An electrochemical biosensor based on novel butylamine capped CZTS nanoparticles immobilized by uricase for uric acid...

Quaternary chalcopyrite, i.e., Cu₂ZnSnS₄ (CZTS) nanoparticles films have been proposed as a novel matrix system for enzyme-based electrochemical biosensors providing a non-toxic, low-cost alternative for the fabrication of bioelectrodes. The easy tuneability of the band gap of CZTS by varying the cation ratio and size of nanoparticles facilitate to impart desirable electrical properties in the material. Butylamine capped spherical CZTS nanoparticles of size 15-16 nm and band gap 2.65 eV have been synthesized by colloidal hot injection technique. The films of CZTS onto ITO substrates are deposited using dip coating technique, and uricase enzyme have been immobilized onto CZTS films using EDC-NHS binding chemistry. Electrochemical analyses of this bioelectrode revealed that the uricase/CZTS/ITO/glass electrode exhibits good linearity over a wide range of 0-700 μM uric acid concentration with a limit of detection (LOD) of 0.066 µM. The low value of 0.13 × 10^-4 M of Michaelis-Menten constant (K_m) indicate the enhanced affinity of immobilized enzyme (uricase) towards uric acid. Thus, the present report confirms the promising application of the p-type CZTS thin film matrix for the realization of an electrochemical biosensor.