An oxazine-based near-infrared fluorescent probe for selective in cellular imaging of exogenous nitrite

[Display omitted] •An oxazine-based fluorescent probe for nitrite based on PET mechanism.•Near-infrared emission located in 590–820nm with detection limit at 45nM.•Selective monitoring exogenous nitrite by HeLa and V79 cells in vitro imaging. A near-infrared fluorescent probe based on benzo[a]phenoxazine containing o-phenylenediamine group as reactive site was designed and synthesized. The titration experiment showed that the probe gave colorimetric response towards sodium nitrite with the absorption maxima at 630nm and 542nm in pH=5.0 disodium hydrogen phosphate-citric acid buffers containing 30% DMSO; its emission was located in 590–820nm with the 9.1-fold fluorescent enhancement under excitation at 580nm. Moreover, the probe can detect nitrite quantitatively in a concentration range of 0.0–26.0μM and the detection limit is as low as 45nM. The salient features of this method are high sensitivity and selectivity, fast detection and low detection limit. Fluorescence confocal imaging experiments with V79 and HeLa cells indicate that the probe has the potential application in quantitative detection exogenous nitrite level for in cellular imaging.