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Here, we synthesized gold nanocluster aggregates (GNCA) and constructed a gold nanocluster aggregates-phenol derivative system based on van der Waals for ratiometric fluorescence detection of dopamine (DA), norepinephrine (NE), and resorcinol (Rs), respectively. Novel fluorescent GNCA were rapidly prepared by one-pot method in an alkaline environment regulated by PEI instead of NaOH. PEI wrapped around and connected gold nanoclusters to form GNCA with long fluorescence lifetime and high fluorescent stability. Additionally, Rs was adsorbed on the surface of GNCA via van der Waals to develop the GNCA-Rs system. When NE and DA were introduced to the GNCA-Rs system, two new fluorescence peaks at 513 nm and 474 nm appeared, owing to the fluorescent polycondensation reaction of Rs with NE and DA, respectively. Thus, non-enzymatic fluorescence detections of NE and DA were achieved. When the GNCA-Rs system was used as a fluorescent probe, the linear detection ranges of NE and DA were 0.01–400.0 μM and 0.001–400.0 μM respectively, with detection limits (LOD) of 78.0 nM and 3.0 nM. The high sensitivity was attributed to physical adsorption based on van der Waals interactions and polycondensation processes. Similarly, van der Waals developed a GNCA-DA system with remarkable sensitivity (LOD=1.4 nM) for the detection of Rs. In this study, we not only proposed an efficient approach for constructing fluorescent probes, but also presented a novel strategy for the detection of catecholamines. • Novel gold nanocluster aggregates (GNCA) were rapidly prepared with PEI as alkaline modifier. • Multiwfn program demonstrated that GNCA-phenol derivative systems were assembled by van der Waals. • The fluorescence reaction of Rs and NE was proposed. • This strategy showed wide detection ranges and high sensitivities. [ABSTRACT FROM AUTHOR]

Single-nucleotide variant (SNV) is crucial in clinical diagnostics as a useful biomarker, because it is closely associated with many diseases, such as genetic disorders and tumors. In this study, an enzyme-free and selective fluorescence biosensor is proposed for β -thalassemia SNV detection based on X-shaped probe, locked nucleic acid (LNA), and toehold-mediated strand-displacement reaction (TMSDR)-assisted recycling technology. On one hand, the LNA-integrated X-shaped probe has high recognition ability for SNV sequence even in the presence of a large amount of wild-type sequence, i.e., the rare SNV can be detected down to 0.01% variant allele frequency (VAF). On the other hand, the introduction of TMSDR-assisted recycling amplification system remarkably improves the sensitivity of the sensor with the detection limit as low as 6 fM mutation gene. Moreover, the designed X-shaped probe is universal because its functionalized oligonucleotides could be decoupled from the target-specific regions. These experimental results demonstrate that this developed method offers high specificity and sensitivity for SNV detection, which might be a potential alternative as an effective mutation detection technology for the detection of β -thalassemia SNV and other gene-related diseases. [ABSTRACT FROM AUTHOR]

Highlights: [•] An easy-to-make colorimetric and fluorometric sensor 1 for Pb2+ was obtained. [•] The assay carried in aqueous solution with low limit detection as 37nMmolL−1. [•] The high selectivity and sensitivity of 1 for Pb2+ was for 1’s distinctive structure. [•] 1−Pb2+ shows longer wavelength absorption and emission and strong fluorescence. [Copyright &y& Elsevier]

Purpose: To use noninvasive fluorescence imaging to investigate the influence of molecular weight (MW) of proteins on the rate of loss from a subcutaneous (SC) injection site and subsequent uptake by the draining lymph nodes in mice. Methods: Bevacizumab (149 kDa), bovine serum albumin (BSA, 66 kDa), ovalbumin (44.3 kDa) or VEGF-C156S (23 kDa), labeled with the near infrared dye IRDye 680, were injected SC into the front footpad of SKH-1 mice. Whole body non-invasive fluorescence imaging was performed to quantitate the fluorescence signal at the injection site and in axillary lymph nodes. Results: The half-life values, describing the times for 50% loss of proteins from the injection site, were 6.81 h for bevacizumab, 2.85 h for BSA, 1.57 h for ovalbumin and 0.31 h for VEGF-C156S. The corresponding axillary lymph node exposure, represented as the area of the % dose versus time curve, was 6.27, 5.13, 4.06 and 1.54% dose ∙ h, respectively. Conclusions: Our results indicate that the rate of loss of proteins from a SC injection site is inversely related to MW of proteins, while lymph node exposure is proportionally related to the MW of proteins in a mouse model. [ABSTRACT FROM AUTHOR]

Abstract: A new compound, 1-[p-(dimethylamino)benzoyl]-4′-phenyl-semicarbazide (1) was synthesized and showed highly selective response to Cu2+ over other metal ions such as Pb2+, Mg2+, Fe2+, Co2+, Zn2+, Cd2+, Hg2+, Ni2+, Ca2+, Ag+, Na+, K+, and Li+. The control compound, 1-[p-(dimethylamino)benzoyl]-4-phenyl-thiosemicarbazide (2), showed different fluorescence spectral response to Cu2+. A 1:1 complex between Cu2+ and 1 was formed while 1:1 and 1:2 complexes between Cu2+ and 2 were formed. The binding model between the receptor (1 or 2) and Cu2+ was supported by IR spectra, mass spectra, and computation model. 1 possessed higher selectivity towards Cu2+ compared with 2 owing to the difference of complexation ability between urea and thiourea groups. [Copyright &y& Elsevier]

Abstract: The zinc complex of 2-[2-(3, 5-bis(2-pyridylmethyl)aminomethyl-4-hydroxy-phenyl) ethylene]-5-methylpyrazine (1) could bind with the calf thymus deoxyribonucleic acid (ct-DNA). The binding behaviors between them were studied by fluorescence and absorption spectral assay. The absorption titration of 1-Zn with ct-DNA showed no bathochromic shift and hypochromic effect. No anisotropy increase was observed when ct-DNA was added to 1-Zn solution. They both proved the lack of intercalation interaction between 1-Zn and ct-DNA. The ionic strength experiment, Scatchard plot, study of interaction between 1-Zn and denatured ct-DNA all revealed that the interaction mode between 1-Zn and ct-DNA was electrostatic interaction. Binding constant was estimated to be 7.96×104 LmoL−1. [Copyright &y& Elsevier]

Abstract: A new fluorescent sensor (1) containing bis(2-pyridylmethyl)amine group as a binding moiety for Pb2+ was developed. Compound 1 shows selective response to Pb2+ over other metal ions in pH 7.0 HEPES buffer solution. The fluorescence intensity enhancement was ascribed to the complex formation between Pb2+ and 1 which blocked the photo-induced electron transfer process. [Copyright &y& Elsevier]

Abstract: A novel compound, p-(dimethylamino)benzamido-thiosemicarbazide (1), based on intramolecular charge transfer fluorescence was synthesized. In pH 7.4 Tris–HCl buffer, the emission intensity of 1 increased upon the addition of HSA or BSA due to the energy transfer from the protein to 1 and also the hydrophobic microenvironment provided by HSA or BSA. The binding constants between 1 and proteins were 1.41×105 mol−1 L for HSA and 8.68×104 mol−1 L for BSA, respectively. There is only one binding site. The interaction between 1 and proteins was further investigated by synchronous fluorescence. [Copyright &y& Elsevier]

The intramolecular charge transfer (ICT) dual fluorescence of p-dimethylaminobenzamide (DMABA) in acetonitrile was found to show highly sensitive response to HSO4− over several other anions such as H2PO4−,AcO− and ClO4−. In the presence of bisulfate anion the dual fluorescence intensity ratio and the total intensity of DMABA decreased while the dual emission band positions remained unchanged. Absorption titration indicated that a 1:1 hydrogen bonding complex was formed between bisulfate anion and DMABA, which gave a binding constant of 2.02×104 mol−1 l that is two orders of magnitude higher than those for other anions. The obvious isotopic effect observed in the fluorescence quenching [KSV(HSO4−)/KSV( DSO4−)=1.63] suggests that the hydrogen atom moving is an important reaction coordinate. It was assumed that the dual fluorescence response was due to proton coupled electron transfer mediated by hydrogen bonds within the 1:1 HSO4−-DMABA hydrogen-bonding complex. [Copyright &y& Elsevier]

α-Glucosidase, which directly involves in the metabolism of starch and glycogen and causes an increase in blood sugar level, is the major target enzyme for the precaution and therapy of type II diabetes. Based on the previous work, we adopted a post-synthetic modification method to encapsulate Tb3+ into Ce-MOF nanozyme which owned mixed valence states. Tb@Ce-MOF displayed induced luminescence characteristic and exceptional oxidase-like activity that could oxidize colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue ox-TMB. α-Glucosidase can hydrolyze the substrate l -ascorbic acid-2- O -α- d -glucopyranosyl (AAG) to generate ascorbic acid (AA), which could increase the Ce3+/Ce4+ redox valence mode in Tb@Ce-MOF, leading to the inhibition of the allochroic reaction of TMB and the decreased absorption of ox-TMB at 652 nm. The energy transfer (EnT) process from Ce3+ to Tb3+ will enhance due to the increased Ce3+/Ce4+ mode in Tb@Ce-MOF, which will result in an enhanced fluorescence signal of Tb@Ce-MOF at 550 nm. But the addition of inhibitor acarbose will inhibit the above process. We have constructed a dual-mode detection platform of α-glucosidase and its inhibitor via colorimetric and fluorometric method. The linear range of α-glucosidase were 0.01–0.5 U/mL (colorimetric mode) and 0.8–1.5 U/mL (fluorometric mode), respectively, with a detection limit as low as 0.0018 U/mL. Furthermore, our approach was also successfully employed to the analysis of α-glucosidase in serum samples. [Display omitted] • Dual-mode nanoprobe was constructed based on Tb(Ⅲ)-modified Ce-MOF. • Tb@Ce-MOF exhibited intrinsic oxidase-like and induced luminescence properties. • The nanoprobe exhibited colorimetric and fluorometric response to α-glucosidase. • Dual-mode sensing platform enabled the accurate detection of α-glucosidase in human serum. [ABSTRACT FROM AUTHOR]

Visual monitoring of the degradation of nerve agent simulants based on the switchable fluorescence of UiO-66-NH2 was developed. In the hydrolysis, the decomposition products perturbed the linker-to-cluster charge transfer and stimulated the fluorescence recovery. Moreover, a "soft" solid-state platform utilizing agarose hydrogels was proposed to visualize the degradation of gaseous simulants without bulk water. [ABSTRACT FROM AUTHOR]

We report the synthesis of 9,10-disubstituted-2,3,6,7-tetraphenylanthracenes, of which the photophysical properties are altered significantly by the 9,10-functionalities; the emission wavelengths range from 410 to 610 nm with outstanding quantum yields for most fluorophores. [ABSTRACT FROM AUTHOR]

MOF-based luminescent sensors have garnered considerable attention due to their potential in recognition and discrimination with high sensitivity, selectivity, and fast response in the last decades. Herein, this work describes the bulk preparation of a novel luminescent homochiral MOF, namely, [Cd(s-L)](NO3)2 (MOF-1), from an enantiopure pyridyl-functionalized ligand with rigid binaphthol skeleton under mild synthetic condition. Except for the features of porosity and crystallinity, the MOF-1 has also been characterized with water-stability, luminescence, and homochirality. Most important, the MOF-1 exhibits highly sensitive molecular recognition toward the4-nitrobenzoic acid (NBC) and moderate enantioselective detection of proline, arginine, and 1-phenylethanol. [ABSTRACT FROM AUTHOR]

Abstract We report a highly sensitive fluorescent probe based on p -dimethylaminobenzoyl derivatives (probe L) for the detection of Cu2+ and Zn2+. In this work, the probe L exhibited a fluorescent turn-on sensing model to Cu2+ and Zn2+ with a distinct fluorescent color change from colorless to green and yellow respectively. Probe L exhibited high selectivity as a fluorescent Cu2+/Zn2+ probe with a limit of detection (LOD) of 45 nM/17 nM. The results of 1H NMR titrations revealed that the response of L to Cu2+ and Zn2+ was triggered by the interaction of the thiophene unit and the metal ion. Furthermore, the fluorescence titrations and Job's plot curves displayed the binding ratio of 1:2 for Cu2+ and 1:1 for Zn2+ metal- L complex formation respectively. Density functional theory calculation also demonstrated the possibility of molecular luminescence and the process of metal- L complex formation. Additionally, fluorescent test strips have been prepared for convenient detection of Cu2+ and Zn2+, which means the convenient and rapid assay in real samples can be achieved. Graphical abstract Unlabelled Image Highlights • A single fluorescent probe for Cu2+ and Zn2+ was presented. • Different fluorescence responses to Cu2+ and Zn2+ were achieved. • This method has very low detection limits for Cu2+ and Zn2+. • The probe has good reversibility. • The probe has been successfully applied to test strips and sample testing. [ABSTRACT FROM AUTHOR]

In this work, a simple and easily synthesized Schiff-based derivative colorimetric and fluorescent sensor ( 1 ), 4-dimethylamino-benzoic acid (2-imidazole formaldehyde)-hydrazide, was obtained for the detection of Cu 2+ and S 2− . The compound 1 exhibited dual spectral responses to Cu 2+ , that is, vivid color change and fluorescence enhancement in the presence of Cu 2+ . The detection limits were valued as 0.46 μM and 15 nM according to absorption and fluorescent response, respectively. Both of them are below the World Health Organization (WHO) guidelines for drinking water (31.5 μM). In addition, the ensemble ( 1-Cu 2+ ) selectively and sensitively detected a low concentration of S 2− . As the addition of S 2− instantly removed Cu 2+ from the ensemble ( 1-Cu 2+ ) resulting in a color change from yellow to colorless and a “turn-off” fluorescent response. The detection limit for S 2− was estimated as 0.12 μM (from fluorescent method) and 0.68 μM (from absorption method), respectively, each of which was also lower than the maximum allowable level of S 2− (15 μM) in drinking water defined by the WHO. The binding process was confirmed via UV–vis absorption, fluorescence measurements, 1 H NMR, mass spectroscopy and density functional theory calculation. What's more, successful practical application of test paper is used to inspect the S 2− which means the convenient and rapid assay in real samples can be achieved. [ABSTRACT FROM AUTHOR]

Highly toxic organophosphorus nerve agents often exist in the form of gas in the environment and can damage human neuroregulatory system by inhibiting the activity of acetylcholinesterase (AChE). However, fluorescent probes based on small organic molecules bring a secondary burden to environment, and their sensitivity and specificity for sarin simulant diethyl chlorophosphate (DCP) detection are unsatisfactory. Nanozyme cascade systems with signal amplification can be used for highly sensitive identification of analytes, but are rarely used in ratiometric analysis of DCP. Combination of enzyme cascades and ratiometric fluorescence ensures the accuracy and sensitivity of the output signal. We prepared a self-assembled nanohybrid (Ag–AuNCs@UiO-66-NH 2) by metal-organic framework material and gold nanoclusters. On the one hand, UiO-66-NH 2 with enzyme-like activity was used to hydrolyze DCP into diethyl phosphate (DEP) and chloridion (Cl−). Cl− hindered aggregation-induced enhanced emission (AIEE) of AuNCs by binding with Ag+ and decreased the fluorescence of AuNCs. On the other hand, ligand metal charge transfer effect (LMCT) of UiO-66-NH 2 was blocked by DCP to enhance the fluorescence of UiO-66-NH 2. Combining ratiometric analysis and nanozyme cascade reaction, an ultra-sensitive fluorescence sensor for detecting DCP was constructed, and ensured the accuracy of experimental results. In addition, Ag–AuNCs@UiO-66-NH 2 was embedded into the agarose hydrogel substrate, the resulting agarose hydrogel film allowed quantitative assessment of DCP vapor and high sensitivity was demonstrated (detection limit as low as 1.02 ppb). A strategy combining enzyme cascade with ratiometric fluorescence was proposed, which improved the accuracy and sensitivity of the analysis results. The soft-solid platform based on agarose hydrogel film was constructed to realize the quantitative monitoring of sarin simulant gas. The LOD value obtained in this work is much lower than the immediately life-threatening or health threatening concentration of sarin. [Display omitted] • A nanohybrid was synthesized by self-assembly of UiO-66-NH 2 and Ag–AuNCs. • An ultrasensitive ratiometric fluorescence sensor for DCP was constructed. • Ratiometric analysis and cascade reaction ensured accuracy and sensitivity. • The composite hydrogel realizes the visual monitoring of DCP vapor. [ABSTRACT FROM AUTHOR]

We report on a simple strategy for the determination of zinc ion by using surface-modified quantum dots. The probe consists of manganese-doped quantum dots made from zinc sulfide and capped N-acetyl-L-cysteine. The particles exhibit bright yellow-orange emission with a peak at 598 nm which can be attributed to the T→A transition of Mn(II). This bright fluorescence is effectively quenched by modifying the sulfur anion which suppresses the radiative recombination process. The emission of the probe can then be restored by adding Zn(II) which causes the formation of a ZnS passivation layer around the QDs. The fluorescence enhancement caused is linear in the 1.25 to 30 μM zinc concentration range, and the limit of detection is 0.67 μM. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Developing a fluorescence sensor capable of precisely identifying highly toxic nerve agents has become a focus of research, given that they are easily available and can be used by terrorists to threaten the security of the world. In this work, we designed a ratiometric fluorescence sensing platform with Cu2+-modified UiO-66-NH 2 (Cu2+@UiO-66-NH 2) and o-phenenediamine (OPD) as signal indicators and successfully used for the liquid and gas detection of the nerve agent simulant diethyl chlorophosphate (DCP). UiO-66-NH 2 obtained oxidase activity by simple Cu2+ modification, which catalyzed the oxidation of OPD to give a yellow fluorescent product 2, 3-diaminophenazine (DAP). In this detection system, the fluorescence of UiO-66-NH 2 was greatly enhanced by blocking the ligand metal charge transfer (LMCT) process inside the framework by DCP. At the same time, the amino group of DAP was phosphorylated by DCP, and the attenuation of DAP fluorescence was observed by the static quenching effect. In addition, the Cu2+@UiO-66-NH 2 /OPD loaded agarose hydrogel device can be used to detect DCP vapor with naked eyes and showed satisfactory detection result (LOD: 6.65 ppb). • A ratiometric fluorescence sensing based on Cu2+-functionalized MOF was achieved. • Ratiometric fluorescence response was based on LMCT and static quenching effect. • The sensor based on Cu2+@UiO-66-NH 2 /OPD has a good ability to detect DCP. • The composite hydrogel can visually detect DCP vapor. [ABSTRACT FROM AUTHOR]

• The synthetic route of the probe is very simple. • The probe has good reversibility in physiological environment. • The probe Cu-1 shows excellent selectivity toward Cys. • This assay has high sensitivity and exhibits short response time. • This probe is AIE-active leading to high luminous efficiency in cell imaging. In this work, an effective and simple aggregation-induced emission (AIE) active fluorescent probe based on ESIPT luminescence principle, 2-hydroxy-1-naphthal-4-aminoantipyrine (1), was synthesized via a simple chemical reaction. It displayed strong fluorescence enhancement in water. The AIE mechanism of 1 was explored by electron microscopy and computational analysis. We demonstrate the combination effect of intramolecular hydrogen bonds and π-π stacking to endow 1 with such a property. Importantly, the ensemble of 1 with copper ions (Cu-1) as a fluorescent probe enables highly selective and sensitive turn-on fluorescence detection of cysteine (Cys) over other interfering substances. Under optimal detection conditions, this probe has a good linear relationship in the concentration range of Cys between 0 and 8 μM, and the detection limit of Cys was estimated as 84 nM. Furthermore, this assay exhibits good reversibility of 1 to Cu2+ and Cys. Due to its good biocompatibility evaluated by CCK-assay, the probe Cu-1 was finally applied in imaging of Cys within Min6 cells successfully. [ABSTRACT FROM AUTHOR]

A caspase-3 controlled condensation was applied to self-assemble biotinylated nanoparticles for capturing FITC-labelled streptavidin and subsequently turning on the fluorescence signal. [ABSTRACT FROM AUTHOR]

Abstract In our study, the carbon nanodots (CDs) were synthesized by one-step solvothermal method using resorcinol as the only presusor. The obtained CDs contained abundant unsaturated oxygen-containing groups resulting from the surface oxidation. A novel, simple, and real-time fluorescent assay for the detection of water in various organic solvents was thus established by reducing the surface oxidation states. Excellent reversibility can be readily achieved by the external stimulus water and N,N′-dicyclohexylcarbodiimide (DCC). The water-induced sensitive (limit of detection = 0.006%, v/v, in ethanol) and ultrafast (<1 s) response in emission properties was capable of water determination in spirit samples in both solution and solid-state paper test strips. Graphical abstract Image 1 Highlights • The CDs were synthesized by one-step solvothermal method using resorcinol as the only presusor. • A simple fluorescent assay for water in organic solvents was developed by changing the surface states of the CDs. • This assay is capable of water determination in spirit samples in both solution and solid-state paper test strips. • This assay bears advantages including rapidity, simplicity, lost cost, good sensitivity, selectivity, and reusability. [ABSTRACT FROM AUTHOR]

A new p-dimethylaminobenzamide derivative based compound BDIH has been synthesized. Cu 2 + turned on the fluorescence of compound BDIH with a 1:2 binding stoichiometry. The fluorescent color of compound BDIH shows an evident change from colorless to bright blue upon the addition of Cu 2 + , which could be visibly detected by the naked eye under UV light at 365 nm. More importantly, the detection limit was found to be 0.64 nM which is far lower than the maximal allowed concentration of the WHO limit (31.5 μM) for drinking water. This selective “turn-on” fluorescence sensor was used to identify Cu 2 + in living cells using confocal fluorescence microscopy, indicating that compound BDIH has a potential application for selective detection of Cu 2 + in organism. [ABSTRACT FROM AUTHOR]

Amino(-NH 2 ) functionalized zirconium metal-organic framework UiO-66 were synthesized in household microwave oven. The structural properties and morphology of the obtained UiO-66-NH 2 nanoparticles were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS). UiO-66-NH 2 sensor show high selectivity and sensitivity toward Cu 2 + over other tested metal ions. In addition, the possible sensing mechanism is also discussed. [ABSTRACT FROM AUTHOR]

A novel p -dimethylaminobenzamide-based Schiff base derivative DTBL was synthesized via a simple reaction and utilized as a “turn-on” fluorescent indicator for copper ion (Cu 2+ ). It showed extraordinary high selectivity toward Cu 2+ in MeCN–H 2 O (v/v = 3:2, pH = 5) HOAc-NaOAc buffer solution, and the fluorescence intensity change were noticeable for the Cu 2+ detection even in the presence of different kinds of foreign ions and compounds at very high concentrations. The 2:1 stoichiometry of DTBL-Cu 2+ complex was calculated from Job’s plot based on fluorescence titrations. The good linear relationship easily exhibited a dynamic response range for Cu 2+ from 0 to 3.4 μM and the detection limit (0.32 nM) of DTBL for Cu 2+ was far lower than the maximum allowable level of the WHO limit (30 μM) for drinking water. Moreover, the adaptability of DTBL for biological applications was also demonstrated by fluorescence imaging of intracellular Cu 2+ in living cells. The results indicate that DTBL should be available for the research on the biological and environmental applications associated with Cu 2+ . [ABSTRACT FROM AUTHOR]

We developed a new core-shell ratiometric fluorescent nanoprobe simply prepared by a seeded growth method. The strong luminescence arising from the shell formed by coordination self-assembly of an alkaline phosphatase (ALP) substrate, l -ascorbic acid 2-phosphate (AAP), and Tb3+, together with the weak fluorescence of the core-a metal-organic framework, UiO-66-NH 2 , constitutes an ideal dual-emission characteristic. Since AAP can be specifically cleaved by ALP, the well-formulated core-shell nanostructure was destroyed upon exposure to ALP. In this case, the luminescence of Tb3+ was quenched due to the inefficient antenna effect, while the fluorescence of UiO-66-NH 2 was strengthened by the synergistical enhancement of dual hydrolysates to inhibit the ligand-to-metal charge transfer (LMCT) process. Using the dual signal response, this nanoprobe was employed for ratiometric fluorescence detection of ALP activity in the range of 0.05–0.6 U mL−1 with a detection limit of 0.018 U mL−1, accompanied by a discernible fluorescence color evolution from turquoise to blue. In virtue of good properties in accuracy, sensitivity, selectivity and simplicity, this assay enabled quantitative detection of ALP activity in human serum and efficient screening of ALP inhibitors. More Importantly, a smartphone-assisted paper-based sensing platform was designed for on-site visual analysis of ALP activity in human serum, which may be very promising as a facile, portable, and robust format to facilitate relevant biological and clinical applications. [Display omitted] • We have developed a core-shell lanthanide-based fluorescent nanoprobe. • The nanoprobe exhibited ratiometric fluorescence response toward ALP. • The synergy from dual products enhanced detection sensitivity. • Smartphone-based visual analysis enabled to evaluate ALP activity in human serum. [ABSTRACT FROM AUTHOR]

In this paper, we describe a novel label-free fluorescence method for microRNA-21 (miR-21) detection based on terbium (Tb3+) and duplex-specific nuclease (DSN) assisted target recycling. Capture probes (Cps), containing a target-binding part and a signal-output part, are immobilized on magnetic beads (MBs). In the presence of the target miR-21, it hybridizes with the target-binding part of a Cp to form a DNA–RNA heteroduplex. Due to the considerable cleavage preference for DNA in DNA–RNA hybrids, DSN hydrolyzes the target-binding part of the Cp while liberating the intact target miR-21 to hybridize with a new Cp and initiate the second cycle of hydrolysis. Eventually, through magnetic separation, only the signal-output part of the Cp could remain in solution and function as a signalling flare to increase the fluorescence intensity of Tb3+ dramatically. By employing the above strategy, this approach can gain an amplified fluorescent signal and detect as low as 8 fM miR-21 under the optimized conditions. Moreover, due to the high selectivity of DSN, the method shows little cross-hybridization among the closely related miRNA family members even at the single-base-mismatched level. Successful attempts were made in applying the approach to detect miR-21 in human cell lysate samples of breast cancer patients. [ABSTRACT FROM AUTHOR]

NH 2 -MIL-53(Al) nanocrystals have been facilely synthesized through microwave ultrasound-assisted method, and the obtained nanocrystals exhibited fluorescence characteristics and were used as sensor for the selective detection of organosulfur compounds in model fuel. [Display omitted] • NH 2 -MIL-53(Al) nanocrystals have been synthesized through microwave ultrasound-assisted method. • The as-synthesized NH 2 -MIL-53(Al) displayed fluorescence characteristics. • NH 2 -MIL-53(Al) based sensor exhibit high detection sensitivity toward organosulfur compounds in model fuel. Amino-MIL-53(Al) (NH 2 -MIL-53(Al)) nanocrystals were successfully obtained through microwave ultrasound-assisted method. The structure and morphology of the as-synthesized NH 2 -MIL-53(Al) nanocrystals were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and N 2 adsorption–desorption isotherms, respectively. Upon excitation at 388 nm, the as-synthesized NH 2 -MIL-53(Al) nanocrystals show strong emission peak at 454 nm in n-octane solution at room temperature. Meanwhile, the fluorescence explorations revealed that NH 2 -MIL-53(Al) can selectively detect organosulfur compounds, including thiophene and benzothiophene through quenching effect in model fuel, with high quenching constant and low detection limit. This work presents a facile platform for the detection of organosulfur compounds in model fuel. [ABSTRACT FROM AUTHOR]

Three deep-blue fluorescent 9,10-bis(4-tert-butylphenyl)phenanthrenes with diphenyl, -naphthyl, and -pyrenyl moieties at C3 and C6 positions were synthesized and used as the host for doped blue fluorescent devices; one of these devices reveals excellent external quantum efficiency of 7.7% and current efficiency of 9.8 cd A−1with low efficiency roll-off, deep-blue color coordinates (0.14, 0.14) and long operational lifetime. [ABSTRACT FROM AUTHOR]

• A ratiometric fluorescent nanoprobe for phosphate was developed. • The response to phosphate is based on chelation-enhanced fluorescence. • The self-calibrating capacity can well alleviate environmental interference. • This probe showed excellent selectivity and sensitivity toward phosphate. • This probe was applied to the quantitation of phosphate in human serum. We report a new fluorescent nanoprobe simply constructed by the surface modification of positively charged polyethylenimine (PEI)-coated gold nanoclusters (AuNCs) with 8-hydroxyquinoline-5-sulfonate (8Q5S) through electrostatic interaction. This nanoprobe showed the intrinsic emission of AuNCs at 650 nm and a weak emission at 490 nm from 8Q5S. Based on chelation-enhanced fluorescence of 8Q5S induced by its specific and high affinity for phosphate upon binding Mg2+ and the stable fluorescence of AuNCs as the reference, this nanoprobe was demonstrated to exhibit highly sensitive, selective, and reliable detection of phosphate in the linear range from 0 to 50 μM with a low detection limit of 0.14 μM. Furthermore, the presented ratiometric fluorescent sensor was successfully employed for accurate quantitation of phosphate in complex human serum samples with satisfactory results. [ABSTRACT FROM AUTHOR]