A new type of sol-gel derived, polishable, amperometric biosensor is introduced. These new biosensors comprise enzymes immobilized in organically modified silica-carbon matrices. The silica backbone contributes rigidity, and the organically modified surface guarantees that water will not penetrate into the bulk of the electrode; the percolating carbon powder provides electric conductivity and shields the enzyme from the hostile environment encountered during the sol-gel molding process, and the encapsulated enzyme provides biocatalysis and specificity. Redox dopants can also be incorporated into the porous matrix for charge mediation. An amperometric glucose biosensor is used as a demonstrative test case. The preparation of unmediated and tetrathiafulvalene-mediated biosensors is described, and their dynamic and steady-state responses are demonstrated.