Biosynthesis and characterization of ruthenium oxide nanoparticles from Gliricidia sepium leaf extract with phytochemical and antibacterial studies

Plant-mediated synthesis of metal nanoparticles provides an eco-friendly, cost-effective and straightforward approach. In this study, ruthenium oxide nanoparticles (RuO2NPs) were synthesized using the leaf extract of Gliricidia sepium, which is rich in bioactive phytochemicals, via a green synthesis method. The formation of nanoparticles was initially indicated by a rapid color change and further confirmed by UV–Visible Diffuse Reflectance Spectroscopy (DRS), showing a surface plasmon resonance peak at 338 nm. The band gap energy (~ 3.00 eV) suggested semiconducting behaviour. Fourier Transform Infrared Spectroscopy (FTIR) revealed functional groups responsible for reduction and stabilization, with strong absorption bands in the 540–700 cm⁻¹ range corresponding to metallic Ru. X-ray Diffraction (XRD) confirmed crystalline nanoparticles with an average size of 16–20 nm, while Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) demonstrated well-dispersed, nearly spherical particles with uniform morphology. Dynamic Light Scattering (DLS) analysis showed a narrow peak at ~ 100 d.nm, indicating monodispersity and aqueous stability. Preliminary phytochemical analysis of G. sepium leaf extract identified alkaloids, flavonoids, tannins, saponins, terpenoids, steroids, phenolics, glycosides and carbohydrates, with flavonoids, phenolics, saponins and alkaloids acting as primary reducing and capping agents during nanoparticle formation. Antibacterial activity, assessed via agar well diffusion against Gram-positive and Gram-negative strains, revealed significant inhibition zones, highlighting the synergistic effect of phytochemicals and metallic nanoparticles. This study demonstrates a simple, sustainable method for synthesizing RuO2NPs with promising antibacterial potential. Future investigations should explore additional biological activities, including antifungal, antioxidant and anticancer effects, as well as their efficacy in photocatalytic degradation of organic dyes, cytotoxicity, biocompatibility and scalability for industrial or biomedical applications.