Composition effect of Cu-based nanoparticles on phytopathogenic bacteria. Antibacterial studies and phytotoxicity evaluation

Abstract

Nanotechnology can offer new possibilities to the agrochemical sector providing plant protection products that can reduce the quantities and frequency of their use, by getting maximum effect on the target pest. Herein, copper based nanoparticles (Cu-based NPs) of different composition have been hydrothermally synthesized in the presence of the biocompatible surfactants polyethylene glycol (PEG1000), tetraethylene glycol (TEG) and polysorbate 20 (Tween 20) and tested in vitro and in vivo on plant pathogenic bacterial strains. The obtained NPs, Cu@Tween20, Cu@TEG, Cu2O@TWEEN20 and CuO@PEG1000 with sizes 46, 39, 12 and 18 nm respectively were evaluated in vitro as antibacterial agents, against three phytopathogenic Gram-negative bacterial strains, Erwinia amylovora, Xanthomonas campestris and Pseudomonas syringae. Cu NPs were found the most potent in the in vitro studies against all bacterial strains studied, with the lowest MIC value <3 μg/mL for E. amylovora and MBC value 100 μg/mL for P. syringae always in comparison with the wide used conventional pesticide Kocide 2000 35 WG tested at the registered dose of 1000 μg/mL. Further investigation was performed on testing the antibacterial activity of Cu@TWEEN20 and Cu2O@TWEEN20 nanoparticles in vivo in pot experiments under greenhouse conditions on bean plants (P. vulgaris). The penetration of the nanoparticles, labelled with Alizarin Red S, was investigated in plant tissues under a fluorescence microscope while their possible impact on plant photosynthesis and growth has been estimated. Cu-based NPs were found to penetrate the plant tissues without causing any toxicity.