Facile Fluorescent Probe Research Articles

Carbon-dots encapsulated luminescent metal–organic frameworks@surface molecularly imprinted polymer: A facile fluorescent probe for the determination of chloramphenicol

In this study, carbon dots (CDs)-encapsulated luminescent metal–organic frameworks@surface molecularly imprinted polymer (CDs@MOF@SMIP) was facilely prepared and applied as fluorescent probe for specific identification and sensitive detection of chloramphenicol (CAP) in food. Fluorescent CDs, serving as signal tags, were encapsulated within metal–organic backbones (ZIF-8), yielding luminescent MOF materials (CDs@ZIF-8). The synthesized CDs, CDs@ZIF-8 and CDs@ZIF-8@SMIP were investigated by morphological and structural characterizations (UV–Vis, XRD, FT-IR, BET, TEM). The CDs@ZIF-8@SMIP probe was demonstrated to have remarkable selectivity and sensitivity towards CAP. Its fluorescence decreased linearly with CAP concentration from 0.323 μg L-1 (0.001 μM) to 8075.0 μg L-1 (25.0 μM), featuring a low detection limit of 0.08 μg L-1. The CDs@ZIF-8@SMIP-based fluorescence strategy achieved satisfactory recoveries (95.5 % − 101.0 %) in CAP-spiked commercial foods with RSD < 4.4 % (n = 3). These results indicate that this method can effectively detect trace CAP in food matrices and has broad application prospects.

A novel fluorescence probe for the recognition of Cd2+ and its application

A facile fluorescence probe BQBH was synthesized and investigated on its spectrum property. The result showed that the BQBH had high sensitivity and selectivity for Cd2+ with lowest detection determined as 0.14 μM by fluorescence response. The 1: 1 binding ratio between BQBH and Cd2+ was determined by Job’s plot, and the binding details were further confirmed by 1H NMR titration, FT-IR spectrum and HRMS analysis. The applications including on test paper, smart phone and cell image were all also investigated.

Facile fluorescent probe for simultaneous fluorescence detection of fluoroquinolones and copper

Facile fluorescent probe for simultaneous fluorescence detection of fluoroquinolones and copper

Using of eosin Y as a facile fluorescence probe in alogliptin estimation: Application to tablet dosage forms and content uniformity testing

New simple sensitive and reliable spectrofluorimetric approach was established for the determination of the antidiabetic drug; Alogliptin (ALG) in its pure and tablet forms. The developed approach is depended on the suppressive action of ALG on the eosin Y native fluorescence. The quenching action of ALG on the eosin Y native fluorescence was measured at acidic medium pH: 3.5, emission wavelength 541 nm (λex. 260 nm). The relative fluorescence intensity (RFI) was measured, and it was directly proportional to ALG concentration in the concentration range of (15–110) μg/mL. The developed and optimized approach was entirely validated regarding to ICH guidelines. The developed method application was successfully extended for ALG content uniformity test (CU). The distribution fraction (DF), rate constants (K), and free energy changes (ΔG°) were calculated. The results obtained were compared to that of the published spectrophotometric one.

Response surface methodology optimization for the synthesis of N, S-codoped carbon dots and its application for tetracyclines detection.

In this study, using a convenient one-pot microwave-assisted method, we rapidly fabricated a N, S-codoped fluorescent carbon dots (NSCDs) through using citric acid (CA) and d-penicillamine (DPA) for the detection of tetracyclines (TC). To rapidly and efficiently optimize the various synthesis parameters and significantly decrease the number of experimental runs, the effect of the synthesis factors on quantum yield (QY) by NSCDs was implemented through means of response surface methodology (RSM). The as-synthesized NSCDs presented superior photoluminescence stability with a strong quantum yield (QY) of 91.55% under optimal conditions, which was consistent with the predicted value using RSM. The fluorescence intensity of the NSCDs could be quenched effectively after adding TC by the inner filter effect (IEE) and photoinduced electron transfer (PET). Thus, the determination of TC by using NSCDs as a facile fluorescent probe was constructed in the range of 0.2-70μM with a limit detection of 0.072μM. Moreover, this detection approach has been utilized to detect TC in actual samples with satisfactory results.

Homocytosine-templated gold nanoclusters as a label-free fluorescent probe: Ferrous ions and glucose detection based on Fenton and enzyme-Fenton reaction

Construction of facile fluorescent probe which own excellent sensing ability for targets is quite challenging. Herein, analytical performance of AuNCs@C20 probe integrated with Fenton and enzyme-Fenton reaction has been developed for ferrous ions (Fe 2+ ) and glucose sensing. Fluorescence of AuNCs@C20 is significantly quenched by ferric ions (Fe 3+ ) and hydroxyl radicals (·OH) which are generated from Fenton reaction between Fe 2+ and H 2 O 2 , and the above approach for turn-off fluorescence probing determination of Fe 2+ and H 2 O 2 is obtained. Glucose can be oxidized by Glucose oxidase (GOx) to generate H 2 O 2 , and then H 2 O 2 is immediately used as substrates for enzyme-Fenton reaction. AuNCs@C20 is further exploited for glucose sensing with satisfactory results. Attributing to the excellent fluorescence quenching efficiency of Fe 3+ and ·OH and the specific catalysis of GOx, this approach exhibits an extremely high sensitivity and selectivity. The limit of detection for Fe 2+ ion and glucose are 67.5 nmol/L and 2.3 μmol/L, respectively. Moreover, preliminary mechanistic investigation demonstrates that the fluorescence quench of AuNCs@C20 is highly related to the efficiency of Fe 3+ and ·OH production in Fenton reaction. Oligonucleotides served as a template in AuNCs@C20 is irreversibly cleaved by ·OH, and nanoclusters aggregate to form the non-fluorescent, larger-sized nanoparticles. This detection strategy provides the valuable insights in exploring nanoclusters based on Fenton or Fenton-like reactions for detecting diverse targets. An innovative strategy based on AuNCs@C20, Fenton and enzyme-Fenton reaction was presented for sensitivity and selectivity detection of Fe 2+ and glucose, and preliminary mechanism investigation was performed. • AuNCs@C20 were prepared by a facile one-step synthesized method. • AuNCs@C20 integrated with Fenton reaction was designed to detect Fe 2+ and glucose. • Possible detecting mechanism has been proposed.

Design of a facile fluorescent probe with a large Stokes shift for hydrogen peroxide imaging in vitro and in vivo.

By modifying 4'‑hydroxybiphenyl‑4‑carbonitrile (BPN-OH) with 2‑(4‑(bromo‑methyl)phenyl)‑4,4,5,5‑tetramethyl‑1,3,2‑dioxaborolane group, a facile fluorescent probe, BPN-TOB, for sensitively tracing H2O2 was designed and synthesized. BPN-TOB displayed a low detection limit (67nM), fast response time (10min), low cytotoxicity, a mega Stokes shift (170nm) and a remarkable fluorescence enhancement (72-fold) in the detection of H2O2. Additionally, probe BPN-TOB could monitor exogenous and endogenous H2O2 in living MGC-803 cells (human gastric cancer cells) and RAW264.7 cells (leukemia cellsin mouse macrophage). In particular, this probe BPN-TOB was successfully utilized for imaging H2O2 in zebrafish.

Carbon dots as an "on-off-on" fluorescent probe for detection of Cu(II) ion, ascorbic acid, and acid phosphatase.

Carbon dot (CD)-based fluorescent probes have been widely exploited; however, multi-component detection using CDs without tedious surface modification is always a challenging task. Here, we develop a convenient and simple CD-based "on-off-on" fluorescent probe for detection of copper(II) ion (Cu2+), ascorbic acid (AA), and acid phosphatase (ACP). Cu2+ leads to the fluorescence quenching of CDs. The limit of detection (LOD) for Cu2+ is 2.4μM. When AA is added into the CDs + Cu2+ solution, Cu2+ is reduced by AA to Cu+, causing the fluorescence recovery of CDs. The fluorescent intensity linearly correlates with the concentration of AA in the range of 100-2800μM with LOD of 60μM. Besides, the probe has potential application for detection of AA in real samples such as VC tablets, orange juice, and fresh orange. The probe can also indirectly detect ACP that enzymatically hydrolyzes ascorbic acid-phosphate (AAP) to produce AA. This work expands the application of CDs in the multi-component detection and provides a facile fluorescent probe for detection of AA in real samples. Graphical abstract.

Transition metal-coordinated graphitic carbon nitride dots as a sensitive and facile fluorescent probe for β-amyloid peptide detection.

Herein, we developed a sensitive graphitic carbon nitride quantum dot (gCNQD)-based fluorescent strategy for β-amyloid peptide monomer (Aβ) determination down to the ng mL-1 level for the first time. To realize this goal, the nanostructured gCNQDs were firstly coordinated with four transition metal ions (Cu2+, Cu+, Fe3+, Zn2+). Our findings showed that the fluorescence (FL) intensity of gCNQDs was quenched in the presence of these metal ions possibly due to the effective chelation with the nitrogen element in gCNQDs and subsequent photoinduced electron transfer (PET) of gCNQDs. The degree of fluorescence quenching was found to be the most intense with the addition of Cu2+ and therefore, we selected Cu2+ as the quencher for the following Aβ determination. Through binding to Cu2+, the introduction of Aβ unexpectedly induced a further decline of FL intensity. Importantly, on account of different peptide sequences coexisting in the same cerebral system, including Aβ1-11, Aβ1-16, Aβ1-38, Aβ1-40 and Aβ1-42, their affinities to Cu2+ could be reflected by the distinguished declining extent of FL intensity. The possible mechanism of Aβ sensing by the probe was clarified by TEM characterization. The developed fluorescent biosensor was demonstrated to give a wide linear range from 1 to 700 ng mL-1 and a low detection limit of 0.18 ng mL-1 for Aβ1-42. In the end, the proposed fluorescence approach was successfully applied to monitoring of Aβ1-42 variations in the cortex and hippocampus of AD rats.

Silver-doped graphite carbon nitride nanosheets as fluorescent probe for the detection of curcumin.

Green fluorescent silver (Ag)-doped graphite carbon nitride (Ag-g-C3 N4 ) nanosheets have been fabricated by an ultrasonic exfoliating method. The fluorescence of the Ag-g-C3 N4 nanosheets is quenched by curcumin. The fluorescence intensity decreases with the increase in the concentration of curcumin, indicating that the Ag-g-C3 N4 nanosheets can function as a non-toxic and facile fluorescence probe to detect curcumin. The fluorescence intensity of Ag-g-C3 N4 nanosheets shows a linear relationship to curcumin in the concentration range 0.01-2.00μM with a low detection limit of 38nM. The fluorescence quenching process between curcumin and Ag-g-C3 N4 nanosheets mainly is based on static quenching. The fluorescent probe has been successfully applied to analyse curcumin in human urine and serum samples with satisfactory results.

A facile fluorescent probe with a large Stokes shift for sequentially detecting copper and sulfide in 100% aqueous solution and imaging them in living cells

The selective detection of Cu2+ and S2− in pure water systems is very challenging. To address this problem, we here present a novel fluorescent probe CF536 for the reversible detection of Cu2+ and S2− in a 100% aqueous solution via a displacement approach based on fluorescence quenching and the ESIPT mechanism, and characterized by IR, NMR, HRMS and X-ray analysis. The introduction of Cu2+ (1.0 equiv.) to the aqueous solution of CF536 led to quenching of the intense green fluorescence within 2min. On the addition of S2− (3.0 equiv.), the emission of the ESIPT probe soon recovered from the CF536-Cu2+ system due to the abolishment of paramagnetic Cu2+. The fluorescence “ON-OFF-ON” cycle can be repeated a minimum of 5 times by the alternate addition of Cu2+ and S2−, implying that CF536 is a renewable dual-functional probe. The probe displayed high selectivity, a rapid response time, excellent water solubility due to introduction of the extremely hydrophilic trihydroxyl group and outstanding anti-interference ability for its large Stokes shift of 101nm (λabs=435nm, λem=536nm), thus making the method highly suitable for bioimaging. The probe CF536 was successfully used for fluorescent imaging of copper and hydrogen sulfide in living cells.

Amide Functionalized Ionic Liquid as Facile Fluorescent Probe for Detection of Nitrophenolic Compounds

Amide Functionalized Ionic Liquid as Facile Fluorescent Probe for Detection of Nitrophenolic Compounds

A fast-response fluorescent probe for hypochlorous acid detection and its application in exogenous and endogenous HOCl imaging of living cells.

A facile fluorescent probe (NBD-DOP) has been developed to detect hypochlorous acid (HOCl) in this study. The probe consists of a NBD fluorophore and a dopamine moiety that reacts with HOCl specifically. The dopamine group quenches the fluorescence of NBD efficiently through a photoinduced electron transfer (PET) effect. Experimental data showed that NBD-DOP could detect HOCl with ultrafast response, high sensitivity and high selectivity in a wide pH range. The probe could also be used to detect the myeloperoxidase enzyme that produces HOCl. Moreover, NBD-DOP has been applied in the imaging of exogenous and endogenous HOCl in living cells by confocal fluorescence microscopy.

As-prepared MoS2 quantum dot as a facile fluorescent probe for long-term tracing of live cells

Recently, the newly emerged two-dimensional nanomaterials, layered transition metal dichalcogenide (e.g. MoS2) nanosheets, have drawn tremendous attentions due to their extraordinary electronic and optical properties, and MoS2 quantum dots (MoS2 QDs) with lateral sizes less than 10 nm have been found to be highly luminescent. In the present study, a facile approach for large-scale preparation of MoS2 QDs by Na intercalation reaction without using any toxic organic reagents is proposed. MoS2 QDs were carefully characterized by various techniques including transmission electron microscopy, atomic force microscopy, dynamic light scattering, spectroscopy, in vitro cytotoxicology, and capillary electrophoresis. The as-prepared MoS2 QDs were strongly fluorescent, highly photo-stable, low in cytotoxicity, and readily reactive to thiols. These inherent properties of MoS2 QDs make them excellent fluorescent probes for long-term live cell tracing. The results of live cells imaging indicated that MoS2 QD stained cells remained highly fluorescent after long-term culture, and could be easily traced from other co-cultured cell lines.

A facile Al(iii)-specific fluorescence probe and its application in biological systems

A facile fluorescent probe for Al(iii) was developed and applied in biological systems.

Ultrasensitive detection of sulfide ions through interactions between sulfide ions and Au(iii) quenching the fluorescence of chitosan microspheres functionalized with rhodamine B and modified with Au(iii)

A rapid and facile fluorescence probe for detecting sulfide ions was developed. The probe can be completely regenerated and was easily separated. The approach described here is a new and convenient way of developing reusable fluorescence probes.

A facile fluorescent probe based on anthraldehyde for trace Fe(iii) ion determination in neutral aqueous solution

A flexible fluorescent probe was synthesized for the determination of Fe(iii) in aqueous solution by conjugating 4-aminoacetophenone into 9-anthraldehyde.

A facile fluorescent probe based on coumarin-derived Schiff base for Al3 + in aqueous media

A facile coumarin-based Schiff base sensor, 7-hydroxy-8-((2-hydroxy-phenylimino)methyl)-coumarin (H2L), has been designed and synthesized for selective detection of Al3+ in methanol–water (1:1, v/v). A fluorescence enhancement of 12-fold at 528nm can be realized upon addition of 5.0 equiv. Al3+ with excitation at 421nm. The mechanism of CN isomerization, coupled with photoinduced energy transfer, is proposed to explain the observed spectral response. Most importantly, this Al3+ sensor has good water-solubility and can be excited with light in the visible range.