Process for the production of surface-functionalized supports that serve as starting materials for microarrays used for immobilizing biomolecules

A process for the production of surface-functionalized supports that serve as starting products for the production of microarrays for immobilizing biomolecules, in which process the surface of a support is coated with an initiator and the coated surface is then put in contact with a solution containing at least one first group of polymerizable monomers, whereby the monomers contain binding sites onto which the biomolecules (probe molecules) can bond, and whereby the conditions under which the monomers are put in contact with the activated support are selected in such a way that the monomers, mediated by the initiator, bind to the support and, on that basis, polymerize to form functional polymer chains in such a manner that a fixed structure consisting of adjacent functional polymer chains is formed on the surface of the support.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
 EXAMPLE Production of Functionalized Glass Supports Glass supports (CCT, Jena) that were silanized on one side were employed. The glass supports were immersed into a 100 mM-solution of benzophenone in acetone for 15 minutes, subsequently rinsed with an mM-solution of benzophenone in acetone and finally dried in the air. Then the glass supports were placed with their side that was silanized and coated with benzophenone onto the monomer solutions described below with the addition of 1 mM of sodium periodate without the inclusion of air bubbles between the glass and the solution. After an equilibration time of 15 minutes, the specimens floating on the monomer solution were exposed to light through the glass. After another reaction time lasting 15 minutes, the supports were thoroughly washed with water, then with acetone and subsequently with water once again. Finally, the specimens were dried. A) Acrylic acid at a concentration of 25 g/L of water was used as the monomer solution. This monomer solution was treated for different exposure times (t UV ) The binding sites prepared with these monomers were carboxyl groups. The differing variants can be summarized as follows: 1 1) acrylic acid 25 g/L 7.5 min t UV 2) acrylic acid 25 g/L 10 min t UV 3) acrylic acid 25 g/L 15 min t UV B) Glycidyl methacrylate at a concentration of 10 g/L of water and 20 g/L of water, each with 25 g/L of hydroxymethyl methacrylamide, was used as the monomer solution. Here, too, different exposure times t UV of 10 minutes (10 and 20 g/L of water) or 15 minutes (only with 20 g/L of water) were employed. The binding sites prepared with these monomers were epoxide groups. The differing variants can be summarized as follows: 2 1) glycidyl methacrylate 10 g/L 10 min t UV 2) glycidyl methacrylate 20 g/L 10 min t UV 3) glycidyl methacrylate 20 g/L 15 min t UV &plus;25 g/L of hydroxymethyl methacrylamide in each case. The specimen underwent biomolecule immobilization and biomolecule assay. A) Biotin was coupled via N-aminoethyl biotinamide (“Biotinamin”; Molecular Probes) to the surfaces activated with EDC/NHS for 1 hour at 25° C. &lsqb;77° F.&rsqb; (reaction at a pH value of 7.4 for 5 hours at 25° C. &lsqb;77° F.&rsqb;); blank specimens were prepared analogously but without “Biotinamin”. B) Biotin was coupled to the surfaces via “Biotinamin” (reaction at a pH value of 9.6 over-night at 25° C. &lsqb;77° F.&rsqb;); blank specimens were obtained through incubation overnight at 25° C. &lsqb;77° F.&rsqb; in a buffer at a pH value of 9.6. The biotin assay for A and B was carried out in each case with 16 mm 2 of functionalized glass: 1) incubation with a streptavidin-alkaline phosphatase conjugate for 30 minutes at room temperature (RT); 2) reaction with paranitrophenyl phosphate (PNP) for 30 minutes at 37° C. &lsqb;98.6° F.&rsqb; and photometric measurement of the conversion at 405 nm. The results of the photometric measurement are shown in FIG. 1 . It can be seen in both cases that there is a very efficient binding of biotin to the functionalized supports. The background signal (here through non-specific binding of the streptavidin conjugate) can be minimized by the appropriate selection of the monomers (B) or by regulating the loading density (A 2 and A 3 ). FIG. 2 shows a flat support 10 having a surface area 11 intended for the functionalization and in this area, there are conical depressions 12 provided at regular intervals. The conical depressions can have a diameter, for instance, of approximately 20 &mgr;m and are at a distance from each other of likewise 20 &mgr;m. The usual spots have a diameter of about 100 &mgr;m to 150 &mgr;m, thus covering between 20 and 40 conical depressions on the surface 11 of the support 10 . Naturally, these figures are not mandatory. It is equally possible to employ supports whose surfaces have depressions with a different shape, diameter, etc. The essential aspect, however, is that, whenever possible, the depressions should taper towards the interior of the support since the slanted faces thus created bring about the desired surface area enlargement. The support 10 shown in FIG. 2 has not yet been surface-functionalized. The surface-functionalized state is depicted in FIG. 3 in a sectional view. Here, one can see a support 100 having a functionalized surface 110 which has been provided with depressions 120 . The polymer chains covalently coupled to the surface 110 within the scope of the functionalization have been designated with the reference numeral 130 . It is evident that more polymer chains 130 can be coupled per conical depression 120 than would be possible on a comparable planer section of the surface 110 , whose size corresponds to that of the cone base surface.