A novel fluorescent sensor for the ultra-fast detection of nitric oxide

Nitric oxide (NO) is a vital signaling molecule involved in the regulation of many physiological and pathological processes, including cancer, bacterial infections and neurodegenerative disease. [1,2] However, its biological effects are strictly dependent on its concentration, potentially shifting from beneficial to harmful. [2] For these reasons, the real-time monitoring of NO is highly desirable, especially due to its high reactivity with various biological targets. This scenario has pushed many efforts towards the development of novel methodologies for NO detection that combine selectivity, sensitivity and fast responsiveness. In this study, we introduce a novel fluorescent probe incorporating a BODIPY fluorophore covalently bound to a trimethoxy aniline derivative, specifically designed for fast and selective NO detection. [3] The probe undergoes nitrosation at its electron-rich amino site via the secondary oxide N₂O₃, leading to enhanced BODIPY fluorescence (Figure 1) and a notable shift in fluorescence lifetime amplitudes. It exhibits an ultra-fast response time (≤ 0.1 s), high sensitivity (LOD = 35 nM), reactivity toward ONOO⁻, independence of the fluorescence response across a broad pH range, remarkable selectivity over numerous analytes, and minimal interference from physiological glutathione levels. Validation in melanoma cell lines highlights its effectiveness for real-time NO detection in complex biological environments, establishing it as a promising tool for biomedical research.