Marine Algae-Mediated Green Synthesis of ZnO Nanoparticles: A Case Study on Sargassum hystrix

This study explores the green zinc oxide nanoparticle (ZnO-NP) production employing an aqueous extract of the brown macroalga Sargassum hystrix and evaluates their action that inhibits against Aspergillus niger and Aspergillus ochraceus. The biosynthesis method employed was environmentally benign, avoiding toxic chemicals, and involved calcination at 450°C. Characterization techniques, including XRD, FTIR, SEM, TEM, and EDX, confirmed the formation of crystalline, the average size of hexagonal/spherical ZnO-NPs is 40 nm. It was determined that functional groups like O-H, C=O, and Zn-O, indicating the role of algal bioactive compounds in nanoparticle stabilization.The antifungal assays demonstrated dose-dependent inhibition, with ZnO-NPs (1% concentration) achieving 85% and 75% growth suppression for A. niger and A. ochraceus, respectively. Mechanistic insights suggest that ZnO-NPs disrupt fungal cell membranes, generate reactive oxygen species (ROS), and impair cellular functions, leading to cell death. The nanoparticles' high surface area and Zn²⁺ ion release further enhanced their efficacy.This study emphasizes the possibilities of Sargassum hystrix-mediated ZnO-NPs as a sustainable alternative to conventional fungicides, offering a green nanotechnology solution for agricultural disease management.