Daylight induced antibacterial activity of gadolinium oxide, samarium oxide and erbium oxide nanoparticles and their aquatic toxicity

Abstract

The present article describes a method of the preparation of three dilanthanide trioxides (Lx(2)O(3)): gadolinium oxide (Gd2O3), samarium oxide (Sm2O3) and erbium oxide (Er2O3) in a shape of nanoparticles. Thermal decomposition of a transient complex formed in situ from Lx(NO3)(3)center dot H2O and glycine was studied using TG/DTA analysis. The resulting 10 (Gd2O3, Er2O3) to 11 nm (Sm2O3) nanoparticles grouped into 8 gm agglomerates were characterized by X-ray powder diffraction analysis, the particle size (PS) and particle size distribution (PSD) analysis. Morphology of the nanoparticles was examined by scanning and transmission electron microscopy. The antibacterial activity against four common human pathogens (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa) was determined both in dark conditions and on daylight was investigated revealing a phototoxic phenomenon. The lowest determined MICs were as low as 5.6 mg ml(-1) against Escherichia coli and Pseudomonas aeruginosa. Moreover, acute aquatic toxicity tests of prepared nanoparticles were driven revealing the moderate toxicities against Desmodesmus subspicatus peaking with EC50 = 0.47 g dm(-3) (Er2O3 nanoparticles).