-gasket has more elasticity and compressibility, so as to enable admit thickness different cassettes. The UBC  22   a  is affixed on the chassis  38 , which has two lines of mortise  44   s  for the foot tenons  42   s  of the swing-frame  40  to insert in. Due to all the mortises  44   s  are loose mortises, so as to make the swing-frame  40   a  and  40   b  being swing-able, reversible and demountable. A predetermined gap is left therebetween of each swing-frame  40  and the U-shaped side opening it facing to. Swing-open a swing-frame  40  allows a cassette  50  to lower into the predetermined gap; swing-close the swing-frame can urge the cassette to abut to the UBC  22   a  tightly, hence the cassette/UBC complex is formed. Hasp  48   b  is a favorite holding means for holding the swing-frame  40  in the swing-closed state. As long as the formed complex (regardless one or two cassettes are assembled in) sets into a LBC  52   a , thereupon the improved VSGE cell  1  is accomplished. Besieges, there is a U-shaped boss  46  sticking out from one face of each swing-frame  40 , so as to makes the swing frame  40   a  and  40   b  being asymmetric from face to face. To reverse the swing-frame  40   a  and/or  40   b  inside face out can change the width of the gaps, so as to have some compatibility to those thickness different cassettes. Due to the cooling-chamber  24  divides the UBC  22   a  into two compartments, both the two upper electrodes  26  are positioned rather high in the UBC, and the employed LBC is shallow; therefore it allows unnecessary to block up the other side opening of the UBC when only a single gel runs in this kind dual gel cell. In  FIG. 1 , cassette  50   a  has been urged tightly abutting to the UBC  22   a  by the swing-frame  40   a , while swing-frame  40   b  is shown in a demounted state. 
       FIG. 2  is an exploded perspective view illustrating the structure of the improved VSGE cell  2 . Drawing  2 -A shows the structure of UBC  22   b ,  34   d  is the banana plug for the lower electrode,  28   c  and  28   d  are two U-shaped groove for the rubber sealing-gaskets  30  to inlay in. Drawing  2 -B shows the structure of the swing-frame-pair, which is formed by two swing-frames  40   c  and  40   d , a chassis  38   b  and a hasp  48   c . Wherein everything is articulated to each other, so that the whole swing-frame pair  2 -B is invertable, and every part wherein is swing-able. After lowering the UBC  2 A along with two cassettes into the swing-frame-pair  2 -B, swing-close it, and holding it in the swing-closed state by the hasp  48   c , thereupon a cassette/UBC complex is formed. As long as the formed complex seats into a LBC  52 , and the heat adsorbing block  5 -C (referring to  FIG. 5 ) lowers into the UBC  2 -A, thereupon the improved VSGE cell  2  is accomplished. The swing-frame-pair  2 -B is invertable, that mines the span between the swing-frame  40   c  and  40   d  is adjustable, and this embodiment has some compatibility to those thickness different cassettes. That is because of the hubs are located biased, not located right on, the central line of the thickness of the swing-frame  40   c  and/or  40   d . The swing-frame urging-mechanism disclosed in this and the above embodiments is novel, simple, flexible, easy to operate, and very compact. Therefore it allows using much smaller LBC, so as to reduce the pH buffer solution-using amount. 
       FIG. 3  is a set of perspective view illustrating the structure of the improved VSGE cell  3 . In  FIG. 3-A , UBC  22   c  has a septum-wall  54   a ,  30   e  and  30   f  are two rubber sealing-gaskets formed by the 8-sectioned rubber tubule as  30   b ,  50   b  is a cassette that has been urged tightly abutting to the UBC by the cylinder-beam  58   b . The urging mechanism employed in this and the next embodiments is a trapezoidal-apron/cylinder-beam urging mechanism. Its principle is that by arranging a UBC along with two cassettes into a trapezoidal-apron, hence a V-shaped gap is formed therebetween when the apron is a right-angle trapezoidal-apron having one oblique sidewall; but two opposite V-shaped gaps are formed therebetween when the apron is a regular trapezoidal-apron having two oblique sidewalls. In the later case, affix the apron on the other two sides of the UBC. Thereafter, pushing a cylinder-beam into a V-shaped gap can urge the cassette(s) and the UBC to abut to each other tightly. Since the trapezoidal-apron is always affixed on some object, therefore it is better to split it into two trapezoidal half-aprons, as the  56   a  and  56   b . So do can offer a great convenience to the operation, but without changing the function of the trapezoidal-apron. In  FIG. 3-A , the two trapezoidal half-aprons  56   a  and  56   b  are formed by splitting a regular trapezoidal-apron into two pieces, and they are affixed aside the UBC  22   c ; the cylinder-beam  58   b  has been pushed into the V-shaped gap  60   b , the cassette  50   b  has been urged to abut to the UBC  22   c  tightly. However, since usually a cassette itself is neither rigid nor strong enough, therefore it is better to interpose a rigidity frame  40   e  between the cassette  50  and the cylinder-beam  58  before it has been pushed into a V-gape, as shown in  FIG. 3-B . Wherein  26  is the wire of the upper electrode,  62  is the wire of the lower electrode. Regardless two or one cassette is assembled in, the cassette/UBC complex is formed. As long as the formed complex sets into a LBC  52 , thereupon the improved VSGE cell  3  is accomplished. To replace diameter different cylinder-beams can make the VSGE cell  3  being compatible with thickness different cassettes. By the same reason as mentioned above, it is unnecessary to block up the other side opening of the UBC, when there is only a single gel running in this dual gel cell  3 . 
       FIG. 4  is a set of perspective view illustrating the structure of improved VSGE cell  4 . Wherein  4 -A shows the structure of the UBC  22   d  and the rigidity frame  40   f . If overlooking the cylinder beam  58   c , essentially  4 -B is a right angle trapezoidal-apron, but has a wide vertical cut-off made on its oblique wall, so that two trapezoidal half-apron  56   c  and  56   d  are formed. The rigidity frame  40   g  forms the vertical sidewall of the apron  4 -B, and  38   b  is the chassis. The method of using this embodiment is to hold the UBC  22   d  along with two cassettes plus the rigidity frame  40   f  in two hands of the operator, and lower them into the right-angle trapezoidal-apron  4 -B, and then pushing the cylinder-beam  58   d  downward into the V-shaped gap  60   c , thereupon a water-tightly abutted cassette/UBC complex is formed. After seating the formed complex into a LBC  52 , and lowering the heat-adsorbing block  5 -C (referring to  FIG. 5 ) into the UBC  22   d , thereupon the improved VSGE cell  4  is accomplished. This embodiment has the same advantage as that of the VSGE cell  3 , but additionally has a heat-absorbing device. 
       FIG. 5  is a set of perspective view illustrating the structures of the improved VSGE cell  5  and  5 ′. In  FIG. 5-A ,  22   e  is a UBC,  54   b  is its septum-wall,  64   a  and  64   b  are two side holding-arms, which are affixed aside the UBC for holding the cam-beams  66   a  and  66   b  aside the two U-shaped side openings respectively, but appropriate gaps are left therebetween. Cassette  50   d  and rigidity-frame  40   i  have been placed at their working positions, urged to tightly abut to the UBC  22   e , so that the cassette/UBC complex is formed. As long as the formed complex seats into a LBC  52 , thereupon the improved VSGE cell  5  is accomplished. As shown in this drawing, the cam-beams  66   a  and  66   b  both are demountable and replaceable, the  66   a  is in a demounting and turn-open state, but  66   b  is in its working position and is turned-close, each  65  is a lever for turning the cam-beam open or close. There are two ways to make this embodiment to compatible with thickness different cassettes. One way is to replace ellipticity different cam-beams; the other way is to use thumbscrews to urge the cassettes. Therefor eight screw holes  67   s  have been equipped on the four end-pieces of the two side holding-arms  67   a  and  67   b  in order to use the thumbscrews (not showing in this drawing).  FIG. 5-B  shows another embodiment of the cam-beam urging mechanism. Wherein,  38   c  is a chassis,  66   c  is a cam-beam (it is demountable and replaceable), which is held in its working position by two side holding-arms  64   c  and  64   d , whereof the other ends are joined to a vertical rigidity frame  40   h , so that the C-plus-I shaped structure  5 -B is formed (by viewing from above) for accommodating the UBC and the cassettes. After lowering the UBC  22   d  (referring to  FIG. 4-A ) along with two cassettes plus the rigidity frame  40   f  into this C-plus-I shaped structure  5 -B, and then turn-close the cam-beam  66   c , thereupon another cassette/UBC complex is formed. As long as the formed complex sets into a LBC  52 , and the heat-absorbing block  5 -C lowers into the UBC  22   d , thereupon the improved VSGE cell  5 ′ is accomplished.  FIG. 5-C  shows the structure of the heat-adsorbing block  70 , wherein  68  is a mass of gel ice (its alternative name is cellulose gum, its chemical composition is sodium methyl cellulose or some analogous) or a block of metal,  69  is an electric insulating crust,  71  is a groove for the upper electrode wire to inlay in,  34   c  is a banana plug. This heat-adsorbing block  70  should be kept in a freezer or any cooled enough place before using, and then be lowered into a UBC for absorbing the Joule-heat during electrophoresis. Additionally, block  70  can significantly reduce the using amount of the upper pH buffer solution, as well as allow the upper electrode  26  to mount thereon. Besides, heat-adsorbing block  70  also can be utilized in other kind electrophoresis cells, such as the so-called blotting cells, due to essential they are also gel electrophoresis cells, and wherein the gel slabs are vertically orientated. 
       FIG. 6  is a set of exploded perspective view illustrating the structures of the improved VSGC cassettes  6 -A,  6 -B and  6 -C respectively. In cassette  6 -A,  72   a  is a larger sidewall,  72   b  is a smaller sidewall,  74   a  and  74   a ′ are a pair of flanged spacer strip; each of them has a flat spacer strip part with a flanged strip part aside it; the two flat spacer strip parts are clamped between the respective left and right margins of the two sidewalls  72   a  and  72   a ′ so as to define a cavity between the four elements for the gel matrix to be cast in; while the two flanged strip parts rest on the respective left and right edges of the smaller sidewall  72   b , so as to form a U-notched upper opening with even rim for the cassette (due to the flanged strip parts have the same thickness as the smaller sidewall), whereby enables the cassette  6 -A to achieve a leak-free abutting to the UBC. Cassette  6 -B is essentially same to the cassette  6 -A, but herein the two flanged spacer strips  74   b  and  74   b ′ are glued on the larger sidewall  72   c , thus cassette  6 -B is a two-element cassette; it still can have two glass and/or ceramics sidewalls. The spacer strips  74   b  and  74   b ′ both can be formed by the extruded plastic strips, so as to reduce the cost. Polar plastic, such as PVC is a good material for making various spacer strips of the present invention, due to the gel matrix can adhere better to the polar plastic material. When a spacer strip is made of some kind flexible PVC, it can adhere on the sidewalls by itself, so as to offer great convenience for the cassette assembling, referring to the report (2); but hard PVC strips can be glued firmer on the sidewall. Sins the flanged spacer strips  74   b  and  74   b ′ are glued on the larger sidewall  72   c  of cassette  6 -B, therefore both of them also can be made of glass. The method is that first glues a narrower glass strip (as thick as the small sidewall  72   d ) onto a wider glass strip (its thickness defines the thickness if the gel casting cavity) to form a flanged spacer strip as the  74   b , and then glues it on the larger sidewall  72   c . Or quite the contrary, first glues a wider glass strip on the larger sidewall  72   c , then glues a narrower glass strip atop the wider one to form the flanged spacer strip as the  74   b . In cassette  6 -C, the two flanged spacer strips  74   c  and  74   c ′ are fused with the larger sidewall  72   e . Since usually plastic spacer strips cannot to fuse with a glass sidewall, therefore when we say some spacer strips are fused with a sidewall in this document, it means that both of them are integrated formed either by molded injecting plastic, or by die pressing glass (as making a glass ashtray). In addition, when we say some spacer strips are affixed on a sidewall, it means that the spacer strips can either be glued on the sidewall, or are fused with the sidewall. Cassette  6 -C is also a two-element cassette, wherein the flanged spacer strip  74   c  and  74   c ′ are integrated formed with the larger sidewall  72   e . Since it must be molding formed, therefore it allows some small modification to be made on the mold without increasing the cost. Actually, the four 45 degree transition angles are made at the upper and lower end positions of the two flanged spacer strips  74   c  and  74   c ′, as showing in  FIG. 6-C . And correspondingly, the four corners of the smaller sidewall  72   f  have been ground off The advantage of doing such a small modification is due to it can restrain the smaller sidewall  72   f  from sliding to any direction. Regardless the larger sidewall is plastic or glass, the smaller sidewalls in cassette  6 -A,  6 -B or  6 -C still can be ceramic or glass, since they are the inner sidewalls, facing to the UBC, unnecessary to be transparent. 
       FIG. 7  is a set of fragmentary perspective view illustrating the structures of the improved VSGC cassettes  7 -A and  7 -B. In cassette  7 -A, the U-shape flanged spacer  76  is formed by linking the two flanged spacer strips  74   a  and  74   a ′ (as in cassette  6 -A or  6 -B) to each other by a flanged spacer strip beam adjoined therebetween at their two lower ends. Therefore a U-shaped flanged spacer is formed, which has two upward sidearm and a bottom horizontal beam. The flat spacer part of the horizontal beam portion has degenerated into one shark tooth  78  for clipping between the lower margins of the two sidewalls  72   g  and  72   h , so as to increase the compression strength of the bottom margin area (the mastoid  84  of cassettes  7 -B and the mastoids in the two-element cassettes, as in cassette  9 , cassette  11 , cassettes  6 -B and  6 -C, all have the same function as the shark tooth  78 ); while the flanged part of the horizontal beam portion has narrowed down approximately 1 to 2 mm from its top edge, but except the very left and very right two tab areas, which rest on the respective very left and very right ends of the bottom edge of the smaller side wall  72   h . As a result, the lower opening  80  has been diverted from usually downward direction into the abutting face direction of the cassette  7 -A or cassette  7 -B. This U-shaped flanged spacer  76  is glued on the larger sidewall  72   g  in cassette  7 -A, but the U-shaped flanged spacer  76 ′ is fused with the larger sidewall  72   g ′ in cassette  7 -B. Thereafter, the only two remaining assembling seams  82 ,  82 ′ and the lower opening  80  are all located on the abutting face of cassette  7 -A or cassette  7 -B. This characteristic of cassette  7 -A and  7 -B is valuable, but only if it is aware. The value is the assembling seams  82 ,  82 ′ and the lower opening  80  of cassette  7 -A and  7 -B can be sealed up simultaneously by resting a U-shaped rubber sealing gasket on them for gel casting. 
       FIG. 8  is a set of front view showing the position relationship of the U-shaped rubber sealing-gasket versus the cassette  7 -A or  7 -B during gel casting or electrophoresis running respectively. Wherein  8 -A shows that the U-shaped rubber sealing-gasket  30  ought to rest on the two vertical assembling seams  82  and  82 ′ as well as on the lower opening  80  of the cassette  7 -A or  7 -B during performing the gel casting. However, when the U-shaped rubber-sealing gasket  30  is a part of a VSGE cell, it means that the cassettes  7 -A and  7 -B can undergo the gel casting within the VSGE cell, and subsequently to carry out the electrophoresis just by shifting the cassette downward for a little distance, as shown in  FIG. 8-B . It is worth to point out that although there are two vertical assembling seams  82  and  82 ′ on the abutting faces of cassette  7 -A or  7 -B, but no upper pH buffer solution can leak out by either along or across them during electrophoresis running. That is because of the assembling seam  82  and  82 ′ are also filled with gel matrix, after the gel matrix to be cast into the cassette by using our gel casting method; besides, the rubber sealing-gasket  30  always rests on the assembling seam  82  and  82 ′ during electrophoresis running. This situation is also true to all the cassettes  6 -A,  6 -B, and  6 -C as well as to the cassette  10  and cassette  11 . 
       FIG. 9  is an exploded perspective view of the improved VSGC cassette  9 . Wherein  72   i  is a longer sidewall,  72   j  is a shorter sidewall,  74   d  and  74   d ′ are two flanged spacer strips; each of them has a flat spacer strip part with a flanged tab part atop it, Thereof the two flat spacer strip parts are clipped between the respective left and right margins of the two sidewalls  72   i  and  72   j , while the two atop flanged tab parts rest atop the respective left and right ends of the top edge of the shorter sidewall  72   j . The flanged spacer strips  74   d  and  74   d ′ are glued on, or fused with, the shorter sidewall  72   j , but leaving the longer sidewall  72   i  demountable. Cassette  9  still can have two glass and/or ceramic sidewalls if the spacer strips are glued on the shorter wall. Each of the flanged spacer strips  74   d  and  74   d ′ can be an integrated one piece as showing in the drawing, but also can be formed by a flat spacer strip of plastic or glass with a square tab of plastic or glass to be glued on it, as the  74   d″.    
       FIG. 10  is an exploded perspective view of the improved VSGC cassette  10 . Wherein  72   k  and  72   k ′ are two identical sidewalls,  74   e  and  74   e ′ are a pair of flanged spacer strips; each of them has a T-shaped cross section. Whereof the two flat spacer strip parts are clamped between the respective left and right margins of the two identical sidewalls  72   k  and  72   k ′, while the two T-head parts rest on the respective left and right side edges of the two identical side walls, then a U-notched upper opening is formed simply due to the spacer strips are longer than the sidewalls. Herein the formed U-notched upper opening exposes to the two opposite face directions of cassette  10 . The two spacer strips  74   e  and  74   e ′ are allowed to affix on any one of the two sidewalls. Besides, both of the upper inner angles of the glass sidewalls  72   k  and  72   k ′ are ground off, so as to form a V-shaped beak  86  within the U-notched upper opening of this kind cassette. 
       FIG. 11  is an exploded perspective view of the improved VSGC cassette  11 . Wherein  72   m  is a narrower sidewall,  72   n  is a wider sidewall,  74   f  and  74   f ′ are a pair of flanged spacer strip; each of them has a flat spacer strip part with a flanged tab part atop it on one face, while with a flanged strip part aside it on the other face. Whereof the two flat spacer strip parts are clamped between the respective left and right margins of the two side walls  72   m  and  72   n , the two atop flanged tab parts rest on the respective left and right ends of the top edge of the wider sidewall  72   n , while the two aside flanged strip parts rest on the respective left and right edges of the narrower sidewall  72   m . The two spacer strips  74   f  and  74   f ′ are affixed on the wider sidewall  72   n , but leaves the narrower sidewall  72   m  being demountable. This cassette also can have the V-shaped beak  86  as the cassette  10 , and still can have two glass and/or ceramic sidewalls when the two spacer strips are glued on the wider sidewall. Cassette  10  and  11  are ideal for the 2 nd -D electrophoresis running of the 2-D gel electrophoreses method. Because, each of these cassettes has two abutting faces, whereby can form an infinite cassette/UBC complex by alternately abutting with appropriate UBC modules. In addition, the V-shaped beak  86  provided an advantage that allows using a much thicker gel cylinder to run the 1 st -D isoelectric focusing of the 2-D gel electrophoreses, so as to significantly enhance the sensitivity of the 2-D gel electrophoresis analysis method. 
       FIG. 12  is an exploded fragmentary perspective view diagramming a way to modify a regular UBC as well as a regular rubber sealing-gasket in order to make the cassettes  7 -A or  7 -B can undergo the gel casting in situ exactly at their electrophoresis running position. Wherein the modification includes that; on one hand, makes each U-shaped side opening of an ordinary UBC to have a downward, coplanar and penetrable lip  88 , by such as punching a row of small hole  90  thereon; on the other hand, splits the horizontal beam part of a regular U-shaped rubber sealing gasket into two strands, so as to form a horizontal loop  92  at the bottom of the modified U-shaped rubber sealing gasket  30 ′. After inlaying the modified rubber sealing gasket  30 ′ into the modified U-shaped groove  28 ′, the lower horizontal loop  92  just loops around the row of small hole  90 . However, for showing all things clearly in a single drawing, the modified rubber sealing gasket  30 ′ has been pulled out off the modified U-shaped groove  28 ′, as shown in  FIG. 12 . The way to use this embodiment is that firstly to adhere a strip of water dipped semipermeable membrane  94  aside the horizontal loop  92 , and then to force the cassette  7 -A or  7 -B to rest on the modified UBC  22   e  by aiming the lower opening  80  of the cassette at the row of small hole  90 . As a result, the semipermeable membrane  94  is tightly clamped therebetween, functionally to seal up the lower opening  80  of the cassette  7 -B or  7 -A. This embodiment enables the cassettes  7 A or  7 -B to undergo the gel casting in situ exactly at theirs electrophoresis running position, and subsequently to carry out the electrophoresis without need to move or remove anything. Although 30 years ago in U.S. Pat. No. 3,419,580, a semipermeable membrane had been employed to seal up the lower opening of the gel-casting cavity of the VSGE cell. However, there was no independent gel-casting cassette in that VSGE cell, and wherein the semipermeable membrane was a build-in part of the VSGE cell, so it was not easy to be replaced from time to time. 
       FIG. 13  is a perspective view of a segment of the infinite cassette/UBC complex  13 . Wherein each  11  is a cassette  11  or a cassette  10 , each  22   m  is a UBC module, each  86  is a V-shaped beak of the cassette, and each  96  symbolizes a clamping means. This drawing shows that by abutting the cassette  10  or  11  alternately with the UBCm modular can form an infinite cassette/UBC complex. This complex  13  can be extended as long as required, and stooped at any length by clamping two plastic plats at the two ends respectively. This embodiment can guarantee a numerous vertical slab gels to carry out the electrophoresis parallel in it under an identical condition. Therefore it is ideal for multiple the 2nd-D electrophoresis running of the 2-D gel electrophoreses simultaneously. 
       FIG. 14  is a set of front view showing a method for snugly encasing the VSGC cassettes into a plastic membrane pouch for gel casting. The method is that firstly to place one or several pieces of face-to-face arranged cassettes  50  into a roomy plastic membrane pouch  100   a , which has a lower softening point; then using some means to hold the open mouth area of the pouch, so as to prevent the mouth area from over shrinking; and then using a hot air blower to blow the plastic pouch  100   a  causing it shrinking. Thereafter the pouch  100   a  snugly wraps around the cassettes  50 . After removing the holding means, the cassettes  50  are ready to be sandwiched between two splints for gel casting. This method is good for encasing any sized VSGC cassettes for gel casting.  FIG. 14-A  shows that a wide camp  96   w  is employed to hold the open mouth.  FIG. 14-B  shows that by partially fusing the open mouth area, such as the  98  labeled area, and then to cut it off after shrinking. 
       FIG. 15  is a set of front view showing a method for snugly encasing the VSGC cassettes into an elastic membrane pouch for gel casting. Wherein  50  is one or several pieces of face-to-face arranged cassettes, but are placed upside-down;  100   b  is an elastic membrane pouch that has a tail tubule  110   a  at the bottom, and its cuff area has been curled up, so that a thicken beaded cuff  102  is formed;  104  and  104 ′ are two fingers, or any kind of stretching means, for propping up the elastic pouch  100   b  until it is expanded wide enough. Then wraps the expanded elastic pouch  100   b  around the cassettes  50 , as showing in  FIG. 15-A . After removing the stretching means, releasing the beaded cuff  102  as showing in  FIG. 15-B , and turning the cassettes right side up, thereupon the cassettes  50  are ready for the next step of gel casting. For the gradient gel casting, the gel forming solution should be injected into the pouch  100   b  via its tail tubule  110   a  (referring to  FIG. 18 ). For regular uniform gel casting, the elastic membrane pouch needs not to have the tail tubule  110   a.    
       FIG. 16  is a set of perspective view showing a method for snugly encasing two VSGC cassettes into an ordinary plastic membrane pouch for gel casting. In  FIG. 16-A , two cassette  50  and  50 ′ have been placed into a size appropriate ordinary plastic membrane pouch  100   c .  FIG. 16-B  shows that the cassette  50  and  50 ′ have been arranged to be side-by-side.  FIG. 16-C  and  16 -D shows that a propping means, such as a plastic stick  106   a  or a plastic card  108   a , has already rested on the central line of the pouch  100   c . While  FIG. 16-E  and  16 -F show that by using the propping means as an inflection point to fold up the plastic pouch  100   c  until the cassette  50  and  50 ′ from side-by-side became face-to-face. Thereafter, the cassette  50  and  50 ′ are snugly incased in the pouch  100   c , and ready for the next step of gel casting.  FIG. 16  disclosed a very convenient method to snugly encase two cassettes at once for gel casting. General specking, placing n piece cassettes (n&gt;1) side-by-side into an appropriate membrane pouch, then using n−1 pieces propping means from outside to rest on the pouch at the positions between each two neighboring cassettes, then by using the propping means as the inflection points to zigzag fold up the membrane pouch until all the cassettes from side-by-side became face-to-face, thereupon those cassettes are ready for the next step of gel casting. 
       FIG. 17  is a set of perspective view showing a method for snugly encasing the VSGC cassettes into an ordinary plastic membrane pouch for gel casting. Wherein  17 -A shows that one or several pieces of face to face arranged cassettes  50  have been placed into a roomy plastic membrane pouch  100   d , and have been moved to one side of the pouch. A propping means, such as the plastic stick  106   b , or the bent edge of the plastic card  108   b , is employed to rest on the pouch  100   d  at the position as close as to the cassettes. Then the method is using the propping means as a point of inflection to fold the remainder of the pouch  100   d  towards the cassette side, and to hold it in such a folding state by such as a piece of adhesive tape  112 , as shown in  FIG. 17-B . Thereafter the cassettes  50  are snugly incased in the pouch  100   d , and ready for the next step of gel casting. This method is very convenient and flexible. Besides, it also can be used to cast the gradient gels, provided the employed plastic membrane pouch has a tail tubule at the bottom (referring to  FIG. 18 ). 
       FIG. 18  is a set of front view showing the structure of the membrane pouches, each of them has a tail tubule.  FIG. 18-A  shows the structure of the elastic membrane pouch  100   b ,  110   a  is its tail tubule.  FIG. 18-B  shows the structure of the inelastic membrane pouch  100   d ′,  110   d ′ is its tail tubule. 
       FIG. 19  is a perspective view of the splint pair  19  employed for gel casting. Wherein  114 ′ is a movable splint,  114  is a immovable splint that has a base plate  116  attached under it,  118  is a V-shaped cut off formed on the base pleat  116  for the tail tubule  110  to pass through,  120  is a bottom stand for raising up the splint pair  114  and  114 ′ atop it, so as to perform the gradient gel casting; and each  96  symbolizes a clamping means. 
       FIG. 20  is a perspective view showing the way to sandwich the VSGC cassettes between the splint pair  19  for gel casting. Wherein  50  are the cassettes that have been snugly incased in a membrane pouch;  114  and  114 ′ is a splint pair, each  96  symbolizes a clamping means. For performing regular uniform gel casting, the gel forming solution can be poured into the cassettes from their upper openings. For performing the gradient gel casting, the splint pair  114  and  114 ′ should be raised atop the bottom stand  120 , as showing in  FIG. 19 , the employed pouch should have a tail tubule  110  at the bottom (referring to  FIG. 18 ), and the gel forming solution should be injected into the pouch via its tail tubule  110 . 
     After review the specification and the drawings, it is obvious that almost all aspects, but the structural style, about the VSGE cells and related methods have been improved in the present innovations. So the present innovated VSGE cells are still belong to the most popular styled VSGE cells, as mentioned in the background paragraph. Since the most popular styled VSGE cells are very familiar to every manufacturer as well as to every laboratory technician, so that there is no necessary to point out which face of the cassette is the abutting face that should to be used to abut to the UBC, where of a UBC the cassette should to be abutted at, etc. In addition, when we say two cassettes abut to a UBC, it means that the cassettes are forced to rest on the two U-shaped rubber sealing-gaskets of the UBC respectively, or means that the two cassettes are forced to sandwich a UBC between them.