DNA/Au-Pt bimetallic nanoparticles/graphene oxide-chitosan composites modified pencil graphite electrode used as an electrochemical biosensor for sub-picomolar detection of anti-HIV drug zidovudine

• A biosensor was fabricated for determination of zidovudine. • zidovudine is extensively used in treatment of acquired immune-deficiency syndrome (AIDS) • Initially a pencil graphite electrode was modified by graphene oxide-chitosan mixture. • Then Au- Pt nanoparticles were covered on the previous film. • Finally DNA was electrodeposited on the formed composite. • The fabricated biosensor determines zidovudine with very high sensitivity. Zidovudine (ZDV) has been widely employed in the human immunodeficiency virus type 1 (HIV-1) infection treatment. The short half-life, side effects of high doses, and adverse effects of ZDV necessitate the existence of a fast, simple, and reliable analysis method. In this work, a modified pencil graphite electrode was made using deoxyribonucleic acid/Au-Pt bimetallic nanoparticles/graphene oxide-chitosan (DNA/Au-Pt BNPs/GO-chit/PGE) for the determination of ZDV. Initially, the bare PGE was immersed in the GO-chit solution to create the graphene oxide-chitosan/pencil graphite electrode (GO-chit/PGE). Subsequently, electrodeposition of Au-Pt bimetallic nanoparticles (Au-Pt BNPs) was accomplished on the surface of GO-chit/PGE modified electrode by cyclic voltammetry (CV). Ultimately, DNA was immobilized on the Au-Pt BNPs/GO-chit/PGE applying a constant potential 0.5 V. The electrochemical response of ZDV upon the DNA/Au-Pt BNPs/GO-chit/PGE was measured by applying differential pulse voltammetry (DPV). In the optimum conditions, the proposed sensor displayed a wide linear dynamic range from 0.01 pM to 10.0 nM, a detection limit of 0.003 pM, and high selectivity and well reproducibility. Furthermore, the DNA/Au-Pt BNPs/GO-chit/PGE was successfully utilized to determine ZDV in human serum samples.