Tunable electrochemistry and efficient antibacterial activity of plant-mediated copper oxide nanoparticles synthesized by Annona squamosa seed extract for agricultural utility† Pooja Singh, a Kshitij RB Singh, b Jay Singh, c Subha Narayan Das d and Ravindra Pratap Singh * a 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 (H 2 O 2 ) 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 H 2 O 2 by cyclic voltammetry (CV), and from this it was proved that pm-CuO NPs had a very high electrochemical sensitivity of 49 mA mM 1 cm 2 towards H 2 O 2 and a low detection limit of 574 mM, with these responses obtained under optimized experimental conditions. Thus, pm-CuO NPs also provide a potential sensing platform for electrochemical studies to detect H 2 O 2 produced during plant stress surroundings to properly manage crops susceptible to oxidative damage by elevated H 2 O 2 levels during stress. 1. Introduction Over the past decade, there have been interdisciplinary elds of nanoscience and nanotechnology, interspersing material science, bionanosciences, and biotechnology. The synthesis of metal oxide nanoparticles is an important research subject in modern physics due to their extraordinary capabilities in the elds of electronics, magnetics, optoelectronics, information storage and drug delivery. 1–4 Nanoparticles of different shapes and sizes are subject to great interest due to their possible applications in industry, biomedical diagnostics, environ- mental remediation and electronics. Both metal and metal oxide nanoparticles have a large surface volume ratio and are considered most promising and remarkable agents in the agricultural domain. Recently, copper (Cu) and copper oxide nanoparticle have shown various applications in addressing physical, chemical and environmental issues and have also provided various solutions for solving problems pertaining to biological sciences. Chemical and physical methods can be used to synthesize nanoparticles, but they tend to be expensive, harmful to the environment, and need high energy consump- tion. Thus, routes involving a biological synthesis utilizing various extracts of plants, enzymes or microorganisms, including bacteria, and fungi, have been suggested as possible environment-friendly alternative methods over chemical and physical methods. 5–8 Moreover, the synthesis of nanoparticles utilizing plant extracts is more benecial than other biological processes as plant organs are more stable, environmentally friendly, show a higher yield of nanoparticles, and are faster than the single-step biosynthesis process. 9 The plant extracts consist of various avonoids, alkaloids and proteins, which a Department of Biotechnology, Indira Gandhi National Tribal University, Amarkantak, M.P., 484887, India. E-mail: rpsnpl69@gmail.com; ravindra.singh@igntu.ac.in; Tel: +91-91-0934-6565 b Department of Chemistry, Govt. V. Y. T. PG Autonomous College, Durg, Chhattisgarh, India c Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi, U.P., 221005, India d Department of Botany, Indira Gandhi National Tribal University, Amarkantak, M.P., 484887, India † Electronic supplementary information (ESI) available. See DOI: 10.1039/d1ra02382a Cite this: RSC Adv. , 2021, 11, 18050 Received 25th March 2021 Accepted 5th May 2021 DOI: 10.1039/d1ra02382a rsc.li/rsc-advances 18050 | RSC Adv. , 2021, 11, 18050–18060 © 2021 The Author(s). Published by the Royal Society of Chemistry RSC Advances PAPER Open Access Article. Published on 19 May 2021. Downloaded on 9/1/2021 10:49:46 PM. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. View Article Online View Journal | View Issue