Chemistry: electrical and wave energy – Apparatus – Coating – forming or etching by sputtering
Patent
1994-05-31
1996-01-09
Niebling, John
Chemistry: electrical and wave energy
Apparatus
Coating, forming or etching by sputtering
2041828, 264259, C25B 900
Patent
active
054826136
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention concerns a method and apparatus for making a gel plate with a microporous membrane for separating and transferring macromolecules by electrophoresis, the method and the apparatus utilizing a cassette with a rectangular frame and a removable bottom plate and into which the gel is poured in liquid form.
The applicant has already proposed a method and a manufacturing apparatus of that type, described in International Patent Application WO 93/01491, in which the gel in liquid form is first poured into the cassette until it is level with the top edge of the rectangular frame, after which a dry microporous membrane is laid progressively on to the gel and the frame, traction is applied to the periphery of the membrane to tension it in substantially uniform manner, and the gel is allowed to solidify while keeping the membrane tensioned.
That method and apparatus allow gel plates to be made with one face covered by an adhering microporous membrane, generally of nitrocellulose or nylon, satisfying a number of criteria, such as the homogeneity of the gel, uniformity of its thickness, absence of air bubbles between the gel and the membrane, flatness of the membrane and cleanness of its free face.
That method and apparatus also make it possible to avoid some problems with the prior art, such as the gel overflowing onto the free face of the membrane and the formation of folds in the membrane, resulting from its elongation during its impregnation by the gel, which problems are generally encountered when the liquid gel is poured onto the membrane placed on a support.
SUMMARY OF THE INVENTION
The present invention concerns improvements in the method and the apparatus described in the cited prior application of the applicant, these improvements making it possible to simplify and make easier the manufacture of a gel plate with a microporous membrane.
The invention thus provides a method of making a gel plate with a microporous membrane for separating and transferring macromolecules by electrophoresis, the gel being poured in liquid form into a cassette comprising a rectangular frame and a removable bottom plate, the method being characterized in that it consists in
- firstly placing a dry microporous membrane on the rectangular frame and putting this membrane under tension in substantially uniform manner by exerting traction forces on the edges of the membrane,
- then pouring the liquid gel into the cassette under the membrane, until it fills the space defined in the frame by the tensioned membrane and the bottom plate,
- and allowing the gel to solidify while keeping the membrane under tension.
The method according to the invention has the advantage that the microporous membrane is placed on the rectangular frame and put under tension before the liquid gel is poured in, which is much simpler and easier to perform than is laying a microporous membrane progressively onto a layer of liquid gel filling a cassette.
According to another characteristic of the invention, the method also consists in pouring the gel into the cassette via one end thereof, this end being opposite to the end having a comb on the bottom plate for forming wells in the gel plate for receiving samples of macromolecules.
The end of the cassette used for pouring in the gel is advantageously raised slightly, which allows the air contained between the bottom plate and the membrane to be expelled progressively as the gel is poured, in order to guarantee that there are no bubbles of air between the gel and the membrane.
The traction forces are preferably applied continuously to two opposite edges of the membrane in directions radiating from a fixed point located on a median axis of the membrane, for example in the vicinity of a transverse edge thereof.
In order to facilitate the tensioning of the membrane, the method according to the invention consists initially in fixing two extensible longitudinal strips on the two said edges of the membrane, for example by an adhesive, and in exerting the aforesaid traction forces
REFERENCES:
patent: 5293703 (1994-03-01), Coste et al.
patent: 5344543 (1994-09-01), Boquet
Bertin & Cie
Delacroix-Muirheid C.
Niebling John
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