Search

Abstract We reported a novel and readily synthesized fluorescent "turn-on" probe L (Dansyl-Glu-Pro-Gly-Cys) based on dansyl group combine tetrapeptide. The probe L exhibited highly sensitive fluorescent recognition to Cd2+ ions in HEPES buffer solutions (10.0 mM, pH 7.4). The 2:1 binding stoichiometry of L with Cd2+ were determined based on fluorescence titration and the Job's plot investigation. The competitive experiments were found to be highly selective for the Cd2+ ions even in the existence of excess competing metal ions including Zn2+, Pb2+, Hg2+ and Cu2+ ions. The binding constant of the complex L -Cd was calculated to be 5.18 × 1010 M−2, and showed great affinity compared to other probes. In addition, the detection limit of the probe L for Cd2+ ions was calculated to be 45 nM, which presented a pronounced sensitivity toward Cd2+ ions. Most importantly, the probe L had wide range of pH and good biocompatibility, and were successfully applied to selectively detected Cd2+ ions within pH range of 7–12 and bioimaging studies in live cells. Graphical Abstract Unlabelled Image Highlights • A novel fluorescent peptide-based probe (L) was synthesized. • L exhibited exclusively selective fluorescent "turn-on" response toward Cd2+ ions. • L displayed high sensitivity for Cd(II) with a low detection limit of 45 nM. • L could serve as a potential probe to detect Cd2+ ions in living cells. [ABSTRACT FROM AUTHOR]

The zinc ions (Zn 2+ ) play extremely irreplaceable role in the organism and the environment, the design and synthesis of a biomolecule-based fluorescence chemosensor for the detection of Zn 2+ with high sensitivity is very important. Herein, a novel tetrapeptide-based dansyl fluorescent “turn-on” response chemosensor ( L ) has been designed and synthesized by solid phase peptide synthesis (SPPS). As designed, L can detect Zn 2+ ions with specifically and sensitively based on photo-induced electron transfer (PET) mechanism in 100% aqueous solutions, and other metal ions do not interfere with Zn 2+ ions recognition. The stoichiometric ratio of L with Zn 2+ ions was 2:1, which matches with fluorescence titration and Job-plot assay. In addition, the reversibility and circularly process of the detection of L was confirmed by adding bonding agent Na 2 EDTA. Moreover, L exhibits excellent biocompatibility and low biotoxicity with the limit of detection (LOD) for Zn 2+ about 18 nM, and has been successfully utilized for fluorescence imaging of Zn 2+ ions in living HeLa cells under physiological conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel dual-functional probe FLH was developed. • FLH has ability to fast (response time <50 s) and sensitively (LOD = 1.5 nM) detect Cu2+. • FLH -Cu2+ complex displayed colorimetric and fluorescent response toward CN−. • FLH was successfully applied to detect Cu2+ and CN− in test strips and real samples. • FLH was almost no toxicity and successfully detected Cu2+ and CN− in living cells. A novel dual-functional peptide probe FLH based on fluorescent "on–off–on" strategy and colorimetric visualization method was designed and synthesized. This new probe exhibited highly selective and rapid detection of Cu2+ with significant fluorescent "turn-off" response, with a visible colorimetric change from yellow to orange. The combination ratio of FLH to Cu2+ (1:1) was determined using ESI-HRMS spectra and Job's plot. The fluorescent emission showed a good linear response (R2 = 0.9986) with a low detection limit of 1.5 nM. In addition, the FLH -Cu2+ complex displayed colorimetric changes and a fluorescent "off–on" response toward CN− over a wide pH range from 7 to 12. This detection behavior was observed within 20 s, with a limit of detection (LOD) for CN− at 12.7 nM. Based on stability and accuracy, FLH was next developed as dual-functional test strips, and was also successfully applied to detect Cu2+ and CN− in two actual water samples. More importantly, the cytotoxicity studies indicated that FLH had good biocompatibility and low toxicity, and was successfully utilized for monitoring Cu2+ and CN− in living cells through fluorescence imaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • The fluorescent probe DSD based on the dipeptide receptor was synthesized. • DSD exhibited fluorescent quenching for Cu2+ and recovered rapidly by adding CN−. • The detection limit of 2.4 nM for Cu2+ and 41.9 nM for CN−. • DSD was successfully applied for detecting and imaging Cu2+ and CN− in live cells. A novel fluorescent probe (DSD) was reasonably designed and synthesized with dansyl-labeled dipeptide (Dan-Ser-Asp-NH 2). DSD featured remarkably large Stokes shift (230 nm) and perfect water solubility, and exhibited high selectivity and rapid recognition toward Cu2+ via fluorescence quenching. The detection limit of DSD for Cu2+ was 2.4 nM, indicated that DSD has excellent sensitivity. In addition, the stoichiometry between DSD and Cu2+ were detected as 1:1 by fluorescence titration, Job's plot and ESI-HRMS data. As designed, DSD -Cu2+ system was able to sequentially detect CN− according to the displacement approach with fluorescence "off–on" response, and the detection limit for CN− was calculated to be 41.9 nM. Specifically, the response time of DSD with Cu2+ and CN− was less than 40 s, which rendered it suitable for real time detection in actual water samples. In addition, with the alternate addition of Cu2+ and CN−, the reversible cycles could be repeated for at least 10 times, indicated that DSD was a promising reversibility probe. DSD showed low toxicity and good biocompatibility, and was successfully applied to detect Cu2+ and CN− in living cells. [ABSTRACT FROM AUTHOR]