Development and Validation of a Nitric Oxide-Responsive Optical Probe for Cardiovascular Disease with Acute Lung Injury In Vivo Imaging

Nitric oxide plays an important role in the occurrence and development of cardiovascular disease. However, due to the reactive and transient nature of NO, directly detecting its levels is challenging in the clinic, and currently used imaging methods have difficulty imaging NO levels at the living level. In this study, we developed a nitric oxide (NO)-responsive probe (NOP) and its nanoformulation (NanoNOP). NanoNOP exhibited excellent stability, sensitivity, and selectivity toward NO, with enhanced fluorescence and photoacoustic (PA) signals upon NO exposure. In cellular studies, NanoNOP demonstrated strong NO responsiveness in foam cells, a key cell type in cardiovascular disease, with significantly higher photoacoustic and fluorescence signals compared to control macrophages. In vivo studies in mice with acute lung injury (ALI) revealed elevated NO levels in the aortic region, confirmed by ex vivo immunohistochemical analysis showing increased iNOS expression and NO production. NanoNOP also demonstrated excellent biocompatibility, with no significant changes in body weight or organ damage. These findings highlight NanoNOP as a promising tool for studying NO-related pathologies and developing targeted therapeutic strategies.