Covalent functionalization of graphene oxide with l-lysine for highly sensitive and selective simultaneous electrochemical detection of rifampicin and acetaminophen

In the present work, graphene oxide covalently functionalized with L-lysine (LSN@GO)-based electrochemical sensor has been developed for the ultrasensitive individual as well as the first ever simultaneous detection of Rifampicin (RIFA) and Acetaminophen (APAP) drugs. The synthesized LSN@GO composite, as well as its precursors LSN and GO, were characterized using FT-IR, XRD, TGA, XPS, SEM and EDAX. The electrochemical studies were performed using Cyclic Voltammetry (CV), Linear Sweep Voltammetry (LSV), and Electrochemical Impedance Spectroscopy (EIS). The fabricated LSN@GO/GCE electro-sensor's interface exhibited efficient electrical activity for the analysis of RIFA and APAP under the optimized conditions, owing to its substantial electrochemically active surface area and exceptional electron transport capabilities. The detection of RIFA and APAP in various pH environments entailed a proton-dependent mechanistic approach. The sensor displayed a robust linear correlation over a broad range (0.5 to 10 mu M) for both RIFA and APAP, with low detection limits of 4.3 nM for RIFA and 5.8 nM for APAP (S/N = 3), along with quantification limits of 14.6 nM for RIFA and 19.4 nM for APAP (S/N = 10) for their individual detection. For simultaneous detection, the detection limit of 4.2 nM for RIFA and 6.0 nM for APAP were observed. We successfully detected spiked RIFA and APAP in real drug and urine samples without pre-treatment, demonstrating significant detection limits and no notable interference from excipients with satisfactory recovery data. The developed sensing platform demonstrated exceptional electrochemical performance for the detection of RIFA and APAP, showcasing significant potential for applications in clinical diagnosis and pharmaceuticals.{GRAPHIACAL ABSTRACT}