Antibacterial Activity and Mechanistic Insights into Bioinspired Hydrophilic Selenium–Iron-Sulfur Hybrid (Se–S–Fe) Nanostructures

Hybrid nanoparticles (HNPs) offer integrated advantages in comparison to the singular-component systems of nanomaterials. This study reports a simple, one-pot green synthesis of hydrophilic selenium-iron-sulfur hybrid nanoparticles (Se-S-Fe HNPs) using an Alstonia scholaris extract. The size and surface charge of the Se-S-Fe HNPs, characterized by advanced material characterization techniques, significantly influenced their antimicrobial activity against Escherichia coli and Bacillus megaterium. However, mechanistic studies uncovered distinct modes of action against these bacterial species. Transcriptomic analysis revealed Se-S-Fe HNPs disrupted protein synthesis in E. coli and elevated the expression of outer membrane proteins OmpA and OmpC. In B. megaterium, the HNPs induced hyperosmotic shock and broad metabolic changes, impacting amino acid biosynthesis and protein localization. This work introduces a facile and environmentally friendly method for producing effective antimicrobial nanomaterials with distinct mechanisms of action depending on bacterial species.