Highly Sensitive Enzymatic Biosensor Based on Polyaniline-Wrapped Titanium Dioxide Nanohybrid for Fish Freshness Detection.

Herein, we envisage the fabrication of a highly sensitive enzymatic electrochemical biosensor for selective detection of xanthine (Xn) using xanthine oxidase (XOs) immobilized polyaniline-wrapped titanium dioxide (PANI@TiO 2 ) nanohybrid as a sensing platform. The PANI@TiO 2 nanohybrid was synthesized via chemical polymerization using ammonium per sulfate as an oxidant. Various microscopic, spectroscopic, and electrochemical techniques have been utilized to confirm the electrophoretic deposition of the PANI and PANI@TiO 2 nanohybrids on to indium tin oxide (ITO) coated glass substrate. The fabricated XOs/PANI@TiO 2 /ITO electrode exhibits enhanced electron transfer kinetics with an electron transfer rate constant of 0.904 cm s -1 . The electrochemical results show that the fabricated biosensor can detect Xn in the concentration range 1-100 µM, with a limit of detection of 0.1 µM (S/N = 3) and a response time of 10 s. The validation of the biosensors has been conducted using real samples obtained from the rohu (Labeo rohita) fish. The proposed biosensor can be a reliable analytical tool for determining Xn concentration in commercial fish and meat samples.