A Novel “Off-On” Fluorescent Probe Based on Carbon Nitride Nanoribbons for the Detection of Citrate Anion and Live Cell Imaging

A novel fluorescent “off-on” probe based on carbon nitride (C(3)N(4)) nanoribbons was developed for citrate anion (C(6)H(5)O(7)(3−)) detection. The fluorescence of C(3)N(4) nanoribbons can be quenched by Cu(2+) and then recovered by the addition of C(6)H(5)O(7)(3−), because the chelation between C(6)H(5)O(7)(3−) and Cu(2+) blocks the electron transfer between Cu(2+) and C(3)N(4) nanoribbons. The turn-on fluorescent sensor using this fluorescent “off-on” probe can detect C(6)H(5)O(7)(3−) rapidly and selectively, showing a wide detection linear range (1~400 μM) and a low detection limit (0.78 μM) in aqueous solutions. Importantly, this C(3)N(4) nanoribbon-based “off-on” probe exhibits good biocompatibility and can be used as fluorescent visualizer for exogenous C(6)H(5)O(7)(3−) in HeLa cells.