Antimicrobial Magnesium Hydroxide Nanoparticles as an Alternative to Cu Biocide for Crop Protection

摘要

In agriculture, prolonged use of Copper (Cu) biocides increases the risk of development of Cu resistance and their accumulation in soil, demanding an alternative. In this paper, we report antimicrobial Magnesium (Mg) hydroxide nanoparticles (NPs) as an alternative to Cu biocides with low cytotoxicity. To improved bioavailability, Mg hydroxide NPs were synthesized followed by coating with water-soluble capping agents, trisodium citrate (zeta potential, ξ=−22 mV) or betaine (ξ=+35 mV). Electron microscopy study confirmed the formation of ˜10 nm size cubical NPs with citrate and ˜100 nm size lamellar NPs with betaine. As-synthesized Mg hydroxide NPs inhibited bacterial growth of X. alfalfae, P. syringae and E. coli within 4 hours. Significant bacterial growth inhibition and killing were observed at 24 hours post treatment. Phytotoxicity studies on tomato plants showed no significant tissue injury. Therefore, Mg hydroxide NPs has potential to serve as Cu alternative.