“…Although it was observed that the specific catalytic activity of the nanogold-enzyme bioconjugate material was comparable (and at times marginally in excess of) to that of the free enzyme in solution, and that the immobilized enzyme exhibited enhanced temperature and pH stability (Gole et al, 2001a(Gole et al, , 2001b(Gole et al, , 2002, the reuse characteristics of the bioconjugate material were poor. Indeed, separation of the biocatalyst material from the reaction medium often could not be achieved, even by ultracentrifugation (Gole et al, 2001a(Gole et al, , 2001b(Gole et al, , 2002.This is clearly a major disadvantage in the use of otherwise biocompatible gold nanoparticles in the immobilization of enzymes. This problem may be overcome if the gold nanoparticles could be tethered at high density to a more massive surface, such as that provided by micron-sized particles.…”