Narasimman_2026_3.Biotech_16_121

Silver nanoparticles were biosynthesized using an aqueous extract of the brown seaweed Sargassum polycystum and evaluated for their neuroprotective potential in an aluminium chloride (AlCl)-induced zebrafish model of neurotoxicity. Physicochemical characterization confirmed stable, spherical nanoparticles with a surface plasmon resonance peak at 445 nm, nanoscale size distribution, and negative zeta potential, indicating good colloidal stability. The synthesized AgNPs exhibited moderate antioxidant activity in DPPH and ABTS assays. Embryo toxicity assessment demonstrated biocompatibility at lower concentrations, while higher doses produced concentration associated developmental toxicity. In adult zebrafish, AlCl exposure induced significant locomotor impairment, anxiety-like behaviour, and cognitive deficits. Co-treatment with AgNPs, particularly at 100 microg/L, significantly improved locomotor activity, reduced anxiety-associated behaviours, and restored learning and memory performance. Biochemical analyses showed a significant reduction in malondialdehyde levels and acetylcholinesterase activity in AgNP-treated groups, indicating Attenuation of oxidative stress and cholinergic dysfunction. Histopathological evaluation further confirmed preservation of neuronal architecture and reduced neurodegeneration following AgNP treatment. Based on the results indicate that S. polycystum derived silver nanoparticles provide concentration associated neuroprotection against aluminium chloride -induced neurotoxicity in zebrafish and May represent a promising green nanotherapeutic approach for neurodegenerative disorders. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-026-04716-z.