A FRET-ICT Dual-Modulated Ratiometric Fluorescence Sensor for Monitoring and Bio-Imaging of Cellular Selenocysteine.

Since the fluctuation of cellular selenocysteine (Sec) concentration plays an all-important role in the development of numerous human disorders, the real-time fluorescence detection of Sec in living systems has attracted plenty of interest during the past decade. In order to obtain a faster and more sensitive small organic molecule fluorescence sensor for the Sec detection, a new ratiometric fluorescence sensor was designed based on the fluorescence resonance energy transfer (FRET) strategy with coumarin fluorophore as energy donor and 4-hydroxy naphthalimide fluorophore (with 2,4-dinitrobenzene sulfonate as fluorescence signal quencher and Sec-selective recognition site) as an energy acceptor. The sensor exhibited only a blue fluorescence signal, and displayed two well distinguished emission bands (blue and green) in the presence of Sec with ∆λ of 68 nm.