Sol-gel based matrix

A method for the production of a sol-gel based matrix comprising the steps of:

• a) providing a first alkoxysilane of the general formula:
• R1—Si(OR2)3
• and a second alkoxysilane of the general formula:
• wherein
• R1 represents a straight or branched C1-C6 alkyl or C2-C6 alkenyl, a C3-C6 cycloalkyl, a C1-C6 aminoalkyl, a C1-C6 hydroxyalkyl, a C1-C6 cyanoalkyl, a phenyl, a group of the formula —Y—(X—Y)nH, wherein Y independently is selected from straight or branched C1-C6 alkylene, X is a hetero atom or group selected among O, S, NH, and n is an integer of 1-5,
• or R1 represents a C1-C6 alkyl substituted with a group Z,
• wherein Z independently is selected form the group comprising hydrogen, cyano, halogen, hydroxy, nitro, amide C1-C24-alkyl, C1-C24-haloalkyl, C2-C24-alkenyl, C2-C24-alkynyl, aryl, C1-C24-alkoxy, C1-C24-alkylsulfonyl, amino, aminocarbonyl, aminothiocarbonyl, aminocarbonylamino, aminothiocarbonylamino, aminocarbonyloxy, aminosulfonyl, aminosulfonyloxy, aminosulfonylamino, amidino, carboxyl, carboxyl ester comprising a C1-C6 alkyl alcohol moiety, (carboxyl ester)amino comprising a C1-C6 alkyl alcohol moiety, (carboxyl ester)oxy comprising a C1-C6 alkyl alcohol moiety, sulfonyl, sulfonyloxy, thiol, thiocarbonyl, C1-C24-alkylthio, 5 or 6 membered heteroaryl, or a C3-C7 cycloalkyl;
• R2 independently represents a straight or branched C1-C6 alkyl;
• and
• R3 represents a linker chosen from a group of the formula
• —R4—(X—R4)n—
• wherein R4 independently is selected from straight or branched C2-C6 alkylene, C2-C24-haloalkylene, X is a hetero atom or group selected among O, S, NH, and n is an integer of 0-12,
• b) preparing a first sol-gel component by polymerisation of the first alkoxysilane in the presence of an acid catalyst,
• c) preparing a second sol-gel component by polymerisation of the second alkoxysilane in the presence of Lewis acid catalyst,
• wherein an additional alkoxysilane is added in at least one of steps b) or c), said additional alkoxysilane being of the formula:
• R5—Si(OR2)3
• wherein R2 is as defined above and R5 represents a group having covalently attached an indicator or reference dye,
• d) Mixing the first sol-gel component and the second sol-gel component for the preparation of a sol-gel based matrix.