Sustainable Green Synthesis of ZnO Nanoparticles using Syzygium Cumini Fruit Extract: Structural, Optical, and Antibacterial Investigations

Abstract

An eco-friendly and biocompatible alternative to the conventional chemical and physical synthesis methods ZnO nanoparticles were synthesized using Syzygium cumini fruit extract through a simple and eco-friendly green synthesis route. The phase formation and purity of ZnO nanoparticles were identified by XRD analysis, showing distinct diffraction peaks corresponding to the hexagonal wurtzite structure of ZnO with high crystallinity and average crystallite size in the nanometer range. FTIR spectroscopy confirms the presence of hydroxyl, carbonyl, and amine groups, indicating that plant biomolecules are involved in nanoparticle stabilization. Further, the surface morphology of the synthesized ZnO nanoparticles was revealed by SEM analysis, which exhibited predominantly spherical to irregularly shaped nanoparticles with slight agglomeration due to the presence of plant-derived capping agents. UV–Visible spectral analysis showed a sharp absorption peak at around 310 nm, confirming the optical properties of ZnO nanoparticles with an estimated band gap of 2.8 eV, suggesting nanoscale dimensions and quantum confinement effects. Antibacterial studies show strong inhibitory effects of the synthesized ZnO nanoparticles against Gram-positive Propionibacterium acnes (P. acnes) and Gram-negative Bacteroides fragilis bacteria, which can thus be said to constitute evidence of their effective antibacterial potential. The synergistic action of ZnO nanoparticles and Syzygium cumini phytochemicals enhances ROS generation and disrupts bacterial cell integrity.