Selective and sensitive detection of nitric oxide in aqueous and biological settings using a novel fluorescent cobalt-MOF

Nitric oxide (˙NO) plays a crucial role in various biological processes, but its reactive nature and short half-life make its precise detection challenging. Developing sensitive and selective probes for ˙NO detection is essential for advancing biological and biomedical research. Here, we report the design of a hydrolytically stable and highly luminous amine-functionalized cobalt-based metal–organic framework (MOF), PUC-9, as a novel ˙NO sensor. PUC-9 exhibits a distinct fluorescence “turn-off” response to ˙NO via a deamination-based quenching mechanism, effectively differentiating it from other reactive oxygen and nitrogen species (ROS and RNS). It demonstrates a low detection limit (LOD) of 0.019 μM and a notable Stern–Volmer constant (Ksv) of 0.13 × 105 M−1. With minimal cytotoxicity, PUC-9 enables ˙NO detection comparable to standard assays through absorbance, fluorescence, and imaging-based methods, showing its reliability and versatility across different detection platforms. These findings establish PUC-9 as a highly sensitive and selective tool for ˙NO detection in aqueous media and biological environments.