Surfactant-modulated discriminative sensing of HNO and H 2 S with a Cu 2+ -complex-based fluorescent probe

Recent investigations revealed the close relationship between H2S and HNO in biological systems. It is significant to develop an efficient fluorescent sensor to realize the discriminative sensing of HNO and H2S. Herein, we designed and synthesized a novel fluorescent sensor (CuHCD) with hemicyanine-carbazole as fluorophore and bipyridine-triazole-Cu2+complex as receptor, which enabled the selective recognition of HNO and H2S, respectively via the non-covalent modulation of surfactant assemblies. The CuHCD/surfactant sensor system exhibited excellent selectivity for H2S at 5 mM SDS in HEPES buffer, and displayed high specificity for HNO at 1 mM SDS in HEPES buffer over other common anions and reactive species. Different detection mechanisms in sensing H2S and HNO were deeply investigated. The results showed that H2S seized Cu2+ from the complex to recover the fluorescence of HCD, while HNO reduced Cu2+ to Cu+ in the complex to turn on the fluorescence. In different SDS micellar systems, HCD possessed different dispersity and binding capacity with Cu2+, which led to the selective detection of H2S and HNO, respectively. The hypothesis was further confirmed by replacing SDS micelles with liposome under the same conditions.