Au-Ag nanoparticles-graphene quantum dots as sensor for highly sensitive electrochemical determination of insulin level in pharmaceutical samples

Abstract

This study was performed on the synthesis of Au-Ag nanoparticles-graphene quantum dots (Au-Ag NPs/GQDs) as a highly sensitive electrochemical sensor of insulin levels in prescription drugs for type 2 diabetic patients. To fabricate the Au-Ag NPs/GQDs modified GCE electrode (Au-Ag NPs/GQDs/GCE), GQDs were synthesized using the hydrothermal method on GCE, and then Au-AgNPs were electrodeposited on GQDs/GCE. The structural analyses of Au-Ag NPs/GQDs/GCE using SEM and XRD showed uniform coverage of the bimetallic nanoparticles in fcc crystal structure on the GQDs. The electrochemical studies for determination of insulin using CV and DPV showed that the linear range, limit of detection and sensitivity were obtained 10 to 120 µM, 1.1 nM and 0.24184µA/µM, respectively which were comparable or better than sensing results of other reported insulin sensors in literature. The selectivity of proposed insulin sensor was investigated in presence of biological species human serum sample such as thiourea, glucose, methionine, cysteine, ascorbic acid, uric acid and glutathione and results indicated the interference biological species did not show any interference effect on insulin determination. The applicability of sensor was studied for the determination of insulin in insulin glargine injection sample and results exhibited to the acceptable values for recovery and RSD, demonstrating the proposed sensor can be used as reliable and precise sensor to determine insulin in biological and clinical samples