Green synthesis and characterisation of spherical and rod shaped CuO nanostructures using Carica papaya: Antimicrobial potential against oral biofilms and haemolytic assessment – An in-vitro study

Background: Copper oxide nanoparticles (CuO NPs) have broad-spectrum antimicrobial properties and hemocompatibility. Conventional synthesis methods, however, often involve toxic reagents and environmentally hazardous processes. Carica papaya, rich in polyphenols, flavonoids and have phytochemical-mediated reducing and stabilizing capabilities. Green synthesis approaches utilizing plant extracts show better biocompatibility, cost-effectiveness, and ecological safety. Objective: This study aims to green synthesize spherical and rod-shaped CuO nanostructures using Carica papaya leaf extract and evaluate their physicochemical, antimicrobial, and hemolytic properties. Methods: CuO NPs and nanorods (NRs) were synthesized using aqueous Carica papaya leaf extract. Characterization of the herbal extract was done using X-ray diffraction (XRD), Fouriertransform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Antimicrobial activity against Escherichia coli and Staphylococcus aureus was assessed using agar well diffusion. Hemolytic potential was determined using human blood samples.