Synthesis, physico-chemical characterization, antimicrobial activity and toxicological features of AgZnO nanoparticles

Abstract

Silver-zinc oxide nanoparticles (AgZnO NPs) were chemically synthesized by the deposition of Ag NPs on the surface of ZnO NPs using silver nitrate, three types of anionic polyelectrolytes and citric acid as reagents. The Wavelength Dispersive X-ray Fluorescence (WDXRF) spectrometry of AgZnO NPs revealed 0.41–0.69 wt% Ag, and balance ZnO. The existence of Ag NPs on the surface of ZnO NPs with hexagonal wurtzite structure was highlighted by X-ray Diffraction (XRD) analysis, scanning electron microscopy (SEM), and Ultraviolet–Visible (UV–Vis) spectroscopy. The diffuse reflectance absorption of AgZnO NPs in the visible light region increased with the increase of Ag NPs content. The Fourier Transform Infrared (FTIR) spectrometry revealed no chemical bonding between Ag NPs and ZnO NPs and confirmed the presence of functional groups characteristic to ZnO and carboxylic acid salts. The newly synthesized AgZnO NPs displayed antimicrobial activity against all the tested medically relevant pathogens, with minimal (biofilm) inhibitory concentrations ranging from 1.875 mg/mL to 7.5 mg/mL. Although the in vitro genotoxicity assay revealed a relatively high micronuclei index, the in vivo micronucleus (MN) test revealed a low MN frequency in animals treated with AgZnO NPs. The histopathological analysis revealed non-significant structural changes of the hepatic parenchyma, renal cortex and intestinal mucosa and minimal inflammatory reactions. The AgZnO NPs administration induced TUNEL positive nuclei of Kupffer cells in the liver parenchyma. The present study shows that the newly synthesized AgZnO NPs are active against planktonic and adherent microorganisms and could be exploited to develop novel antimicrobial strategies for the biotechnology and biomedical fields. Easy scalability of the developed chemical synthesis is a major advantage in producing large batches of AgZnO NPs with reproducible properties. Keywords: Chemically synthesized AgZnO nanoparticles, Anionic polyelectrolytes, Medically relevant pathogens, Antimicrobial activity, Genotoxicity, Immunohistopathology