A review of the biogenic fabrication of metal oxide nanoparticles using phytochemical reducing and stabilizing agents across diverse systems

The transition from laboratory-scale nanofabrication to sustainable industrial manufacturing is currently hindered by the “precision-toxicity trade-off,” where high-quality metal oxide nanoparticles (MONPs) traditionally require hazardous precursors or energy-intensive physical methods. This comprehensive review (covering literature from 2019 to 2026) proposes a biogenic surface engineering framework that uses plant-derived metabolites (phenols and flavonoids) as sophisticated dual-function capping ligands for specific metal oxides, including TiO₂, NiO, CuO, and CeO₂. Quantitative findings revealed that biogenically synthesized TiO₂ exhibited a maximum dye degradation efficiency of 98.5%. Furthermore, biogenic capping creates a steric barrier that preserves crystal integrity, prevents hydroxylation-driven surface reconstruction, and significantly enhances biocompatibility. Advanced characterization techniques, including high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS), validated the presence and functional roles of these organic interfaces. By bridging the gap between atomic-level precision and environmental sustainability, this synthesis creates a roadmap for the next generation of functional materials in energy, sensing, and nanomedicine.