Kun Yao

A quinoline-based Cu2 + ion complex fluorescence probe for selective detection of inorganic phosphate anion in aqueous solution and its application to living cells

A quinaldine functionalized probe QP has been designed and synthesized. It exhibited selective turn-off fluorescence response toward Cu2+ ion over most of the biologically important ions at physiological pH. The binding ratio of the probe QP and Cu2+ ion was determined to be 1:1 through fluorescence titration, Jobs plot and ESI-MS. The binding constant (K) of Cu2+ to probe QP was found to be 2.12×104M-1. Further, the Cu2+ ensemble of probe QP was found to respond H2PO4- and HPO42- among other important biological anions via fluorescence turn-on response at physiological pH. Fluorescence microscopy imaging using living Hela cells showed that probe QP could be used as an effective fluorescent probe for detecting Cu2+ cation and H2PO4- and HPO42- anions in living cells.

A new fluorescent probe based on quinoline for detection of Al3+ and Fe3+ with “off–on–off” response in aqueous solution

A new quinoline-based fluorescent probe 1 has been designed and synthesized. Fluorescence emission spectra of the probe showed red-shift and obvious enhancement of fluorescent intensity upon the addition of Al3+ (turn-on). 1–Al3+ showed high selectivity for Fe3+ over other metal ions, and eliminated the interference of Al3+ during Fe3+ detection (turn-off). It showed highly selective relay recognition of Al3+ and Fe3+ via a fluorescence “off–on–off” mechanism. Fluorescence spectra indicated that the response of 1–Al3+ to Fe3+ was caused by central metal displacement. The detection limits for the analysis of Al3+ and 1–Al3+–Fe3+ ions were calculated to be 2.20 × 10−6 M and 1.96 × 10−5 M, respectively. Living HeLa cell imaging studies revealed that the probe was cell-permeable and it could be used to detect intracellular Al3+ and Fe3+ ions.

A novel turn-on fluorescent probe for Al3 + and Fe3 + in aqueous solution and its imaging in living cells

A quinoline-based fluorescence probe has been prepared and characterized. Probe 1 showed a selective sensing ability for Al3+ and Fe3+ ions through fluorescence enhancement response at 515nm when it was excited at 360nm. In the presence of Fe3+ ion, probe 1 exhibited a detection limit of 2.10×10-6M. As for Al3+, its detection limit of 3.58×10-7M was significantly lower than the highest limit of Al3+ in drinking water recommended by the WHO (7.41μM), representing a rare example in reported fluorescent probe for Al3+ ion. The fluorescence microscopy experiments have demonstrated that probe 1 could be used in live cells for the detection of Al3+ and Fe3+ ions.

Acridine-based fluorescence chemosensors for selective sensing of Fe 3+ and Ni 2+ ions

Two novel acridine-based fluorescence chemosensors (L1 and L2) were prepared and their metal ions sensing properties were investigated. L1 (L2) exhibited an excellent selective fluorescence response toward Fe3+ (Ni2+) and the stoichiometry ratio of L1-Fe3+ and L2-Ni2+ were 1:1. The detection limits of L1 and L2 were calculated by the fluorescence titration to be 4.13μM and 1.52μM, respectively, which were below the maximum permissive level of Fe3+ and Ni2+ ions in drinking water set by the EPA. The possible mechanism of the fluorescence detection of Fe3+ and Ni2+ had been proposed according to the analysis of Jobs plot, IR spectra and ESI-MS. The determination of Fe3+ and Ni2+ ions in living cells had been applied successfully.

Phenanthroline-based fluorescence sensors for Eu3+ ion and subsequent enantioselective discriminating of malate

ABSTRACT A pair of novel chiral fluorescent and colorimetric sensors L1 and D1 had been designed and synthesized, which were based on phenanthroline as the fluorophore and mandelohydrazide as the binding site. They showed selective recognition toward Eu3+ ion as ‘turn-off’ mode in DMSO-H2O solution (v/v = 1:5, 10 mM HEPES, pH = 7.4). The fluorescence discrimination towards chiral carboxylate anions had been studied for L1-Eu3+ and D1-Eu3+ complex and they showed good enantioselective recognition ability towards malate as ‘turn-on’ mode. The interaction of sensor L1, D1 with Eu3+ and L1-Eu3+, D1-Eu3+ towards malate caused different color changes in the naked eye. Graphical Abstract