Title : One health approach to green nanomedicine: Ecofriendly synthesis of spinacia oleracea-mediated silver nanoparticles for potential management of rheumatoid arthritis

Background: The One Health concept recognizes the interconnection between human health, environmental sustainability, and innovative healthcare technologies. Rheumatoid arthritis (RA) is a chronic systemic autoimmune inflammatory disorder that affects approximately 1% of the global population and is associated with progressive joint destruction, disability, and extra-articular organ involvement. Conventional therapies are often associated with adverse effects following long-term use, creating a need for safer and environmentally sustainable therapeutic alternatives. Green synthesis of nanoparticles using medicinal plants represents an eco-friendly approach that minimizes hazardous chemical use while producing biocompatible nanomaterials for biomedical applications.

Objective: This study aimed to synthesize silver nanoparticles (AgNPs) using aqueous leaf extract of Spinacia oleracea through a green chemistry approach and evaluate their physicochemical characteristics, drug release behavior, and in vitro anti-inflammatory activity for potential application in rheumatoid arthritis.

Methods: Silver nanoparticles were biosynthesized by reducing silver nitrate with aqueous Spinacia oleracea leaf extract. The synthesized nanoparticles were characterized using UV-Visible spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), particle size analysis, polydispersity index (PDI), zeta potential, drug entrapment efficiency, and in vitro drug release studies. Drug release kinetics were evaluated using zero-order, first-order, Higuchi, and Korsmeyer-Peppas models. Anti-inflammatory activity was assessed by the inhibition of protein denaturation assay using methotrexate as the reference standard.

Results: Successful biosynthesis of AgNPs was confirmed by a visible color change from green to dark brown and a characteristic surface plasmon resonance peak at 424 nm. The Spinacia oleracea extract exhibited a λmax at 266 nm with excellent linearity (R² = 0.9962) over a concentration range of 20–100 µg/mL. FTIR analysis indicated compatibility between the plant constituents and silver nanoparticles without significant chemical interaction. SEM images demonstrated predominantly spherical nanoparticles. Among the developed formulations, F3 exhibited the highest entrapment efficiency (90.7%), particle size of 55 nm, PDI of 0.448, and zeta potential of +23.3 mV, indicating good colloidal stability. Sustained drug release of 99.32% was achieved over 24 h. Drug release predominantly followed the Higuchi diffusion model (R² = 0.9358), with substantial agreement to the zero-order model (R² = 0.9255). The biosynthesized AgNPs demonstrated significant inhibition of protein denaturation, indicating promising anti-inflammatory activity comparable with the standard drug.

Conclusion: The present study demonstrates that green synthesized Spinacia oleracea-mediated silver nanoparticles possess desirable physicochemical properties, sustained release characteristics, and significant in vitro anti-inflammatory activity. The environmentally benign synthesis process aligns with One Health principles by reducing chemical waste while offering a promising nanomedicine platform for chronic inflammatory diseases. These findings support further preclinical and clinical investigations to establish the therapeutic potential of biosynthesized silver nanoparticles in rheumatoid arthritis management.

Keywords: One Health, Green nanotechnology, Spinacia oleracea, Silver nanoparticles, Rheumatoid arthritis, Antiinflammatory activity, Sustainable nanomedicine.

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