Development of ratiometric fluorescent probes based on peptides for sensing Pb<SUP>2+</SUP> in aquatic environments and human serum

초록

The detection of Pb2+ ions in aquatic environments and biofluid samples is crucial for assessment of human health. Herein, we synthesized two fluorescent probes (1 and 2) consisting of the peptide receptor for Pb2+ and a benzothiazolyl-cyanovinylene fluorophore that exhibited excimer-like emission when it aggregated. The peptide-based probes sensitively detected Pb2+ in purely aqueous solution (1% DMF) through ratiometric fluorescent response with a decrease in monomer emission at 520 nm and an increase in excimer emission at 570 nm. Specially, probe 2 showed remarkable detection features such as high selectivity for Pb2+ over 15 metal ions, high binding affinity (K-d = 5.83 x 10(-7) M) for Pb2+, significant emission intensity changes, low detection limit (3.8 nM) of Pb2+, high water solubility, and visible light excitation (450 nm). Probe 2 was successfully used to quantify nanomolar concentration (0 similar to 800 nM) of Pb2+ in real water samples (ground water and tap water). Specially, 2 was successfully applied for the quantification of Pb2+ in human serum by combination of microwave-assisted human serum digestion and filtration of digested serum by anion exchange cartridge. We clearly investigated the binding mode of 2 with Pb2+ using H-1 NMR, IR spectroscopy, pH titration, confocal microscopy, and size analysis. The peptide-based fluorescent probe might have great application potential for sensing Pb2+ in aquatic environments and biofluid samples.

키워드