Silica sol-gel composite film as an encapsulation matrix for the construction of an amperometric tyrosinase-based biosensor

An amperometric tyrosinase enzyme electrode for the determination of phenol s was developed by a simple and effective immobilization method using sol-g el techniques. A grafting copolymer was introduced into sol-gel solution an d the composition of the resultant organic-inorganic composite material was optimized, the tyrosinase retained its activity in the sol-gel thin film a nd its response to several phenol compounds was determined at 0 mV vs. Ag/A gCl (sat. KCI). The dependences of the current response on pH, oxygen level and temperature were studied, and the stability of the biosensor was also evaluated. The sensitivity of the biosensor for catechol, phenol and p-cres ol was 59.6, 23.1 and 39.4 muA/mM, respectively. The enzyme electrode maint ained 73% of its original activity after intermittent use for three weeks w hen storing in a dry state at 4 degreesC. (C) 2000 Elsevier Science S.A. Al l rights reserved.