Abstract: Avidin has been entrapped within silica matrices under ambient processing conditions. Properties of the entrapped avidin including stability and its binding with biotin have been investigated by measuring changes in fluorescence. The relative rates of binding to biotin in a range of organically modified silicate were used to compare diffusion properties within gels and their suitability for entrapment of biosensor reagents. Results showed that none of the sol-gel processing conditions used in this study denatured the biomolecules, with the silicate-entrapped generally avidin having better stability towards denaturing conditions than in solution. The avidin retains its binding ability even as the gels aged. Addition of specific organically modified silanes to sol-gel derived materials resulted in a slight improvement in stability and greater accessibility of avidin to external reagents...