BACKGROUND OF THE INVENTION Electrophoretic separation methods are based on the varying migration rate of the individual components of a sample to be examined, in a carrier medium, when an electric field is applied. Capillary electrophoresis is very widespread. In this, a carrier medium and a sample to be examined are transported in a capillary system comprising a capillary separating path, between the ends of which the electric field is applied. Transport of the carrier medium in the capillary system and injection of the sample to be examined, into the carrier medium, may take place using pumps and valves or with electric fields which are accordingly applied to various sections of the capillary system. The individual components of the sample injected into the carrier medium migrate at varying rates in the electric field of the separating path, whereupon the sample is separated. The individual components can be detected with the assistance of a detector connected to the capillary separating path. To simultaneously analyse different samples, separation apparatus with several parallel capillaries has also already been proposed (Anal. Chem. 1992,64, 967 to 972).

US-A-4. 908. 112 proposes the miniaturisation of branched capillary systems, including a separating path. Here, the capillary system is arranged on a semi-conductor chip. Transport of the carrier medium and injection of the sample to be separated are effected using electric fields which can be applied between individual sections of the capillary system. The dimensions of the channel system are very small, but in contrast the attainable field intensities are very great. In this way, there are very small amounts of carrier medium and very small volumes of sample. In addition, the separating process can be carried out very rapidly at the large voltages applied, typically ca. 30 kV.

Gel electrophoresis represents a further, very widespread, electrophoretic separation method. In this method, separation of the sample into its components is not effected in solution, but in a stationary carrier material, a gel. Gel electrophoresis is an established separation method for charged biomolecules. In this, the components with different charges migrate to the poles of opposite charge, while the neutral components remain at the starting point.

Polyacrylamide gels (PAGE) are frequently used for separation. The pore size of the polyacrylamide gels enables separation to take place according to charge and steric hindering of the sample molecules in the gel. In the case of proteins, when adding sodium dodecyl sulphate (SDS), a good correlation is achieved between the migration distance of the separated sample molecules and the corresponding molar mass, which is however independent of the charge of the molecules. Isoetectric focussing (IEF or IF) as a precursor to SDS-PAGE also enables many extremely complex substance mixtures to be separated.

A further development of gel electrophoresis, which has been established in the meantime, is the so-called 2D-gel electrophoresis, in which a sample is separated into two dimensions (2D) according to different properties of the molecules. This type of 2D gel electrophoresis separation is described, for example, in"A. T. Andrews, Electrophoresis, Theory, Techniques and Biochemical and Clinical Applications, Clarendon Press, Oxford 1986, pages 223 to 230". This 2-dimensional separation method is used in particular as a combination of isoelectric focussing in the first dimension and gel electrophoresis, for example SDS-PAGE, in the second dimension. The resulting gel pattern in the first dimension throws light on the isoelectric point of the respective component and in the second dimension on the molar mass of the relevant component. A typical separation analysis in 2D gel electrophoresis, with ca. 10,000 types of molecule, is effected in a period of more than two hours for one measurement. It is used to a large extent in proteomics research.

The primary aim of proteomics research is to correlate one or more defined proteins with pathogens, and to hasten the development of medicaments by explaining the structure of these proteins using appropriate analytical methods.

To carry out electrophoretic separation on a carrier consisting of glass or plastic in a check- card format, previously thin structures (capillaries) were firstly etched into the carrier. These capillaries were filled with a hydrogel and closed with a cover. Using such"microfluidics", separations of, for example, proteins in the serum can be carried out by gel electrophoresis or isoelectric focussing. However, the following technical difficulties occur, and have not yet been fully eliminated : 1. filling of the capillaries with gels is complex and not fully reproducible owing to the danger of air bubbles forming; 2. the required surface treatment of the capillaries is not uniform and 3. the production costs for such separating devices are still too high.

In addition, the surface of the channels must be modified in a subsequent step, in order to prevent the adsorption of analytes. This is particularly important, since owing to the small channel cross-sections, the surface-volume ratio is unfavourable and has an especially critical affect on small amounts of samples. Normally, a dissolved sample is placed on a dry chip. A stream of liquid from the starting point to the detection point is produced by capillary effects. Detection is usually effected by optical, electrical or immunological methods.

The problem is therefore to develop a microseparator for the electrophoretic separation of proteins and other biomolecules, which no longer has the above-mentioned disadvantages.

This is advantageously achieved whereby channel-like structures are no longer milled or etched into the carrier, as was previously usual, but hydrogel structures are applied to the carrier matrix or the required structures are produced in a hydrogel layer.

SUMMARY OF THE INVENTION The object of the invention is a microseparator for the electrophoretic separation of proteins and other biomolecules, which has hydrogel structures, which consist of channels of crosslinkable polymers applied to a carrier matrix or a layer of crosslinkable polymers, the structure being imparted by physical or chemical means and which are optionally divided into functionalised part zones.

To produce such a microseparator, a crosslinkable polymer having homogeneous and reproducible properties may be applied evenly to a conduit which has electrical terminals, the structure being imparted by photolithography or by embossing or by other microstructuring processes.

With one exposure, polymerisation and structuring can be carried out in one operation without the need for time-consuming and expensive microstructuring. The areas not belonging to the structure may be washed away and made impassable to the biomolecules by intensive crosslinking. What is more, the structures formed can be functionalised, for example by a pH gradient, so that the hydrogel strips are prepared for specific separation tasks.

Objects of the invention are also biochips, whose special separating properties can be set by mixing different starting polymers for the hydrogel and by changing the proportions in the mixture depending on the respective separating task.

BRIEF DESCRIPTION OF THE FIGURES Fig. 1 illustrates the most important operational steps in producing a microseparator for the electrophoretic separation of proteins and other biomolecules.

Fig. 2 shows a two dimensional microseparating device according to one embodiment of the invention.

Fig. 3 shows a production apparatus according to one embodiment of the invention.

Fig. 4 shows a three dimensional microseparating device according to one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION Fig. 1 illustrates the most important operational steps in producing a microseparator for the electrophoretic separation of proteins and other biomolecules.

In a first step of the process, the crosslinkable polymer is applied to the conduit. In the second step, structure is imparted to the crosslinkable polymer by photolithography (producing the hydrogel structure) and optionally by subsequent embossing of the resulting hydrogel. Subsequently, in the third process step, functionalisation of selected hydrogel zones may take place, i. e. for example the production of a pH gradient for isoelectric focussing. In the fourth step of the process, a cover plate is applied.

Various methods are available to form the microseparator. It preferably takes place by lithographic exposure of the crosslinkable polymer through a mask to energy-rich radiation, subsequently washing away the soluble components, whereby the structured hydrogel layer remains. If required, further structuring may take place by embossing.

Another structuring method consists in applying a substance that initiates crosslinking to selected areas of the layer of crosslinkable polymer and subsequently washing away the uncrosslinked areas, whereby a structured hydrogel layer is obtained.

It is also possible to produce the hydrogel layer by applying a substance that initiates crosslinking through a mask or by selective spraying onto the layer of the crosslinkable polymer.

Finally, it is also possible remove the hydrogel layer that has been rendered insoluble by crosslinking, at selected places, by exposing to laser light and thereby imparting the structure.

The hydrogel structure is then suitably covered with a protecting layer that is impermeable to water and does not conduct light, for example foil. The carrier matrix is generally made of glass, metal, ceramics or a polymeric plastic material. It may be coated on one or both sides with a hydrogel. An especially appropriate process for producing the microseparator according to the invention consists in firstly producing a large area of carrier matrix with the required hydrogel structures, and then cutting this up into the microseparators for the electrophoretic separation of proteins and other biomolecules.

The electrical voltage necessary to carry out gel electrophoresis at the electrical terminals provided on the microseparator, also called a microchip or biochip, can be generated by conduits embedded in the carrier matrix or by electrodes immersed in electrolyte solutions.

To produce the hydrogel layer on the carrier matrix, a water-soluble crosslinkable prepolymer is used, which in the copolymer chain contains units which are, for example, derived from the following monomer elements ; a vinyl lactam (a), a vinyl alcohol (b), optionally a lower alkanecarboxylic acid vinyl ester (c), a vinylic crosslinker (d) and optionally a vinylic photoinitiator (e). Water-soluble, crosslinkable prepolymers of this kind have already been described in detail, for example, in European patent application EP-A-712 867.

Hydrogels obtained from these have, until now, usually been used to produce contact lenses, but are also eminently suitable for producing the microseparator according to the invention.

Important criteria determining the suitability of a prepolymer for use in the process according to the invention are that the prepolymer is soluble in water and that it comprises cross- linkable groups.

In accordance with the invention, the criterion that the prepolymer is soluble in water denotes in particular that the prepolymer is soluble in a concentration of approximately from 3 to 90 % by weight, preferably approximately from 5 to 60 % by weight, especially approximately from 10 to 60 % by weight, in a substantially aqueous solution. Insofar as it is possible in an individual case, prepolymer concentrations of more than 90 % are also included in accordance with the invention. Especially preferred concentrations of the prepolymer in solution are from approximately 15 to approximately 50 % by weight, especially from approx- imately 15 to approximately 40 % by weight, for example from approximately 25 % to approximately 40 % by weight.

The average molecular weight Mn of the prepolymer is, within wide limits, not critical, but is in general >1000 and preferably ! 2000. A preferred molecular weight range is from about 2500 to about 2000000, especially from 5000 to 1000000, more preferred from 10000 to 200000, even more preferred from 10000 to 100000 and in particular from 10000 to 50000.

A water-soluble prepolymer according to the invention preferably comprises a suitable polymeric backbone and crosslinkable groups.

Suitable polymeric backbones include polyvinyl alcohols (PVA), polymeric diols other than PVA, polymers comprising saccharides, polymers comprising vinylpyrrolidone, polymers comprising alkyl (meth) acrylates, polymers comprising alkyl (meth) acrylates that have been substituted by hydrophilic groups, such as by hydroxy, carboxy or by amino, polymers comprising a polyalkylene oxide, or copolymers or mixtures thereof.

"Crosslinkable groups"denotes customary crosslinkable groups well-known to the person skilled in the art, such as, for example, photocrosslinkable or thermally crosslinkable groups.

Crosslinkable groups such as those already proposed for the preparation of contact lens materials are especially suitable. Those include especially, but not exclusively, groups comprising carbon-carbon double bonds, such as an acrylate, methacrylate, acrylamide, methacrylamide, vinyl or styryl group. To demonstrate the large variety of suitable crosslinkable groups, there are mentioned here, merely by way of example, the following crosslinking mechanisms: radical polymerization, [2+2] cycloaddition, Diels-Alder reaction, ROMP (Ring Opening Metathesis Polymerization), vulcanization, cationic crosslinking and epoxy hardening. A preferred crosslinkable group is a group comprising a carbon-carbon double bond, in particular an acrylate, methacrylate, acrylamide or methacrylamide group.

The prepolymer used in accordance with the invention preferably comprises crosslinkable groups in an amount of from approximately 0.5 to approximately 80 % equivalents, based on the equivalents of monomers that form the polymeric backbone, especially approximately from 1 to 50 %, preferably approximately from 1 to 25 %, preferably approximately from 2 to 15 % and especially preferably approximately from 3 to 10 %. Also especially preferred are amounts of crosslinkable groups of from approximately 0.5 to approximately 25 % equivalents, especially approximately from 1 to 15 % and especially preferably approximately from 2 to 12 %, based on the equivalents of monomers that form the polymeric backbone.

Preferably, the prepolymers used in the process according to the invention are previously purified in a manner known per se, for example by precipitation with organic solvents, such as acetone, filtration and washing, extraction in a suitable solvent, dialysis or ultrafiltration, ultrafiltration being especially preferred. By means of that purification process the pre- polymers can be obtained in extremely pure form, for example in the form of concentrated aqueous solutions that are free, or at least substantially free, from reaction products, such as salts, and from starting materials, such as, for example, non-polymeric constituents. The preferred purification process for the prepolymers used in the process according to the invention, ultrafiltration, can be carried out in a manner known per se. It is possible for the ultrafiltration to be carried out repeatedly, for example from two to ten times. Alternatively, the ultrafiltration can be carried out continuously until the selected degree of purity is attained. The selected degree of purity can in principle be as high as desired. A suitable measure for the degree of purity is, for example, the concentration of dissolved salts obtained as by-products, which can be determined simply in known manner.

One group of suitable prepolymers being useful in the process of the invention are crosslinkable polyalkylene oxide derivatives as disclosed, for example in EP-A-0,932, 635, EP-A-0,958, 315, EP-A-0-961,941 or EP-A-1, 017, 734.

A particular preferred prepolymer according to the invention comprises a 1, 3-diol basic structure in which a certain percentage of the 1, 3-diol units have been modified to a 1,3- dioxane having in the 2-position a radical that is polymerizable but not polymerized. The polymerizable radical is especially an aminoalkyl radical having a polymerizable group bonded to the nitrogen atom.

The prepolymer according to the invention is preferably a derivative of a polyvinyl alcohol having a molecular weight of at least about 2 000 that, based on the number of hydroxy groups of the polyvinyl alcohol, comprises from approximately 0.5 to approximately 80 % of units of formula wherein R is C1-C8-alkylene, R1 is hydrogen or C1-C7-alkyl and R2 is an olefinically unsaturated, electron-attracting, copolymerizable radical preferably having up to 25 carbon atoms. R2 is, for example, an olefinically unsaturated acyl radical of formula R3-CO-, in which R3 is an olefinically unsaturated copolymerizable radical having from 2 to 24 carbon atoms, preferably from 2 to 8 carbon atoms, especially preferably from 2 to 4 carbon atoms. In another embodiment, the radical R2 is a radical of formula -CO-NH- (R4-NH-CO-O) q-R5-0-CO-R3 (2), wherein q is zero or one and R4 and R5 are each independently C2-C8-alkylene, Ce-Cis- arylen, a saturated divalent C6-C10-cycloaliphatic group, C7-C4-arylenealkylene or C7-C14- alkylenearylene or C13-C6-arylenealkylenearylene, and R3 is as defined above.

The prepolymer used according to the invention is therefore especially a derivative of a polyvinyl alcohol having a molecular weight of at least about 2 000 that, based on the number of hydroxy groups of the polyvinyl alcohol, comprises from approximately 0.5 to approximately 80 % of units of formula wherein R is C1-C8-alkylene, Ri is hydrogen or C1-C7-alkyl, p is zero or one, q is zero or one, R3 is an olefinically unsaturated copolymerizable radical having from 2 to 8 carbon atoms and R4 and R5 are each independently C2-C8-alkylene, C6-C12-arylene, a saturated divalent C6-C10-cycloaliphatic group, C7-C14-arylenealkylene or C7-C14-alkylenearylene or C13-C16- arylenealkylenearylene.

An alkylen radical R may be straight-chained or branched. Suitable examples include octylene, hexylen, pentylen, butylen, propylene, ethylene, methylene, 2-propylene, 2- butylen and 3-pentylene. Alkylen R has preferably 1 to 6 and especially preferably 1 to 4 carbon atoms. The meanings methylene and butylen are especially preferred.

R, is preferably hydrogen or C1-C4-alkyl, especially hydrogen.

Alkylen R4 or R5 preferably has from 2 to 6 carbon atoms and is especially straight-chained Suitable examples include propylene, butylene, hexylene, dimethylethylene and, especially preferably, ethylene.

Arylene R4 or R5 is preferably phenylene that is unsubstituted or is substituted by C1-C4-alkyl or C1-C4-alkoxy, especially 1, 3-phenylene or 1, 4-phenylene or methyl-1, 4-phenylene.

A saturated divalent cycloaliphatic group R4 or R5 is preferably cyclohexylene or cyclo- hexylene-C1-C4-alkylene, for example cyclohexylenemethylene, that is unsubstituted or is substituted by one or more methyl groups, such as, for example, trimethylcyclohexylene- methylene, for example the divalent isophorone radical.

The arylene unit of alkylenearylene or arylenealkylene R4 or R5 is preferably phenylene, unsubstituted or substituted by C1-C4-alkyl or IC1-C4-alkoxy, and the alkylen unit thereof is preferably C1-C8-alkylene, such as methylene or ethylene, especially methylene. Such radicals R4 or R5 are therefore preferably phenylenemethylene or methylenephenylene.

Arylenealkylenearylene R4 or R5 is preferably phenylene-C1-C4-alkylene-phenylene, for example phenyleneethylenephenylene.

The radicals R4 and R5 are each independently preferably C2-C6-alkylene ; phenylen, unsubstituted or substituted by C1-C4-alkyl ; cyclohexylene ; cyclohexylene-C1-C4-alkylene, unsubstituted or substituted by C1-C4-alkyl ; phenylene-C1-C4-alkylene ; C1-C4-aikylene- phenylen ; or phenylene-C1-C4-alkylene-phenylene.

The olefinically unsaturated copolymerizable radical R3 having from 2 to 24 carbon atoms is preferably C2-C24-alkenyl, especially C2-C8-alkenyl and especially preferably C2-C4-alkenyl, for example ethenyl, 2-propenyl, 3-propenyl, 2-butenyl, hexenyl, octenyl or dodecenyl. The meanings ethenyl and 2-propenyl are preferred, so that the group-CO-R3 is preferably the acyl radical of acrylic or methacrylic acid.

The divalent group-R4-NH-CO-O-is present when q is one and absent when q is zero.

Prepolymers in which q is zero are preferred.

The divalent group-CO-NH- (R4-NH-CO-O) q-R5-0- is present when p is one and absent when p is zero. Prepolymers in which p is zero are preferred.

In prepolymers in which p is one the index q is preferably zero. Prepolymers in which p is one, the index q is zero and R5 is C2-C8-alkylene are especially preferred.

A preferred prepolymer used according to the invention is therefore especially a derivative of a polyvinyl alcohol having a molecular weight of at least about 2000 that, based on the number of hydroxy groups of the polyvinyl alcohol, comprises from approximately 0.5 to approximately 80 % of units of formula (3) in which R is C1-C6-alkylene, p is zero and R3 is C2-C8-alkenyl.

A further preferred prepolymer used according to the invention is therefore especially a derivative of a polyvinyl alcohol having a molecular weight of at least about 2000 that, based on the number of hydroxy groups of the polyvinyl alcohol, comprises from approximately 0.5 to approximately 80 % of units of formula (3), in which R is C1-C6-alkylene, p is one, q is zero, R5 is C2-C6-alkylene and R3 is C2-C8-alkenyl.

A further preferred prepolymer used according to the invention is therefore especially a derivative of a polyvinyl alcohol having a molecular weight of at least about 2000 that, based on the number of hydroxy groups of the polyvinyl alcohol, comprises from approximately 0.5 to approximately 80 % of units of formula (3) in which R is C1-C6-alkylene, p is one, q is one, R4 is C2-C6-alkylene, phenylen, unsubstituted or substituted by C1-C4-alkyl, cyclohexylene or cyclohexylene-C1-C4-alkylene, unsubstituted or substituted by C1-C4-alkyl, phenylene-C1- C4-alkylene, C1-C4-alkylene-phenylene or phenylene-C1-C4-alkylene-phenylene, R5 is C2-C6- alkylen and R3 is C2-C8-alkenyl.

The prepolymers used according to the invention are preferably derivatives of polyvinyl alcohol having a molecular weight of at least about 2000 that, based on the number of hydroxy groups of the polyvinyl alcohol, comprises from approximately 0.5 to approximately 80 %, especially approximately from 1 to 50 %, preferably approximately from 1 to 25 %, preferably approximately from 2 to 15 % and especially preferably approximately from 3 to 10 %, of units of formula (3). Prepolymers according to the invention which are provided for the manufacture of contact lenses comprise, based on the number of hydroxy groups of the polyvinyl alcohol, especially from approximately 0.5 to approximately 25 %, especially approximately from 1 to 15 % and especially preferably approximately from 2 to 12 %, of units of formula (3).

Derivatized polyvinyl alcohols according to the invention preferably have an average molecular weight Mn of at least 10 000. As an upper limit the polyvinyl alcohols may have an average molecular weight of up to 1 000 000. Preferably, the polyvinyl alcohols have a molecular weight of up to 300 000, especially up to approximately 100 000 and especially preferably up to approximately 50 000. <BR> <BR> <P>Polyvinyl alcohols suitable in accordance with the invention usually have a poly (2-hydroxy) - ethylene structure. The polyvinyl alcohols may, however, also comprise hydroxy groups in the form of 1, 2-glycols, such as copolymer units of 1, 2-dihydroxyethylene, as may be obtained, for example, by the alkaline hydrolysis of vinyl acetate/vinyiene carbonate copolymers.

In addition, the polyvinyl alcohols used may also comprise small proportions, for example up to 20 %, preferably up to 5 %, of copolymer units of ethylene, propylene, acrylamide, methacrylamide, dimethacrylamide, hydroxyethyl methacrylate, methyl methacrylate, methyl acrylate, ethyl acrylate, vinylpyrrolidone, hydroxyethyl acrylate, allyl alcohol, styrene or similar customarily used comonomers.

Polyvinyl alcohol is usually prepared by hydrolysis of the corresponding homopolymeric poly- vinyl acetate. In a preferred embodiment, the polyvinyl alcohol derivatized in accordance with the invention comprises less than 50 % of polyvinyl acetate units, especially less than 20 % of polyvinyl acetate units. Preferred amounts of residual acetate units in the polyvinyl alcohol derivatized in accordance with the invention, based on the sum of vinyl alcohol units and acetate units, are approximately from 3 to 20 %, preferably approximately from 5 to 16 % and especially approximately from 10 to 14 %.

The prepolymers comprising units of formula (1) or (3) are known, for example, from U. S. patent No. 5,508, 317 and may be prepared according to the processes described therein.

The aqueous solution of the prepolymer is preferably a pure solution which means a solution which is free or essentially free from undesired constituents, for example, free from monomeric, oligomeric or polymeric starting compounds used for the preparation of the prepolymer, and/or free from secondary products formed during the preparation of the prepolymer. Especially preferred examples of such solutions are a solution of the prepolymer in pure water or in an artificial lacrimal fluid, as defined hereinbefore.

In addition, the aqueous solutionof the prepolymer may contain an additional vinylic comonomer. The vinylic comonomer which, in accordance with the invention, may be used in addition in the crosslinking, may be hydrophilic or hydrophobic, or a mixture of a hydrophobic and a hydrophilic vinylic monomer. Suitable vinylic monomers include especially those customarily used in the manufacture of contact lenses. A hydrophilic vinylic monomer denotes a monomer that typically yields as homopolymer a polymer that is water-soluble or can absorb at least 10 % by weight of water. Analogously, a hydrophobic vinylic monomer denotes a monomer that typically yields as homopolymer a polymer that is water-insoluble and can absorb less than 10 % by weight of water.

Generally, approximately from 0.01 to 80 units of a typical vinylic comonomer react per unit of formula (1) or (3).

If a vinylic comonomer is used, the crosslinked polymers according to the invention preferably comprise approximately from 1 to 15 %, especially preferably approximately from 3 to 8 %, of units of formula (1) or (3), based on the number of hydroxy groups of the poly- vinyl alcohol, which are reacted with approximately from 0.1 to 80 units of the vinylic monomer.

The proportion of the vinylic comonomers, if used, is preferably from 0.5 to 80 units per unit of formula (1), especially from 1 to 30 units per unit of formula (1), and especially preferably from 5 to 20 units per unit of formula (1).

It is also preferable to use a hydrophobic vinylic comonomer or a mixture of a hydrophobic vinylic comonomer with a hydrophilic vinylic comonomer, the mixture comprising at least 50.

% by weight of a hydrophobic vinylic comonomer. In that manner the mechanical properties of the polymer can be improved without the water content falling substantially. In principle, however, both conventional hydrophobic vinylic comonomers and conventional hydrophilic vinylic comonomers are suitable for the copolymerization with polyvinyl alcohol comprising groups of formula (1).

Suitable hydrophobic vinylic comonomers include, without the list being exhaustive, Ci-Cis- alkyl acrylates and methacrylates, C3-C, 8alkyl acrylamides and methacrylamides, acrylo- nitrile, methacrylonitrile, vinyl-C,-C, 8alkanoates, C2-C, 8alkenes, C2-C, 8haloalkenes, styrene, C,-C6alkylstyrene, vinyl alkyl ethers, in which the alkyl moiety contains from 1 to 6 carbon atoms, C2-C, 0perfluoroalkyl acrylates and methacrylates or correspondingly partially fluorinated acrylates and methacrylates, C3-Cr2perfluoroalkyl-ethyl-thiocarbonylaminoethyl acrylates and methacrylates, acryloxy-and methacryloxy-alkylsiloxanes, N-vinylcarbazole, Ci-Cizaikyi esters of maleic acid, fumaric acid, itaconic acid, mesaconic acid and the like. C,- C4alkyl esters of vinylically unsaturated carboxylic acids having from 3 to 5 carbon atoms or vinyl esters of carboxylic acids having up to 5 carbon atoms, for example, are preferred.

Examples of suitable hydrophobic vinylic comonomers include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, vinyl acetate, vinyl propionate, vinyl- butyrate, vinyl valerat, styrene, chloroprene, vinyl chloride, vinylidene chloride, acrylonitrile, 1-butene, butadiene, methacrylonitrile, vinyltoluene, vinyl ethyl ether, perfluorohexylethylthio- carbonylaminoethyl methacrylate, isobornyl methacrylate, trifluoroethyl methacrylate, hexa- fluoroisopropyl methacrylate, hexafluorobutyl methacrylate, tris-trimethylsilyloxy-silyl-propyl methacrylate, 3-methacryloxypropylpentamethyldisiloxane and bis (methacryloxypropyl)- tetramethyldisiloxane.

Suitable hydrophilic vinylic comonomers include, without the list being exhaustive, hydroxy-- substituted C-C6-alkyl acrylates and methacrylates, acrylamide, methacrylamide, C,-C4-alkyl acrylamides and methacrylamides, ethoxylated acrylates and methacrylates, hydroxy-- substituted C,-C6-alkyl acrylamides and methacrylamides, hydroxy-substituted C,-C6-alkyl vinyl ethers, sodium ethylenesulfonate, sodium styrenesulfonate, 2-acrylamido-2-- methylpropanesulfonic acid, N-vinylpyrrole, N-vinylsuccinimide, N-vinylpyrrolidone, 2-or 4- vinylpyridine, acrylic acid, methacrylic acid, amino- (the term"amino"also including quaternary ammonium), mono-C,-C6-alkylamino-or di-C,-C6-alkylamino-C-C6-alkyl acrylates and methacrylates, allylalcohol and the like. Hydroxy-substituted C2-C4alkyl (meth) acrylates, five-to seven-membered N-vinyl lactams, N, N-di-C,-C4alkyl (meth) acrylamides and vinylically unsaturated carboxylic acids having a total of from 3 to 5 carbon atoms, for example, are preferred.

Examples of suitable hydrophilic vinylic comonomers include hydroxyethyl methacrylate, hydroxyethyl acrylate, acrylamide, methacrylamide, dimethylacrylamide, allyl alcohol, vinyl- pyridine, vinylpyrrolidone, glycerol methacrylate, N- (1, 1-dimethyl-3-oxobutyl) acrylamide, and the like.

Preferred hydrophobic vinylic comonomers are methyl methacrylate and vinyl acetate.

Preferred hydrophilic vinylic comonomers are 2-hydroxyethyl methacrylate, N-vinylpyrrol- idone and acrylamide.

The aqueous solution of the prepolymer preferably does not contain a comonomer.

The aqueous solution of the prepolymer, in addition to water, may contain a further solvent, for example an alcohol, such as methanol, ethanol or n-or iso-propanol, or a carboxylic acid amide, such as N, N-dimethylformamide, or dimethyl sulfoxide. The aqueous solution preferably contains no further solvent.

In the case of photocrosslinking it is appropriate to add a photoinitiator to the aqueous solution, which can initiate radical crosslinking. Examples thereof are familiar to the person skilled in the art and suitable photoinitiators that may be mentioned specifically are benzoin methyl ether, 1-hydroxycyclohexylphenyl ketone, or Darocure or Irgacure types, for example Darocure 1173 or Irgacure) 2959. The amount of photoinitiator may be selected within wide limits, an amount of up to 0.05 g/g of prepolymer and especially of up to 0.003 g/ g of prepolymer having proved beneficial.

The viscosity of the prepolymer solution is, within wide limits, not critical, but the solution should preferably be a flowable solution that can be deformed strain-free.

The crosslinking of the prepolymers may be carried out, for example, by the action of heat or by irradiation, photocrosslinking using, for example, visible light, UV light or ionising radiation, such as gamma radiation orX-radiation, in particular using UV light, being preferred. The photocrosslinking can be carried out according to the invention in a very short time, for example in less than five minutes, preferably in <1 minute, especially in 1 to 60 seconds, especially preferably, in 2 to 30 seconds, and in particular in 2 to10 seconds.

The photocrosslinking is carried out preferably directly from an aqueous solution of the pre- polymers according to the invention, which can be obtained by the preferred purification step, ultrafiltration, after the addition of the non-crosslinkable further polymer and, where appropriate an additional vinylic comonomer. For example, an approximately 15 to 40 % aqueous solution can be photocrosslinked.

The microseparator according to the invention should enable simple, quick and specific detection to be made of a limited number of defined proteins in body fluids. In contrast to the tasks of proteomics research, this does not concern the separation of as many proteins as possible, but the simple, simultaneous detection of in general up to about 20 known proteins.

Since the analytes are known, the separating process of the biochip can be specially optimised to this task, in order that a sample of body fluid can be analysed without additional preparation of the sample, using only the specific biochip. A medical diagnosis is thus the task of analysis, which can be advantageously carried out using a specific biochip with mass-tailored separating properties.

Objects of the invention are therefore also biochips, whose special separating properties can be set by mixing different starting polymers for the hydrogel and by changing the proportions in the mixture depending on the respective separating task.

Such a microseparator consists essentially of hydrogel channels which are placed on a carrier plate. They are produced by dispensing a viscous, crosslinkable polymer solution in the form of a caterpillar track. By triggering a crosslinking reaction, for example by UV- radiation in the presence of a photoinitiator, the polymer solution is converted into a hydrogel. If the geometric accuracy of the dispensing caterpillar does not satisfy requirements, then geometrically precisely defined structures can be attained by means of locally restricted radiation using a mask. The hydrogel structures thus produced form permeable channels, in which sample preparation and/or separation of the sample into individual components takes place by chromatography or electrophoresis.

If the hydrogels are prevented from drying out by a closed housing, the channels only require contact with à flat carrier plate, which considerably reduces the size of the solid-solid interfaces. Thus, with small channel dimensions, a more favourable surface-volume ratio is achieved, and the risk of adsorption and denaturing phenomena of the analytes (usually proteins) is reduced. Furthermore, the surface of a flat carrier plate can be more easily modified than that of channels etched into a substrate.

If a suitable non-hydrogel material is available as matrix, the hydrogel channels may also be fully embedded into this, thereby giving higher mechanical carrying capacity to the hydrogel channels.

The specific separating properties of the hydrogel channels necessary for the analytical task are set by different starting polymers. For example, the pore size of the hydrogel which is crucial for separation according to molecule size can be set by a different crosslinking density. In order that individual starting polymers not intended for every analytical purpose could be produced, a process was developed according to the invention, in which two different starting polymers, for example for separation according to molecule size one polymer with a very low and a second with a very high crosslinking density, are co-dispensed through a common tube after passing through a mixing zone, for example in the form of a static mixer. If required, a static mixer can be integrated in the tube. The separating capability of the hydrogel channel resulting from crosslinking may be adjusted to any extent by changing the proportions of the two components by volume within the given extreme values.

This process allows both a constant separating characteristic and a variable characteristic over the entire length of the channel, since the proportions of the two components by volume can be modified to any extent by the dispensing method.

A further advantage of this process lies in the flexibility of the production apparatus illustrated in fig. 3, which contains as essential elements: - a receiving device for the carrier plate of the biochip; - a precise dispensing tube which can be moved in all directions over the carrier plate, optionally with a static mixer; - a programmable dispensing device, which allows the simultaneous dispensing of at least two starting polymers as solutions in a freely selectable volume ratio that can be changed to any extent by the dispensing method (for example continuous or discontinuous). Different solutions can be introduced to the dispensing tube by means of reversing valves.

- a device for crosslinking the dispensed caterpillar tracks to the hydrogel channels, for example by heat or actinic radiation in the presence of suitable polymerisation initiators, preferably by radiating with UV light (not illustrated) ; - a device for positioning a lithographic mask over the base plate with the applied polymer solutions for the geometrically precise production of the hydrogel channels (not illustrated).

What is crucial to flexibility is the co-dispensing of complementary starting polymers, since by means of simple switching between the supply containers of the different starting polymers, backed up by a control of the dose, it is possible to have any combination of separating characteristics on the same chip and it is simple to exchange the chip with any one from a large series of different chips. To avoid the spread of materials, spent and rinsing volumes can be removed without problems by a collection device which pivots between the dosing tube and chip.

By spatially restricting separation on the channels within a given area, it is possible to have a combination of channels acting in different ways. For example, in a first step, the sample may be separated according to isoelectric point via a stationary pH gradient (fig. 4).

Vertically to this separating channel are channels which effect separation according to molecule size through the pore size of the hydrogel. This illustrates the second dimension of separation. Since the analytical task is defined as described above, it is sufficient for the second separating dimension to link up to the first separating dimension only at those places where the analytes to be detected may be expected.

Accordingly, an especially efficient method of separating proteins and other biomolecules according to the invention consists in using a two-dimensional microseparator.

A two-dimensional separating device of this kind has, in a first dimension, a functionalised gel structure for separation of the proteins and other biomolecules to be detected by isoelectric focussing, to which electrolyte-filled channels are attached in a second dimension vertically connected thereto, in which channels the molecules leaving the hydrogel zone can be detected by chemical or physical methods. Preferably in the first dimension of the hydrogel structure, separation takes place by means of a pH gradient present in the hydrogel, while, in the second dimension, the proteins or other biomolecules can be detected by measuring the change in optical properties (e. g. refractive index) or electrical properties (e. g. impedance measurements).

Fig. 2 shows such a separating device with isoelectric, pH-dependent focussing as a first step of the process and a subsequent capillary gel electrophoresis, which is carried out in capillary channels placed vertically thereto, whereby the capillary channels are placed in a structured hydrogel layer. The 2D capillary gel electrophoresis which may be carried out by a two-dimensional microseparator according to the invention is carried out in the following steps: First of all, the sample to be examined is cleaned of other constituents which are not proteins or other biomolecules.

Then, the proteins and other biomolecules are separated by electric focussing. To do this, the protein mixture is firstly added to the hydrogel with a stable pH gradient and an electrical field is applied. Each protein or other biomolecule then migrates to the position in the pH gradient which corresponds to its isoelectric point.

In the next step, the now neutral proteins and other biomolecules are made mobile again by rebuffering, and subsequently spatially concentrated to be transferred to the microchannels for the capillary gel electrophoresis. Capillary gel electrophoresis then separates the proteins and other biomolecules according to their size. Small proteins and other biomolecules migrate more rapidly than large proteins and other biomolecules and reach the detection zone earlier.

At the end of electrophoresis, the proteins and other biomolecules pass through a detection zone. Here, analysis takes place by means of an external measuring unit. The following methods may be used for detection: fluorescence spectroscopy, interferometry, polarography, ellipsometry or electrical methods with microelectrodes.

In an especially appropriate two-dimensional microseparator, partial areas of the hydrogel are of such a structure that suitable areas are created for storing substances, and these can be emptied or filled by mechanical, electric, thermal or other means. A supply container may be integrated into the microseparator, by means of which acid or alkali may be released, this being necessary to rebuffer the proteins and other biomolecules that are immobilised at the isoelectric point.

Further separating dimensions can be joined together in the same way as the second separating dimension is connected to the first, as shown in fig. 4. The upper limit to the total number of separating dimensions is only defined by the geometry of the chip and the total length of the separating paths. In principle, the different separating mechanisms of analytical (bio) chemistry can be joined together in any sequence, combination or repetition. This includes, for example, in addition to the above-mentioned isoelectric focussing and molecular size separation, in particular also specific affinity for analytes or impurities.

In or to separate the analytes by migration in the channels, chromatography or electrophoresis may be used for example. For chromatography, a dried hydrogel can be used, which, when an aqueous sample is added and further water is made available at the point of adding the sample, produces a stream of liquid by adsorption of the water. This stream of liquid can be increased by attaching a superabsorber to the end of the channel.

For electrophoresis, electrodes are attached at the point of addition of the sample and at the crosslinking points between the channels and the end points of the channels, so as to build up electric-potential gradients.

In principle, the two methods can also be combined.

To detect the analytes, similarly there are several methods available, which are known in principle. For example, staining reagents can be diffused or injected from cross-channels in the area of the expected flow points of the analytes. A further staining method is to remove the chip cover and for the channels to make contact with a coloured foil, which allows the appropriate staining reagents at the expected points to diffuse into the channels. When using chromatographic methods as a last separating dimension, microelectrodes can be used, which recognise the analytes for example through a change in impedance. Of course, microelectrodes and staining reagents can also be combined to improve the sensitivity of detection. Very specific detection of analytes is made possible using labelled antibodies/antigens, which are fixed in channels or form the complex to be detected by means of a contact foil equivalent to the above-described staining foil through diffusion of the analytes to antibodies or vice versa.

The hydrogel materials to be used are based on starting polymers, which are chemically modified by principally known methods, and may be converted into gels by means of crosslinkable side groups in solution. Broad possibilities of variation are possible on a polyvinyl alcohol basis, which was described for example in US patent 5,583, 163. For example, if a solution of a PVA modified with cationic side groups is mixed with a solution of an anionic PVA, a clear mixed solution is obtained, which can be dispensed. As well as PVA, other polymers or copolymers can also be used. They are modifiable by means of available functional groups in polymer-analogous reactions, provided that the desired properties are not attained by monomer mixing.

The microseparators according to the invention based on hydrogel are substantially easier and cheaper to produce than previous conventional devices for capillary gel electrophoresis of proteins and other biomolecules. The microseparators according to the invention are therefore suitable for mass production and can be used as one-way articles in all scientific, medicinal or biological laboratories.

They can be used in particular for medicinal diagnostics, self diagnosis and to verify the therapeutical result.