ZrS₂ Nanoparticles Embedded in Chitosan-Based Hydrogel for the Electrochemical Detection of Antimalarial Drug Amodiaquine in Serum Samples

In this study, we report the synthesis of ZrS₂ nanoparticles embedded in a chitosan-based hydrogel (ZrS₂/CS hydrogel) for the electrochemical detection of amodiaquine (ADQ). The ZrS₂ nanoparticles are synthesized via a hydrothermal synthesis technique. Morphologically, transmission electron microscopy images show that the ZrS₂ nanoparticles agglomerated to form nanoclusters. Scanning electron microscopy images reveal the porous interconnected structure of the stacked hydrogel layer with ZrS₂ nanoparticles that have a high surface area and electrochemically active sites. These ZrS₂ nanoparticles embedded in the hydrogel enhanced the high electron transport during the redox process. Differential pulse voltammetry is employed to electrochemically detect ADQ in a wide linear range of 0.02 nM to 2 μM. The sensitivity of ADQ is calculated to be 1.138 μA/nM with a limit of detection of 0.4 nM and a limit of quantification of 1.33 nM. The possible mechanism behind the enhanced performance can be ascribed to the electrochemical oxidation of ADQ, its corresponding quinone-imine, and the improved interaction between the electrode and electrolyte solution, leading to enhanced electron transfer and more stable signals for electrochemical sensing. The sensor developed here has a highly selective response toward ADQ over other interferents such as NaCl, urea, uric acid, glucose, ascorbic acid, and dopamine. In simulated human serum, the sensor shows a recovery rate from 98.58 to 100.62%, suggesting its potential in developing electrochemical sensors. The repeatability and reproducibility results of the ZrS₂/CS hydrogel show excellent consistent results, with relative standard deviations of 3.41 and 3.46%, respectively, further affirming the reliability of the sensor. This approach opens up future research directions for detecting various analytes in point-of-care and other biomedical devices.