Bifunctional Fluorescent Probe Research Articles

A bifunctional fluorescent probe for sensing of Al3+ and H2S.

Al3+ and H2S play essential roles in various physiological processes. However, excess Al3+ and H2S are harmful to health. Therefore, it is necessary to design a sensitive method for the detection of Al3+ and H2S. In this work, compound L was developed based on salicylaldoxime and 4-aminobenzamide. L displayed aggregation-induced emission (AIE) characteristics in the solid state due to a unique dimer formation via intermolecular hydrogen bonds. In addition, L could serve as a multi-responsive fluorescence probe for Al3+ based on the coordination reaction in a MeOH/H2O (9/1, v/v, pH = 7.4) medium and for H2S based on the addition reaction in EtOH/H2O (7/3, v/v, pH = 7.4) solution. In addition, L showed a fluorescence colorimetric response to Al3+ in the solid state. Furthermore, L was applied to detect Al3+ and H2S in actual water samples.

A bi-functional fluorescent probe for visualized and rapid natural drug screening via GSTs activity monitoring

Glutathione S-transferase (GSTs), as an important target for drug screening, is closely associated with physiological and pathological process regulation. Hence, effective monitoring of GSTs activity is benificial for GSTs-induced diseases diagnosis and therapeutic drugs discovery. Resorufin-typed probes with high sensitivity, excellent selectivity, and low cytotoxicity have become a powerful tool for target monitoring. In this study, a bi-functional fluorescent probe, resorufin-typed probe (RP) with resorufin as a fluorophore was designed as the GSTs substrate and drug screening tool. GSTs can trigger significant fluorescence signal enhancement of RP by catalyzing the combination of glutathione (GSH) and its recognition site in RP. Meaningfully, the change of fluorescence signal positively correlated with GSTs activity can be used to monitor the regulatory effect of natural drugs on GSTs. Based on the axis relation of “drug-GSTs activity-fluorescence signal”, this powerful probe was successfully employed for visual and rapid screening GSTs-targeted natural compounds in vitro by monitoring the change of GSTs activity. Natural compound 1, 2 and 7 (C1, C2 and C7) were screened as the GSTs inhibitors, and C7 was helpful for enhancing the sensitivity of cisplatin in cancer cells. Overall, the designed natural drug screening strategy based on bi-functional fluorescence probe demonstrated its hopeful application to drug rapid discovery.

Rational design of a bifunctional fluorescent probe for distinguishing Hcy/Cys from GSH with ideal properties

By pairing two fluorophores according to their optical properties such as absorption spectral overlap and absorptivity, fluorescent quantum yield and emission spectral separation, a bifunctional fluorescent probe, TQBF-NBD, was rationally designed and synthesized to discriminatively sense Hcy/Cys and GSH with good selectivity and sensitivity. It is noted that this probe could work under a single-wavelength excitation and displayed a mega-large Stokes shift. TQBF-NBD reacted with Hcy/Cys to give a mixed green-red fluorescence and displayed a red fluorescence upon the treatment with GSH. Distinguishable imaging of intracellular Hcy/Cys from GSH with the help of TQBF-NBD was realized in living cells and zebrafish.

New carbazole fluorescent sensor for ultrasensitive and ratiometric sensing of SO2 derivatives and hydrazine

The probe CBTA is a novel bifunctional fluorescent probe that can detect bisulfite and hydrazine hydrate in a rational manner. And probe CBTA could specifically detect bisulfite and hydrazine hydrate among different analytes. Moreover, the response time of probe CBTA to SO2 derivatives and hydrazine is extremely short, and the detection limits for bisulfite and hydrazine are as low as 5.6 nmol and 39 nmol. Cellular experiments also indicated that the probe CBTA was low in cytotoxicity and could be applied to cellular fluorescence imaging. Therefore, the probe CBTA could provide an efficient means for detecting SO2 derivatives and hydrazine in vitro.

Small-molecule Bifunctional Fluorescent Probes for the Differential Detection of Multiple Guests.

During the last few years, the preparation of bifunctional fluorescent probes, which exhibit differential response towards multiple analytes, has attracted considerable attention since they are cost-effective and highly desirable for real-time applications. This review focuses on the recent advances in the design principles, recognition mechanisms, and applications of multifunctional fluorescent probes for the differential detection of multiple guests.

A HBT-based bifunctional fluorescent probe for the ratiometric detection of fluoride and sulphite in real samples.

Based on a core of 2-(benzo[d]thiazol-2-yl)phenol (HBT), a bifunctional ratiometric fluorescent probe, HBT-FS, was constructed for the discriminative detection of fluoride (F-) and sulphite (SO32-) with high sensitivity and selectivity. HBT-FS itself displayed a green fluorescence with λEmmax = 498 nm. The treatment of HBT-FS with F- resulted in a red fluorescence (λEmmax = 634 nm) with a large Stokes shift and a 291-fold enhancement in the ratio of the fluorescence intensity (I634 nm/I498 nm). Upon the addition of SO32-, HBT-FS exhibited a blue fluorescence (λEmmax = 371 nm) and the ratiometric fluorescence enhancement was remarkable (9445 folds for I371 nm/I498 nm). HBT-FS was successfully used to qualitatively and quantitatively determine F- and SO32- in a ratiometric manner in real samples.

A mitochondrial-targeted fluorescent probe to sense pH and HOCl in living cells

A series of rosamine dyes were designed and synthesized through one-step reaction. Among them, bifunctional fluorescent probe RosPO(OH)2 showed excellent water solubility and large molar extinction coefficient. RosPO(OH)2 underwent a two-step ionization process as the pH value of the HEPES buffer increased, accompanied a blue shift of UV absorption and an enhancement of fluorescence intensity. This means it can be used as a pH sensor. After the addition of HOCl, the fluorescence of RosPO(OH)2 was quenched and the color of the solution changed from pink to colorless which permitted "naked eye" detection. RosPO(OH)2 could be used as a sensor for detecting HOCl with high selectivity, rapid response, low detection limit (52 nM) and a wide range of pH application (pH 1–10). Colocalization results showed that RosPO(OH)2 could specifically stain in mitochondria. Due to the low toxicity and the excellent water solubility of RosPO(OH)2, it had been successfully applied to image pH and HOCl in living cells.

Circular orientation fluorescence emitter imaging (COFEI) of rotational motion of motor proteins

Single-molecule fluorescence polarization technique has been utilized to detect structural changes in biomolecules and intermolecular interactions. Here we developed a single-molecule fluorescence polarization measurement system, named circular orientation fluorescence emitter imaging (COFEI), in which a ring pattern of an acquired fluorescent image (COFEI image) represents an orientation of a polarization and a polarization factor. Rotation and pattern change of the COFEI image allow us to find changes in the polarization by eye and further values of the parameters of a polarization are determined by simple image analysis with high accuracy. We validated its potential applications of COFEI by three assays: 1) Detection of stepwise rotation of F1-ATPase via single quantum nanorod attached to the rotary shaft γ; 2) Visualization of binding of fluorescent ATP analog to the catalytic subunit in F1-ATPase; and 3) Association and dissociation of one head of dimeric kinesin-1 on the microtubule during its processive movement through single bifunctional fluorescent probes attached to the head. These results indicate that the COFEI provides us the advantages of the user-friendly measurement system and persuasive data presentations.

A novel bifunctional fluorescent and colorimetric probe for detection of mercury and fluoride ions

A fluorescent and colorimetric probe L1 based on a simple coumarin derivative for detection of Hg2+ and F- ions was developed. Upon addition of Hg2+ and F- ions, L1 underwent desulfurization and desilylation, respectively, to induce marked increase in the fluorescence intensity and sharp color change from light yellow to dark purple and light brown, respectively. Probe L1 could be used for sensing and for quantitative measurement of Hg2+ and F- ions by both UV-vis and fluorescence spectra. The bifunctional probe exhibited a high selectivity over other competitive cations and anions and could be used in both organic and aqueous media over a wide pH range.

Correction to 'Bifunctional fluorescent probes for detection of amyloid aggregates and reactive oxygen species'.

[This corrects the article DOI: 10.1098/rsos.171399.].

Bifunctional Fluorescent Probe for Sequential Sensing of Thiols and Primary Aliphatic Amines in Distinct Fluorescence Channels.

Thiols and primary aliphatic amines (PAA) are ubiquitous and extremely important species in biological systems. They perform significant interplaying roles in complex biological events. A single fluorescent probe differentiating both thiols and PAA can contribute to understanding the intrinsic inter-relationship of thiols and PAA in biological processes. Herein, we rationally constructed the first fluorescent probe that can respond to thiols and PAA in different fluorescence channels. The probe exhibited a high selectivity and sensitivity to thiols and PAA. In addition, it displayed sequential sensing ability when the thiols and PAA coexisted. The application experiments indicated that the probe can be used for sensing thiols and PAA in human blood serum. Moreover, the fluorescence imaging of endogenous thiols and PAA as well as antihypertensive drugs captopril and amlodipine in living cells were successfully conducted.

Bifunctional fluorescent probes for detection of amyloid aggregates and reactive oxygen species.

Protein aggregation into amyloid deposits and oxidative stress are key features of many neurodegenerative disorders including Parkinson's and Alzheimer's disease. We report here the creation of four highly sensitive bifunctional fluorescent probes, capable of H2O2 and/or amyloid aggregate detection. These bifunctional sensors use a benzothiazole core for amyloid localization and boronic ester oxidation to specifically detect H2O2. We characterized the optical properties of these probes using both bulk fluorescence measurements and single-aggregate fluorescence imaging, and quantify changes in their fluorescence properties upon addition of amyloid aggregates of α-synuclein and pathophysiological H2O2 concentrations. Our results indicate these new probes will be useful to detect and monitor neurodegenerative disease.

A unique bifunctional probe for detecting silicate anions and cupric cations: the modified silica nanoparticles and their coordination

A bifunctional fluorescence probe L for detecting silicate anions and cupric cations was prepared.

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).

A Rhodium-Cyanine Fluorescent Probe: Detection and Signaling of Mismatches in DNA.

We report a bifunctional fluorescent probe that combines a rhodium metalloinsertor with a cyanine dye as the fluorescent reporter. The conjugate shows weak luminescence when free in solution or with well matched DNA but exhibits a significant luminescence increase in the presence of a 27-mer DNA duplex containing a central CC mismatch. DNA photocleavage experiments demonstrate that, upon photoactivation, the conjugate cleaves the DNA backbone specifically near the mismatch site on a 27-mer fragment, consistent with mismatch targeting. Fluorescence titrations with the 27-mer duplex containing the CC mismatch reveal a DNA binding affinity of 3.1 × 106 M-1, similar to that of other rhodium metalloinsertors. Fluorescence titrations using genomic DNA extracted from various cell lines demonstrate a clear discrimination in fluorescence between those cell lines that are proficient or deficient in mismatch repair. This differential luminescence reflects the sensitive detection of the mismatchrepair-deficient phenotype.

Recent Progresses on Mitochondria-Targetable Fluorescent Probes

Over the past few years, many bifunctional fluorescent probes based on small organic molecules, which can be located on the mitochondria to detect specific reactive small molecules (RSMs), including reactive oxygen species, reducing species, metal ions, proton and small anions, have been reported to be successful in achieving visual imaging in mitochondria. For further detection and imaging of the reactive small molecules in tissue, the design and synthesis of two-photon fluorescent probes and near-infrared fluorescent probes bearing good optical properties become increasingly popular. The recently reported mitochondrial fluorescent probes are classified, summarized and reviewed. The bright prospects of these probes in the application of preliminary diagnosis and therapy of some diseases are also discussed.

A bifunctional colorimetric fluorescent probe for Hg(2+) and Cu(2+) based on a carbazole-pyrimidine conjugate: chromogenic and fluorogenic recognition on TLC, silica-gel and filter paper.

A bifunctional fluorescent probe based on a carbazole-pyrimidine conjugate for Hg(2+) and Cu(2+) detection was designed and synthesized. Probe 3 exhibits red shifts in its absorption and fluorescence spectra with significant visual color changes in the presence of these ions. The detection limits of probe 3 for these metal ions were in the nanomolar range. The probe could also be useful as a solid optical sensor for Hg(2+) and Cu(2+).

A highly selective ratiometric bifunctional fluorescence probe for Hg(2+) and F(-) ions.

A triarylborane derivative BN-S, which contains a Hg(2+)-responsive dithioacetal group and a F(-)-responsive boryl group, has been designed and synthesized via the functionalization of 2-dimesitylboryl-2'-(N,N-dimethylamino)biphenyl core skeleton with a dithioacetal substituent. This compound displays intense intramolecular charge transfer fluorescence, even for its nano-aggregates in water. The Hg(2+)-promoted deprotection of the dithioacetal group and complexation of F(-) with the tri-coordinate boron center cause hypochromism of fluorescence to different extents. And thus BN-S behaves as a promising ratiometric bifunctional fluorescence probe to detect Hg(2+) and F(-) simultaneously. In addition, the detection of Hg(2+) is performable in aqueous medium using its nano-aggregates.

A naphthalimide-based bifunctional fluorescent probe for the differential detection of Hg²⁺ and Cu²⁺ in aqueous solution.

A novel fluorescent probe NPM based on naphthalimide was designed and synthesized. Interestingly, NPM exhibited highly selective fluorescence turn-on for Hg(2+) and turn-off for Cu(2+) in aqueous solution (10 mM HEPES, pH 7.5). Its fluorescence intensity enhanced in a linear fashion with the concentration of Hg(2+) and decreased in a nearly linear fashion with the concentration of Cu(2+). Thus NPM could be potentially used for the quantification of Hg(2+) and Cu(2+) in aqueous solution. A series of model compounds were rationally designed and synthesized in order to explore the sensing mechanisms and binding modes of NPM with Hg(2+) and Cu(2+).

Vitamin B6cofactor based fluorescent probe for sensing an anion (F−) and cation (Co2+) independently in a pure aqueous medium

A new highly selective and sensitive bifunctional fluorescent probe for Co2+and F−ions has been derived from a vitamin B6cofactor and the response mechanism has been analyzed using DFT calculations.