Design, synthesis and characterization of a novel fluorescent probe for nitric oxide based on difluoroboradiaza-s-indacene fluorophore

Nitric oxide (NO) is a gaseous, free radical, which plays a role as an intracellular second messenger and a diffusible intercellular messenger. To obtain evidence for NO function in vivo, 1,3,5,7-tetramethyl-8-(4′-aminophenyl-N-(2′′-amino)-phenzyl)-difluoroboradiaza-s-indacene (TMAPABODIPY) was designed and synthesized as a fluorescent probe for nitric oxide, which features high photostability and no pH dependency over a wide pH range. The fluorescence of TMAPABODIPY itself is very strong. When TMAPABODIPY traps NO in the presence of dioxygen, the weak fluorescent triazole form is obtained, which offers the advantages of specificity, and sensitivity for direct detection of NO. The relationship was obtained between the quenching fluorescence intensity and NO concentration in the range 0.02-4.0 μmol l−1. The detection limit is 5 nmol l−1 (S/N = 3). The proposed method has been used to monitor the release of NO from S-nitrosocysteine, a NO-releasing agent.