Phyto-Assisted Synthesis of Silver Nanoparticles (Ag-NPs) Using Delonix elata Extract: Characterization, Antimicrobial, Antioxidant, Anti-Inflammatory, and Photocatalytic Activities.

The aim of present study mainly focuses on the green synthesis of silver nanoparticles (Ag-NPs) utilizing an aqueous extract of Delonix elata, which is an ecologically friendly and sustainable approach. The synthesized Ag-NPs were characterized by UV-visible spectroscopy, FTIR, XRD, SEM with EDAX, TEM and X-ray photoelectron spectroscopy (XPS). A prominent absorption peak at 404 nm in the UV-visible spectrum proved successful nanoparticle synthesis, while FTIR confirmed various functional groups, including methyl, carboxylic acids, and phenolic compounds, involved in the reduction and capping of Ag-NPs. The XRD spectrum shows distinct peaks at 2θ values of 38.02º, 46.15º, 64.41º, and 77.31º, which correspond to the (111), (200), (220), and (311) crystalline planes, respectively. The outcomes validate the existence of Ag-NPs by confirming the face-centered cubic (FCC) shape. SEM and TEM showed spherically arranged particles ranging from 7 to 25 nm. EDAX spectra indicated significant silver content (65.5%) with protein capping. The D. elata produced Ag-NPs had an average zeta potential of - 19.8 mV and a standard variation of 0.8 mV, indicating considerable electrostatic stability. The X-ray photoelectron spectroscopy (XPS) assessment confirmed the production of metallic silver and revealed the surface state makeup of Ag-NPs. Ag-NPs exhibited excellent antibacterial activity, with inhibition zones against E. coli (15.2 mm), P. aeruginosa (17.5 mm), S. mutans (19.2 mm), and S. aureus (12.5 mm). Additionally, the nanoparticles demonstrated strong antioxidant activity, with inhibition rates of 72.55% (ABTS) and 78.23% (DPPH) at 100 μg/mL. Anti-inflammatory tests showed 87% membrane stability in human red blood cells at 100 μg/mL. Additionally, cytotoxicity test against MCF-7 cancer cells revealed an IC₅₀ of 23.43 μg/mL. Treated cells showed significant morphological changes, but no changes were noticed in the control cells. Furthermore, Ag-NPs showed promising photocatalytic activity, achieving 85.3% degradation of methylene blue, highlighting their potential for biomedical and environmental applications.