Synthesis of a new fluorescent small molecule probe and its use for in vivo lipid imaging

A new small molecule probe for in vivo lipid imaging, LipidGreen (compound 5), was developed. LipidGreen stained lipid droplets in 3T3L1 cell lines and fat deposits in zebrafish without apparent toxicity up to 100 μM. The utility of LipidGreen as a drug screening platform for fat regulation was also demonstrated in live zebrafish.     

Single molecule spectroscopy as a probe for dye-polymer interactions

Experimental (Single Molecule Spectroscopy) and theoretical (quantum-chemical calculations and Monte Carlo and molecular dynamics simulations) techniques are combined to investigate the behavior and dynamics of a polymer-dye molecule system. It is shown that the dye molecule of interest (1,1'-dioctadecyl-3,3,3',3'-tetramethylindo-dicarbocyanine) adopts two classes of conformations, namely planar and nonplanar ones, when embedded in a poly(styrene) matrix. From an in-depth analysis of the fluorescence lifetime trajectories, the planar conformers can be further classified according to the way their alkyl side chains interact with the surrounding poly(styrene) chains.     

Pyrene as a fluorescent probe for DNA base radicals

The steady-state emission spectra of 5-(1-pyrenyl)-modified pyrimidine and 8-(1-pyrenyl)-modified purine nucleosides in water at different pH values provide important information about the acidity or basicity of photochemically generated DNA base radicals which are key intermediates in DNA-mediated charge transport processes.     

HKGreen-3: a rhodol-based fluorescent probe for peroxynitrite

A novel fluorescent probe, HKGreen-3, for sensing peroxynitrite is designed on the basis of the rhodol scaffold and a peroxynitrite-specific oxidation reaction. The probe turns out to be highly sensitive and selective for detecting peroxynitrite in both chemical and biological systems.     

Synthesis of a new fluorescent probe specific for catechols

[reaction: see text] The synthesis of a new fluorescent probe, specific for the catechol moiety, has been conducted by preparation of alpha,alpha-dibromomalonamides containing an appropriate fluorophore. N,N'-Bis-anthracen-9-ylmethyl-2,2-dibromomalonamide reacted with various catechols in the presence of cesium carbonate to generate highly fluorescent derivatives.     

Anaphthalimide-based fluorescent probe for mercaptocontaining compounds

A polarity-sensitive fluorescent probe MNP was rationally designed and synthesized with naphthalimide as the fluorophore and maleimide as the receptor for thiols. MNP is weakly fluorescent due to the photoinduced electron-transfer(PET) from the fluorophore to the receptor, and it displays evidently solvatochromic UV–vis and fluorescence spectra: the emission shifted from 495 nm in n-hexane to545 nm in phosphate buffer solution. Michael addition reaction between thiols and the maleimide in MNP inhibited the PET process, which led to about eight-fold fluorescence enhancement. In addition,MNP showed highly sensitivity to mercapto-containing proteins and it could detect as low as 20.4 mg/m L of BSA in PBS. MNP has potential in fluorescent imaging of thiols in living cells.     

Copper nanocluster-based fluorescent probe for hypochlorite

Copper nanoclusters (Cu-NCs) were fabricated by chemical reduction of Cu(II) ions using formaldehyde as the reductant and poly(vinyl pyrrolidone) as the protecting agent. The resulting Cu-NCs were characterized by TEM, FT-IR, UV–vis and XPS and fluorescence spectroscopy. The Cu-NCs display a luminescence quantum yield of about 13 %, and the emission peaks shift from 398 to 457 nm on increasing the excitation wavelength from 310 to 390 nm. The Cu-NCs possess a storage stability of at least 2 months and are stable in the presence of high concentrations of salt. Their fluorescence is strongly quenched by hypochlorite, while other common cations, anions and hydrogen peroxide have minor (or no) effects on fluorescence. On this basis, a fluorometric hypochlorite assay was developed that has a 0.1 μM detection limit and a linear range that extends from 1 to 30 μM. The method was successfully used to the determination of hypochlorite in local tap water samples, and the results agreed well with those obtained by a colorimetric method.

Hypochlorite ion is found to quench the fluorescence copper nanoclusters synthesized by reduction of Cu(II) ion by formaldehyde in the presence of poly(vinyl pyrrolidone) serving as protecting agent. This finding resulted in a new fluorescence assay for hypochlorite.

     

Strongly fluorescent cysteamine-coated copper nanoclusters as a fluorescent probe for determination of picric acid

Microchimica Acta - A fluorometric assay is described for doxycycline detection. It is based on the use of nitrogen-doped carbon quantum dots (NCQDs) coated with molecularly imprinted polymers...     

罗丹明类测定三聚氰胺的荧光探针的合成及应用研究

报道了罗丹明乙二醛酰腙的合成及与三聚氰胺的反应。在pH 3.0的缓冲溶液中三聚氰胺对罗丹明乙二醛酰腙的荧光强度有增强作用,其增强程度与三聚氰胺的浓度成正比,据此建立了一种新的测定三聚氰胺含量的荧光分析法。该方法线性范围为0.5~10.0 mg/L,r=0.994,检出限为0.15 mg/L,样品测定的RSD为1.7%(n=7)。     

Development of a light-up fluorescent probe for HRAS G-quadruplex DNA

The development of small-molecule G-quadruplex DNA probes has attracted significant attention in recent years. However, G-quadruplexes can display a wide variety of topologies, which process different structures and functions. Therefore, selective discrimination one G-quadruplex structure over another is promising. Herein, we reported the design, synthesis and biological evaluation of a long-chain fatty amine functionalized triphenylamine-quinolinium conjugate 1b. Significant enhancement of the fluorescence intensity (over 180 fold) was observed when 1b bound with HRAS G-quadruplex DNA, while much weaker enhancements were presented in the presence of other G-quadruplexes (45–90-fold) and single/double-stranded DNAs (less than 20-fold), indicating 1b had an excellent selectivity to HRAS. The details of the interactions were investigated by UV–Vis, FID and CD analysis. The results show 1b could interact and stabilize HRAS structure mainly by π-π stacking binding mode. The introduced amine chain of the structure core was found to be better in the terms of inducing selectivity toward G-quadruplex structure. In addition, the application of 1b as a fluorescent agent for living cell imaging was also demonstrated.     

Review: fluorescent cyclodextrins for molecule sensing

Cyclodextrins (CDs), which are spectroscopically inert, were converted into fluorescent CDs by modification with one or two fluorophores. Many fluorescent CDs changed the fluorescent intensities upon addition of guest compounds, causing the locational change of the fluorophore mostly from inside to outside of the CD cavities. On this basis, the fluorescent CDs were used as fluorescent chemosensors for molecule recognition. Modified CDs bearing two naphthalene or pyrene moieties exhibit intramolecular excimer emission and their guest-responsive excimer intensity variations were used for molecule sensing. Fluorescent CDs bearing a dansyl moiety decreased the fluorescence intensity upon guest addition, reflecting the environmental change around the fluorophore from the hydrophobic interior of the CD cavities to bulk water solution. Modified CDs bearing a p-N,N-dimethylaminobenzoyl (DMAB) moiety exhibit dual emissions from nonpolar planar (NP) and twisted intramolecular charge transfer (TICT) excited states, and the TICT emission intensity was useful for sensing molecules. A biotin-bound DMAB system was also constructed, and the presence of the protein (avidin) was found to enhance the NP fluorescence. This avidin-bound DMAB system showed higher sensitivities and stronger binding ability for guest species than the system without avidin.     

A benzothiazole-based fluorescent probe for thiol bioimaging

This study reports a benzothiazole-based fluorescent probe with simple structure for thiols. This probe exhibited high on/off signal ratios and good selectivity toward thiols over other analytes, and was successfully applied to the imaging of thiols in living cells.     

A novel fluorescent probe for NAD-consuming enzymes

A novel, fluorescent NAD derivative is processed as substrate by three different NAD-consuming enzymes. The new probe has been used to monitor enzymatic activity in a continuous format by changes in fluorescence and, in one case, to directly visualize alternative reaction pathways.     

A cell-permeable green fluorescent probe for dsDNA

The sensitive and selective detection of nucleic acids is important for basic research and many applied fields. Herein, a novel green DEAB-TO-1 was designed and synthesized. DEAB-TO-1 shows significant fluorescence enhancement (800-fold) when bound to ctDNA and a distinct selectivity for dsDNA over RNA (5.9 times). Moreover, the limit of detection is 0.57 ng/mL. It is live-cell-permeant DNA intecalator, indicating a promising candidate for nucleus-specific imaging and a good counter-stain compatibility with other dyes.     

荧光探针在氰化物分析中的研究进展

氰化物极易与细胞色素氧化酶键合,抑制电子转移、导致组织缺氧,从而显示较强的毒性。荧光化学传感器作为简易、灵敏且可视化的方法广泛应用于氰化物的检测。本文对荧光探针在氰化物检测中的应用进行综述,概述了氰化物的毒性机制和荧光探针对氰化物的响应机理。同时,本文总结了荧光探针在水体、食品和生物组织中对氰化物的检测及生物成像中的应用,并对荧光探针在结构设计中如何提高生物兼容性和靶向性等进行了展望,以期为光化学探针分子的设计及应用提供理论与研究依据。     

Berberine alkaloid as a sensitive fluorescent probe for bile salt aggregates

Effect of sodium cholate (NaC) bile salt on the absorption and fluorescence properties of berberine cation was studied in aqueous solution and water-cosolvent mixtures. The alteration of the fluorescent behavior with increasing NaC concentration showed an entirely different trend from that found previously in the presence of sodium dodecylsulfate. Binding to bile salt agglomerates led to significant fluorescence intensity enhancement, and the fluorescence lifetime of berberine proved to be highly sensitive to the structure and size of the aggregates. The dual exponential decay kinetics above 10 mM NaC concentration showed that the probe resided in two totally different binding sites. At 2-10 mM NaC concentrations, only primary aggregates were detected. The aggregate disrupting power of cosolvents decreased in the series of dimethylformamide, acetonitrile, formamide, and methanol. These compounds enhanced the water accessibility of berberine bound to aggregates and diminished the number of secondary aggregates.     

Benzothiazole-substituted benzofuroquinolinium dye: a selective switch-on fluorescent probe for G-quadruplex

A new switch-on fluorescent probe containing the natural product cryptolepine analogue benzofuroquinolinium moiety (binding scaffold) and a benzothiazole moiety (signalling unit) shows a remarkable fluorescence enhancement selective for the G-quadruplex nucleic acid structure. Binding studies revealed that the highly selective response of the fluorescent probe arises from end-stack binding to G-quadruplex.