Effect of copper ions concentration on the particle size of alginate-stabilized Cu2O-Cu nanocolloids and its antibacterial activity against rice bacterial leaf blight (Xanthomonas oryzae pv. oryzae)

Abstract

Abstract In this study, nano Cu2O-Cu/alginate was synthesised by the chemical reduction of tetra-amminecopper (II) ion complexes soluble using hydrazine as a reducing agent and alginate as a stabiliser. The influence of various copper ion concentrations on particle size and morphology of produced nano Cu2O-Cu/alginate was investigated. The transmission electron microscopy (TEM) analysis and X-ray diffraction (XRD) measurement revealed that the synthesised nano Cu2O-Cu/alginate was mostly composed of Cu2O-Cu in the form of a Cu2O@Cu core–shell structure with particle sizes of 4.2, 5.3, and 8.4 nm for 60, 80, and 100 mM of copper ion initial concentrations, respectively. The obtained nano Cu2O-Cu/alginate exhibited high antibacterial activity against Xanthomonas oryzae pv. Oryzae (Xanthomonas OO). The results showed that the nano Cu2O-Cu/alginate containing 30 mg.l−1 of copper ions completely inhibited the growth of Xanthomonas OO bacteria, which are responsible for the rice leaf blight disease. Nano Cu2O-Cu/alginate materials can be used as a fungicide to replace toxic agro-chemicals and potentially applied to the development of sustainable agricultural production.