Sol–gel based composite of gold nanoparticles as matix for tyrosinase for amperometric catechol biosensor

Composite of sol–gel and PVP stabilized gold nanoparticles has been synthesized chemically and is used as an immobilization matrix for tyrosinase enzyme. The composite was spin coated on ITO electrode which was then characterized for its optical and electrochemical behavior. Cyclic voltametric study of ITO/Sol–AuNPs composite electrode showed well defined redox couple for Fe+ ions which is due to high electro-conductivity supplied mainly by gold nanoparticle coverage. The capacitance and faradic current are found to be 6.0 × 10−5 mF and 3.172 × 10−4 A respectively. The analytical performance of composite based catechol biosensor has been evaluated as a function of catechol concentration, buffer concentration and buffer pH. The system showed linearity from 1.0 × 10−6 M to 6 × 10−6 M with sensitivity of 0.01 A/M and LOD as 3 × 10−7 M. Effect of presence of gallic acid, catechin and cresol have been studied using amperometry which showed that these species does not interfere with catechol estimation.