Glucosamine modified near-infrared cyanine as a sensitive colorimetric fluorescent chemosensor for aspartic and glutamic acid and its applications

A glucosamine modified near-infrared cyanine fluorescent probe has been synthesized and developed as an efficient and visual sensor for the trace level determination of glutamic acid (Glu) and aspartic acid (Asp) with no interference by other amino acids. A prominent fluorescence enhancement at 805 nm and a remarkable color change from pale red to colorless were observed in the presence of Glu and Asp respectively. This probe may also serve as a highly sensitive acidic pH probe with a pK(a) value of 5.82. Furthermore, the chemosensor has been successfully applied for the imaging of Glu and Asp in living cells, and the cytotoxicity assay exhibited that it is of low toxicity under the experimental conditions.