Bacterial membrane vesicle release triggered by dramatic interfacial electron transfer between diatoms and water

Diatoms have been shown to share approximately 40 % average genomic identity with distantly related heterokonts, indicating their potential to acquire exogenous genes in natural environments. Based on this characteristic, we previously employed diatom biosilica (DBs) for lysis-free extraction of pathogenic bacterial DNA within 3 min. This capability was hypothesized to arise from the induction of bacterial membrane vesicle (BMV) formation and subsequent DNA release, mediated by the generation of interfacial reactive oxygen species (ROS). To gain a comprehensive understanding of the mechanism underlying rapid interfacial ROS generation, we modified DBs by depositing cerium and calcium onto their surfaces to form corresponding metal oxides. These modifications conferred distinct electron-withdrawing properties to DBs, enabling regulation of electron transfer at the DBs-water interface and modulating the extent of interfacial ROS production. Cerium deposited DBs (Ce-DBs), the one with higher reduction potentials, generated significantly greater level of interfacial ROS and induced a more pronounced formation of BMVs, with increases of 610.69 % and 23.08 % (protein concentration of BMVs), respectively, compared with the pristine DBs. These findings were further corroborated by assessments of bacterial oxidative stress through analysis of relative gene expression levels and transcriptomic profiles, supporting the critical role of interfacial electron transfer. Furthermore, the enhanced interfacial electron transfers endowed Ce-DBs with superior extraction efficiency, as evidenced by the lowest PCR C_t values for pathogen detection. Our results elucidate the mechanistic basis of rapid interfacial ROS generation by DBs and its functional significance in DNA extraction and extracellular vesicle formation, highlighting its potential for important clinical applications.