Bimetallic nanocomposite produced from Acacia tortilis subsp. raddiana for the mitigation fungal pathogens in tomatoes

This study investigates the green synthesis of silver (AgNPs), iron oxide (FeONPs), and silver-iron oxide (Ag-FeONPs) nanoparticles using Acacia tortilis subsp. raddiana seed extract and evaluates their antifungal activity against tomato pathogens. Various analytical techniques, including UV-Vis spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and gas chromatography-mass spectrometry (GC-MS), were employed to confirm the synthesis of nanoparticles, characterize their structural and morphological properties, and identify bioactive compounds. UV-Vis spectroscopy confirmed nanoparticle formation with absorption peaks at 428 nm for AgNPs, 331 nm for FeONPs, and 359 nm for Ag-FeONPs. FTIR analysis indicated functional groups from the seed extract responsible for the reduction and stabilization of nanoparticles. DLS measurements revealed average sizes of 248 nm for AgNPs, 213 nm for FeONPs, and 208 nm for Ag-FeONPs, with moderate polydispersity. SEM and TEM images revealed predominantly spherical nanoparticles with some agglomeration. GC-MS analysis of the seed extract identified bioactive compounds that likely contribute to its antifungal activity. In vitro antifungal tests showed that both AgNPs and bimetallic Ag-FeONPs completely inhibited Alternaria sp. (100%). Suppression of Sclerotinia sclerotiorum reached 65% with both AgNPs and Ag-FeONPs. Fusarium venenatum and Fusarium equiseti were inhibited by 20-32% AgNPs and 32-40% Ag-FeONPs, respectively. These findings demonstrate that AgNPs and Ag-FeONPs exhibit superior antifungal activity compared to FeONPs.According to these results, nanoparticles made from A. raddiana show promise as environmentally friendly antifungal agents for the long-term control of tomato diseases.