Gold nanoparticles-enhanced amperometric tyrosinase biosensor based on three-dimensional sol-gel film-modified gold electrodes.

An amperometric biosensor for the determination of catechol was developed by immobilizing tyrosinase (tyr) on gold nanoparticles (AuNPs) and a (3-mercaptopropyl)-trimethoxysilane (MPTS) sol-gel three-dimensional network film-modified gold electrode. The AuNPs self-assembled in a sol-gel network provided an excellent microenvironment for an enzymatic reaction between tyrosinase and the substrate. It was found that the AuNPs could significantly affect the electron-transfer kinetics of the enzyme reaction, and remarkably enhance the electrochemical reduction of the corresponding o-quinones at the electrode surface. The nanostructured electrode showed high sensitivity (306.7 mA M(-1) cm(-2)) toward catechol, with an amperometric detection limit of 0.56 μM. The catalytic current of the biosensor was linear with the catechol concentration ranging from 1.7 to 96 μM with a correlation coefficient of 0.9992. The proposed biosensor exhibited a short response time, good anti-interferent ability, and excellent operational and storage stability.