Evaluation of Reduced Graphene Oxide Modified with Antimony and Copper Nanoparticles for Levofloxacin Oxidation

This work presents, for the first time, the oxidation mechanism of levofloxacin combining electrochemical experiments and molecular modelling techniques. Levofloxacin is one of the most widely used antibiotics in the world. The detection of this antibiotic is important, because it cannot be fully assimilated by the human organism, therefore levofloxacin is considerate a hazardous pollutant for environment. Sensors based on reduced graphene oxide (rGO) modified with antimony and copper nanoparticles (NPs) were synthesized, characterized and evaluated for the electrochemical detection of the levofloxacin. The morphological and electrochemical characterization of the composites confirmed that the rGO was modified with the metallic nanoparticles. Molecular modelling studies were performed applying Density Functional Theory (DFT) approach, which indicated that the mechanism of levofloxacin oxidation is given by the loss of two electrons: one from N14 atom and other from C13 atom of the levofloxacin molecule. The glassy carbon electrode (GCE) modified with the SbNPs/rGO and CuNPs/rGO composites were evaluated for the determination of levofloxacin using differential pulse voltammetry (DPV) and achieved detection limit of 4.1×10−8 mol L−1 and 1.7×10−8 mol L−1, respectively, presenting as alternative composites to be used in the analysis of antibiotics.