Cross-linked enzyme matrix and uses thereof

A composite membrane for an enzyme sensor, comprising:

• an inner membrane layer comprising a restorable polymerizable membrane, the inner membrane layer adapted to function as an interference rejection membrane;
• an outer membrane layer comprising polyurethane, and adapted to be disposed adjacent a flow channel during use;
• and
• an enzyme layer disposed between and in contact with the inner and the outer membrane layers, said enzyme layer comprising a matrix comprising:
• at least one enzyme selected from the group consisting of creatinase and sarcosine oxidase;
• a cross-linking agent;
• and
• an enzyme stabilizer selected from the group consisting of polyethyleneimine, polypropyleneimine, poly(N-vinylimidazole), polyallylamine, polyvinylpyridine, polyvinylpyrrolidone, polylysine, and protamine;
• wherein the outer membrane is adapted to control diffusion of an analyte into the enzyme layer.

A composite membrane for an enzyme sensor, comprising:

• an inner membrane layer comprising a restorable polymerizable membrane, the inner membrane layer adapted to function as an interference rejection membrane;
• an outer membrane layer comprising polyurethane, and adapted to be disposed adjacent a flow channel during use;
• and
• an enzyme layer disposed between and in contact with the inner and the outer membrane layers, said enzyme layer comprising a matrix comprising:
• creatininase;
• creatinase;
• sarcosine oxidase;
• glutaraldehyde;
• and
• polyethyleneimine,
• wherein the outer membrane is adapted to control diffusion of an analyte into the enzyme layer.