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A new coumarin-based probe 3-acetyl-7-diethylaminocoumarinthiosemicarbazone (DCT) is synthesized for Al3+ fluorescence detection in CH 3 CH 2 OH/H 2 O (6 : 4, v / v). The fluorescence intensity at 428 nm was enhanced about 15-fold with the fluorescence changed from colorless to blue. The binding constantof Al3+ with DCT is 5.04 × 106 M−1. The limit of detection (LOD) of Al3+ is calculated to be 82 nM. Furthermore, the binding details are determined by Job's plot and ESI - MS studies, which indicated that a stoichiometric ratio of 1 : 1 complex is formed between Al3+ and DCT. Cell imaging confirmed that DCT could useful for detecting Al3+ in HepG2 cells. • Probe DCT is highly selective and sensitive towards Al3+in aqueous solution phase with LOD is 82 nM,which could monitor intracellular Al3+ levels. • The mechanism indicated that a ratio of 1 : 1 complex is formed between Al3+ and DCT. [ABSTRACT FROM AUTHOR]

In this paper, a novel fluorescent probe HBT-H based on benzothiazole has been designed and synthesized. The probe has excellent selectivity and can be used for specific detection of Cu2+. Under 360 nm UV excitation, the probe HBT-H itself has a fluorescence emission peak at 487 nm, emitting cyan blue fluorescence, fluorescence quenching after added Cu2+. The detection limit of Cu2+ recognition by HBT-H probe was calculated as 3.08 × 10−7 M. According to Job's plot and high resolution mass spectrometry, the complexation ratio of HBT-H to Cu2+ was 2:1. The sensor mechanism was confirmed as excited intramolecular proton transfer (ESIPT). Surprisingly, the probe HBT-H system responded well to pH, showing green fluorescence under acidic conditions and cyan blue fluorescence under alkaline conditions. In addition, the probe HBT-H has excellent membrane permeability and low cytotoxicity, which could not only detect Cu2+ in actual water samples, but also recognize Cu2+ in human breast cancer cells (MCF-7). [Display omitted] • The probe could selectively detect Cu2+ from solutions or water samples. • The detection limit of Cu2+ with this probe was as low as 3.08 × 10−7 M. • The probe could be used to judge the acid-base properties colorimetrically. • The probe was successfully applied to the imaging of human breast cancer cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • An indene-chalcone-based fluorescence probe with lysosome-targeting has been developed. • The crystal structure of the probe was reported. • The probe could monitor carboxylesterase (CEs) with a short response time (20 min), low detection limit (1.3 × 10−4 U/mL) and large stokes shift (155 nm). • The probe has been successfully applied to the imaging of endogenous CEs in the lysosomes of living cells and zebrafish. An indene-chalcone-based fluorescence probe 1 was synthesized and characterized. Under physiological conditions (containing 5% DMSO), probe 1 showed satisfactory stability with a low background signal and recognized carboxylesterases (CEs) based on the catalytic hydrolysis of ester groups, releasing a significant green fluorescence. Probe 1 presents several features including a short response time (within 20 min), low detection limit (1.3 × 10−4 U/mL) and large stokes shift (over 155 nm). Notably, commercial lysosomal dye co-staining experiments illustrated the lysosomal localization function of 1 , with the probe also being used for cell and zebrafish imaging of endogenous CEs. [ABSTRACT FROM AUTHOR]

• The probe exhibited excellently selective and sensitive detection for Hg2+ over other relevant analytes. • The fluorescent response was fast within 120 s and a dramatic color changes (from colorless to light green) could be observed by naked eyes. • The detection limit of the probe was 0.019 μM. • The probe was successfully applied to detecting Hg2+ in real water samples and HeLa cells. Mercury ions are highly toxic to living organisms and environment, hence Monitoring and quantification of mercury ions remain great significance. Herein, we have designed and synthesized a novel reaction-based fluorescence probe RANS for detection of Hg2+ by using a xanthene derivate as fluorophore and a thiosemicarbazide moiety as the recognition site. By applying mercury-promoted desulfurization reactions, probe RANS exhibited excellent capability of detecting Hg2+, such as rapid response (120 s), high sensitivity (0.019 μM) and good selectivity. Upon reaction with Hg2+, the thiosemicarbazide group of probe RANS formed 1,3,4-oxadiazole along with a significant color change from colorless to light green. Importantly, RANS has been successfully applied to selectively imaging Hg2+ in living cells with low cytotoxicity and quantitative detection of Hg2+ in real water samples. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A rational design of probe Chol-6RN strives to minimize the interference between recognition moiety and functional moiety. • The probe Chol-6RN is better than the control probe Chol-RN in the linearity and the detection limit. • The cell imaging experiments show that Chol-6RN has good biocompatibility and membrane permeability. To improve the sensitivity and detection limit of probe, we made good use of the advantage of 6-carboxyrhodamine to design a new cholesterol-conjugated fluorescent probe Chol-6RN for Cu2+ detection. The probe Chol-6RN exhibits a sensitive response towards Cu2+ by fluorescence spectrum in aqueous solution. The linearity of Chol-6RN is from 5 μM to 40 μM of Cu2+ with an excellent linear correlation (R2 = 0.99110) and the detection limit for Cu2+ is 1.12 μM, they are better than the control probe Chol-RN. The MTT assay indicates that Chol-6RN is negligible cytotoxicity to HeLa cells after 24 h at a concentration less than 30 μM. The cell imaging displays that Chol-6RN is capable of detecting Cu2+ in live cells and the sensibility of Chol-6RN is better than Chol-RN. [ABSTRACT FROM AUTHOR]

Red emissive B,N co-doped carbon dots (BN-CDs) were hydrothermally synthesized from cresyl violet and boric acid. The BN-CDs exhibited excellent photostability, low cytotoxicity, excitation/emission maxima at 520/616 nm, and a relatively high quantum yield of 18%. The BN-CDs can binded to mercury(II), and this results in quenching of the red-colored fluorescence. However, on subsequent addition of the biothiol (such as cysteine, homocysteine or glutathione), fluorescence recovers. Therefore, the BN-CDs can be used as a multifunctional probe based on "on-off-on" fluorescence response for the detection of Hg(II) and biothiols. The following detection limits were accomplished: (a) Hg(II): 2.8 μM; (b) glutathione: 1.7 μM; (c) cysteine: 2.3 μM; (d) homocysteine: 3.0 μM. The BN-CDs also have been successfully applied for the imaging of Hg(II) and biothiols in HepG2 cells with excellent bio-compatibility. [ABSTRACT FROM AUTHOR]