Electrochemical detection of chloramphenicol drug based on ZnO and ZnO/graphene oxide composite nanoparticles

Abstract

The release of pharmaceuticals in the environment represents a significant ecological problem due to their complex structure making them challenge to be decomposed and removed by standard waste-water treatment processes. Zinc oxide (ZnO) represents a semiconductor compound with exceptional optical and electrochemical properties, chemical and photochemical stability, nontoxicity, biocompatibility, etc. Due to their adjustable multifunctional properties, ZnO based materials have concerned general scientific and technological attention. Nowadays these materials are used for a range of applications in electronics, opto-electronics, biosensing, bioimaging, drug delivery, antimicrobial and anticancer agents, implants as well as sensing in environmental applications. The main object of this study was to improve efficiency of ZnO particles toward electrochemical sensing of water pollutants and electrocatalysis. In order to modify electrochemical properties, zinc oxide/graphene oxide (ZnO/GO) composites with different ZnO:GO weights ratio were prepared using a microwave (MW) assisted synthesis of precipitate. Two different amounts of GO (0.1 and 0.5 wt.%) were dispersed in 100 mL of distilled water. After stirring for 5 min an appropriate amount of ZnCl2 was added to the GO water dispersion. Subsequently, 20 mL of 1.75 M NaOH was added dropwise to the mixture with constant stirring. After being stirred at 50 C for 90 min in total, the as-prepared precipitate was microwave processed in a MW oven (2.45 GHz, 130 W) for 5 min. After cooling to room temperature, the precipitate was centrifuged and rinsed to remove the surface residues of the starting chemical solutions. The synthesized powder was dried in an oven at 80 C for 24 h. The particles crystal structure and phase composition were investigated by X-ray diffraction and Raman spectroscopy. The particles morphology was determined with FE–SEM. The optical properties were studied using UV–Vis DRS and PL spectroscopy. The electrochemical sensing activity of ZnO and ZnO/GO electrodes was tested for detection of chloramphenicol water solution whereas electrocatalytic activity was tested for water splitting when samples were used as anode materials and evaluated by linear sweep voltammetry in 0.1M NaOH and 0.1 M H2SO4 electrolytes. ZnO/GO electrodes were tested as-prepared and after in situ reduction of GO at -1.4 V vs. SCE in 0.1 M KCl. Electrochemical activity of prepared composites was correlated with the presence of GO and reduced GO particles.