A Voltammetric Biosensor Based on Glassy Carbon Electrode Modified with DsDNA/ZIF-8/CNT for Determination of Malathion

Abstract

In this work, we constructed an electrochemical biosensor based on a glassy carbon electrode modified by dsDNA/ZIF-8/CNT for sensitive and selective measurement of malathion (MAL). First, we investigated the interaction between MAL and salmon sperm dsDNA by computational (molecular docking) and experimental (UV-visible spectroscopy, and electrochemistry) methods. Then, we prepared the ZIF-8/CNT sensor and immobilized dsDNA on it. The ZIF-8/CNT was characterized by fourier transform infrared spectroscopy, X-ray scattering spectroscopy, and field-emission scanning electron microscopy. We optimized the factors affecting the electrochemical response of MAL and immobilization of the dsDNA on the surface of ZIF-8/ CNT/GCE, such as microliter of ZIF-8/CNT, concentration of the dsDNA and the time required for immobilization of dsDNA on the surface of ZIF-8/CNT-GCE, the effect of buffer pH on the MAL accumulation, the effect of MAL accumulation time, and the effect of pH the measurement solution. After optimizing the effective parameters, we drew the calibration curve using the differential pulse voltammetry (DPV) technique and obtained the concentration range of 0.20-50.00 μM with a detection limit of 1.0 nM. Furthermore, the RSD% for five consecutive tests of 2.00 μM MAL was obtained 2.4%. Also, the dsDNA/ZIF-8/CNT sensor showed good recovery in fruit samples.