Selenium nanoparticles as catalysts for nitric oxide generation.

The critical role of nitric oxide (NO), a potent signalling molecule, in various physiological processes has driven the development of NO delivery strategies for numerous therapeutic applications. However, NO's short half-life poses a significant challenge for its effective delivery. Glutathione peroxidase, a selenium-containing antioxidant enzyme, can catalyse the decomposition of S-nitrosothiols (endogenous NO prodrugs) to produce NO in situ. Inspired by this, we explored selenium nanoparticles (SeNPs) for their enzyme-mimicking NO-generating activity. Stabilised with polyvinyl alcohol (PVA) or chitosan (CTS), SeNPs demonstrated tuneable NO generation when exposed to varying concentrations of NO prodrug, nanoparticles, and glutathione (GSH). In the presence of GSH, a naturally occurring antioxidant in the human body, 0.1 µg mL-1 of SeNPs could catalytically generate 7.5 µM of NO under physiological conditions within 30 min. We investigated the effects of nanoparticle crystallinity and NO prodrug type on NO generation, as well as the stability and sustained NO generation of the catalytic nanoparticles. PVA-stabilised SeNPs were non-toxic to NIH 3T3 cells and effectively dispersed Pseudomonas aeruginosa biofilms upon NO generation. This study broadens the repertoire of nanomaterials for NO generation and highlights SeNPs as a non-toxic alternative for therapeutic NO delivery.