Fluorescent Probe For Selective Detection Research Articles

Reaction‐based AIE‐active Fluorescent Probes for Selective Detection and Imaging

AbstractFluorescent probes have been widely investigated for their features of rapid response, easy operation and high sensitivity. Among them, reaction‐based fluorescent probes, for their unique reaction‐based nature, guarantee them with excellent selectivity, effectively avoiding the possible interference from other chemical and biological species in physiological environment. Conventional reaction‐based fluorescent probes are aggregation‐caused quenching (ACQ) fluorophores. The application of these kinds of probes are limited for their poor photostability and narrow Stokes shifts. Compared with ACQ fluorophores, aggregation‐induced emission (AIE) fluorophores become emissive in aggregation states with higher signal‐to‐noise ratio, better photostability and larger Stokes shifts. In this review, we summarize the latest developed reaction‐based AIE‐active probes, including the design principle and application in various sensing systems and give an outlook for the future development of this kind of promising fluorescent probes.

A fluorescent probe based on tetrahydro[5]helicene for highly selective recognition of hydrogen sulfide

Endogenous hydrogen sulfide plays an important role in various physiological and pathological processes and the convenient and selective recognition of hydrogen sulfide has become a research hotspot. We designed and synthesized a tetrahydro[5]helicene and 2,4-dinitrobenzene conjugate (HD-DNP) as an effective fluorescent probe for selective detection of H2S. The selective deprotection of 2,4-dinitrophenyl ether group of HD-DNP by H2S led to a dramatic fluorescent enhancement (101-fold) at 500 nm and colorimetric change in DMSO–PBS solution. HD-DNP displays many advantages including low background without any self-fluorescence, as well as high selectivity towards common bio-thiols such as Cysteine, Homocysteine and Glutathione. The detection limit of this probe for H2S was found to be about 2.4 μM with a wide linear range (10–70 μM). The response mechanism of the probe with HS− is confirmed to be thiolysis of the dinitrophenyl ether induced by HS− through 1H NMR comparison investigations.

Dendrimeric rhodamine based fluorescent probe for selective detection of Au

Dendrimeric rhodamine-derived chemosensor for highly selective determination of Au in aqueous acidic solutions has been developed. The response mechanism is based on the destruction of the dendrimeric molecule to provide fluorescence enhancement via reducing intramolecular quenching. The probe exhibits linear signal response and allows determination of Au content in aqueous solutions from 5 × 10−8 M.

A proximity-induced covalent fluorescent probe for selective detection of bromodomain 4

Lysine acetylation is one of the most prevalent and important posttranslational modifications (PTMs) in proteins. The process can be recognized by bromodomains (BRDs), which are a class of protein-interaction modules involved in chromatin remodeling and transcriptional activation. The development of BRD fluorescent probes will be useful for monitoring the activity of BRDs in living cells as well as aiding inhibitor development. Herein we designed a peptide-based probe based on the proximity-induced protein conjugation reaction. The peptide-based probe is capable of covalently and selectively reacting with the unique cysteine residue in the bromodomain through proximity effect. Our experimental data showed that the probe displayed noticeable fluorescence response upon addition of BRD4(1). In-gel fluorescence scanning demonstrated that BRD4(1) can be covalently labelled by the probe. Moreover, the probe was shown to selectively detect BRD4(1) over other proteins. We envision that the probe developed in this study will provide a useful tool to further investigate the biological roles of BRDs.

Singlet oxygen probes made simple: Anthracenylmethyl substituted fluorophores as reaction-based probes for detection and imaging of cellular 1O2

Singlet oxygen plays an important role in cancer chemotherapy and biology of reactive oxygen species. In recent years, there are some reports of selective fluorescent probes for detection and imaging of singlet oxygen but the existing probes have some major drawbacks including complicated synthetic routes, poor fluorescence enhancement effects. We report herein that anthracenylmethyl modified non-fluorescent derivatives of fluorescein and rhodamine-6G can reacts with 1O2, which resulted in CC bond cleavage that detach anthracene unit from the fluorophores resulting in strong fluorescence enhancement. These probes exhibit high selectivity and sensitivity in detection and imaging of 1O2 in chemical and in living cells. Our approach makes it simple and flexible for development of reaction-based 1O2 fluorescent probes for broad application in chemical, biomedical, and environmental sciences.

A ratiometric two-photon fluorescent probe for selective detection of endogenous formaldehyde via Aza-Cope reaction

A ratiometric two-photon fluorescent probe, MQAP, based on 6-substituted quinoline skeleton, has been developed for the detection of formaldehyde (FA) in aqueous solution, living cells, and living zebrafish. After treatment with FA, the fluorescence emission wavelength of MQAP red-shifts significantly from 405 nm to 490 nm, and the emission intensity ratio (I490nm/I405nm) dramatically increases from 0.34 to 7.52 (about 22 times). The response mechanism was proposed to be FA-induced 2-aza-Cope rearrangement on MQAP, as confirmed by LC–MS, theoretical calculation, UV-vis and fluorescence spectra. MQAP is almost insensitive to the change of pH value within the biologically relevant pH range, with a large two-photon absorption cross-section at 720 nm (185 GM). Additionally, MQAP has increased tissue penetration depth up to 150 μm, and low cytotoxicity to living cells. To demonstrate its biological applicability, MQAP was successfully used to detect endogenous FA in living cells and living 5-day-old zebrafish.

A FRET based colorimetric and fluorescence probe for selective detection of Bi3+ ion and live cell imaging

A Rhodamine B- quinoline conjugate (RSQ) functions as a colorimetric and fluorescence probe for selective recognition of Bi3+ ion based on CHEF assisted FRET process. RSQ visibly changes its colour and fluorescence profile upon addition of Bi3+ ion. The distinctive colour change allows facile discrimination of Bi3+ over other common cations. Lowest concentration of Bi3+ detected by RSQ is 0.05 μM. RSQ efficiently images intracellular Bi3+ in live SiHa cells.

A Novel Dicyanoisophorone-Based Ratiometric Fluorescent Probe for Selective Detection of Cysteine and Its Bioimaging Application in Living Cells.

A selective and ratiometric turn-on fluorescent probe was designed and synthesized by using a novel dicyanoisophorone-based derivative and acrylate moiety. The probe displayed high stability and good selectivity to cysteine (Cys) over homocysteine (Hcy) and glutathione (GSH). It also exhibited rapid response to Cys within 180 s. Most importantly, the fluorescence intensity ratio at 590 and 525 nm (I590/I525) was linearly dependent on the Cys concentration in the range from 0 to 40 μM and the detection limit calculated to be 0.48 μM. This probe was also applied for bioimaging of intracellular Cys in living HeLa cells with low cytotoxicity.

Dicationic imidazolium salts as fluorescent probes for selective detection of Fe3+ ion in pure aqueous media

A series of N, N’-disubstituted imidazolium salts: 3-(4-cyanobenzyl)-1-((1-(4-cyanobenzyl)pyridin-1-ium-3-yl)methyl)-2-methyl-1H-imidazolium bromide (1a), 3-(naphthalene-2-ylmethyl)-1-((-1-(naphthalene-2-ylmethyl)pyridin-1-ium-3-yl)methyl)-2-methyl-1H-imidazolium bromide (1b), 3-(4-cyanobenzyl)-1-((1-(4-cyanobenzyl)pyridin-1-ium-3-yl)methyl)-2-methyl-1H-imidazolium hexafluorophosphate (1c) and 3-(naphthalene-2-ylmethyl)-1-((-1-(naphthalene-2-ylmethyl)pyridin-1-ium-3-yl)methyl)-2-methyl-1H-imidazolium hexafluorophosphate (1d) were synthesized in good to excellent yields. The physical and chemical properties of highly water soluble bromide salts (1a and 1b) were modulated by counter anion exchange with PF6 anion (1c and 1d). These probes detect Fe (III) ion over other metal ions such as Na+, K+, Ba2+, Mn2+, Mg2+, Fe3+, Fe2+, Ca2+, Cu2+, Cr3+, Co2+, Al3+, Pb2+ and Zn2+ in aqueous media by fluorescence “turn-off” mechanism. Fluorescence quenching was also observed in the case of Fe2+, Cr3+ and Cu2+ ions to some extent. The emission intensity of probe 1a was quenched by 92% on the subsequent addition of aliquots of Fe3+ ion in pure aqueous media. Job’s plot studies of 1a-Fe3+ complex confirmed the 1:1 stoichiometry. The Stern-Volmer (S-V) plot indicates the static type of quenching mechanism at even low concentrations. The detection limit for 1a was found to be 2.81 × 10−5 M.

Fluorescent Zn-PDC/Tb3+ Coordination Polymer Nanostructure: A Candidate for Highly Selective Detections of Cefixime Antibiotic and Acetone in Aqueous System.

Tb3+-doped zinc-based coordination polymer nanospindle bundles (Zn-PDC/Tb3+, or [Zn(2,5-PDC)(H2O)2]·H2O/Tb3+) were synthesized by a simple solution precipitation route at room temperature, employing Zn(NO3)2, Tb(NO3)3, and 2,5-Na2PDC as the initial reactants, and a mixture of water and ethanol with the volume ratio of 10:10 as the solvent. The as-obtained nanostructures presented strong fluorescent emission under the excitation of 298 nm light, which was attributed to the characteristic emission of the Tb3+ ion. It was found that the above-mentioned strong fluorescence of the nanostructures could be selectively quenched by cefixime (CFX) in aqueous solution. The other common antibiotics hardly interfered. Thus, as-obtained Zn-PDC/Tb3+ nanostructures could be prepared as a highly sensitive fluorescence probe for selective detection of CFX in an aqueous system. The corresponding detection limit reached 72 ppb. The theoretic calculation and UV-vis absorption experiments confirmed that the fluorescence quenching of Zn-PDC/Tb3+ nanostructures toward CFX should be attributed to the electron transfer and the fluorescence inner filter effect between the fluorescent matter and the analyte. In addition, the strong fluorescence of the nanostructures could also be selectively quenched by acetone in the water system.

A mitochondria-targeted fluorescent probe for selective detection of mitochondrial labile Fe(ii).

Mitochondria are iron-rich organelles that are involved in the process of energy production through the electron-transporting system and heme synthesis. We developed a new mitochondria-targeted fluorescent probe, MtFluNox/Ac-MtFluNox, for Fe(ii) based on N-oxide chemistry, which we recently established as a Fe(ii)-selective fluorogenic switch. The deacetylated form MtFluNox showed a turn-on response towards Fe(ii) with high metal selectivity in cuvette experiments, and an imaging study using its cell-compatible analogue Ac-MtFluNox demonstrated mitochondria-specific fluorescence enhancement in response to Fe(ii) in living cells. Furthermore, the probe was able to detect endogenously accumulated Fe(ii) induced as a result of the inhibition of heme synthesis.

Synthesis of a BODIPY disulfonate near-infrared fluorescence-enhanced probe with high selectivity to endogenous glutathione and two-photon fluorescent turn-on through thiol-induced SNAr substitution.

A BODIPY disulfonate BODIPY-diONs with two-photon fluorescent turn-on effect was developed as fluorescence probe for selective detection of glutathione over cysteine and homocysteine. BODIPY-diONs is weakly fluorescent due to the 2,4-dinitrobenzenesulfonyl quencher group. When GSH was added, a SNAr substitution reaction was triggered. The red emission of the BODIPY fluorophore at 675 nm was switched on, with a 27-fold emission enhancement in fluorescence intensity. The color of the solution changed from blue to green together with fluorescence appeared within 5 s. The absorbance and emission maxima of the probe BODIPY-diONs were achieved at 650 nm and 675 nm, respectively (quantum yield: 0.11). Interestingly, under the sapphire pulsed laser's 800 nm irradiation, in presence of GSH, the two-photon excited fluorescence (TPEF) of probe BODIPY-diONs was turned on, affording an OFF-ON response signal and a strong emission band at 682 nm. Furthermore, for detection of GSH, the chemodosimeter BODIPY-diONs exhibits high sensitivity and excellent anti-interference with low detection limit of 0.17 μM, and it works effectively within a wide pH range. Furthermore, the imaging studies proved that the probe BODIPY-diONs is suitable for the detection of GSH in complete physiological media.

A highly sensitive fluorescent probe for selective detection of cysteine/homocysteine from glutathione and its application in living cells and tissues

A fluorescent probe NIPY-NBD was designed for detecting Cys/Hcy against GSH and applied in cell/tumor tissue imaging.

A novel long-wavelength fluorescent probe for selective detection of hydrogen sulfide in living cells

Sensitive detection of endogenous H2S by a low cytotoxicity probe.

A novel fluorescent probe for selective detection of hydrogen sulfide in living cells

A low cytotoxicity probe for the sensitive detection of endogenous H2S.

All-inorganic CsPbBr3 perovskite quantum dots as a photoluminescent probe for ultrasensitive Cu2+ detection

Pollutions caused by heavy metals has become a wordwide concerned issue. Herein, CsPbBr3 perovskite quantum dots are used as fluorescent probe for selective detection of copper ions in organic phase with a limit of detection (LOD) down to 0.1 nM.

A highly selective fluorescent probe for detection of Cd2+ and HSO3 - based on photochromic diarylethene with a triazole-bridged coumarin-quinoline group.

A novel photochromic diarylethene containing a quinoline-linked 3-aminocoumarin Schiff base unit (1O) was synthesized and used for the selective detection of Cd2+ and HSO3−. The synthesized probe exhibited a straightforward response for the selective detection of Cd2+. Its fluorescence emission red-shifted ∼126 nm and was enhanced 24.9 fold in the presence of Cd2+. Meanwhile, the fluorescence color of 1O changed from dark cyan to golden yellow. The binding stoichiometry between 1O and Cd2+ was determined to be 1 : 1. A molecular logic circuit with three inputs and one output was successfully constructed with its light and metal-responsive behaviors. In addition, 1O was able to selectively recognize HSO3− with a 135-fold enhanced fluorescence emission and a notable fluorescence color change from dark cyan to bright cyan. The 1H NMR and mass spectrometry analyses suggest that the HSO3− sensing of 1O is based on the hydrolysis of the Schiff base group of 1O.

A novel BODIPY-based fluorescent probe for selective detection of hydrogen sulfide in living cells and tissues

Hydrogen sulfide (H2S) is a critical biological messenger in numerous physiological and pathophysiological processes. Small-molecule fluorescent probes combined with fluorescent microscopy have been developed for the sensitive detection of H2S. Here, we designed and synthesized a long-wavelength BODIPY-based probe (TMSDNPOB) based on the thiolysis of dinitrophenyl ether according to photo-induced electron transfer theory and the results of computational calculation. 4,4-Difluoro-8-phenyl-1,5,7-trimethyl-3-(4-(2,4-dinitrophenoxy)styryl- 4-bora-3a,4a-diaza-s-indacene (TMSDNPOB) is nearly non-fluorescent, but the reaction product (TMSHOB) emits strong red fluorescence at 592nm when excited at 574nm. The long wavelengths of the designed probe indicate low background interference from biological matrix and little photo damage on fluorescence imaging of H2S. With the advantages of the turn-on probe for H2S including high sensitivity, high selectivity, good biocompatibility and low toxicity, the probe has been used for imaging H2S in living cells and liver tissues.

Two sugar-rhodamine “turn-on” fluorescent probes for the selective detection of Fe3 +

Two new sugar-rhodamine fluorescent probes (RDG1 and RDG2) have been synthesized and characterized by 1H NMR, 13C NMR and HRMS. Their UV–Vis, fluorescence spectra and fluorescence-response to Fe3+ are investigated and discussed. RDG1 had a very nice linear relationship between UV absorbance and Fe3+ concentration with the correlation coefficient as high as 0.997 and the detection limit is 3.46×10−6M. Upon the addition of Fe3+, the spirolactam ring of RDG1 was opened and a 1:1 metal ligand complex was formed from Job's plot. The results showed that RDG1 can be used as an effective fluorescent probe for selective detection of Fe3+ in water. RDG2 was incorporated the well-known rhodamine group and a water-soluble d-glucose group within one molecule and can be used for detecting Fe3+ in natural water as a selective fluorescent sensor. The addition of Fe3+ into RDG2 resulted in a strongly enhanced fluorescence as well as color change of solution from colorless to pink. Job's plot of RDG2 indicated 1:1 stoichiometry of RDG2-Fe3+. RDG2 can serve as a probe for Fe3+ between pH=4.0 to 7.0 and it's detection limit is 2.09×10−6M. The OFF-ON fluorescent mechanisms of RDG1-Fe3+ and RDG2-Fe3+ are proposed.

Solvent control bifunctional fluorescence probe for selective detection of Cu2+ and Hg2+ via the excimer of pyrenylacetamide subunits

A new highly sensitive fluorescence sensor having two pyrenylacetamide moieties covalently bound to 2-[4-(2-aminoethylsulfanyl)butylsulfanyl]ethanamine was prepared via the ready synthetic approach using a conventional three-step synthesis. Its excimer and its sensing behavior towards metal ions were investigated by fluorescence spectroscopy. The results showed that the sensor exhibited bifunctional behaviors by sensitive sensing toward Cu2+ in ethanol and offered sensitive sensing toward Cu2+ and Hg2+ in aqueous methanol solutions. These high selectivities of the sensor were confirmed by an efficient quenching of the excimer bands of pyrenylacetamide at 480nm, whereas other ions including Ag+, Ca2+, Cd2+, K+, Mn2+, Na+, Pb2+ Zn2+, Ba2+, Fe2+, Li+, Mg2+ and Co2+ ions induced small or negligible spectral change. The detection limits of the sensor were approximately 0.6 and 0.8 ppb for Hg2+ and Cu2+, respectively, which were much lower than drinking water permission concentrations by the United States Environmental Protection Agency (U.S. EPA) and World Health Organization (WHO).