WO1999053306A1 - Electrophoresis cassette having a tape assembly including a weakened portion which facilitates opening the cassette - Google Patents

Electrophoresis cassette having a tape assembly including a weakened portion which facilitates opening the cassette Download PDF

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Publication number
WO1999053306A1
WO1999053306A1 PCT/US1999/008387 US9908387W WO9953306A1 WO 1999053306 A1 WO1999053306 A1 WO 1999053306A1 US 9908387 W US9908387 W US 9908387W WO 9953306 A1 WO9953306 A1 WO 9953306A1
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WO
WIPO (PCT)
Prior art keywords
cassette
tape
tape assembly
reinforcing member
plate
Prior art date
Application number
PCT/US1999/008387
Other languages
French (fr)
Inventor
Bruce R. Turner
Original Assignee
Erie Scientific Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Erie Scientific Company filed Critical Erie Scientific Company
Priority to AU35665/99A priority Critical patent/AU3566599A/en
Publication of WO1999053306A1 publication Critical patent/WO1999053306A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/416—Systems
    • G01N27/447—Systems using electrophoresis
    • G01N27/44704—Details; Accessories

Definitions

  • This invention relates to electrophoresis cassettes, and in particular, to gel slab electrophoresis cassettes which are aligned in a vertical orientation.
  • Electrophoresis involves the separation of charged molecules in an electric field. It is based upon the principle that an electric field will cause charged molecules to migrate into separate fractions. Usually, separation of the charged molecules is based on the strength of the electrical field and the net charge, size and shape of the molecules. The rate of separation can also be based on other parameters, such as the isoelectric point, ionic strength, viscosity, and temperature of the medium in which the charged molecules are moving. Since proteins and other biological molecules, such as DNA, RNA, enzymes, -2- carbohydrates and the like are charged, electrophoresis techniques are ideal for use in separating these molecules for either analytical or preparative purposes.
  • Electrophoresis is generally performed in gels cast in tubes, slabs or on flat beds.
  • a tube gel unit is formed in a glass tube which is typically 12 cm. in length and between about 3 and 5 mm. in internal diameter.
  • the gel usually is formed between two non-conducting plates spaced apart by two spacer strips at the edges and clamped together to make a water-tight seal.
  • the gel tube units and gel slab cassettes are mounted vertically.
  • the flat bed gel units on the other hand, are mounted horizontally since the gels are poured on horizontal surfaces and they do not include top plates.
  • Gel electrophoresis devices may be broadly categorized as vertical gel electrophoresis devices or as horizontal gel electrophoresis devices.
  • the vertical gel electrophoresis devices include a bottom tank and a top tank removably situated inside the bottom tank so as to provide two spaces for electrolytes, i.e., a first or lower space between the respective walls of the bottom and top tanks and a second or upper space inside the top tank.
  • Both tanks include a vertically extending electrophoresis gel slab cassette, which contains a gel slab for separation of a mixture of charged biological molecules, and separate electrodes.
  • the electrophoresis devices the only intended path for electricity is from the electrode in the top space to an electrode in the bottom space, via electrolytes in the top space, the gel, and electrolytes in the bottom space, in that order. Buffer solutions are generally selected to function as the electrolytes in the tanks.
  • electrophoresis cassettes typically include a slab of gel, cast in a sandwich-type arrangement between two die-electric or non-conducting flat plates, such as glass, to form a sheet of gel between the glass surfaces. Clear glass plates are generally selected to permit monitoring of the gel-forming solution as it is injected into the space between the plates, as well as monitoring of the finished gel as electrophoresis is taking place. While the gels used in the different types of electrophoresis cassettes may vary in shape, a common gel configuration is that of a thin, flat slab being generally of uniform thickness.
  • the glass plates of electrophoresis cassettes are typically separated by thin, flat, rectangular-shaped spacer strips positioned between the glass plates and along their opposing vertical side edges.
  • the electrophoresis cassettes are generally held together by clamps at each vertical edge to form the water-tight seals. To accomplish this, the clamps typically extend along the entire length of the opposing vertical side edges of the glass plates of the electrophoresis cassettes.
  • the surfaces at each end of the gel slab are connected to separate electrodes via the buffer solutions.
  • a potential is applied across the gel slab by connecting each buffer solution to opposite polarities of a voltage source.
  • the mixture of charged biological molecules to be sorted is placed at the negative electrode end of the gel slab, usually in preformed wells.
  • the electrical field applied across the gel slab reacts with the negative charges on the biological molecules to provide a force propelling the charged biological molecules through the gel slab towards the positive electrode. Smaller charged biological molecules have less resistance to travelling through the gel slab than larger -4- charged biological molecules, resulting in a separation and sorting of the biological molecules by size as they migrate through the gel slab.
  • the gels can be analyzed by staining or autoradiography followed by densitometry, or by blotting to a membrane for nucleic acid hybridization, autoradiography or immunodetection.
  • the autoradiography method relied upon to view the electrophoretic separation of charged biological molecules in a gel slab involves, for instance, the use of radiolabeled molecules.
  • the gel slab used for electrophoresis is removed from its cassette following the electrophoresis run and placed along-side a photographic medium which is exposed by the radioactive emissions of the radio-labeled biological molecules. Developing the emissions in the photographic medium produces a series of stripes representative of the position of each set of radio-labeled biological molecules.
  • the migration patterns of multiple rows obtained after the migration i.e., a group of zones formed by electrophoresis on the gel slab, is recorded as an autoradiogram.
  • the mixture of charged biological molecules consists of DNA or RNA molecules
  • the base arrangement of the DNA or RNA molecules is determined by comparing positions of the separated zones in the respective rows with one another.
  • a stain is used to stain the migrated molecules.
  • This method generally involves removing the gel slab used for electrophoresis from its cassette following the electrophoresis run, and exposing it to, for example, Coomassie Blue to stain the separated fractions and also to produce a series of visible stripes representative of the position of each set of stained biological molecules.
  • the molecular weights of the charged biological molecules, such as proteins, can be determined by comparing positions of the stained stripes in the respective rows with one another and against a row of visible stripes formed with markers having known molecular weights.
  • the separated molecules may be stained by photographic amplification systems using silver or other first row transition metals.
  • an electrophoresis cassette which includes a front plate, a back plate, at least one spacer positioned between the front plate and back plate, a holding member, and a tape assembly.
  • the front plate includes a left side and a right side, with each of the left and right sides having a sidewall with a front edge and an interior edge.
  • the back plate includes a corresponding left side and a corresponding right side, with each of the left and right sides having a sidewall with a back edge and an interior edge.
  • the spacer or spacers positioned between the front and back plates create(s) an inter-plate distance between the two plates, thereby forming a gel slot in cooperation with the front and back plates.
  • the holding member is connected to one of the left and right sides of the front plate, as well as to the corresponding left or right side of the back plate.
  • the tape assembly is connected to the other one of the left and right sides of the front plate, and to the corresponding left or right side of the back plate, and includes at least one piece of tape, a plate- facing side, an outwardly-facing side, and a weakened portion, the weakened portion facilitating the opening of the cassette.
  • Fig. 1 is an exploded, perspective view of a version of the electrophoresis cassette according to the principles of the invention. -7-
  • Fig. 2 is an assembled, perspective view of the electrophoresis cassette shown in Fig. 1 ;
  • Fig. 3 is a perspective view of the electrophoresis cassette shown in Fig. 1, with one side of the cassette shown in an open position following the severing of the tape assembly on that particular side of the cassette;
  • Fig. 4A is a top view of the tape assembly substantially as shown in Fig 1 ;
  • Fig. 4B is an end view of the assembly shown in Fig. 4A;
  • Fig. 4C is a top view of a portion of the assembly shown in Figs. 4A and 4B;
  • Fig. 5 is a top view of several of the tape assemblies depicted in Figs. 4A-4C in one stage of a manufacturing process used to form such tape assemblies;
  • Fig. 6A is a top view of another version of the tape assembly according to the principles of the invention.
  • Fig. 6B is an end view of the assembly shown in Fig. 6 A;
  • Fig. 6C is a top view of a portion of the assembly shown in Figs. 6A and 6B;
  • Fig. 7A is a top view of a further version of the tape assembly;
  • Fig. 7B is an end view of the assembly shown in Fig. 7 A;
  • Fig. 8 A is a top view of an additional version of the tape assembly
  • Fig. 8B is an end view of the assembly shown in Fig. 8 A;
  • Fig. 9A is a top view of yet another version of the tape assembly
  • Fig. 9B is an end view of the assembly shown in Fig. 9 A;
  • Fig. 10A is a top view of an additional version of the tape assembly
  • Fig. 10B is an end view of the assembly shown in Fig. 10A;
  • Fig. 11A is a top view of another version of the tape assembly
  • Fig. 1 IB is an end view of the assembly shown in Fig. 11 A; -8-
  • Fig. 11C is a perspective, partial cross-sectional view of a portion of a side of one version of the electrophoresis cassette, incorporating a tape assembly substantially as shown in Figs. 11 A and 1 IB;
  • Fig. 12 is a perspective view of a portion of a side of another version of the cassette, shown in partial cross-section;
  • Fig. 13 is a perspective view of a portion of an additional version of the cassette, also shown in partial cross-section;
  • Fig. 14 is a perspective view of a portion of a side of yet another version of the electrophoresis cassette, shown in partial cross-section;
  • Fig. 15 is a perspective view of a portion of a side of a further version of the cassette, shown in partial cross-section;
  • Fig. 16 is a perspective view of a portion of a side of another version of the electrophoresis cassette, shown in partial cross-section.
  • FIG. 1 shows one version 10 of an electrophoresis cassette according to the principles of the invention.
  • This cassette 10 includes a front plate 12, a back plate 14, at least one spacer 16, a holding member 18, and a tape assembly 20.
  • the front plate 12 includes a left side 22 and a right side 24 with each of the corresponding left and right sides 22, 24 having a sidewall 26 with a front edge 28 and an interior edge 30.
  • the back plate 14 has a corresponding left side 32 and a corresponding right side 34, with each of the corresponding left and right sides 32, 34 including a sidewall 36 with a back edge 38 and an interior edge 40.
  • the term "corresponding" refers to the particular left or right side of the back plate which is positioned generally behind the left or right side, respectively, of the front plate.
  • the -9- particular cassette shown in fact, includes a left spacer 42 and a right spacer 44 positioned between the front and back plates 12, 14, thereby creating an inter-plate distance 46 (see Fig. 11C) between the front and back plates 12, 14, and forming a gel slot 48 in cooperation with the front and back plates 12, 14.
  • the holding member 18 is connected to one of the left and right sides 22, 24 of the front plate 12, and to the corresponding left or right side 32, 34 of the back plate 14.
  • the tape assembly 20 is connected to the other one of the left and right sides 22, 24 of the front plate 12 and to the corresponding left or right side 32, 34 of the back plate 14.
  • the tape assembly 20 has at least one piece of tape 50, a plate-facing side 52, an outwardly-facing side 54, and a weakened portion 56, with the weakened portion 56 facilitating the opening of the cassette.
  • a left spacer 42 and right spacer 44 are used, as noted above.
  • an electrophoresis cassette may have a single spacer, or more than two spacers.
  • the spacer(s) need not be rectangular, and need not be positioned with exterior sidewalls(s) flush with the front and back plate sidewalls of the cassette, i.e., the spacer(s) may be placed "inboard" of such sidewalls. Examples of some of the many variations may be found in Danby et al. U.S. Patent No.
  • the holding member 18 is conveniently a tape assembly identical to the tape assembly 20.
  • the assembly 20 may be referred to as a first tape assembly 57, while the holding member 18 may be called a second tape assembly 58, it being understood that the assembly 58 is identical to the assembly 20.
  • 18 may be any element or combination of elements suitable for use in an electrophoresis cassette to connect the particular left or right side 22, 24 of the front plate 12 to the corresponding left or right side 32, 34 of the back plate 14.
  • Various forms of holding members are known to those of ordinary skill in the art, with one particular example being the side clamp 48 described in Danby et al., U.S. Patent No. 4,929,329, cited above.
  • each of the first and second tape assemblies 57, 58 includes a piece of tape 50 having a substantially rectangular portion 60, with the length of the portion 60 generally corresponding with the height of the cassette 10, and the width of the portion 60 being sufficient to connect the front plate 12 to the back plate 14 along their respective left and right sides 22, 24, 32, 34.
  • the substantially rectangular portion 60 has an upper end 61, a lower end 63, a left edge 65, and a right edge 67.
  • Each of these particular tape assemblies 57, 58 advantageously includes a weakened portion 56 in the form of perforations 62, as well as a reinforcing member 64 and a grippable portion in the form of a projecting tab 66.
  • each tape assembly is shown in a planar, unassembled position, with the assembled position being shown in phantom.
  • the perforations 62 form a first, straight line 68 and a second, straight line 70 along the length of the assemblies 57, 58, with the lines 68, 70 being spaced apart so as to have a particular inter-line width 72.
  • the reinforcing member 64 is positioned on the plate- facing side 52 of the tape assembly 20, and, in fact, is connected directly to the piece of tape 50. As shown in Figs.
  • the projecting tab 66 is an integral part of the tape 50 of each tape assembly 57, 58, formed by sizing each tape assembly 57, 58 so as to have a tab 66 extending from the rectangular portion upper end 61.
  • This particular tab 66 is formed of the tape 50 and the reinforcing member 64, and is sized so that a technician or other operator may securely grasp it.
  • the tab 66 is -11- aligned with the first and second lines of perforations 68, 70, and has a width similar to the inter-line width 72 between the first and second lines 68, 70. This particular arrangement allows a technician to open a particular side of the cassette 10 easily and conveniently, simply by grasping the projecting tab 66 and pulling the tab 66 down and away from the rest of the particular tape assembly 57, 58.
  • Each of the first and second tape assemblies 57, 58 may be made of any material or materials suitable for use in an electrophoresis cassette.
  • the particular material or materials used should be resistant to the electrophoresis chemicals and gels, and also should be non-conductive.
  • a vinyl tape and a polyester reinforcing member may be used to advantage.
  • one suitable vinyl tape is number 471 vinyl tape available from 3M's Industrial Tape & Specialties Division, St. Paul, MN 55144-1000. This particular vinyl tape happens to be a yellow, pressure-sensitive, adhesive tape, with the adhesive being an acrylic material.
  • Suitable polyester reinforcing member material is Mylar®, which may be obtained from Adhesives Research, Inc., Glenrock, PA 17327, under the product code ARCARE 8651.
  • the particular tape assembly or assemblies made according to the principles of the invention may come in any of a number of different shapes and sizes.
  • the particular assemblies 57, 58 shown extend along virtually the entire length of the left and right sides of the electrophoresis cassette 10.
  • the dimensions of each of the tape assemblies 57, 58 are determined, in part, by the length and thickness of the front plate 12, back plate 14, and spacers 42, 44.
  • the front plate 12, back plate 14 and spacers 42, 44 shown in Figs. 1-3 each may suitably have a length (vertical height) of about 3.15 inches (80 millimeters) and a thickness of about 0.04 inches (1 millimeter).
  • the front and back plates 12, 14 may have a width of about 3.94 inches -12-
  • each of the spacers 42, 44 may suitably have a width of about 0.28 inches (7 millimeters).
  • the height of the front plate 12 is somewhat less than the height of the back plate 14 at the upper end 82 of the gel slot 48, which enhances the contact of the uppermost end of a gel slab (not shown) formed in the gel slot 48 with a buffered solution in an upper tank or reservoir (not shown).
  • the height of the front plate 12 at the upper end 82 of the gel slot 48 may suitably be about 2.75 inches (70 millimeters).
  • the curve 84 in the front plate 12 leading to this shortened region at the upper end 82 of the gel slot 48 may suitably have a radius of about 0.06 inch (1.5 millimeters).
  • each of the tape assemblies 57, 58 shown in Figs. 1-4B may have a length of about 3.15 inches (80 millimeters), excluding the projecting tab 66, and a width of about 0.75 inch (19 millimeters).
  • the first and second lines 68, 70 of perforations 62 may be positioned centrally with respect to the width of the tape assemblies 57, 58, with each assembly 57, 58 having an inter-line width 72 of about 0.12 inch (3 millimeters), a width which advantageously corresponds with the combined thickness of the particular spacer, front plate and backplate discussed above.
  • the width of the reinforcing member 64 suitably corresponds with the inter-line width 72, namely, a width of about 0.12 inch (3 millimeters).
  • the projecting tab 66 which extends from the upper end 61 of the substantially rectangular tape portion 60 may have a width of about 0.12 inch (3 millimeters) and a length of about 0.3 inches (7.6 millimeters), and, if desired, may have a rounded or contoured end, as shown in Figs. 4A and 4C.
  • the polyester reinforcing member advantageously has a thickness of about 2 mil (0.002 inches; 0.05 millimeters) and may run the full length of the tape assembly 50, from the end -69 of the tab 66 to the lower end 63 of the rectangular portion 60.
  • the reinforcing -13- member 64 may advantageously have a modulus of elasticity which is lower than that of the material used for the tape 50. By having a lower modulus of elasticity, the reinforcing member 64 will stretch less than the tape 50, thereby providing even greater assistance to the technician, as the technician peels away the perforated, reinforced portion 73 of one or both of the tape assemblies 57, 58.
  • tape assemblies 57, 58 shown in Figs. 1-4C may be manufactured in any of a number of different ways, as will be readily apparent to those of ordinary skill in the art.
  • tape assemblies according to the principles of the invention may be formed on a commercial scale using an in-line process.
  • the roll of tape used to form the tape assemblies initially may be cut to the particular tape assembly width.
  • the reinforcing member material may, if desired, be cut to its appropriate width.
  • the roll of reinforcing member material and the roll of tape may be placed in proper alignment at one end of a machine, and subsequently unwound, passed across a roller or rollers, and laid onto a release liner, for example, a silicone-coated, 60- pound, white, kraft paper, release liner, with the reinforcing member material and tape being placed onto the release liner in the appropriate alignment.
  • a release liner for example, a silicone-coated, 60- pound, white, kraft paper, release liner
  • this tape/reinforcing member/release liner combination is rewound at a subsequent point in the in-line process, as additional reinforcing member material and tape are being adhesively positioned on the release liner.
  • This combination tape/reinforcing member/release liner then may be run through a series of several stations, typically several rollers and cutting elements.
  • one of the stations typically will have rotary cutters which are spaced apart so as to provide a desired inter-line width 72 between the first and second lines 68, 70 of perforations 62.
  • Each of the rotary cutters is equipped with serrations, and the tape typically is positioned or "pinched" between the cutters and a pressure roller, resulting in the formation of the perforations 62.
  • a rotary die or dies may be used to cut the tape, so that the tape has the desired length and width, as well as a projecting tab 66 of suitable dimensions. It should be noted that if the roll of tape has been cut to the appropriate width at the beginning of the manufacturing process, then there is no need for the rotary die or dies to stamp the tape assembly width at this later point in the process.
  • the scrap material (not shown) surrounding the assemblies 20 then may be removed manually or by machine, at which point the release liner supporting the assemblies 20 is rolled up for subsequent use. Fig.
  • FIG. 5 shows the result of such an in-line process, depicting a series of tape assemblies 20 releasably adhered to a silicone-coated, kraft paper, release liner 80, and ready for subsequent use in forming electrophoresis cassettes.
  • a series of tape assemblies 20 adhered to a release liner 80 may be obtained from M&C Specialities, Inc., 90 James Way, Southhampton, PA 18966, under the product code A-860-058.
  • the perforations 62 in the assemblies 20 suitably may be "micro-perforations," a term which is known in the tape-perforating art. And, in fact, the perforations in the A-860-058 tape assemblies from M&C Specialities are micro-perforations.
  • a partially-completed cassette may be formed in any of a number of different ways, as will be readily apparent to one of ordinary skill in the art.
  • an in-line process is used, in which a series of stations is established along a conventional, low- friction, belt assembly line.
  • a series of "vehicles" are placed upon the belt.
  • Each vehicle is essentially a frame for receiving various elements of the electrophoresis cassette as it is being constructed.
  • a backplate may be -15- placed horizontally into the vehicle, and a dispensing tip or tips may dispense droplets of a UV-sensitive adhesive on the backplate, with each side of the backplate receiving three drops or dots of adhesive.
  • the left and right spacers may be manually placed onto the backplate.
  • another tip or plurality of tips may dispense two dots of UV-sensitive adhesive on each spacer, following which, an operator may manually place the front plate onto the spacers.
  • each partially-assembled cassette is presented to the operator on edge, thereby allowing the operator to advance a tape assembly from a tape dispensing machine, and to align and place the tape assembly on the side of the cassette. This assembly subsequently may be flipped over, thereby exposing the other side, at which point the operator may advance another tape assembly from the tape dispensing machine, and secure the assembly to this other side of the cassette.
  • the completed cassettes may be placed into holding racks and given a detergent wash, followed by several ultrasonic rinses using de- ionized water. Then, the cassettes may be wrapped for shipment or filled with a particular gel, as desired.
  • an electrophoresis gel (not shown) may be introduced into the gel slot 48 formed by the spacers 42, 44, front plate 12, and back plate 14. Before pouring a gel into the cassette 10, a well-forming comb (not shown) may be positioned inside the top of the gel slot 48, as known by those of ordinary skill in the art.
  • Figs. 6A-6C show another version of the tape assembly 120 according to the principles of the invention. This particular tape assembly 120 is very similar to the tape assembly 20 shown in Figs.
  • this assembly 120 also includes a tape piece 50 having a projecting tab 66, as well as a first, straight line 68 of perforations 162 along the length of the tape assembly 120, and a second, straight line 70 of perforations 162 parallel to the first line 68.
  • this particular version 120 does not include a reinforcing member.
  • the perforations 162 formed in the tape 50 are approximately three times as long as the perforations 62 formed in the version 20 shown in Fig. 4C.
  • the spacing 86 between each of these elongated perforations 162 along the first line 68 and along the second line 70 is similar to the inter-perforation spacing 86 of each of the first and second lines 68, 70 in the tape assembly version 20 shown in Fig. 4C.
  • the interline width 72 of the assembly 120 shown in Fig. 6C is generally similar to that of the Fig. 4C assembly 20.
  • Tape assembly 120 may be made and used according to the methods discussed above in conjunction with the assembly 20. With reference to Figs. 7A and 7B, a further version of the tape assembly
  • the assembly 220 includes a piece of tape 50 having a substantially rectangular portion 60, with a single, straight line 88 of perforations 62 centrally positioned between the left and right edges 65, 67 of the tape portion 60, and running along the entire length of the tape portion 60.
  • the assembly 220 includes a reinforcing member in the form of a monofilament line 94, which is positioned on the plate-facing side 52 of the assembly 220 in general -17- alignment with the single, straight line 88 of perforations 62.
  • the monofilament line 94 has an extending portion 95 which extends beyond the upper end 61 of the rectangular portion 60, thereby allowing a technician to grasp the line 94 and sever the tape 50.
  • This particular tape assembly 220 may be made and used according to the methods discussed above in conjunction with the tape assembly 20 shown in Figs. 1-4C.
  • Figs. 8A-10B depict additional versions of the tape assembly which are somewhat similar in nature to the versions shown in Figs. 1-7B.
  • these additional embodiments incorporate a thinned region or regions 96 along the length of the tape assembly, instead of the perforations 62, 162 used in the earlier embodiments.
  • the tape assembly 320 of Figs. 8 A and 8B includes a piece of tape 50 having a substantially rectangular portion 60 with an upper end 61, a lower end 63, a left edge 65, and a right edge 67, and a projecting tab 66 extending from the upper end 61.
  • the piece of tape includes a first, straight, thinned line 106 along the length of the tape 50, as well as a second, straight, thinned line 108 parallel to the first line 106.
  • These lines have an inter-line width 72 which corresponds generally with the width and alignment of the projecting tab 66, all of which is positioned centrally between the left and right edges 65, 67 of the piece of tape 50.
  • the tape assembly 320 further includes a reinforcing member 64 having a width substantially similar to the inter-line width 72 of the first and second thinned lines 106, 108, and underlying the tape 50 between those lines 106, 108.
  • this reinforcing member 64 extends along the entire length of the tape 50, from the end 69 of the projecting tab 66 to the lower end 63 of the rectangular portion 60.
  • This particular version of the tape assembly 320 may be made by a process similar to the process discussed above in conjunction with the tape assembly 20 depicted in Figs. 1-4C. The only significant change is that, instead of using a station having a rotary cutter or pair of cutters with serrations, a wheel, -18- pair of wheels, or any other object having one or more parallel, heated, non-cutting edge(s) may be used.
  • the assembly 420 of Figs. 9A and 9B is similar to that shown in Figs. 8A and 8B, except that the assembly 420 of Figs. 9A and 9B does not include a reinforcing member.
  • this particular version of the tape assembly 520 includes a single, straight, thinned line 110 running the length of the tape 50, and positioned centrally between the left and right edges 65, 67 of the tape portion 60.
  • This particular assembly 520 further includes a monofilament line 94 which runs the length of the tape 50, and which is centrally positioned on the plate-facing side 52 of the tape 50, generally equidistant between the left and right edges 65, 67 of the tape portion 60.
  • this monofilament line 94 has an extending portion 95 which extends beyond the upper end 61 of the rectangular portion 60, thereby allowing a technician to grasp the monofilament 94 and sever the piece of tape 50.
  • FIG. l lA-l lC A further aspect of the invention is depicted in Figs. l lA-l lC.
  • These particular drawings show a version of the tape assembly 620 which includes a front tape piece 112 for placement along at least a portion of the length of a side 22, 24 of the front plate 12, a back tape piece 114 for placement along at least a portion of the length of a corresponding side 32, 34 of the back plate 14, and a bridge member 116 along at least a portion of the length of the front tape piece 112 and the back tape piece 114.
  • This particular version of the bridge member 116 is connected to the front tape piece 112 and the back tape piece 114 by thermal welding, with the weakened portion 56 of the tape assembly 620 being represented, at least in part, by a front thermal weld line 144 bonding the front tape piece 112 to the bridge member 1 16, and a back thermal weld line 146 -19- bonding the back tape piece 114 to the bridge member 116.
  • the front tape piece 112 has an inner edge 118
  • the back tape piece 1 14 also has an inner edge 122 with the front tape piece inner edge 118 ending generally at the front plate interior edge 30, and the back tape piece inner edge 122 ending generally at the back plate interior edge 40. In this manner, and as best shown in Fig.
  • the inter-plate distance 46 between the front and back plate sidewalls 26, 36 is substantially free of both the front tape piece 112 and the back tape piece 114. Moreover, this inter-plate distance 46 substantially corresponds with the thickness of the spacer 16.
  • the bridge member 116 itself has a front edge 124, a back edge 126, an upper end 128 having a projecting tab 130, a lower end 132, and a width 134 which generally corresponds with the combined thickness of the front plate 12, back plate 14, and spacer 16. Moreover, as shown in Fig. 11C, the bridge member 116 extends from the front plate front edge 28 to the back plate back edge 38.
  • This particular tape assembly 620 may be made using a method somewhat similar to the methods of manufacture discussed in conjunction with the various tape assembly embodiments discussed above.
  • an in-line process may be used.
  • two rolls of tape may be aligned in a side-by-side relationship, with any desired spacing between the two rolls.
  • the spacing between the two rolls may suitably correspond to the desired space between the front tape piece inner edge 118 and back tape piece inner edge 122 in the completed tape assembly 620.
  • Each of these rolls then may be simultaneously unwound and adhered to a silicone-coated, kraft-paper release liner.
  • the material used for the bridge member 116 may be simultaneously placed in its proper connecting relationship on the upper surface 136 of the front and back tape pieces 112, 114.
  • the bridge member 116 may be applied in a subsequent step, once the front and back tape pieces 112, 114 have been releasably adhered to the silicone-coated release -20- liner.
  • the material used for the bridge member 1 16 may be any material or combination of materials suitable for use in an electrophoresis cassette.
  • 3M's No. 471 vinyl tape version without the pressure-sensitive adhesive may be used to advantage, and may be adhered to the upper surface 136 of each of the front and back tape pieces 112, 114 by a continuous, in-line, thermal welding process, as discussed briefly above.
  • the unwelded sub-assembly may be passed along two thin heating elements or rolls which form the front and back thermal weld lines 144, 146, thereby defining a central portion 148 between the weld lines 144, 146.
  • the vinyl tape or any other appropriate material may be attached to the front and back tape pieces 112, 114 using any suitable method known in the art.
  • the tape pieces 112, 114 and bridge member 116 may be connected using an adhesive, an ultrasonic weld, or the like.
  • Individual tape assemblies 620 then may be formed by moving the kraft paper/tape/bridge member sub-assembly through a die cutting operation to produce the tape assembly 620 shown in Figs. l lA-l lC.
  • a tape assembly 620 may be applied to the front and back plates 12, 14 as discussed above in conjunction with other embodiments, in order to complete an electrophoresis cassette. Then, in use, once a technician is ready to open up a side of the electrophoresis cassette, the technician may sever the bridge member 116 simply by grasping the tab 130 and pulling the central portion 148 of the bridge member 116 away from the rest of the cassette, with the central portion 148 tending to sever where the weld lines 144, 146 have been formed.
  • the tape assembly 720 shown in Fig. 12 is somewhat similar to the tape assembly 620 shown in Figs. 11 A-l 1C, but includes perforations 62 in the bridge member 116, in the form of a first, straight line of perforations 68 and a second, straight line of perforations 70 parallel to the first line 68.
  • the inter-line width 72 between the lines of perforations 68, 70 is generally the same as the width of the tab 130 and the spacer 16.
  • This particular embodiment may be made using a combination of the manufacturing methods discussed above.
  • this sub-assembly then may be passed across a pair of rotary cutters having serrations which form cuts in the bridge member, thereby forming the perforations 62.
  • a technician or other operator need only pull on the tab portion 130, with the bridge member 116 tearing along the perforation lines 68, 70, thereby opening the electrophoresis cassette.
  • the tape assembly 820 depicted in Fig. 13 is quite similar to that shown in Fig. 12, further including a reinforcing member 64 underlying the portion 138 of the bridge member 116 between the first and second lines of perforations 68, 70.
  • the reinforcing member 64 is directly connected to this central portion 138 of the bridge member 116, and also extends from the upper end 128 of the tape assembly 820, so as to form the undersurface of the projecting tab 130.
  • Fig. 14 illustrates yet another version of the tape assembly 920, which is somewhat similar to the versions 720, 820 shown in Figs. 12 and 13.
  • This particular tape assembly 920 is similar in that the inner edges 118, 122 of the front and back tape pieces 112, 114 end generally at the front plate interior edge 30 and back plate interior edge 40, respectively.
  • these front and back tape pieces 112, 114 are connected by a bridge member 116 which is sized so that the bridge member front edge 124 terminates at about the front plate sidewall front edge 28, and the bridge member back edge 126 terminates at about the back plate sidewall back edge 38.
  • This particular tape assembly 920 also includes a reinforcing member 64 positioned on the plate-facing side 52 of the tape assembly 920, and connected directly to the bridge member 116. However, the tape assembly 920 includes no perforations.
  • this particular assembly 920 may be manufactured using various combinations of the manufacturing methods discussed above.
  • the resulting electrophoresis cassette subsequently may be opened by pulling on the projecting tab 130, which includes a portion of the reinforcing member 64 on its undersurface.
  • the reinforcing member 64 has a modulus of elasticity which is lower than that of the bridge member 116 material, thereby enabling the reinforcing member 64 to tear through the surrounding bridge 116 material relatively easily.
  • Fig. 15 illustrates a tape assembly 1020 in which the inner edge 118 of the front tape piece 112 and the inner edge 122 of the back tape piece 114 both extend beyond the front and back plate interior edges 30, 40, and into a portion of the inter-plate distance 46 between the front and back plates 12, 14.
  • the inner edges 118, 122 of the front and back tape pieces 112, 114 are separated by a distance of about 0.01 millimeter, thereby forming a gap 140.
  • This particular tape assembly 1020 further includes perforations 62 in the form of a single, straight line 88 along the length of the bridge member 116, with the line of perforations 88 being centrally located between the front and back edges 124, 126 of the bridge member 116, thereby positioning the perforated line 88 directly above the gap 140 between the inner edges 118, 122 of the front and back tape pieces 112, 114.
  • This tape assembly 1020 also includes a reinforcing member 64 in the form of a monofilament 94, which is positioned directly beneath the perforated line 88 of the bridge member 116.
  • This monofilament 94 has an extending portion 95 which extends from the upper end 142 of the bridge member 116, thereby enabling an operator to grasp and pull the monofilament 94, in order to sever the bridge member 116.
  • This particular version of the tape assembly 1020 may be manufactured using the various methods discussed above. -23-
  • Fig. 16 depicts a tape assembly 1120 in which the inner edge 118 of the front tape piece 112 ends generally at the front plate interior edge 30, whereas the inner edge 122 of the back tape piece 114 extends beyond the back plate interior edge 40, and into a portion of the inter-plate distance 46.
  • This particular assembly 1120 also includes a reinforcing member 64 positioned on the plate- forming side 52 of the tape assembly 1120, connected directly to the bridge member 116, so as to overlie the inter-plate distance 46 between the front and back plates 12, 14.
  • the bridge member 116 further includes a tab 130 extending from its upper end 142, formed of bridge member 116 material and reinforcing member 64 material.
  • This particular tape assembly 1120 may be made and used as described above.

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Abstract

An electrophoresis cassette (10) includes a front plate (12), a back plate (14), at least one spacer (16) positioned therebetween, a holding member (18), and a tape assembly (20). The spacer(s) (16) positioned between the front and back plates (12, 14) create(s) an inter-plate distance (46) between the two plates (12, 14), thereby forming a gel slot (48) in cooperation with the front and back plates (12, 14). The holding member (18) is connected to one of the left and right sides (22, 24) of the front plate (12), as well as to the corresponding left or right sides (32, 34) of the back plate (14). The tape assembly (20) is connected to the other side of the left and right sides (22, 24) of the front plate (12), and to the corresponding left or right side (32, 34) of the back plate (14), and includes at least one piece of tape (50), a plate-facing side (52), an outwardly-facing side (54), and a weakened portion (56), the weakened portion (56) facilitating the opening of the cassette (10).

Description

ELECTROPHORESIS CASSETTE HAVING A TAPE ASSEMBLY INCLUDING A WEAKENED PORTION WHICH FACILITATES OPENING THE CASSETTE
Background of the Invention
Field of the Invention
This invention relates to electrophoresis cassettes, and in particular, to gel slab electrophoresis cassettes which are aligned in a vertical orientation. Description of the Related Art
Electrophoresis involves the separation of charged molecules in an electric field. It is based upon the principle that an electric field will cause charged molecules to migrate into separate fractions. Usually, separation of the charged molecules is based on the strength of the electrical field and the net charge, size and shape of the molecules. The rate of separation can also be based on other parameters, such as the isoelectric point, ionic strength, viscosity, and temperature of the medium in which the charged molecules are moving. Since proteins and other biological molecules, such as DNA, RNA, enzymes, -2- carbohydrates and the like are charged, electrophoresis techniques are ideal for use in separating these molecules for either analytical or preparative purposes.
Electrophoresis is generally performed in gels cast in tubes, slabs or on flat beds. A tube gel unit is formed in a glass tube which is typically 12 cm. in length and between about 3 and 5 mm. in internal diameter. In a gel slab, the gel usually is formed between two non-conducting plates spaced apart by two spacer strips at the edges and clamped together to make a water-tight seal. The gel tube units and gel slab cassettes are mounted vertically. The flat bed gel units, on the other hand, are mounted horizontally since the gels are poured on horizontal surfaces and they do not include top plates. Gel electrophoresis devices may be broadly categorized as vertical gel electrophoresis devices or as horizontal gel electrophoresis devices. Typically, the vertical gel electrophoresis devices include a bottom tank and a top tank removably situated inside the bottom tank so as to provide two spaces for electrolytes, i.e., a first or lower space between the respective walls of the bottom and top tanks and a second or upper space inside the top tank. Both tanks include a vertically extending electrophoresis gel slab cassette, which contains a gel slab for separation of a mixture of charged biological molecules, and separate electrodes. In the electrophoresis devices, the only intended path for electricity is from the electrode in the top space to an electrode in the bottom space, via electrolytes in the top space, the gel, and electrolytes in the bottom space, in that order. Buffer solutions are generally selected to function as the electrolytes in the tanks. To prevent the gel electrophoresis devices from shorting out and to force the electric current through the gel slab, it is imperative that the buffer solution in the top space remain separated at all -3- times from the buffer solution in the bottom space. In other words, the electrical connection between the two electrodes is only through the gel slab.
As indicated, electrophoresis cassettes typically include a slab of gel, cast in a sandwich-type arrangement between two die-electric or non-conducting flat plates, such as glass, to form a sheet of gel between the glass surfaces. Clear glass plates are generally selected to permit monitoring of the gel-forming solution as it is injected into the space between the plates, as well as monitoring of the finished gel as electrophoresis is taking place. While the gels used in the different types of electrophoresis cassettes may vary in shape, a common gel configuration is that of a thin, flat slab being generally of uniform thickness. The glass plates of electrophoresis cassettes are typically separated by thin, flat, rectangular-shaped spacer strips positioned between the glass plates and along their opposing vertical side edges. The electrophoresis cassettes are generally held together by clamps at each vertical edge to form the water-tight seals. To accomplish this, the clamps typically extend along the entire length of the opposing vertical side edges of the glass plates of the electrophoresis cassettes.
In performing an electrophoresis separation of a mixture of charged biological molecules, the surfaces at each end of the gel slab are connected to separate electrodes via the buffer solutions. A potential is applied across the gel slab by connecting each buffer solution to opposite polarities of a voltage source. The mixture of charged biological molecules to be sorted is placed at the negative electrode end of the gel slab, usually in preformed wells. The electrical field applied across the gel slab reacts with the negative charges on the biological molecules to provide a force propelling the charged biological molecules through the gel slab towards the positive electrode. Smaller charged biological molecules have less resistance to travelling through the gel slab than larger -4- charged biological molecules, resulting in a separation and sorting of the biological molecules by size as they migrate through the gel slab.
Following electrophoresis runs, the gels can be analyzed by staining or autoradiography followed by densitometry, or by blotting to a membrane for nucleic acid hybridization, autoradiography or immunodetection. The autoradiography method relied upon to view the electrophoretic separation of charged biological molecules in a gel slab involves, for instance, the use of radiolabeled molecules. Typically, the gel slab used for electrophoresis is removed from its cassette following the electrophoresis run and placed along-side a photographic medium which is exposed by the radioactive emissions of the radio-labeled biological molecules. Developing the emissions in the photographic medium produces a series of stripes representative of the position of each set of radio-labeled biological molecules. In other words, the migration patterns of multiple rows obtained after the migration, i.e., a group of zones formed by electrophoresis on the gel slab, is recorded as an autoradiogram. When the mixture of charged biological molecules consists of DNA or RNA molecules, the base arrangement of the DNA or RNA molecules is determined by comparing positions of the separated zones in the respective rows with one another.
In the more common method relied upon to view the electrophoretic separation of charged biological molecules in a gel slab, a stain is used to stain the migrated molecules. This method generally involves removing the gel slab used for electrophoresis from its cassette following the electrophoresis run, and exposing it to, for example, Coomassie Blue to stain the separated fractions and also to produce a series of visible stripes representative of the position of each set of stained biological molecules. The molecular weights of the charged biological molecules, such as proteins, can be determined by comparing positions of the stained stripes in the respective rows with one another and against a row of visible stripes formed with markers having known molecular weights. In -5- addition to Coomassie Blue, the separated molecules may be stained by photographic amplification systems using silver or other first row transition metals.
The comparison in either of the above recited methods is carried out based on the electrophoresis principle that charged biological molecules having equal molecular weights, charges, and shapes migrate by equal distances if the electrophoresis is started from the same line and under the same conditions, such as ionic strength, viscosity and temperature.
While vertical electrophoresis gel slab cassettes have been successfully used to carry out electrophoresis, they are not without drawback. During the initial assembly, the vertical electrophoresis gel slab cassettes traditionally available generally are assembled with tape running along the entire opposing vertical side edges of the two glass plates, in order to hold the cassettes together. When it is time to remove the gel slabs from the cassettes following the electrophoresis runs, the tape must be cut with, for example, a razor blade or sharp knife, since it will often tear, if peeled uncut, making it more difficult to remove. Another disadvantage associated with this method of opening the cassettes is the risk that the technicians handling the cassettes will cut themselves. The significance of this risk is underscored by the fact that the electrophoresed biological materials are often body fluids which may be contaminated with infectious diseases, such as AIDS, hepatitis and herpes. Consequently, there is a demand in the electrophoresis industry for electrophoresis gel slab cassettes which can be easily and conveniently assembled and opened following electrophoresis without having to resort to razor blades or knives, and for -6- electrophoresis gel slab cassettes which can be opened in a way which will not increase the risk to technicians of exposure to infectious diseases. Summary of the Invention
The present invention overcomes the above-mentioned drawbacks by providing an electrophoresis cassette which includes a front plate, a back plate, at least one spacer positioned between the front plate and back plate, a holding member, and a tape assembly. The front plate includes a left side and a right side, with each of the left and right sides having a sidewall with a front edge and an interior edge. The back plate includes a corresponding left side and a corresponding right side, with each of the left and right sides having a sidewall with a back edge and an interior edge. The spacer or spacers positioned between the front and back plates create(s) an inter-plate distance between the two plates, thereby forming a gel slot in cooperation with the front and back plates. The holding member is connected to one of the left and right sides of the front plate, as well as to the corresponding left or right side of the back plate. The tape assembly is connected to the other one of the left and right sides of the front plate, and to the corresponding left or right side of the back plate, and includes at least one piece of tape, a plate- facing side, an outwardly-facing side, and a weakened portion, the weakened portion facilitating the opening of the cassette.
Brief Description of the Drawings The accompanying drawings, which are incorporated into, and constitute a part of, this specification, illustrate several versions of the invention, and, together with the general description of the invention given above, and the detailed description of the drawings given below, serve to explain the principles of the invention.
Fig. 1 is an exploded, perspective view of a version of the electrophoresis cassette according to the principles of the invention; -7-
Fig. 2 is an assembled, perspective view of the electrophoresis cassette shown in Fig. 1 ;
Fig. 3 is a perspective view of the electrophoresis cassette shown in Fig. 1, with one side of the cassette shown in an open position following the severing of the tape assembly on that particular side of the cassette;
Fig. 4A is a top view of the tape assembly substantially as shown in Fig 1 ;
Fig. 4B is an end view of the assembly shown in Fig. 4A;
Fig. 4C is a top view of a portion of the assembly shown in Figs. 4A and 4B;
Fig. 5 is a top view of several of the tape assemblies depicted in Figs. 4A-4C in one stage of a manufacturing process used to form such tape assemblies;
Fig. 6A is a top view of another version of the tape assembly according to the principles of the invention;
Fig. 6B is an end view of the assembly shown in Fig. 6 A;
Fig. 6C is a top view of a portion of the assembly shown in Figs. 6A and 6B; Fig. 7A is a top view of a further version of the tape assembly;
Fig. 7B is an end view of the assembly shown in Fig. 7 A;
Fig. 8 A is a top view of an additional version of the tape assembly;
Fig. 8B is an end view of the assembly shown in Fig. 8 A;
Fig. 9A is a top view of yet another version of the tape assembly; Fig. 9B is an end view of the assembly shown in Fig. 9 A;
Fig. 10A is a top view of an additional version of the tape assembly;
Fig. 10B is an end view of the assembly shown in Fig. 10A;
Fig. 11A is a top view of another version of the tape assembly;
Fig. 1 IB is an end view of the assembly shown in Fig. 11 A; -8-
Fig. 11C is a perspective, partial cross-sectional view of a portion of a side of one version of the electrophoresis cassette, incorporating a tape assembly substantially as shown in Figs. 11 A and 1 IB;
Fig. 12 is a perspective view of a portion of a side of another version of the cassette, shown in partial cross-section;
Fig. 13 is a perspective view of a portion of an additional version of the cassette, also shown in partial cross-section;
Fig. 14 is a perspective view of a portion of a side of yet another version of the electrophoresis cassette, shown in partial cross-section; Fig. 15 is a perspective view of a portion of a side of a further version of the cassette, shown in partial cross-section; and
Fig. 16 is a perspective view of a portion of a side of another version of the electrophoresis cassette, shown in partial cross-section.
Detailed Description of the Drawings Figs. 1-3 show one version 10 of an electrophoresis cassette according to the principles of the invention. In this version 10, and in other versions described below, the same reference numbers are used for similar components. This cassette 10 includes a front plate 12, a back plate 14, at least one spacer 16, a holding member 18, and a tape assembly 20. In more detail, the front plate 12 includes a left side 22 and a right side 24 with each of the corresponding left and right sides 22, 24 having a sidewall 26 with a front edge 28 and an interior edge 30. The back plate 14 has a corresponding left side 32 and a corresponding right side 34, with each of the corresponding left and right sides 32, 34 including a sidewall 36 with a back edge 38 and an interior edge 40. As used herein, the term "corresponding" refers to the particular left or right side of the back plate which is positioned generally behind the left or right side, respectively, of the front plate. The -9- particular cassette shown, in fact, includes a left spacer 42 and a right spacer 44 positioned between the front and back plates 12, 14, thereby creating an inter-plate distance 46 (see Fig. 11C) between the front and back plates 12, 14, and forming a gel slot 48 in cooperation with the front and back plates 12, 14. The holding member 18 is connected to one of the left and right sides 22, 24 of the front plate 12, and to the corresponding left or right side 32, 34 of the back plate 14. In addition, the tape assembly 20 is connected to the other one of the left and right sides 22, 24 of the front plate 12 and to the corresponding left or right side 32, 34 of the back plate 14. The tape assembly 20 has at least one piece of tape 50, a plate-facing side 52, an outwardly-facing side 54, and a weakened portion 56, with the weakened portion 56 facilitating the opening of the cassette.
For the particular cassette 10 illustrated in Figs. 1-3, a left spacer 42 and right spacer 44 are used, as noted above. It should be appreciated by those of ordinary skill, however, that an electrophoresis cassette may have a single spacer, or more than two spacers. Furthermore, the spacer(s) need not be rectangular, and need not be positioned with exterior sidewalls(s) flush with the front and back plate sidewalls of the cassette, i.e., the spacer(s) may be placed "inboard" of such sidewalls. Examples of some of the many variations may be found in Danby et al. U.S. Patent No. 4,929,329, entitled "Electrophoresis Cassette System with Apparatus and Method for Filling Same," and Sanford et al. U.S. Patent No. 5, 186,807, entitled "Electrophoresis Gel Slab Cassettes Having Pull Cords and Methods," the entire disclosure of each of these patents being incorporated herein in its entirety by reference. In addition, the holding member 18 is conveniently a tape assembly identical to the tape assembly 20. For sake of clarity, in such a version, the assembly 20 may be referred to as a first tape assembly 57, while the holding member 18 may be called a second tape assembly 58, it being understood that the assembly 58 is identical to the assembly 20. However, it should be noted that the holding member -10-
18 may be any element or combination of elements suitable for use in an electrophoresis cassette to connect the particular left or right side 22, 24 of the front plate 12 to the corresponding left or right side 32, 34 of the back plate 14. Various forms of holding members are known to those of ordinary skill in the art, with one particular example being the side clamp 48 described in Danby et al., U.S. Patent No. 4,929,329, cited above.
As best shown in Figs 1-4C, each of the first and second tape assemblies 57, 58 includes a piece of tape 50 having a substantially rectangular portion 60, with the length of the portion 60 generally corresponding with the height of the cassette 10, and the width of the portion 60 being sufficient to connect the front plate 12 to the back plate 14 along their respective left and right sides 22, 24, 32, 34. The substantially rectangular portion 60 has an upper end 61, a lower end 63, a left edge 65, and a right edge 67. Each of these particular tape assemblies 57, 58 advantageously includes a weakened portion 56 in the form of perforations 62, as well as a reinforcing member 64 and a grippable portion in the form of a projecting tab 66. Note that, in the exploded view of the cassette 10 shown in Fig. 1, each tape assembly is shown in a planar, unassembled position, with the assembled position being shown in phantom. As best seen in Figs. 4A and 4C, the perforations 62 form a first, straight line 68 and a second, straight line 70 along the length of the assemblies 57, 58, with the lines 68, 70 being spaced apart so as to have a particular inter-line width 72. As shown in Fig. 4B, the reinforcing member 64 is positioned on the plate- facing side 52 of the tape assembly 20, and, in fact, is connected directly to the piece of tape 50. As shown in Figs. 1-4A and 4C, the projecting tab 66 is an integral part of the tape 50 of each tape assembly 57, 58, formed by sizing each tape assembly 57, 58 so as to have a tab 66 extending from the rectangular portion upper end 61. This particular tab 66 is formed of the tape 50 and the reinforcing member 64, and is sized so that a technician or other operator may securely grasp it. In addition, as shown in Figs. 1-4A and 4C, the tab 66 is -11- aligned with the first and second lines of perforations 68, 70, and has a width similar to the inter-line width 72 between the first and second lines 68, 70. This particular arrangement allows a technician to open a particular side of the cassette 10 easily and conveniently, simply by grasping the projecting tab 66 and pulling the tab 66 down and away from the rest of the particular tape assembly 57, 58.
Each of the first and second tape assemblies 57, 58 may be made of any material or materials suitable for use in an electrophoresis cassette. The particular material or materials used should be resistant to the electrophoresis chemicals and gels, and also should be non-conductive. If desired, a vinyl tape and a polyester reinforcing member may be used to advantage. For example, one suitable vinyl tape is number 471 vinyl tape available from 3M's Industrial Tape & Specialties Division, St. Paul, MN 55144-1000. This particular vinyl tape happens to be a yellow, pressure-sensitive, adhesive tape, with the adhesive being an acrylic material. Suitable polyester reinforcing member material is Mylar®, which may be obtained from Adhesives Research, Inc., Glenrock, PA 17327, under the product code ARCARE 8651.
As will be understood by those of ordinary skill in the art, the particular tape assembly or assemblies made according to the principles of the invention may come in any of a number of different shapes and sizes. For example, the particular assemblies 57, 58 shown extend along virtually the entire length of the left and right sides of the electrophoresis cassette 10. Accordingly, in this particular version of the cassette 10, the dimensions of each of the tape assemblies 57, 58 are determined, in part, by the length and thickness of the front plate 12, back plate 14, and spacers 42, 44. If desired, the front plate 12, back plate 14 and spacers 42, 44 shown in Figs. 1-3 each may suitably have a length (vertical height) of about 3.15 inches (80 millimeters) and a thickness of about 0.04 inches (1 millimeter). The front and back plates 12, 14 may have a width of about 3.94 inches -12-
(100 millimeters), while each of the spacers 42, 44 may suitably have a width of about 0.28 inches (7 millimeters). In addition, the height of the front plate 12 is somewhat less than the height of the back plate 14 at the upper end 82 of the gel slot 48, which enhances the contact of the uppermost end of a gel slab (not shown) formed in the gel slot 48 with a buffered solution in an upper tank or reservoir (not shown). Given the exemplary dimensions discussed immediately above, the height of the front plate 12 at the upper end 82 of the gel slot 48 may suitably be about 2.75 inches (70 millimeters). If desired, the curve 84 in the front plate 12 leading to this shortened region at the upper end 82 of the gel slot 48 may suitably have a radius of about 0.06 inch (1.5 millimeters). Given the dimensions of the front plate 12, back plate 14, and first and second spacers 42, 44 discussed above, each of the tape assemblies 57, 58 shown in Figs. 1-4B may have a length of about 3.15 inches (80 millimeters), excluding the projecting tab 66, and a width of about 0.75 inch (19 millimeters). The first and second lines 68, 70 of perforations 62 may be positioned centrally with respect to the width of the tape assemblies 57, 58, with each assembly 57, 58 having an inter-line width 72 of about 0.12 inch (3 millimeters), a width which advantageously corresponds with the combined thickness of the particular spacer, front plate and backplate discussed above. In addition, the width of the reinforcing member 64 suitably corresponds with the inter-line width 72, namely, a width of about 0.12 inch (3 millimeters). The projecting tab 66 which extends from the upper end 61 of the substantially rectangular tape portion 60 may have a width of about 0.12 inch (3 millimeters) and a length of about 0.3 inches (7.6 millimeters), and, if desired, may have a rounded or contoured end, as shown in Figs. 4A and 4C. In addition, the polyester reinforcing member advantageously has a thickness of about 2 mil (0.002 inches; 0.05 millimeters) and may run the full length of the tape assembly 50, from the end -69 of the tab 66 to the lower end 63 of the rectangular portion 60. If desired, the reinforcing -13- member 64, polyester or otherwise, may advantageously have a modulus of elasticity which is lower than that of the material used for the tape 50. By having a lower modulus of elasticity, the reinforcing member 64 will stretch less than the tape 50, thereby providing even greater assistance to the technician, as the technician peels away the perforated, reinforced portion 73 of one or both of the tape assemblies 57, 58.
The tape assemblies 57, 58 shown in Figs. 1-4C may be manufactured in any of a number of different ways, as will be readily apparent to those of ordinary skill in the art. By way of example, tape assemblies according to the principles of the invention may be formed on a commercial scale using an in-line process. For example, if desired, the roll of tape used to form the tape assemblies initially may be cut to the particular tape assembly width. Likewise, the reinforcing member material may, if desired, be cut to its appropriate width. Then, the roll of reinforcing member material and the roll of tape may be placed in proper alignment at one end of a machine, and subsequently unwound, passed across a roller or rollers, and laid onto a release liner, for example, a silicone-coated, 60- pound, white, kraft paper, release liner, with the reinforcing member material and tape being placed onto the release liner in the appropriate alignment. Ideally, this tape/reinforcing member/release liner combination is rewound at a subsequent point in the in-line process, as additional reinforcing member material and tape are being adhesively positioned on the release liner. This combination tape/reinforcing member/release liner then may be run through a series of several stations, typically several rollers and cutting elements. For example, in order to produce the tape assembly 20, one of the stations typically will have rotary cutters which are spaced apart so as to provide a desired inter-line width 72 between the first and second lines 68, 70 of perforations 62. Each of the rotary cutters is equipped with serrations, and the tape typically is positioned or "pinched" between the cutters and a pressure roller, resulting in the formation of the perforations 62. -14-
At some stage in the in-line process, a rotary die or dies may be used to cut the tape, so that the tape has the desired length and width, as well as a projecting tab 66 of suitable dimensions. It should be noted that if the roll of tape has been cut to the appropriate width at the beginning of the manufacturing process, then there is no need for the rotary die or dies to stamp the tape assembly width at this later point in the process. The scrap material (not shown) surrounding the assemblies 20 then may be removed manually or by machine, at which point the release liner supporting the assemblies 20 is rolled up for subsequent use. Fig. 5 shows the result of such an in-line process, depicting a series of tape assemblies 20 releasably adhered to a silicone-coated, kraft paper, release liner 80, and ready for subsequent use in forming electrophoresis cassettes. If desired, such a series of tape assemblies 20 adhered to a release liner 80 may be obtained from M&C Specialities, Inc., 90 James Way, Southhampton, PA 18966, under the product code A-860-058. The perforations 62 in the assemblies 20 suitably may be "micro-perforations," a term which is known in the tape-perforating art. And, in fact, the perforations in the A-860-058 tape assemblies from M&C Specialities are micro-perforations.
Once a tape assembly 20 is formed, using either the method described above or any other suitable method, the tape assembly 20 may be applied to the left and/or right sides 22, 24, 32, 34 of the front and back plates 12, 14 of a partially-completed cassette (not shown). A partially-completed cassette may be formed in any of a number of different ways, as will be readily apparent to one of ordinary skill in the art. For example, in one method, an in-line process is used, in which a series of stations is established along a conventional, low- friction, belt assembly line. In order to facilitate production of cassettes on the assembly line, a series of "vehicles" are placed upon the belt. Each vehicle is essentially a frame for receiving various elements of the electrophoresis cassette as it is being constructed. By way of example, at a first operator station, a backplate may be -15- placed horizontally into the vehicle, and a dispensing tip or tips may dispense droplets of a UV-sensitive adhesive on the backplate, with each side of the backplate receiving three drops or dots of adhesive. In this same station, the left and right spacers may be manually placed onto the backplate. In a second station, another tip or plurality of tips may dispense two dots of UV-sensitive adhesive on each spacer, following which, an operator may manually place the front plate onto the spacers. At a third station in the in-line process, the vehicle or fixture including the elements assembled thus far moves into an un-manned ultraviolet light box where an entry shutter to the box is closed, and the assembled elements are exposed to ultraviolet light, thereby curing the adhesive. At this point, the exit shutter opens, and the fixture and cassette elements continue along the conveyor belt. At a fourth station, each partially-assembled cassette is presented to the operator on edge, thereby allowing the operator to advance a tape assembly from a tape dispensing machine, and to align and place the tape assembly on the side of the cassette. This assembly subsequently may be flipped over, thereby exposing the other side, at which point the operator may advance another tape assembly from the tape dispensing machine, and secure the assembly to this other side of the cassette. If desired, the completed cassettes may be placed into holding racks and given a detergent wash, followed by several ultrasonic rinses using de- ionized water. Then, the cassettes may be wrapped for shipment or filled with a particular gel, as desired. Once a cassette 10 made according to the principles of the invention has been formed, an electrophoresis gel (not shown) may be introduced into the gel slot 48 formed by the spacers 42, 44, front plate 12, and back plate 14. Before pouring a gel into the cassette 10, a well-forming comb (not shown) may be positioned inside the top of the gel slot 48, as known by those of ordinary skill in the art. This comb may drop approximately one centimeter into the gel slot 48, and facilitates the formation of wells in -16- the gel during gel polymerization. The gel itself may be placed into the cassette 10 using any of a number of various filling methods, as are commonly understood by those of ordinary skill in the art. Most typically, if a comb is used, the particular gel is placed into the cassette through the opening in the bottom of the cassette. Returning to the drawings, Figs. 6A-6C show another version of the tape assembly 120 according to the principles of the invention. This particular tape assembly 120 is very similar to the tape assembly 20 shown in Figs. 4A-4C, in that this assembly 120 also includes a tape piece 50 having a projecting tab 66, as well as a first, straight line 68 of perforations 162 along the length of the tape assembly 120, and a second, straight line 70 of perforations 162 parallel to the first line 68. However, this particular version 120 does not include a reinforcing member. In addition, and as best seen by comparing Fig. 6C with Fig. 4C, the perforations 162 formed in the tape 50 are approximately three times as long as the perforations 62 formed in the version 20 shown in Fig. 4C. Nonetheless, the spacing 86 between each of these elongated perforations 162 along the first line 68 and along the second line 70 is similar to the inter-perforation spacing 86 of each of the first and second lines 68, 70 in the tape assembly version 20 shown in Fig. 4C. Also, the interline width 72 of the assembly 120 shown in Fig. 6C is generally similar to that of the Fig. 4C assembly 20. Tape assembly 120 may be made and used according to the methods discussed above in conjunction with the assembly 20. With reference to Figs. 7A and 7B, a further version of the tape assembly
220 includes a piece of tape 50 having a substantially rectangular portion 60, with a single, straight line 88 of perforations 62 centrally positioned between the left and right edges 65, 67 of the tape portion 60, and running along the entire length of the tape portion 60. In addition, the assembly 220 includes a reinforcing member in the form of a monofilament line 94, which is positioned on the plate-facing side 52 of the assembly 220 in general -17- alignment with the single, straight line 88 of perforations 62. The monofilament line 94 has an extending portion 95 which extends beyond the upper end 61 of the rectangular portion 60, thereby allowing a technician to grasp the line 94 and sever the tape 50. This particular tape assembly 220 may be made and used according to the methods discussed above in conjunction with the tape assembly 20 shown in Figs. 1-4C.
Figs. 8A-10B depict additional versions of the tape assembly which are somewhat similar in nature to the versions shown in Figs. 1-7B. A key difference is that these additional embodiments incorporate a thinned region or regions 96 along the length of the tape assembly, instead of the perforations 62, 162 used in the earlier embodiments. In particular, the tape assembly 320 of Figs. 8 A and 8B includes a piece of tape 50 having a substantially rectangular portion 60 with an upper end 61, a lower end 63, a left edge 65, and a right edge 67, and a projecting tab 66 extending from the upper end 61. In addition, the piece of tape includes a first, straight, thinned line 106 along the length of the tape 50, as well as a second, straight, thinned line 108 parallel to the first line 106. These lines have an inter-line width 72 which corresponds generally with the width and alignment of the projecting tab 66, all of which is positioned centrally between the left and right edges 65, 67 of the piece of tape 50. The tape assembly 320 further includes a reinforcing member 64 having a width substantially similar to the inter-line width 72 of the first and second thinned lines 106, 108, and underlying the tape 50 between those lines 106, 108. Furthermore, this reinforcing member 64 extends along the entire length of the tape 50, from the end 69 of the projecting tab 66 to the lower end 63 of the rectangular portion 60. This particular version of the tape assembly 320, as well as the versions depicted in Figs. 9A-10B, may be made by a process similar to the process discussed above in conjunction with the tape assembly 20 depicted in Figs. 1-4C. The only significant change is that, instead of using a station having a rotary cutter or pair of cutters with serrations, a wheel, -18- pair of wheels, or any other object having one or more parallel, heated, non-cutting edge(s) may be used. By moving the tape 50 along such an edge, the tape 50 becomes thinned, and therefore weakened, along that contact point, without sacrificing the tensile strength of the tape 50. The assembly 420 of Figs. 9A and 9B is similar to that shown in Figs. 8A and 8B, except that the assembly 420 of Figs. 9A and 9B does not include a reinforcing member. With reference to Figs. 10A and 10B, this particular version of the tape assembly 520 includes a single, straight, thinned line 110 running the length of the tape 50, and positioned centrally between the left and right edges 65, 67 of the tape portion 60. This particular assembly 520 further includes a monofilament line 94 which runs the length of the tape 50, and which is centrally positioned on the plate-facing side 52 of the tape 50, generally equidistant between the left and right edges 65, 67 of the tape portion 60. In addition, this monofilament line 94 has an extending portion 95 which extends beyond the upper end 61 of the rectangular portion 60, thereby allowing a technician to grasp the monofilament 94 and sever the piece of tape 50.
A further aspect of the invention is depicted in Figs. l lA-l lC. These particular drawings show a version of the tape assembly 620 which includes a front tape piece 112 for placement along at least a portion of the length of a side 22, 24 of the front plate 12, a back tape piece 114 for placement along at least a portion of the length of a corresponding side 32, 34 of the back plate 14, and a bridge member 116 along at least a portion of the length of the front tape piece 112 and the back tape piece 114. This particular version of the bridge member 116 is connected to the front tape piece 112 and the back tape piece 114 by thermal welding, with the weakened portion 56 of the tape assembly 620 being represented, at least in part, by a front thermal weld line 144 bonding the front tape piece 112 to the bridge member 1 16, and a back thermal weld line 146 -19- bonding the back tape piece 114 to the bridge member 116. The front tape piece 112 has an inner edge 118, and the back tape piece 1 14 also has an inner edge 122 with the front tape piece inner edge 118 ending generally at the front plate interior edge 30, and the back tape piece inner edge 122 ending generally at the back plate interior edge 40. In this manner, and as best shown in Fig. 11 C, the inter-plate distance 46 between the front and back plate sidewalls 26, 36 is substantially free of both the front tape piece 112 and the back tape piece 114. Moreover, this inter-plate distance 46 substantially corresponds with the thickness of the spacer 16. The bridge member 116 itself has a front edge 124, a back edge 126, an upper end 128 having a projecting tab 130, a lower end 132, and a width 134 which generally corresponds with the combined thickness of the front plate 12, back plate 14, and spacer 16. Moreover, as shown in Fig. 11C, the bridge member 116 extends from the front plate front edge 28 to the back plate back edge 38.
This particular tape assembly 620 may be made using a method somewhat similar to the methods of manufacture discussed in conjunction with the various tape assembly embodiments discussed above. For example, an in-line process may be used. In particular, two rolls of tape may be aligned in a side-by-side relationship, with any desired spacing between the two rolls. For example, in producing the tape assembly 620 shown in Figs. 11 A-l 1 C, the spacing between the two rolls may suitably correspond to the desired space between the front tape piece inner edge 118 and back tape piece inner edge 122 in the completed tape assembly 620. Each of these rolls then may be simultaneously unwound and adhered to a silicone-coated, kraft-paper release liner. If desired, the material used for the bridge member 116 may be simultaneously placed in its proper connecting relationship on the upper surface 136 of the front and back tape pieces 112, 114. Alternatively, the bridge member 116 may be applied in a subsequent step, once the front and back tape pieces 112, 114 have been releasably adhered to the silicone-coated release -20- liner. The material used for the bridge member 1 16 may be any material or combination of materials suitable for use in an electrophoresis cassette. For example, 3M's No. 471 vinyl tape version without the pressure-sensitive adhesive may be used to advantage, and may be adhered to the upper surface 136 of each of the front and back tape pieces 112, 114 by a continuous, in-line, thermal welding process, as discussed briefly above. In this process, the unwelded sub-assembly may be passed along two thin heating elements or rolls which form the front and back thermal weld lines 144, 146, thereby defining a central portion 148 between the weld lines 144, 146. Alternatively, the vinyl tape or any other appropriate material may be attached to the front and back tape pieces 112, 114 using any suitable method known in the art. For example, the tape pieces 112, 114 and bridge member 116 may be connected using an adhesive, an ultrasonic weld, or the like. Individual tape assemblies 620 then may be formed by moving the kraft paper/tape/bridge member sub-assembly through a die cutting operation to produce the tape assembly 620 shown in Figs. l lA-l lC. Once such a tape assembly 620 has been formed, it may be applied to the front and back plates 12, 14 as discussed above in conjunction with other embodiments, in order to complete an electrophoresis cassette. Then, in use, once a technician is ready to open up a side of the electrophoresis cassette, the technician may sever the bridge member 116 simply by grasping the tab 130 and pulling the central portion 148 of the bridge member 116 away from the rest of the cassette, with the central portion 148 tending to sever where the weld lines 144, 146 have been formed.
The tape assembly 720 shown in Fig. 12 is somewhat similar to the tape assembly 620 shown in Figs. 11 A-l 1C, but includes perforations 62 in the bridge member 116, in the form of a first, straight line of perforations 68 and a second, straight line of perforations 70 parallel to the first line 68. The inter-line width 72 between the lines of perforations 68, 70 is generally the same as the width of the tab 130 and the spacer 16. -21-
This particular embodiment may be made using a combination of the manufacturing methods discussed above. In particular, once the front tape piece 112, back tape piece 114, and bridge member 116 (for example, No. 471 vinyl tape with the pressure-sensitive adhesive) have been assembled on the silicone release liner, this sub-assembly then may be passed across a pair of rotary cutters having serrations which form cuts in the bridge member, thereby forming the perforations 62. In use, a technician or other operator need only pull on the tab portion 130, with the bridge member 116 tearing along the perforation lines 68, 70, thereby opening the electrophoresis cassette.
The tape assembly 820 depicted in Fig. 13 is quite similar to that shown in Fig. 12, further including a reinforcing member 64 underlying the portion 138 of the bridge member 116 between the first and second lines of perforations 68, 70. The reinforcing member 64 is directly connected to this central portion 138 of the bridge member 116, and also extends from the upper end 128 of the tape assembly 820, so as to form the undersurface of the projecting tab 130. Fig. 14 illustrates yet another version of the tape assembly 920, which is somewhat similar to the versions 720, 820 shown in Figs. 12 and 13. This particular tape assembly 920 is similar in that the inner edges 118, 122 of the front and back tape pieces 112, 114 end generally at the front plate interior edge 30 and back plate interior edge 40, respectively. In addition, these front and back tape pieces 112, 114 are connected by a bridge member 116 which is sized so that the bridge member front edge 124 terminates at about the front plate sidewall front edge 28, and the bridge member back edge 126 terminates at about the back plate sidewall back edge 38. This particular tape assembly 920 also includes a reinforcing member 64 positioned on the plate-facing side 52 of the tape assembly 920, and connected directly to the bridge member 116. However, the tape assembly 920 includes no perforations. As should be apparent to one of ordinary skill in -22- the art, this particular assembly 920 may be manufactured using various combinations of the manufacturing methods discussed above. The resulting electrophoresis cassette subsequently may be opened by pulling on the projecting tab 130, which includes a portion of the reinforcing member 64 on its undersurface. Preferably, the reinforcing member 64 has a modulus of elasticity which is lower than that of the bridge member 116 material, thereby enabling the reinforcing member 64 to tear through the surrounding bridge 116 material relatively easily.
Fig. 15 illustrates a tape assembly 1020 in which the inner edge 118 of the front tape piece 112 and the inner edge 122 of the back tape piece 114 both extend beyond the front and back plate interior edges 30, 40, and into a portion of the inter-plate distance 46 between the front and back plates 12, 14. In this particular version 1020, the inner edges 118, 122 of the front and back tape pieces 112, 114 are separated by a distance of about 0.01 millimeter, thereby forming a gap 140. This particular tape assembly 1020 further includes perforations 62 in the form of a single, straight line 88 along the length of the bridge member 116, with the line of perforations 88 being centrally located between the front and back edges 124, 126 of the bridge member 116, thereby positioning the perforated line 88 directly above the gap 140 between the inner edges 118, 122 of the front and back tape pieces 112, 114. This tape assembly 1020 also includes a reinforcing member 64 in the form of a monofilament 94, which is positioned directly beneath the perforated line 88 of the bridge member 116. This monofilament 94 has an extending portion 95 which extends from the upper end 142 of the bridge member 116, thereby enabling an operator to grasp and pull the monofilament 94, in order to sever the bridge member 116. This particular version of the tape assembly 1020 may be manufactured using the various methods discussed above. -23-
Fig. 16 depicts a tape assembly 1120 in which the inner edge 118 of the front tape piece 112 ends generally at the front plate interior edge 30, whereas the inner edge 122 of the back tape piece 114 extends beyond the back plate interior edge 40, and into a portion of the inter-plate distance 46. This particular assembly 1120 also includes a reinforcing member 64 positioned on the plate- forming side 52 of the tape assembly 1120, connected directly to the bridge member 116, so as to overlie the inter-plate distance 46 between the front and back plates 12, 14. The bridge member 116 further includes a tab 130 extending from its upper end 142, formed of bridge member 116 material and reinforcing member 64 material. This particular tape assembly 1120 may be made and used as described above. While the present invention has been illustrated by description of several versions, and while the illustrative versions have been described in considerable detail, it is not the intention to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. By way of example, although the versions of the weakened portion discussed above generally are straight and parallel, the weakened portion may take on any of a number of different conformations and/or patterns, as long as they facilitate the severing of the tape assembly. The invention, in its broader aspects, is, therefore, not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the general inventive concept.
Having described the invention, what is claimed is:

Claims

-24-
1 An electrophoresis cassette, comprising: a front plate including a left side and a right side, each of the left and right sides having a sidewall with a front edge and an interior edge; a back plate including a corresponding left side and a corresponding right side, each of the corresponding left and right sides having a sidewall with a back edge and an interior edge; at least one spacer positioned between the front and back plates, thereby creating an inter-plate distance between the front and back plates, and forming a gel slot in cooperation with the front and back plates; a holding member connected to one of the left and right sides of the front plate, and to the corresponding left or right side of the back plate; and a tape assembly connected to the other one of the left and right sides of the front plate, and to the corresponding left or right side of the back plate, the tape assembly having at least one piece of tape, a plate-facing side, an outwardly-facing side, and a weakened portion, the weakened portion facilitating the opening of the cassette.
2. The cassette of claim 1 wherein the weakened portion includes perforations.
3. The cassette of claim 2 wherein the perforations form a first line along at least a portion of the length of the tape assembly.
4. The cassette of claim 3 wherein the tape assembly includes a reinforcing member. -25-
5. The cassette of claim 4 wherein the reinforcing member extends along at least a portion of the length of the tape assembly.
6. The cassette of claim 5 wherein the reinforcing member is positioned on the plate-facing side of the tape assembly.
7. The cassette of claim 6 wherein the reinforcing member is directly connected to the piece of tape.
8. The cassette of claim 5 wherein the perforations form a second line along at least a portion of the length of the tape assembly.
9. The cassette of claim 8 wherein the second line is generally parallel to the first line.
10. The cassette of claim 9 wherein the first and second lines are spaced apart so as to have a particular inter-line width, and the reinforcing member is positioned within the inter-line width.
11. The cassette of claim 10 wherein the reinforcing member is positioned on the plate-facing side of the tape assembly.
12. The cassette of claim 11 wherein the reinforcing member is directly connected to the piece of tape. -26-
13. The cassette of claim 10 wherein the tape assembly includes a grippable portion.
14. The cassette of claim 13 wherein the tape assembly includes a vinyl tape, and the reinforcing member includes polyester.
15. The cassette of claim 14 wherein the holding member includes a tape assembly.
16. The cassette of claim 3 wherein the perforations form a second line along at least a portion of the length of the tape assembly.
17. The cassette of claim 16 wherein the second line is generally parallel to the first line.
18. The cassette of claim 17 wherein the tape assembly includes a grippable portion.
19. The cassette of claim 18 wherein the tape assembly includes a vinyl tape.
20. The cassette of claim 19 wherein the holding member includes a tape assembly.
21 . The cassette of claim 1 wherein the weakened portion includes a thinned portion. -27-
22. The cassette of claim 21 wherein the thinned portion forms a first line along at least a portion of the length of the tape assembly.
23. The cassette of claim 22 wherein the tape assembly includes a reinforcing member.
24. The cassette of claim 23 wherein the reinforcing member extends along at least a portion of the length of the tape assembly.
25. The cassette of claim 24 wherein the reinforcing member is positioned on the plate- facing side of the tape assembly.
26. The cassette of claim 25 wherein the reinforcing member is directly connected to the piece of tape.
27. The cassette of claim 24 wherein the weakened portion includes a second thinned portion forming a second line along at least a portion of the length of the tape assembly.
28. The cassette of claim 27 wherein the second line is generally parallel to the first line.
29. The cassette of claim 28 wherein the first and second lines are spaced apart so as to have a particular inter-line width, and the reinforcing member is positioned within the inter-line width. -28-
30. The cassette of claim 29 wherein the reinforcing member is positioned on the plate- facing side of the tape assembly.
31. The cassette of claim 30 wherein the reinforcing member is directly connected to the piece of tape.
32. The cassette of claim 29 wherein the tape assembly includes a grippable portion.
33. The cassette of claim 32 wherein the tape assembly includes a vinyl tape, and the reinforcing member includes polyester.
34. The cassette of claim 33 wherein the holding member includes a tape assembly.
35. The cassette of claim 22 wherein the weakened portion includes a second thinned portion forming a second line along at least a portion of the length of the tape assembly.
36. The cassette of claim 35 wherein the second line is generally parallel to the first line.
37. The cassette of claim 36 wherein the tape assembly includes a grippable portion. -29-
38. The cassette of claim 37 wherein the tape assembly includes a vinyl tape.
39. The cassette of claim 38 wherein the holding member includes a tape assembly.
40. The cassette of claim 1 wherein the tape assembly includes a front tape piece along at least a portion of the length of the side of the front plate, a back tape piece along at least a portion of the length of the corresponding side of the back plate, and a bridge member along at least a portion of the length of the front tape piece and the back tape piece, the bridge member connecting the front tape piece with the back tape piece.
41. The cassette of claim 40 wherein the bridge member has a front edge and a back edge, both the front edge and the back edge being positioned between the front plate front edge and the back plate back edge.
42. The cassette of claim 41 wherein the front tape piece has an inner edge and the back tape piece has an inner edge, the front tape piece inner edge ending generally at or before the front plate interior edge, and the back tape piece inner edge ending generally at or before the back plate interior edge, thereby leaving the inter-plate distance between the front and back plate sidewalls substantially free of both the front tape piece and the back tape piece.
43. The cassette of claim 42 wherein the bridge member includes perforations. -30-
44. The cassette of claim 43 wherein the tape assembly includes a reinforcing member extending along at least a portion of the length of the bridge member.
45. The cassette of claim 44 wherein the reinforcing member is positioned on the plate-facing side of the tape assembly.
46. The cassette of claim 45 wherein the reinforcing member is directly connected to the bridge member.
47. The cassette of claim 42 wherein the tape assembly includes a reinforcing member extending along at least a portion of the length of the bridge member.
48. The cassette of claim 47 wherein the reinforcing member is positioned on the plate- facing side of the tape assembly.
49. The cassette of claim 48 wherein the reinforcing member is directly connected to the bridge member.
50. The cassette of claim 40 wherein the front tape piece has an inner edge and the back tape piece has an inner edge, at least one of the front and back tape piece inner edges extending beyond the interior edge of the front or back plate, respectively, into the inter-plate distance between the front and back plates.
51. The cassette of claim 50 wherein the bridge member includes perforations. -31-
52. The cassette of claim 51 wherein the tape assembly includes a reinforcing member extending along at least a portion of the length of the bridge member.
53. The cassette of claim 52 wherein the reinforcing member is positioned on the plate-facing side of the tape assembly.
54. The cassette of claim 53 wherein the reinforcing member is directly connected to the bridge member.
55. The cassette of claim 50 wherein the tape assembly includes a reinforcing member extending along at least a portion of the length of the bridge member.
56. The cassette of claim 55 wherein the reinforcing member is positioned on the plate-facing side of the tape assembly.
57. The cassette of claim 56 wherein the reinforcing member is directly connected to the bridge member.
58. The cassette of claim 40 wherein the bridge member includes perforations.
59. The cassette of claim 58 wherein the tape assembly includes a reinforcing member extending along at least a portion of the length of the bridge member.
60. The cassette of claim 59 wherein the reinforcing member is positioned on the plate-facing side of the tape assembly. -32-
61. The cassette of claim 60 wherein the reinforcing member is directly connected to the bridge member.
62. The cassette of claim 40 wherein the tape assembly includes a reinforcing member extending along at least a portion of the length of the bridge member.
63. The cassette of claim 62 wherein the reinforcing member is positioned on the plate-facing side of the tape assembly.
64. The cassette of claim 63 wherein the reinforcing member is directly connected to the bridge member.
65. The cassette of claim 1 wherein the tape assembly includes a reinforcing member.
66. The cassette of claim 65 wherein the reinforcing member extends along at least a portion of the length of the tape assembly.
67. The cassette of claim 66 wherein the reinforcing member is positioned on the plate-facing side of the tape assembly.
68. The cassette of claim 67 wherein the reinforcing member is directly connected to the piece of tape. -33-
69. The cassette of claim 66 wherein the weakened portion further includes perforations.
70. The cassette of claim 69 wherein the perforations form a first line along at least a portion of the length of the tape assembly.
71. The cassette of claim 70 wherein the tape assembly includes a grippable portion.
72. The cassette of claim 71 wherein the tape assembly includes a vinyl tape, and the reinforcing member includes polyester.
73. The cassette of claim 72 wherein the holding member includes a tape assembly.
-34-
74. A method of forming an electrophoresis cassette having a front plate, a back plate, at least one spacer, a holding member, and a tape assembly, the front plate including a left side and a right side, with each of the sides having a sidewall with a front edge and an interior edge, the back plate including a corresponding left side and a corresponding right side, with each of the corresponding sides having a sidewall with a back edge and an interior edge, the spacer positioned between the front and back plates, thereby creating an inter-plate distance between the front and back plates, and forming a gel slot in cooperation with the front and back plates, the holding member connected to one of the left and right sides of the front plate and to the corresponding left or right side of the back plate, the tape assembly having at least one piece of tape, a plate-facing side, an outwardly- facing side, and a weakened portion, the method comprising the step of: connecting the tape assembly to the other one of the left and right sides of the front plate, and to the corresponding left or right side of the back plate, thereby forming the electrophoresis cassette.
75. The method of claim 74 wherein the weakened portion includes perforations.
76. The method of claim 74 wherein the weakened portion includes a thinned portion. -35-
77. The method of claim 74 wherein the weakened portion includes a front thermal weld line bonding a front tape piece to a bridge member along at least a portion of the length of the side of the front plate, and a back thermal weld line bonding a back tape piece to the bridge member along at least a portion of the length of the corresponding side of the back plate.
78. The method of claim 74 wherein the tape assembly includes a reinforcing member.
-36-
79. A method of opening a side of an electrophoresis cassette having a front plate, a back plate, at least one spacer, a holding member, and a tape assembly, the front plate including a left side and a right side, with each of the sides having a sidewall with a front edge and an interior edge, the back plate including a corresponding left side and a corresponding right side, with each of the corresponding sides having a sidewall with a back edge and an interior edge, the spacer positioned between the front and back plates, thereby creating an inter-plate distance between the front and back plates, and forming a gel slot in cooperation with the front and back plates, the holding member connected to one of the left and right sides of the front plate, and to the coπesponding left or right side of the back plate, the tape assembly having at least one piece of tape, a plate- facing side, an outwardly- facing side, and a weakened portion, the tape assembly being connected to the other one of the left and right sides of the front plate, and to the coπesponding left or right side of the back plate, the method comprising the step of: severing the tape assembly substantially along the tape assembly's longitudinal axis, thereby opening the side of the electrophoresis cassette.
80. The method of claim 79 wherein the tape assembly includes a grippable portion, the severing step including pulling on the grippable portion.
81. The method of claim 79 wherein the weakened portion includes perforations, the severing step including severing the tape assembly along the perforations.
82. The method of claim 81 wherein the tape assembly includes a grippable portion, the severing step including pulling on the grippable portion. -37-
83. The method of claim 79 wherein the weakened portion includes a thinned portion, the severing step including severing the tape assembly substantially along the thinned portion.
84. The method of claim 83 wherein the tape assembly includes a grippable portion, the severing step including pulling on the grippable portion.
85. The method of claim 79 wherein the weakened portion includes a front thermal weld line bonding a front tape piece to a bridge member along at least a portion of the length of the side of the front plate, and a back thermal weld line bonding a back tape piece to the bridge member along at least a portion of the length of the corresponding side of the back plate, the severing step including severing the front and back thermal weld lines.
86. The method of claim 85 wherein the tape assembly includes a grippable portion, the severing step including pulling on the grippable portion.
87. The method of claim 79 wherein the tape assembly includes a reinforcing member, the severing step including removing at least a portion of the reinforcing member.
88. The method of claim 87 wherein the tape assembly includes a grippable portion, the severing step including pulling on the grippable portion.
89. The cassette of claim 4 wherein the reinforcing member has a modulus of elasticity lower than that of the piece of tape. -38-
90. The cassette of claim 23 wherein the reinforcing member has a modulus of elasticity lower than that of the piece of tape.
91. The cassette of claim 62 wherein the reinforcing member has a modulus of elasticity lower than that of the bridge member.
92. The cassette of claim 65 wherein the reinforcing member has a modulus of elasticity lower than that of the piece of tape.
PCT/US1999/008387 1998-04-16 1999-04-16 Electrophoresis cassette having a tape assembly including a weakened portion which facilitates opening the cassette WO1999053306A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU35665/99A AU3566599A (en) 1998-04-16 1999-04-16 Electrophoresis cassette having a tape assembly including a weakened portion which facilitates opening the cassette

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US6129798A 1998-04-16 1998-04-16
US09/061,297 1998-04-16

Publications (1)

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WO1999053306A1 true WO1999053306A1 (en) 1999-10-21

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PCT/US1999/008387 WO1999053306A1 (en) 1998-04-16 1999-04-16 Electrophoresis cassette having a tape assembly including a weakened portion which facilitates opening the cassette

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4929329A (en) * 1987-04-27 1990-05-29 Eg&G, Inc. Electrophoresis cassette system with apparatus and method for filling same
US4954236A (en) * 1989-06-28 1990-09-04 Bio-Rad Laboratories, Inc. Apparatus and method for gel casting and electrophoresis in a single enclosure
US5186807A (en) * 1991-08-13 1993-02-16 Erie Scientific Company Electrophoresis gel slab cassettes having pull cords and methods
US5228970A (en) * 1991-09-13 1993-07-20 Millipore Corporation Gel electrophoresis cassette with removable strip

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4929329A (en) * 1987-04-27 1990-05-29 Eg&G, Inc. Electrophoresis cassette system with apparatus and method for filling same
US4954236A (en) * 1989-06-28 1990-09-04 Bio-Rad Laboratories, Inc. Apparatus and method for gel casting and electrophoresis in a single enclosure
US5186807A (en) * 1991-08-13 1993-02-16 Erie Scientific Company Electrophoresis gel slab cassettes having pull cords and methods
US5228970A (en) * 1991-09-13 1993-07-20 Millipore Corporation Gel electrophoresis cassette with removable strip

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Publication number Publication date
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