Polymer–Clay Nanocomposite-Based Acetylcholine esterase Biosensor for Organophosphorous Pesticide Detection

Abstract

In this study, a nanocomposite of chitosan (CH)–montmorillonite (MT) clay was prepared via uniform dispersion of MT particles in a homogenous CH solution and deposited onto indium tin oxide (ITO) coated glass substrate. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy, Fourier transform infrared spectroscopy, and electrochemical techniques were used for the characterization of the CH–MT nanocomposite. The XRD and TEM results confirmed the exfoliation and intercalation of the MT clay into CH matrix. This CH–MT nanocomposite was employed for the fabrication of enzymatic biosensor via immobilization of acetylcholine esterase (AChE) for organophosphorous (chlorpyriphos) detection. It was found that the diffusion coefficient, electron transfer rate, surface concentration were increased after the immobilization of AChE onto CH–MT/ITO electrode. This AChE/CH–MT/ITO bio-electrode showed the linearity range from 0.5 to 1000 µg L−1 with an LOD of 0.448 µg L−1 and sensitivity of 69.6 µA mM−1 cm2. The apparent Michaelis–Menten constant (\(K_{\text{m}}^{\text{app}}\)) was obtained as 0.219 mM as a function of chlorpyriphos. This prepared bioelectrode can be an excellent platform for chlorpyriphos detection.