Modulating Photodissociation and Photobleaching via Plasmon Resonance to Enhance Light-Induced Nitric Oxide Release

Localized therapeutic action and targeted drug release offer compelling advantages over traditional systemic drug administration. This is particularly important for nitric oxide (NO), whose biological effects vary greatly depending on concentration and cellular environment. Light-sensitive NO donors are promising for achieving precise, on-demand NO release. However, their efficiency and photostability are limited by competing photophysical processes and the generation of reactive oxygen species (ROS). In this study, we investigate hybrid systems composed of photosensitive nitric oxide (NO) donors and silver island films (SIFs). The influence of localized surface plasmon on non-radiative relaxation pathways and ROS generation is the main focus of the paper. Upon excitation at 500 nm, we observed several-fold increase in NO release, attributed to resonant interactions between the plasmonic field and the dye molecules. By tuning the thickness of a SiO2 buffer layer, we identified key parameters affecting process efficiency: the spectral overlap between the plasmon resonance and the sensitizer’s absorption band, and the distance between the nanoparticle and the molecule. Additionally, singlet oxygen generation increase was observed. These findings demonstrate the potential of plasmonic enhancement to controllably boost photochemical activity in organic systems, paving the way for advanced applications in phototherapy and biomedical diagnostics.