Next-generation plant nanobiotechnology can improve seed germination and larvicidal activity with environmentally...

The rapid growth of the global population has increased the demand for enhanced agricultural productivity, prompting the exploration of innovative technologies such as nanotechnology for sustainable crop improvement. In this study, silver nanoparticles (AgNPs), titanium dioxide nanoparticles (TiO₂NPs), and Ag-TiO₂ nanocomposites (NCs) were synthesized using Sargassum wightii extract and evaluated for their physicochemical properties, biological activity, and environmental applicability. The synthesized materials were characterized using UV-Visible spectroscopy, SEM, EDX, XRD, and FTIR analyses, and their energy band gaps were determined from UV-Visible spectra. Seed germination assays were conducted using Kattuyanam and Co39 rice varieties under varying nanoparticle concentrations, while larvicidal activity was assessed against Spodoptera litura. Photocatalytic performance was evaluated through fast green dye degradation under light exposure. The band gap energies were determined to be 2.8 eV for AgNPs, 3.56 eV for TiO₂NPs, and 3.18 eV for Ag-TiO₂NCs. Characterization results confirmed the successful formation, crystallinity, and purity of the synthesized nanoparticles and nanocomposites. Seed germination studies revealed significant improvements in germination percentage, root and shoot elongation, and biomass compared to controls. The Ag-TiO₂ nanocomposites exhibited pronounced larvicidal activity, achieving 96% mortality at 100 µg/mL, and demonstrated high photocatalytic efficiency with up to 91% degradation of fast green dye within 5 h. Overall, the findings indicate that S. wightii-mediated AgNPs, TiO₂ NPs, and Ag-TiO₂ nanocomposites possess multifunctional properties relevant to agricultural enhancement, pest management, and environmental remediation, supporting their potential use in sustainable agriculture.