Electrochemical immunosensor development with chitosan modified reduced graphene oxide-nanoceria nanocomposite for gentamicin detection

A chitosan-modified nanocomposite of reduced graphene oxide and nanoceria (CH-(rGO@CeO2) NC) was synthesised using co-precipitation method to develop an electrochemical biosensor for the detection of the antibiotic gentamicin (GEN). Various techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-Ray Photoelectron Spectroscopy (XPS) and contact angle (CA) were employed for morphological and chemical characterization. Differential pulse voltammetry (DPV) demonstrated excellent electrochemical activity of CH-(rGO@CeO2) NC, making it an ideal transducer material for developing a highly sensitive electrochemical immunosensor. This immunosensor utilized monoclonal antibodies against gentamicin (anti-GEN) that was covalently bound to the CH-(rGO@CeO2) NC modified screen-printed electrode (SPE). Protein kinase A (PKA) was used to regulate immunologic interactions, while BSA was applied to block nonspecific binding sites on the anti-GEN/CH-(rGO@CeO2)/SPE surface. The DPV data for the BSA-anti-GEN/CH-(rGO@CeO2)/SPE immunoelectrode in GEN detection showed a satisfactory linear detection range (1 pM-100 µM), with a limit of detection (LOD) of 0.570 pM and a sensitivity of 2.88 µA pM−1 cm−2. The analysis exhibited a strong linear relationship with an R2 value of 0.973. This CH-(rGO@CeO2) electrochemical immunosensor demonstrated excellent potential for detecting GEN in spiked milk and tap water samples.