Chemistry: electrical and wave energy – Processes and products – Electrostatic field or electrical discharge
Patent
1993-02-23
1995-05-16
Niebling, John
Chemistry: electrical and wave energy
Processes and products
Electrostatic field or electrical discharge
204299R, 204301, 264216, 264217, 425111, G01N 2726, G01N 27447
Patent
active
054157528
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method and to apparatus for fabricating a plate of gel having a microporous membrane, and intended in particular for separating and transferring macromolecules by electrophoresis.
Such plates of gel (generally agarose or polyacrylamide) have one face covered by an adherent microporous membrane (generally of nitrocellulose or of "nylon"), and must satisfy a certain number of criteria such as gel uniformity, constant gel thickness, absence of bubbles of air between the gel and the membrane, planeness of the membrane, and cleanness of the free face thereof. These plates must also be used shortly after being fabricated since the gel ages poorly (it dries out and cracks quite quickly).
Known methods of fabricating such plates generally consist in placing a membrane by hand on a layer of liquid gel that has been cast onto a support, or in casting the liquid gel onto the membrane that has been placed on the support, and then in allowing the gel to solidify. The results obtained are not very satisfactory with respect to planeness and with respect to cleanness of the membrane, since the liquid gel immediately impregnates the membrane, thereby causing it to lengthen and forming folds or wrinkles, and it may overflow onto the free face of the membrane.
In addition, the above-mentioned known methods are lengthy and fiddly to perform and they do not enable gel plates to be fabricated easily and quickly.
A particular object of the present invention is to avoid those drawbacks of known methods.
An object of the invention is to provide a method and apparatus for fabricating gel plates, enabling the above-mentioned criteria to be satisfied and that are simple and quick in implementation.
Another object of the invention is to provide a method and apparatus for fabricating plates of gel that are of perfect quality and identical to one another.
The invention thus provides a method of fabricating a microporous-membrane gel plate for separating and transferring macromolecules by electrophoresis, the method consisting in casting the gel in liquid form onto a bottom plate carrying a peripheral frame, and being characterized in that it then consists in: placing a dry microporous membrane progressively on the liquid gel; exerting traction on the periphery of the membrane to tension it in substantially uniform manner; and allowing the gel to solidify while keeping the membrane under tension.
Placing the membrane progressively on the layer of liquid gel makes it possible to avoid imprisoning bubbles of air between the gel and the membrane. Uniformly tensioning the membrane placed on the gel makes it possible to ensure that it is plane and serves to accommodate any possible lengthening thereof. By maintaining the membrane under tension, its planeness is conserved during solidification of the gel and subsequently.
Advantageously, the method also consists in giving the membrane an initial shape that has a convex curve towards the gel, in placing the membrane on the gel starting from one end of the plate, and in progressively imparting a plane shape to the membrane as it comes into contact with the gel.
This ensures that the presence of bubbles of air between the gel and the membrane is avoided.
In an implementation of the invention, the method consists initially in fixing the periphery of the membrane on a frame having extensible sides, and then after the membrane has been placed on the liquid gel, in lengthening the sides of said frame to tension the membrane.
Preferably, while the extensible sides of the frame are being lengthened, they are guided along directions that radiate from a fixed point.
The membrane can thus be tensioned in a manner that is substantially uniform in all directions going away from said fixed point, which point is preferably situated on an axis of symmetry of the membrane.
The invention also provides an apparatus for fabricating a microporous-membrane gel plate for separating and transferring macromolecules by electrophoresis, the apparatus comprising a bottom plate carrying a periphe
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patent: 3767560 (1973-10-01), Elevitch
patent: 3808118 (1974-04-01), Golias
patent: 4381168 (1983-04-01), Johnson et al.
patent: 4533307 (1985-08-01), Ansorge
patent: 4861411 (1989-08-01), Tezuka
patent: 4883597 (1989-11-01), Perlman
patent: 4954236 (1990-09-01), Kushner et al.
Bertin & Cie
Niebling John
Starsiak Jr.
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