Fluorescent Probe For Selective Detection Research Articles

Composite Eu@Cd-CP as a fluorescent probe for the detection of some food additives

A transition metal coordination polymer (CP), [Cd(Hdpcp)]n (Cd-CP) was prepared based on 3-(2,4-dicarboxyphenyl)-6-carboxypyridine ligand (H3dpcp), and then its composite Eu@Cd-CP was synthesized by the post-modification through loading Eu3+ ions on Cd-CP. Eu@Cd-CP has outstanding fluorescence stability in aqueous solution with a wide range of pH. Furthermore, Eu@Cd-CP can distinguish sodium salicylate (SS) and sodium dehydroacetate (SA) in some food additives by quenching the characteristic fluorescence of Eu3+ ion. Eu@Cd-CP is the first known CP-based fluorescent probe for selective detection of SS and SA. In addition, the fluorescence mechanisms of discerning above analytes by Eu@Cd-CP have been thoroughly evaluated. It has found that synergistic effect of the dynamic process, photoinduced electron transfer (PET) process, energy absorption competition, and formation of Eu-O bonding interactions in sensing SA lead to the fluorescence quenching of Eu@Cd-CP. The fluorescence response mechanism of Eu@Cd-CP with SA is ascribed to the combination of the dynamic process, PET process, and energy absorption competition. A series of portable devices based on Eu@Cd-CP including fluorescence test strips, lamp beads, and composite films were developed to discern SS and SA via visual changes in luminescence color. This composite material can be potentially used as a multifunctional fluorescent probe for practical applications.

A Coumarin-Based Fluorescent Probe for Selective Detection of Cu(II) and Imaging in Human Cell

A Coumarin-Based Fluorescent Probe for Selective Detection of Cu(II) and Imaging in Human Cell

A triphenylamine-based carbohydrazide hydrazone fluorescent probe for selective detection of hypochlorite and sensing acidic gases.

Hypochlorous acid and its hypochlorite are important reactive oxygen species in the body, and are involved in various physiological processes related to immunity; their rapid detection is of great significance. Here, we synthesized a fluorescent probe (TPAS) by condensation of 4-(diphenylamino)benzaldehyde, carbohydrazide, and salicylaldehyde, which can be used for the detection of ClO- in water and sensing of acidic gas in its solid state. The probe showed strong selective recognition of ClO- in acetonitrile and good tolerance to interference ions. There were good linear responses between the intensity of absorbance and fluorescence and the amount of ClO-. The TPAS solid and its paper strips can emit red fluorescence when exposed to volatile acidic vapours. After being treated with NH3, the red fluorescence can be restored to yellow. The response process of TPAS to ClO- and acid gases was characterized using nuclear magnetic resonance, electrospray ionisation mass spectrometry, transmission electron microscopy, and density functional theory calculations. Furthermore, it can be utilized in analyzing ClO- in commercially available bleaching products; the detection results were basically compatible with the labelled values. In addition, the probe is biocompatible and can be applied for imaging ClO- in zebrafish.

A fluorescent probe for selective detection of lysosomal β-hexosaminidase in live cells

Determining the activity of lysosomal β-hexosaminidase in cells is of great importance for understanding the roles that these enzymes play in pathophysiological events. Herein, we designed the new fluorescent probe, βGalNAc-Rhod-CM(NEt2), which consisted of a βGalNAc-linked rhodol unit serving as a β-hexosaminidase reactive fluorogenic moiety and a N,N′-diethylaminocoumarin (CM(NEt2)) group acting as a fluorescence marker for determining the degree of cell permeabilization. Treatment of βGalNAc-Rhod-CM(NEt2) with β-hexosaminidase promoted generation of Rhod-CM(NEt2), thereby leading to an increase in the intensity of fluorescence of Rhod. However, this probe did not respond to the functionally related glycosidase, O-GlcNAcase. The detection limit of βGalNAc-Rhod-CM(NEt2) for β-hexosaminidase was determined to be 0.52 nM, indicating that it has high sensitivity for this enzyme. Furthermore, the probe functioned as an excellent fluorogenic substrate for β-hexosaminidase with kcat and Km values of 17 sec−1 and 22 μM, respectively. The results of cell studies using βGalNAc-Rhod-CM(NEt2) showed that levels of β-hexosaminidase activity in cells can be determined by measuring the intensity of fluorescence arising from Rhod and that the intensity of fluorescence of CM(NEt2) can be employed to determine the degree of cell permeabilization of the probe. Utilizing the new probe, we assessed β-hexosaminidase activities in several types of cells and evaluated the effect of glucose concentrations in culture media on the activity of this enzyme.

High-contrast NIR fluorescent probes for selective detection of NQO1 in breast cancer

NAD(P)H:quinone oxidoreductase 1 (NQO1) is a potential biomarker for breast cancer (BC) diagnosis and prognosis. However, existing fluorescent probes for NQO1 detection have limitations such as short emission wavelength, weak fluorescence response, or large background interference. Here, we developed two novel near-infrared (NIR) fluorescent probes, DCl-Q and DCl2-Q, that selectively detect NQO1 activity in BC cells and tissues. They consist of a trimethyl-locked quinone as the recognition group and a donor-π-acceptor structure with halogen atoms as the reporter group. They exhibit strong fluorescence emission at around 660 nm upon binding to NQO1. We demonstrated that they can distinguish BC cells with different NQO1 expression levels and image endogenous NQO1 in tumor-bearing mice. Our probes provide a convenient and highly sensitive tool for BC diagnosis and prognosis based on NQO1 detection.

ZnS nanocrystallites as fluorescent probe for selective detection of bilirubin

Selective determination of bilirubin is much essential to identify neonatal hyperbilirubinemia. Herein, we present a simple and precise method for quantitative measuring of bilirubin levels using polyvinylpyrrolidone (PVP) capped ZnS nanocrystallites (ZSP). The crystalline structure and purity are studied from x-ray diffraction (XRD) patterns and the transmission electron microscope (TEM) images. The optical characteristics are analyzed using UV-visible absorption and photoluminescence spectra. For ZSP, the estimated value for the optical band gap is 4.06 eV, surpassing the band gap value of uncapped ZnS (3.89 eV). Upon 265 nm excitation, ZSP nanocrystallites exhibits blue emission peaked at 371 nm wavelength. The fluorescence intensity shows a consistent reduction as the bilirubin concentration rises from 3.0 μM to 80 μM. The spectral overlap between the emission spectrum of ZSP and the absorption spectrum of bilirubin, results in fluorescence attenuation due to the inner filter effect (IFE). The ZnS nanocrystallites exhibit remarkable fluorescence properties and demonstrate high sensitivity in detecting bilirubin, achieving a limit of detection (L.O.D) as low as 56 nM. The selectivity of bilirubin over certain co-existing biomolecules is also analyzed. The utility of the fluorescence probe for practical use is confirmed in spiked human serum and urine samples.

3-aminophenylboronic acid modified carbon nitride quantum dots as fluorescent probe for selective detection of dopamine and cell imaging

Dopamine (DA) is the most abundant catecholamine neurotransmitter in the brain and plays an extremely essential role in the physiological activities of the living organism. There is a critical need for accurately and efficiently detecting DA levels in organisms in order to reflect physiological states. Carbon nitride quantum dots (C3N4) were, in recent years, used enormously as electrochemical and fluorescence probes for the detection of metal ions, biomarkers and other environmental or food impurities due to their unique advantageous optical and electronic properties. 3-Aminophenylboronic acid (3-APBA) can specifically combine with DA through an aggregation effect, providing an effective DA detection method. In this work, 3-APBA modified carbon nitride quantum dots (3-APBA-CNQDs) were synthesized from urea and sodium citrate. The structure, chemical composition and optical properties of 3-APBA-CNQDs were investigated by XRD, TEM, UV–visible, and FT-IR spectroscopy. The addition of DA could induce fluorescence quenching of 3-APBA-CNQDs possibly through the inner filter effect (IFE). 3-APBA-CNQDs shows better selectivity and sensitivity to DA than other interfering substances. By optimizing the experiment conditions, good linearity was obtained at 0.10–51 μM DA with a low detection limit of 22.08 nM. More importantly, 3-APBA-CNQDs have been successfully applied for the detection of DA in human urine and blood samples as well as for bioimaging of intracellular DA. This study provides a promising novel method for the rapid detection of DA in real biological samples.

Off-label use of molecular glue: 3-hydroxythalidomide derived fluorescent probe for selective detection of palladium based on Tsuji-Trost reaction

3-Hydroxythalidomide draws more and more attentions as a molecular glue in the field of biomedicine and analysis, due to its unique bonding mode to CRBN protein and the novel fluorescent properties. However, there is rare reports about the application in the field of chemosensor. Herein, we designed and synthesized a fluorescence turn-on probe using 3-hydroxythalidomide as a fluorophore for the detection of palladium based on Tsuji-Trost reaction. The mechanism of the chemosensor for palladium and the effects of the phosphine ligands were investigated systematically. The results indicated that the probe displayed an excellent linear relationship with palladium concentration (region factor, R2 = 0.998) over the range of 1 × 10−7 M − 4 × 10−6 M, presenting a low detection limit of 1.2 nM. Furthermore, it was successfully applied to the determination of palladium in the samples of pharmaceutical wastewater and spiked water with different oxidation states.

CsBr film as a stable flexible fluorescent probe for selective detection of Pb2+

Researchers have been working to develop stable and convenient test strips for detecting heavy metals. This paper reports a new portable lead ion test strip based on the exceptional photoluminescence properties of CsPbBr3. The CsBr films deposited on different substrates (rigid, semi-rigid, and flexible substrates) display highly selective luminescent response to Pb2+. For the flexible substrate, CsBr fluorescent probe not only shows lightweight, easy to use in large-scale manufacturing but also exhibits long detection lifetime. In comparison to organometallic perovskite fluorescence sensing of Pb2+, the CsBr fluorescent probe displays better stability and higher detection limit. Moreover, the used test strip can be reused to detect Cl− in solution, the CsBr fluorescent probe also shows a potential for multi-testing in recycling applications.

A reaction-based carbazole-dicyanovinyl conjugated colorimetric and ratiometric fluorescent probe for selective detection of cyanide ions

In the present work, 4-(9′-hexylcarbazol-3′-yl)benzylidenemalononitrile 5 (probe L) was tested as a colorimetric and ratiometric fluorescent probe in dimethyl sulfoxide (DMSO) medium towards anions, cations and neutral molecules. The sensing properties of probe L were investigated by using UV–Vis absorption and fluorescence spectroscopy techniques. Probe L showed selectivity and sensitivity towards cyanide ions (CN–) in the presence of analytes used. Upon the addition of CN–, intramolecular charge transfer (ICT) band at 425 nm in UV spectrum disappeared. In addition, ICT emission intensity at 593 nm decreased and ligand-centred (LC) emission intensity at 480 nm increased. These findings indicate that nucleophilic conjugate addition of CN– to the dicyanovinyl group of probe L successfully occurs, hence forming a new adduct between probe L and CN–. In this adduct, π-conjugation was partially blocked, and the ICT transfer was hindered. Adduct formation was proved by Job’s plot, 1H NMR and FT-IR analysis. Probe L showed very low limit of detection (LOD) value of 1.467 nM towards CN–. Probe L was also applied to the CN– detection in real-world water samples by the spike and recovery method. The maximum relative standard deviation (RSD) value was 4.24, indicating this method works successfully. Therefore, probe L could find a potential use in detection of CN– in liquid media.

An acetylpyrene-based fluorescent probe for selective detection of cysteine in vitro and in lipid droplets

The development of organelle-targeted probes that enable specific recognition and detection Cysteine (Cys) may provide an effective way to explore physiological processes and pathological mechanisms associated with the related diseases. In this work, an acetylpyrene-based fluorescent probe CP-1 was designed and synthesized for detecting Cys in vitro and in vivo. The probe exhibited a noticeable fluorescence blue shift upon the addition of Cys under UV light, attributed to the mechanism of the nucleophilic addition reaction. The response mechanism for Cys was studied by time-dependent density functional theory (TD-DFT) calculations and mass spectra (MS). CP-1 can not only specifically recognize Cys in the presence of other amino acids and biothiols, but also exhibit the property of targeting lipid droplets (LDs). Due to the good cell biocompatibility, CP-1 has been successfully employed for real-time tracking Cys in LDs of living cells. The ability to target LDs and the favorable biocompatibility make the probe valuable for investigating Cys-related diseases in living cell systems.

Development of a novel near-infrared fluorescent probe for selective detection of zinc ions in environmental and food samples

This study presents a novel near-infrared fluorescent probe TZn, which utilizes Dicyanoisophorone as the fluorophore and dipicolylamine (DPA) as the zinc ion recognition group. Selective recognition of zinc ions can be achieved in the near-infrared region（652 nm. And the chelation reaction of the probe TZn is verified through theoretical calculations and HPLC-MS. The probe TZn exhibits a large Stokes shift of 110 nm, a low detection limit (0.31 μM), and high selectivity. The probe TZn can also monitor the zinc ion in living cells and actual food samples.

A Fast-Response, Phenanthroimidazole-Based Fluorescent Probe for Selective Detection of HClO.

A new phenanthroimidazole-based fluorescence probe for selective detection of HClO was synthesized and characterized using 1HNMR, 13CNMR, IR, and HRMS. With benzenesulfonohydrazide as the identification group, the probe demonstrated a fast fluorescence response from yellow-green to blue when the HC = N double bond was oxidized and broken into an aldehyde group by HClO. The probe showed high selectivity and sensitivity towards HClO with approximately 4.5-fold fluorescence enhancement and has been successfully applied in the molecular logic gate, determination of HClO in environmental water samples, and portable HClO detection.

Highly sensitive fluorescent probes for selective detection of hypochlorite: Applications in blood serum and cell imaging.

Being one of the vital reactive oxygen species (ROS), abnormal level of hypochlorite ion (ClO-) may pose detrimental threats to living organisms. Therefore, highly selective, and rapid monitoring of ClO- in living system is of prime importance to protect living organisms from its harmful effects. In this regard, design of synthetic fluorescent probes for ClO- has garnered considerable attention. However less fluorescence emission in aggregated state and less photostability of several existing probes for ClO- inspired us to design aggregation induced emission (AIE) active fluorescent probes SH1 and SH2. Probes were rationally designed by introducing thiourea moiety that selectively reacted through desulfurization reaction and resulted in highly selective detection of ClO-. Hypochlorite induced desulfurization reaction was validated through 1H NMR titration and DFT studies. Fine tuning of probes SH1 and SH2 prompted highly sensitive nanoscale (55nM and 77nM) and rapid (15 and 35 sec) detection of ClO-. Probe SH1 displayed less cytotoxic effect to live cells before it was successfully applied for bioimaging of ClO- in live MCF-7 cells. Moreover, probes displayed excellent sensing potential for ClO- in blood serum and real water samples. Advantageously, probe coated portable fluorescent films were fabricated for the easy and fast monitoring of ClO-. Of note, this work offers excellent design strategy for highly selective detection of ClO- that may lead to clinical trials.

Terpyridine-Zn(II) based water-soluble fluorescent probes for selective detection of pyrophosphate ions in aqueous medium and its bioimaging application in living cells

Pyrophosphate (PPi) is a key biomarker for various cellular processes and human diseases and thus the development of receptors to bind selectively with PPi ions and facilitate the monitoring of intracellular PPi concentration in living cells is highly imperative. In the present study, novel water-soluble terpyridine-Zn(II) complexes-based fluorescent probes [TPD-Zn2]Cl4 and [TPTBr-Zn2]Cl4 have been designed and synthesized for the selective and sensitive detection of pyrophosphate (PPi) ions in aqueous environment as well as in living cells. The selectivity investigations of both the fluorescent probes towards different anions in HEPES buffer (pH = 7.4) showed highly selective binding towards PPi ions even in the presence of other concomitant nucleotides. Both the probes [TPD-Zn2]Cl4 and [TPTBr-Zn2]Cl4 have exhibited linear fluorescence enhancement upon the addition of different concentrations of PPi and this enhancement in the intensity could be attributed to the photoinduced electron transfer (PET) inhibition process. This proposed binding mechanism was demonstrated using fluorescence and NMR spectroscopic titrations and also the interaction of [TPD-Zn2]Cl4 and [TPTBr-Zn2]Cl4 probes with PPi ions was examined in detail using density functional theory (DFT) analysis. The Job’s plot has shown the binding of complexes between [TPD-Zn2]Cl4 and [TPTBr-Zn2]Cl4 and PPi in 1:2 stoichiometry and the probes have shown excellent binding affinity towards PPi ions with binding constants of 7.72 × 105 M−2 and 6.74 × 104 M−2, respectively. Noticeably, both the probes exhibited promising sensitivity towards PPi with detection limits as low as 0.47 nM and 0.17 nM, respectively. Cytotoxicity studies of [TPD-Zn2]Cl4 and [TPTBr-Zn2]Cl4 revealed that both the probes are biocompatible and subsequently their diagnostic efficacy as bioimaging probes was demonstrated through monitoring the intracellular PPi concentrations in breast cancer cells (MCF-7).

An “off-on” fluorescent probe for selective detection of glutathione based on 11-mercaptoundecanoic acid capped gold nanoclusters

Glutathione (GSH) is an important biothiol and participates in various physiological processes. Therefore, development of highly sensitive and selective fluorescent probes for detecting GSH is of great significance for drug analysis and disease diagnosis. Herein, 11-mercaptoundecanoic acid (11-MUA) capped gold nanoclusters (AuNCs@11-MUA) combining with copper ions (Cu2+) were applied to construct an "off-on" fluorescent probe for GSH detection. In this strategy, the coordination of Cu2+ with AuNCs@11-MUA leads to the fluorescence quenching of AuNCs@11-MUA, and the fluorescence signal of the system is in the “off” state. Due to the stronger binding ability between GSH and Cu2+, the addition of GSH forces Cu2+ detach from AuNCs@11-MUA, resulting in fluorescence recovery of AuNCs@11-MUA, and the fluorescence signal of the system is in the “on” state. The fluorescence recovery is linearly proportional to the concentration of GSH in the range of 0.05–5 μM. The detection limit is 33.3 nM. The proposed sensor can be used for the accurate detection of GSH in commercial drugs and cell lysate, indicating the potential applicability of the nanoprobe.

High fluorescent nitrogen − doped carbon dots derived from Sanghuangporus lonicericola for detecting tetracyclines in aquaculture water and rat serum samples

Tetracyclines (TCs) are a kind of broad − spectrum and effective antibiotics that have been widely used in veterinary and human medicine, which may pose serious risk to human health if they are accumulated in human body. The fluorescence method using nanomaterials as probes has been gradually used for the detection of TCs because of its simple operation, high sensitivity and recognition ability. Herein, a novel nitrogen doped carbon dots (N − CDs) derived from Sanghuangporus lonicericola was synthesized by hydrothermal method. The N − CDs exhibited bright blue fluorescence, high quantum yield (QY) of 60.99 %, and excellent photostability, which was employed as a fluorescent probe for selective detection of TCs, including oxytetracycline (OXY), doxycycline (DOX), tetracycline (TCY) and minocycline (MNO). The fluorescence intensity of the N − CDs decreased linearly with the increasing concentration of OXY, DOX, TCY and MNO, and their concentrations were in the range of 0.6 – 73.3 μM, 0 – 95.2 μM, 6.5 – 72.3 μM and 10 – 52.6 μM, respectively. As for practical application, the as − prepared N − CDs could not only be effectively applied for determination of TCs in aquaculture water and rat serum samples with low relative standard deviation (RSD) and good recoveries, but also track the concentration change of TCs in rats blood model over time. Towards the fluorescence detection mechanism, the results of UV–vis absorption spectra and fluorescence lifetimes proved that the fluorescent quenching of N − CDs occurred from internal filtration effect (IFE) in the presence of TCs. This work provides guidance for the development of new TCs sensors based on fluorescent nanomaterials, and has a good application prospect in the quality control of agriculture, food and pharmaceutical production processes.

A mitochondria-targeted fluorescent probe based on biocompatible RBH-U for the enhanced response of Fe3+ in living cells and quenching of Cu2+ in vitro

A rhodamine hydrazide conjugating uridine moiety (RBH-U) is firstly synthesized by screening different synthetic routes, and then developed as a fluorescence probe for selective detection of Fe3+ ions in an aqueous solution, accompanied by visual color change with naked eyes. Upon the addition of Fe3+ in a 1:1 stoichiometry, a 9-fold enhancement in the fluorescence intensity of the RBH-U was observed with an emission wavelength of 580 nm. In the presence of other metal ions, the “turn-on” fluorescent probe with pH-independent (value 5.0 to 8.0) is remarkably specific for Fe3+ with a detection limit as low as 0.34 μM. Further, the enhanced fluorescence intensity of RBH-U- Fe3+ can be quenched as a switch-off sensor to assist in the recognition of Cu2+ ions. Additionally, the colocalization assay demonstrated that RBH-U containing uridine residue can be used as a novel mitochondria-targeted fluorescent probe with rapid reaction time. Cytotoxicity and cell imaging of RBH-U probe in live NIH-3T3 cells suggest that it can be a potential candidate for clinical diagnosis and Fe3+ tracking toll for the biological system due to its biocompatibility and nontoxicity in NIH-3T3 cells even up to 100 μM.

A highly selective fluorescent probe for detection of H2S based-on benzothiazole and its application

Hydrogen sulfide plays an essential roles in physiological and pathophysiological process. It is still a challenge to design a simple and reasonable H2S-specfic fluorescent probe. Herein, we develop a simple reaction-based fluorescent probe for detecting H2S in DMF/Tris-HCl buffer system. Fluorescence emission spectra were used to investigate the recognition performance of probe L towards hydrogen sulfide. The results shown that probe L has a specific recognition towards hydrogen sulfide over other tested metal cations and anions with a rapid response. The probe L combined with H2S in a 1: 1 manner with a detection limit of 0.372 μM. The appropriate pH range for detecting H2S was 4 ∼ 8. The proposed recognition mechanism was studied by fluorescence titration spectrum, Job’s plot, 1H NMR titration experiment and mass spectrometry analysis. Moreover, probe L was applied in real water samples, test strips and fluorescent films to detect H2S successfully.

A fluorescent probe for selective detection of boric acids and its application for screening the conversion of the Suzuki-Miyaura coupling reaction.

Boric acid (B(OH)3) plays an important physiological role and is widely used as a food preservative and an antiseptic. Various colorimetric, fluorescent probes have been developed to detect boric acid; however, most of them could not discriminate boric acid over boronic acids (R-B(OH)2) or are limited to boronic acid sensors. Therefore, the development of boric acid-selective probes is necessary. Herein, a salicylimine-based fluorophore, Di-OH, was designed that showed selective fluorescence response to boric acid over boronic acid. Its fluorescence response to boric acid showed a large fluorescence turn-on signal up to 140 fold and excellent selectivity with various analytes. Furthermore, since boric acid is generated in proportion to the consumed boronic acid derivatives during reactions involving oraganoboron compounds, Di-OH allowed the determination of the conversion of the Suzuki-Miyaura coupling reaction using fluorescence spectroscopy and its correlation with the GC conversion was confirmed.