Peptide-based fluorescent chemical sensors for the specific detection of Cu2+ and S2−.

• A new peptide-based chemosensors L used for the detection of Cu2+, Ag+ and S2− ions. • L can detect Cu2+ and S2− at pH under physiological conditions. • L is almost non-cytotoxic. Cu2+ and S2− play important roles in our environment, so it is beneficial to develop sensors capable of detecting Cu2+ and S2− in biological samples. To accomplish this goal, a new peptide-based fluorescent chemical sensor L (FITC-Ahx-His-Glu-Phe-Cys-NH 2) has been designed and synthesized. It can specifically recognize Cu2+ by forming a L -Cu complex which can quench the fluorescence of L. The subsequent addition of S2− can remove Cu2+ from the L -Cu complex, thereby restoring the fluorescence in a process described as an "On-Off-On" cycle. Cu2+ and S2− can be detected by L with extremely high sensitivity and the detection limits is 32 nM and 53 nM respectively. Additionally, the sensor L can detect Cu2+ and S2− at physiological pH conditions. The result of this research is the development of a peptide-based fluorescent chemical sensor L, which can specifically detect Cu2+ and S2− in the environment. [ABSTRACT FROM AUTHOR]