Photostimulated Extended Nitric Oxide (NO) Release from Water-Soluble Block Copolymer to Enhance Antibacterial Activity.

N -Nitrosamines are well established motifs to release nitric oxide (NO) under photoirradiation. Herein, a series of amphiphilic N -nitrosamine-based block copolymers ( BCP x -NO ) are developed to attain controlled NO release under photoirradiation (365 nm, 3.71 mW/cm 2 ). The water-soluble BCP x -NO forms micellar architecture in aqueous medium and exhibits a sustained NO release of 92-160 μM within 11.5 h, which is 36.8-64.0% of the calculated value. To understand the NO release mechanism, a small molecular NO donor ( NOD ) resembling the NO releasing functional motif of BCP x -NO is synthesized, which displays a burst NO release in DMSO within 2.5 h. The radical nature of the released NO is confirmed by electron paramagnetic resonance (EPR) spectroscopy. The gradual NO release from micellar BCP x -NO enhances antibacterial activity over NOD and exhibits a superior bactericidal effect on Gram-positive Staphylococcus aureus . In relation to biomedical applications, this work offers a comprehensive insight into tuning light-triggered NO release to improve antibacterial activity.