Green Synthesis of Copper Oxide Nanoparticles Using Aloe Vera Leaf Extract and Their Potent Antibacterial Applications

The current crisis around antimicrobial resistance requires new, sustainable antibacterial agents. Copper oxide nanoparticles (CuO NPs) prepared under environmentally friendly methods offer solutions to this dilemma and provide a strong biocide tool with inferior environmental footprint. The research develops the field in the field by optimizing a single-step bio synthesis procedure to employ Aloe Vera Miller leaf extract as a rich bio reductive and capping agent source to produce crystalline CuO NPs with primary crystallite size of (21.3 ± 2.1 nm) though SEM revealed moderate aggregation into 50-150 nm cluster, achieving an MIC of 62.5 μg/mL against both E. coli and S. aureus and >99.9% bacterial kill within 4h of colloidal manifest. The synthesis of CuO NPs via precise thermal reduction (80 C, pH 9.0) of 0.1 M Cu (NO3)2·3H2O with Aloe vera gel extract (including phytochemical characterization) prepared by 10% (w/v) phytochemically characterised extract was realised. Characterization of nanoparticles were extensive: NP formation rate was monitored by UV-Vis spectroscopy (285 nm); crystal structure and purity was assured by XRD (monoclinic, space group *C2/c*); their surface functionalization, by FTIR (biomolecular capping, C=O/C-O stretches at 1620/1070 cm-1. WHO-priority pathogenic Escherichia coli (ATCC 25922, Gram-negative) and Staphylococcus aureus (ATCC 29213, Gram-positive) were used to determine antibacterial activity against by broth microdilution (CLSI M07-A10), disk diffusion (ISO 20776-1), and time-kill curves. Mechanistic analyses were composed of ROS measurement (DCFH-DA fluorescence), membranal structural integrity (LDH release, SEM ultrastructural imaging), genomic DNA binding (gel electrophoresis) This work addresses critical gaps in phytochemical reduction kinetics and monodispersity control for Aloe-vera-mediated CuO NPs, while providing a quantified, multi-mechanistic analysis (ROS, membrane, DNA) of their superior Gram-negative/positive activity compared to chemical analogs.