Tunable electrochemistry and efficient antibacterial activity of plant-mediated copper oxide nanoparticles synthesized by Annona squamosa seed extract for agricultural utility

Abstract

The present report deals with the synthesis of plant-mediated copper oxide nanoparticles (pm-CuO NPs) from Annona squamosa aqueous seed extract for effective antibacterial activity and the further utilization of this as a platform for the electrocatalytic determination of hydrogen peroxide (H₂O₂) for applications in the agricultural domain. The structural, optical and morphological characteristics of the synthesized pm-CuO NPs were analyzed by UV-Vis, XRD, FT-IR, AFM, SEM, TEM, HR-TEM and EDX. After this, pm-CuO NPs were preliminarily investigated for antibacterial activity on Gram-positive and Gram-negative bacterial strains, and further, their activity was validated for assessing their antibacterial efficiency on the Xanthomonas oryzae, a plant pathogenic bacteria strain, and the obtained results showed that pm-CuO NPs have potency as an effective antibacterial agent for the treatment of the bacterial blight of rice caused by X. oryzae in the rice crop, which reduces the rice crop productivity. Further, pm-CuO NPs were electrophoretically deposited onto an indium–tin–oxide (ITO) glass substrate and assessed for the electro-oxidation of H₂O₂ by cyclic voltammetry (CV), and from this it was proved that pm-CuO NPs had a very high electrochemical sensitivity of 49 μA μM⁻¹ cm⁻² towards H₂O₂ and a low detection limit of 574 μM, with these responses obtained under optimized experimental conditions. Thus, pm-CuO NPs also provide a potential sensing platform for electrochemical studies to detect H₂O₂ produced during plant stress surroundings to properly manage crops susceptible to oxidative damage by elevated H₂O₂ levels during stress.