Sensitive detection and determination of benzodiazepines using silver nanoparticles-N-GQDs ink modified electrode: A new platform for modern pharmaceutical analysis

In this work, a unique conductive nano-ink based on silver nanoparticle-nitrogen doped graphene quantum dots (Ag/N-GQD) was synthesized and utilized for development of a novel, unique and sensitive biosensor for determination of alprazolam, chlordiazepoxide bis, diazepam, oxazepam and clonazepam. Electrochemical deposition, as a well-controlled synthesis procedure, has been utilized for subsequently layer-by-layer preparation of Ag/N-GQD nano-ink on a chitosan (CS) electropolymerized on the surface of gold electrode using cyclic voltammetry techniques in the regime of -1 to +1 V. The modified electrode appeared as an efficient electroactive interface for detection of selected benzodiazepines by using cyclic voltammetry, differential pulse voltammetry, and square wave voltammetry. The prepared sensor showed a noticeably good electro-activity for electrooxidation of alprazolam, chlordiazepoxide bis, diazepam, oxazepam and clonazepam than bare CS and Ag/N-GQD modified electrodes. Enhancement of peak currents is ascribed to the fast heterogeneous electron transfer kinetics that arise from the synergistic coupling between unique features of CS such as high permeability, excellent film-forming capability, good adhesion, cheapness, nontoxicity, and a susceptibility to chemical modifications, Ag/N-GQD nano-ink as high electrical conductivity. Finally, application of the new sensor for determination of selected benzodiazepine group drugs in unprocessed human plasma samples was studied. In general, the simultaneous attachment of Ag/N-GQD nano-ink to structure of CS provides new opportunities toward biomedical analysis and the personal healthcare.