A novel fluorescence on-off-on peptide-based chemosensor for simultaneous detection of Cu2+, Ag+ and S2-

A novel peptide fluorescent chemosensor L (FITC-Ahx-GCA-NH2) has been designed and synthesized by solid phase peptide synthesis with Fmoc chemistry which can simultaneously detect Cu2+, Ag+ and S2- ions in aqueous solution and living cells. Both Cu2+ and Ag+ non-competitively quench the fluorescence of L at an excitation wavelength of 490 nm. The S2- anion can restore the quenched fluorescence at 520 nm, completing the fluorescent on-off-on cycle. Moreover, L displayed high selectivity and sensitivity for Cu2+, Ag+ and S2-. The detection limits for Cu2+ and S2- with the L-Cu system were 37 nM and 15 nM, respectively, and for Ag+ and S2- in the L-Ag system the detection limits were 13 nM and 70 nM, respectively. Results of this study suggest that L can be used as a highly selective and sensitive peptide-based fluorescent chemosensor for simultaneous detection of Cu2+, Ag+ and S2- ions in both environmental and biological systems.