A novel fluorescence sensor for uranyl ion detection based on a dansyl-modified peptide.

It is of great significance to sensitively and selectively detect uranyl ion (UO) in environmental and biological samples due to the high risks of UO to human health. However, such suitable sensors are still scarce. A novel fluorescence sensor based on a dansyl-modified peptide, Dansyl-Glu-Glu-Pro-Glu-Trp-COOH (D-P5), was efficiently synthesized by Fmoc solid phase peptide synthesis. As the first linear peptide-based fluorescence sensor for UO, D-P5 exhibited high selectivity and sensitivity to UO over 27 metal ions (UO, Cr, Cu, Ba, Hg, Pb, Co, Ag, Fe, Ca, K, Mg, Mn, Na, Ni, Cd, Zn, Al, Dy, Er, Gd, Ho, La, Lu, Pr, Sm, Tm) by a turn-off fluorescence response in 10 mM HEPES buffer (pH 6.3). The effects of anions such as S, NO, SO CO, HCOO, antioxidant ascorbic acid and 4-nitrophenyl acetate on the selectivity for UO detection were also studies. D-P5 sensor could be used for detecting UO in a good linear relationship with concentration in the range of 0-8.0 μM with a low limit of detection of 83.2 nM. Furthermore, the interaction of the sensor with UO was characterized by ESI-MS, IR, XPS and ITC measurements. The 1:1 binding stoichiometry between the sensor and UO was measured by the job's plot and further verified by ESI-MS. The binding constant of the sensor with UO was calculated to be 9.8 × 10 M by modified Benesi-Hildebrand equation. ITC results showed that theΔH andΔS for the interaction of D-P5 with UO were -(7.167 ± 1.25) kJ·mol and 66.5 J·mol·K, respectively. Time-resolved fluorescence spectroscopy indicated that the mechanism of fluorescence quenching of D-P5 by UO ion was static quenching process. In addition, this sensor displayed a good practicality for UO detection in lake water sample without tedious sample pretreatment.