A novel sensitive laccase biosensor using gold nanoparticles and poly L-arginine to detect catechol in natural water.

In this study, the simple, green, and fast layer-by-layer modification of the glassy carbon electrode was mainly performed by electrodeposition of gold nanoparticles and then, poly-l-arginine, and finally, laccase was covalently bonded to poly-l-arginine using glutaraldehyde. This type of fabrication is used for the first time for catechol detection, which provides a bioelectrocatalytic cycle for electron transport in the presence of laccase that results in sensitive and fast detection of catechol. The scanning electron microscopy, Fourier-transform infrared spectroscopy, and electrochemical studies were performed to confirm successful immobilization of the enzyme. The biosensor response was linear in a wide range of catechol trace concentrations, 24.90-274.00 nM, with the detection limit of 18.00 nM. Values of Km , α, n, and Ks for the immobilized enzyme were calculated to be 1.25 × 10-2  µM, 0.56, 3.19, and 0.28 Sec-1 , respectively. It was examined in real sample successfully confirming it is capable of measuring catechol in natural water.