Green Synthesis of Copper Oxide Nanoparticles Using Aquatic Plant Extracts: Evaluation of Antimicrobial and Antioxidant Properties against Human and Aquatic Pathogens

In this work copper oxide nanoparticles (CuONPs) were synthesized using aquatic plants (Nelumbo nucifera, Nymphaea rubra and Eichhornia crassipes) and measured its antioxidant and antibacterial activities against the five human pathogens viz., Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, Acinetobacter baumannii and Staphylococcus aureus) and four aquatic pathogens (Aeromonas hydrophila, Vibrio cholerae Edwardseilla tarda, and Aeromonas caviae). The CuONPs were characterized using FTIR spectroscopy, UV-Visible spectroscopy, XRD, HR-TEM and EDS. The FTIR showed the different phytochemicals of the aqueous extract involved in the formation of nanoparticles. The XRD studies showed that the CuONPs were crystalline in nature. Antibacterial assay was performed by Kirby-Bauer well diffusion assay. Of the assayed CuONPs, synthesized using Nelumbo nucifera, Nymphaea rubra and Eichhornia crassipes showed highest zone of inhibition and exhibited the maximum antibacterial efficacy against Klebsiella pneumoniae (25 mm), Edwardsiella tarda (28 mm) and Staphylococcus aureus (30 mm) respectively. Moreover, antioxidant studies were performed using DPPH scavenging, ABTS•+ decolourization assay, and H2O2scavenging assays in which the Nymphaea rubra mediated CuONPs showed maximum DPPH scavenging activity (73%), ABTS•+ decolourisation activity (81.2%) and hydrogen oxide scavenging activity (82.1%). The results of our study indicate the scope of high medicinal value on application of CuONPs synthesized using aquatic plants. In addition, aquatic weeds may be applied clinically towards various diseases with reported antioxidant and antibacterial properties.