Designing electrochemical NADH sensor using silver nanoparticles/phenothiazine nanohybrid and investigation on the shape dependent sensing behavior

Abstract

Based on the keen interest in biological and pharmaceutical laboratories, herein, we intend to develop a nonenzymatic electrochemical sensor for the detection of NADH using silver nanoparticles(AgNPs)/phenothiazine(PTZ) nanohybrid and also to investigate the shape-dependent electrocatalytic activity and sensing behavior of AgNPs. Nanoparticles of three different shapes, viz. silver nanorods (AgRNPs), silver nanoprisms (AgPNPs) and silver nanospheres (AgSNPs) were synthesized and conjugated with PTZ redox mediator to construct the respective nanohybrids. The nanohybrids (individually) were immobilized on the surface of a screen-printed carbon electrode (SPE) to form PTZ/AgRNPs/SPE, PTZ/AgPNPs/SPE and PTZ/AgSNPs/SPE modified electrodes, respectively. Under optimized conditions, the electrocatalytic activity of the modified electrodes and their quantification efficacy towards NADH sensing were tested using cyclic voltammetry and amperometry and the developed sensors with all the three nanohybrids have shown superior performance. Noticeably, the PTZ/AgRNPs/SPE comprising silver nanorods have exhibited a relatively better response for NADH detection over a wide linear range of 1.9–89 µM with a detection limit and sensitivity of 0.52 µM and 0.689 µA µM−1 cm−2, respectively. Other key parameters that regulate the efficacy of the developed sensor including stability, selectivity and reproducibility were also evaluated and the obtained results are highly satisfactory.