Quantum dot based turn-on fluorescent probes for anion sensing

The design of fluorescent probes for turn-on sensing of anions has been especially significant because it can effectively enhance sensing sensitivity by decreasing the background interference. In the present work, we have systematically studied the potential applications of fluorescent quantum dots (QDs) in turn-on anion sensing. The fluorescence of QDs are firstly quenched by three different mechanisms, i.e. fluorescence resonance energy transfer, electron transfer and surface states modulated fluorescence. The fluorescence of the pre-quenched QDs can then be recovered by various anions due to the modulating effects of added anions on the interaction between QDs and QDs, the interaction between QDs and quenchers, and the surface chemistry of the quenched QDs, respectively. The results described here indicate that turn-on sensing of various anions by QDs-based systems can be achieved by rationally choosing fluorescence modulating strategies, demonstrating the versatility of QDs in the corresponding applications.     

A turn-on fluorescent solid-sensor for Hg(II) detection

A rhodamine organosilane derivative (Rh-UTES) has been obtained by one-pot synthesis. The chemical structure of Rh-UTES was confirmed by nuclear magnetic resonance (NMR) and infrared (FTIR) techniques. To obtain an inorganic-organic hybrid sensor, Rh-UTES was covalently immobilized on a porous silicon microcavity (PSiMc) via triethoxysilane groups. The attachment of the organic derivative into PSiMc was confirmed by FTIR, specular reflectance, and scanning electron microscopy (SEM). The optical performance of Rh-UTES receptor for Hg²⁺ detection was investigated by fluorescent spectroscopy and microscopy. Upon the addition of increasing amounts of Hg²⁺ ions, a remarkable enhancement in emission intensity was produced in both systems. In the solid phase, an increase of integrated fluorescent emission of 0.12- and 0.15-fold after Hg²⁺ receptor coordination was observed. The light harvesting capability of PSiMc devices allowed obtaining an enhanced fluorescent emission after Rh-UTES immobilization (277-fold). The fluorescence microscopy of hybrid PSiMc sensor provided an optical qualitative test for Hg²⁺ detection.     

A rhodamine-B-based turn-on fluorescent sensor for biological iron(III)

Rhodenal, a turn-on fluorescent sensor for iron, derived from rhodamine-B, was synthesized and characterized. Its electronic absorption spectrum in ethanol has bands at 410 (ε = 500 cm^− 1 mol^− 1 L), 316 (ε = 14 × 10³ cm^− 1 mol^− 1 L), and 272 nm (ε = 32 × 10³ cm^− 1 mol^− 1 L), and it is pH sensitive with two pK_a values (1.2 and 2.8). It reacts promptly with Fe^3 +, with a pesudo-first order rate constant of 1 × 10³ s^− 1, with an equilibrium constant of 1.3 × 10⁶ mol^− 1 L, forming a violet complex (λ_max = 540 nm) with a fluorescent emission at 582 nm, with a higher sensitivity and selectivity compared to those of Fe^2 +, Ba^2 +, Al^3 +, K⁺, Ca^2 +, Ni^2 +, Co^2 +, Cd^2 +, Cr^3 +, Hg^2 +, Mg^2 +, Mn^2 +, Na⁺, or Cu^2 +. Biological assays with B16-F10 showed high permeability of plasma membrane to rhodenal and, according to confocal microscopy results, the fluorescent source originated from within the cell revealed iron pools within cytoplasmic and nuclear sub-compartments, making rhodenal a very good prospective Fe^3 + sensor, in aqueous solution and especially for biological iron pool detection.     

氟离子荧光探针的研究进展

氟离子是电负性最强、离子半径最小的阴离子,是一个强路易斯碱,在化学、生物学、医学和军事等方面都具有重要作用。适量的氟化物摄入人体可以预防龋齿、治疗骨质疏松症,但是过量的摄入会导致氟斑牙、氟骨症、尿石症以及癌症等疾病,因此氟离子的识别与检测具有重要意义。化学荧光探针具有选择性好、灵敏度高、方便快捷、成本低廉等优点,近年来化学研究者设计合成了大量的氟离子荧光探针。根据识别机理不同,氟离子荧光探针主要划分为3种:氢键型、路易斯酸受体型、氢键和路易斯酸混合型。综述了近年来不同类型的氟离子荧光探针的研究进展,总结了氢键型和路易斯酸型氟离子荧光探针的优缺点,对未来氟离子荧光探针的研究方向进行了展望。     

线粒体靶向型离子荧光探针的研究进展

线粒体在细胞的能量代谢过程中发挥着关键作用。线粒体内含有各种生物活性物质,它们在人体各种生理和病理过程中发挥着重要作用。综述了近年来有机单、双光子线粒体靶向型离子荧光探针的研究现状,重点介绍了荧光探针的设计机理、识别机理、特点以及生物应用,并对该类探针的未来发展趋势进行了展望。     

Diaminoterephthalate turn-on fluorescence probes for thiols--tagging of recoverin and tracking of its conformational change

Diaminoterephthalates with a maleimide moiety were synthesized and used as fluorescence dyes for sensing thiols. Whereas these "NiWa Blue" dyes showed no emission, the conjugate addition of a thiol to the maleimide group turned on a fluorescence at about 400 nm when irradiating the dye at 338 nm. The neuronal-calcium sensor protein recoverin possesses a single cysteine residue at position 39, which reacts with NiWa Blue, and is therefore labeled by a fluorophore with an emission at about 440 nm. In the absence of Ca(2+), irradiation at 280 nm of a tryptophan residue in close proximity to Cys-bound NiWa Blue lead to strong FRET, which was detected by emission of the dye at 440 nm. In the presence of Ca(2+), the protein holds a conformation with distal Trp and Cys residues, thus FRET of irradiated Trp to Cys-bound NiWa Blue was significantly weakened.     

反应型HClO/ClO-荧光探针的研究进展

次氯酸/次氯酸根是活性氧化物中重要的信号分子,在生物医药和环境安全等方面发挥着重要作用。反应型荧光探针基于出色的灵敏度、实时成像和生物兼容性好等特点,广泛应用于HClO/ClO^-的检测。本文评述了近5年反应型HClO/ClO^-荧光探针的研究进展,包括反应型HClO/ClO^-荧光探针的设计策略和识别机理,并从HClO/ClO^-引发的反应机理角度（碳碳双键的反应、硫族化合物的反应、醛肟基团的反应、腙/席夫碱的反应、酰肼/磺酰肼的反应、N,N-二甲基硫代氨基甲酸酯的反应和苯硼酸/硼酸酯的反应）概述了反应型HClO/ClO^-荧光探针的特点和实际应用,指出反应型HClO/ClO^-荧光探针的发展方向是合成性能优异的识别基团,构建选择性好、水溶性好、低荧光背景、光化学性能稳定和生物毒性低的反应型近红外HClO/ClO^-荧光探针,实现对生物体内外HClO/ClO^-的可视化检测及机理探索。     

Wavelength‐shift fluorescent probes for monitoring of polymerization

The feasibility of using wavelength‐shift fluorescent probes for cure monitoring of an epoxy resin and an acrylic resin was evaluated. 4‐(N,N‐dihexylaminostyryl)‐4′‐pyridinium propylsulfonate (DHASP‐PS), as well as each of other wavelength‐shift fluorescent probes, was dissolved in the epoxy resin, a stoichiometric mixture of diglycidyl ether of bisphenol A and 4,4′‐methylene‐bis(cyclohexylamine). The fluorescence and the excitation spectra of each of the probes dissolved in the epoxy resin were then measured at various times during the cure of the epoxy resin at 60°C. The fluorescence and the excitation spectra of the probe DHASP‐PS dissolved in methyl methacrylate (MMA) were also measured at various times during the cure of the acrylic resin at 55°C. Since the peak fluorescence wavelength of each of the wavelength‐shift fluorescent probes decreased during the cure of the epoxy resin or MMA, these fluorescent probes can be used for monitoring the polymerization reactions of epoxy resins and vinyl resins. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 747–750, 2006     

A graphene oxide-based fluorescent aptasensor for the turn-on detection of epithelial tumor marker mucin 1

Mucin 1 (MUC1) which presents in epithelial malignancies, is a well-known tumor biomarker. In this paper, a highly sensitive and selective fluorescent aptasensor for Mucin 1 (MUC1) detection is constructed, utilizing graphene oxide (GO) as a quencher which can quench the fluorescence of single-stranded dye-labeled MUC1 specific aptamer. In the absence of MUC1, the adsorption of the dye-labeled aptamer on GO brings the dyes in close proximity to the GO surface resulting in high efficiency quenching of dye fluorescence. Therefore, the fluorescence of the designed aptasensor is completely quenched by GO, and the system shows very low background fluorescence. Conversely, and very importantly, upon the adding of MUC1, the quenched fluorescence is recovered significantly, and MUC1 can be detected in a wide range of 0.04-10 μM with a detection limit of 28 nM and good selectivity. Moreover, the results have also been verified for real sample application by testing 2% serum containing buffer solution spiked with a series of concentrations of MUC1.     

识别细胞内金属离子的有机荧光探针研究进展

金属离子广泛存在于组织细胞和体液中,在人体的生理和病理中发挥着十分重要的作用。金属离子的浓度必须精确控制在一定的范围内,某些离子浓度的微弱变化都将引发人体的疾病。由于细胞是生命活动的基本单位,因此研究各种金属离子对生物体的影响,通过对活体细胞内金属离子的荧光显微成像进行细胞内离子的可视化定量和定性分析引起了人们的极大关注。就近年来人们对识别细胞内金属离子的有机荧光探针与细胞成像研究领域的进展进行了评述。     

New fluorescent hyperbranched polymeric sensors as probes for monitoring photopolymerization reactions

Two polychromophoric dansyl hyperbranched fluorescent probes (HBPs) have been used as fluorescent sensors to follow photopolymerization reactions of acrylic monomers through fluorescence monitoring. Simultaneously, photo-DSC measurements were conducted. The combined data obtained by both techniques allowed to measure precise and adequately the kinetics of the systems. Differences are found depending on the composition of the formulation, but no depending on the probe inserted in the systems. The behavior and sensitivity of the functional HBP's have been compared with their low molecular weight monochromophoric reference compounds. Hyperbranched polychromophoric probes showed the same sensitivity towards the process than the monochromophoric probes, confirming the high sensitivity of the hyperbranched probes. Also, the data obtained by fluorescence allow distinguishing the different steps involved in the mechanism of a radical crosslinking polymerization, which could not be observed only with calorimetric measurements. The advantages of the functional HBP fluorescent probes towards their low molecular weight homologues are discussed.     

The use of fluorescent probes for the detection of under-film corrosion

An inexpensive and practical method for detecting under-film aluminium corrosion using a hand-held UV inspection lamp is described. A novel fluorescent probe for under-film iron corrosion is demonstrated. Studies of light transmission and ion transport through three types of paint film show polyester to be the best barrier to ions and epoxy to be the most transparent in the near UV.     

Recent advances of small-molecule fluorescent probes for detecting biological hydrogen sulfide

H₂S is well-known as a colorless,acidic gas,with a notoriously rotten-egg smell.It was recently revealed that H₂S is also an endogenous signaling molecule that has important biological functions,however,most of its physiology and pathology remains elusive.Therefore,the enthusiasm for H₂S research remains.Fluorescence imaging technology is an important tool for H₂S biology research.The development of fluorescence imaging technology has realized the study of H₂S in subcellular organelles,facilitated by the development of fluorescent probes.The probes reviewed in this paper were categorized according to their chemical mechanism of sensing and were divided into three groups:H₂S reducibility-based probes,H₂S nucleophilicity-based probes,and metal sulfide precipitation-based probes.The structure of the probes,their sensing mechanism,and imaging results have been discussed in detail.Moreover,we also introduced some probes for hydrogen polysulfides.     

Two-photon fluorescent probes for biomembrane imaging: effect of chain length

Two-photon fluorescent probes for the cellular membrane, derived from 6-acyl-2-aminonaphthalene as the fluorophore and hexanoyl (CH), lauryl (CL), and stearyl (CS) groups as the receptor, have been synthesized. Their photophysical properties and utility as membrane probes were also studied. Whereas CH cannot be used as a membrane probe due to its high water solubility, CL and CS are useful two-photon probes for membrane lateral heterogeneity, as they can easily stain cells, emit fluorescence with high sensitivity to the environment polarity, and are capable of imaging the membrane lateral heterogeneity in live cells. Moreover, CS is more likely to be located in the plasma membrane due to its negligible water solubility. Our results show that the liquid ordered-like domain covers 31-35% of the cellular surface.