Green synthesis of multifunctional silver nanoparticles using Ocimum tenuiflorum L. inflorescence extract for potential antimicrobial and photocatalytic applications

Green synthesis of silver nanoparticles (AgNPs) using plant-derived resources offers an alternative approach to conventional nanoparticle synthesis by utilizing naturally occurring phytoconstituents as reducing and stabilizing agents. In the present study, silver nanoparticles were synthesized using an aqueous inflorescence extract of Ocimum tenuiflorum L. (Tulsi) and systematically evaluated for their physicochemical characteristics and multifunctional properties. The synthesized Tulsi inflorescence-mediated AgNPs (TI-AgNPs) exhibited a characteristic surface plasmon resonance band at 428 nm, while TEM analysis showed nanoparticles within the 20–90 nm size range and XRD confirmed their crystalline nature. FTIR analysis indicated the involvement of hydroxyl, carbonyl, and other oxygen-containing functional groups in nanoparticle formation and stabilization. The TI-AgNPs demonstrated broad-spectrum antimicrobial activity, with MIC values ranging from 8 to 64 µg/mL against the tested bacterial and fungal strains. DPPH assay showed concentration-dependent antioxidant activity, while the nanoparticles exhibited an IC₅₀ value of 634.71 µg/mL in HEK-293 cells. In addition, TI-AgNPs achieved 93.4% methylene blue removal within 60 min under sunlight irradiation. Overall, the findings demonstrate that O. tenuiflorum L inflorescence can serve as a plant-based source for the synthesis of multifunctional AgNPs with antimicrobial, antioxidant, and dye-removal properties, supporting their further investigation for potential biomedical and environmental applications.