Fluorimetric and colorimetric detection of nitric oxide in living cells by rhodamine derivatives assisted by Cu2+

Two rhodamine-based NO probes were designed and synthesized. Both RB-TP and RB-Py can detect NO by spectroscopic and ‘naked-eye’ methods in HEPES buffer assisted by Cu2+. The detection limits for NO were 5 nM and 20 nM, respectively. Other biologically relevant reactive species, such as image, H2O2, 1O2, and ClO− did not give any obvious interferences. RB-TP and RB-Py have been also applied to detect the intracellular NO by fluorescence imaging method.