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

Abstract

<i>N</i>-Nitrosamines are well established motifs to release nitric oxide (NO) under photoirradiation. Herein, a series of amphiphilic <i>N</i>-nitrosamine-based block copolymers (<b>BCP<i>x</i>-NO</b>) are developed to attain controlled NO release under photoirradiation (365 nm, 3.71 mW/cm²). The water-soluble <b>BCP<i>x</i>-NO</b> 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 (<b>NOD</b>) resembling the NO releasing functional motif of <b>BCP<i>x</i>-NO</b> 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 <b>BCP<i>x</i>-NO</b> enhances antibacterial activity over <b>NOD</b> and exhibits a superior bactericidal effect on Gram-positive <i>Staphylococcus aureus</i>. In relation to biomedical applications, this work offers a comprehensive insight into tuning light-triggered NO release to improve antibacterial activity.