A terphenyl derivative-based colorimetric-fluorimetric probe for the detection of lysine and arginine and their bioimaging.

Lysine (Lys) and arginine (Arg) play a crucial role in the human diets, medical diagnostics, and functional biomaterial synthesis. The imbalance of intake for these two amino acids causes various diseases. Although many analytical techniques have been reported for the detection of amino acids, there are still some issues such as the need for bulky instruments, professional operators, sensitivity to be improved, and real-time detection. Here, a novel colorimetric-fluorimetric probe based on a terphenyl derivative (TPT) has been synthesized for the precise detection of Lys and Arg. In the EtOH-HO solution of TPT, the NH group at the chain end of Lys/Arg undergoes a nucleophilic addition reaction with CN groups of benzothiazole groups of the probe TPT, which breaks the initial long-conjugated system of the probe molecule. As a result, blue shifts can be observed for both UV-vis absorption spectra and fluorescence spectra, accompanying with color changes of the TPT solution. The UV-vis absorption peak of TPT solution shifts from ∼410 nm to ∼325 nm, and the solution color changes from light-yellow to colorless. The fluorescence emission shifts from ∼580 nm to ∼470 nm and the bright-yellow TPT solution changes to blue under the irradiation of 365 nm UV light. For colorimetric method, the limits of detection (LoD) are 0.82 μM and 0.90 μM for Lys and Arg, respectively. For fluorimetric method, they are 2.02 nM and 1.62 nM for Lys and Arg, respectively. In addition, TPT has good selectivity and anti-interference for Lys and Arg. The synthesized probe TPT has been successfully used for the precise detection of Lys and Arg in drugs and for fluorescence imaging of living cells. This work demonstrates that terphenyl-based derivatives are promising organic probes for the detection of Lys and Arg, providing a new way for designing other amino acids probes.