Département de chimie moléculaire

In this paper, a new concept of enzyme inhibition-based biosensor involving a two enzyme system was developed. The latter displays a signal increase instead of a decrease in the presence of an inhibitor. HRP and catalase were thus sep. entrapped into Layered Double Hydroxides (LDH), an anionic clay, as a host matrix. The inner layer was constituted of HRP elec. wired by [Zn2CrABTS] LDH and the outer layer contained catalase immobilized in [Zn3AlCl] LDH. Both enzymes catalyzed the decompn. of H2O2, HRP its redn. and catalase its breakdown into oxygen and water. Nitrite was selected as a specific inhibitor of catalase. In the presence of H2O2, the nitrite addn. blocked the H2O2 consumption by catalase, inducing thus an increase in the amperometric signal of the H2O2 redn. at 0 V by the wired HRP. The optimum configuration of the bi-enzyme biosensor displayed in aerated aq. solns., a nitrite sensitivity of 102 $μ$A M- 1· cm- 2 with a fast response time, the detective limit being 4 $μ$M. [on SciFinder(R)]