汞离子荧光探针的研究进展

综述了近几年来用于检测汞离子的荧光探针的研究进展,重点介绍了以氟硼二吡咯(BODIPY)、罗丹明、1,8-萘酰亚胺作为荧光团的汞离子荧光探针的结构和设计原理,概述了这些汞离子荧光探针在检测过程中的优点,并展望了这些汞离子荧光探针的研究和发展方向.     

罗丹明酰肼类荧光探针的合成及对Hg~(2+)的检测

基于金属离子诱导罗丹明螺内酰胺开环反应特性,合成了一种罗丹明酰肼类荧光探针分子RbH。在乙醇-水溶剂中,罗丹明酰肼探针与汞离子作用后吸收光谱出现明显的增强现象,溶液颜色由无色变为粉红;在580nm处探针溶液具有较强的红光发射,实现了对汞离子的裸眼定性分析和荧光半定量检测。     

一种吡嗪基修饰的罗丹明类荧光探针的合成及性能研究

设计合成一种新型的罗丹明类荧光探针,通过核磁共振氢谱和电喷雾质谱(ESI)对其结构进行表征。通过可见吸收光谱和荧光光谱对其光学性能进行检测,包括:荧光滴定、荧光时间响应、离子干扰、pH响应等。结果表明:该探针可以专一性的识别锡离子,而不受其他金属离子的干扰;响应时间为5 min,线性检测范围为0~30μmol/L,检测限为1μmol/L。表明该探针是一种性能良好的荧光探针。     

罗丹明基“OFF-ON”型荧光探针研究的一些新进展

综述了近年来罗丹明衍生物在分子探针方面研究的一些新进展, 系统阐述了该类探针分子的构筑及探针分子片段由内酰胺螺环构架(无荧光/OFF型)到开环蒽醌体系(有荧光/ON型)转化过程中, 伴随着荧光的变化在离子和小分子检测方面的应用.     

罗丹明类阳离子荧光探针

罗丹明类荧光染料由于具有摩尔消光系数高、光稳定性好、荧光量子产率高、较长的激发波长和发射波长等优异的光物理和光化学性能,现已成为制备荧光探针的一种理想材料之一。本文综述了近5年来基于螺酰胺环"关-开"机理和荧光共振能量转移(FRET)机理的罗丹明类Cu2+、Hg2+、Fe3+、Cr3+等荧光探针的设计合成、性能及其在阳离子分析方面的研究,介绍了具有良好细胞膜渗透性以及对细胞无毒副作用的罗丹明类阳离子荧光探针在活体或活细胞中应用研究的最新进展,并展望了这类荧光探针的发展趋势与应用前景。     

基于罗丹明荧光信号报告基团的细胞通透性铜离子荧光探针

分别以罗丹明B和罗丹明6G为荧光信号报告基团,以增强水溶性为目的的羟乙基肼为修饰基团,合成了反应型的Cu_(2+)离子选择性荧光探针分子L1和L2.紫外光谱和荧光光谱等分析结果表明,探针分子L1和L2对Cu_(2+)离子具有高灵敏度、高选择性的光谱识别行为.探针分子对Cu_(2+)离子的识别过程是通过Cu_(2+)离子催化水解控制氧杂蒽荧光信号的螺环酰肼基团实现荧光信号的开启,从而达到识别检测Cu_(2+)离子的目的,对Cu_(2+)离子的检出限均可达到10-8mol/L量级.同时,探针分子对常见金属离子和铵离子均具有较强的抗干扰能力.由于羟乙基肼的引入增强了探针的水溶性,使得探针L1和L2具有良好的细胞通透性和低毒性,实现了其对β-胰岛细胞(INS-1细胞)中Cu_(2+)离子的荧光成像检测.     

镁离子荧光探针

镁离子（Mg²⁺）在许多生理过程中扮演着重要的角色,因此对镁离子的选择性识别引起了人们极大的关注。本文综述了近年来镁离子荧光探针的最新研究进展。镁离子荧光探针体系主要分为：喹啉类、β-二酮类、冠醚/多醚类、羧酸类、荧光素/罗丹明类、配合物类、聚合物类和纳米材料类等。本文列举了每类探针分子代表性的化合物并总结比较了不同类型的镁离子荧光探针体系。     

水溶性大分子汞离子荧光-比色探针RhBH-P(VP-co-GMA)的合成与性能

采用活性基团修饰法,通过罗丹明B酰肼(RhBH)与乙烯基吡咯烷酮-甲基丙烯酸缩水甘油酯共聚物(P(VP-co-GMA))侧链上环氧基团的开环反应,制得一种键合有罗丹明B酰肼的水溶性聚合物RhBH-P(VP-co-GMA)。在水溶液中,该聚合物本身无色且无荧光,加入汞离子后,罗丹明的螺环结构打开,出现显著的荧光增强和颜色变红,实现了在水溶液中对汞离子的关-开荧光检测和裸眼检测。在此条件下,其他共存离子没有明显响应。研究表明:该聚合物是一种高选择性的Hg2+探针,可以实现水溶液中的汞离子检测。     

铜离子荧光探针的研究进展

高选择性、超灵敏性铜离子荧光探针的设计和开发,在环境检测、食品安全及人体内微量铜元素探测等领域具有重要意义。本文根据荧光分子探针对铜离子的识别机制和化学结构特点,从罗丹明、香豆素、芘基团、萘酰亚胺、氟硼吡咯及其他荧光基团等发色团出发,综述了近年来铜离子荧光探针的研究进展。参考文献27篇。     

罗丹明6G酰肼Hg~(2+)荧光探针及细胞成像应用

合成了罗丹明6G酰肼并研究了各种金属离子对其吸收光谱和荧光光谱的影响,结果表明,罗丹明6G酰肼是一种高选择性汞离子荧光探针。在乙醇/4-羟乙基哌嗪乙磺酸缓冲溶液(pH=7.2,体积比1∶1)中,罗丹明6G酰肼本身无荧光,加入汞离子使其在554 nm产生强发射,发出明亮的黄绿色荧光。其他常见金属离子,包括重金属离子和过渡金属离子,对汞离子引起的荧光增强无影响。罗丹明6G酰肼还被用于活细胞中汞离子的检测。另外,汞离子能使罗丹明6G酰肼在530 nm产生强吸收,溶液由无色变为粉红色。     

Synthesis and application of rhodamine-based fluorescent probe dyes with spacer linker arm

When rhodamine-based fluorescent probe dyes are used to track target molecules they always perturb the behavior of target molecules because of steric hindrance effect. In order to minimize potential steric problems, a kind of rhodamine-based fluorescent probe dye with spacer linker arm was designed and synthesized and its application in immunofluorescence histochemistry was investigated.     

Quantum-dot-labeled DNA probes for fluorescence in situ hybridization (FISH) in the microorganism Escherichia coli.

Semiconductor quantum dots (QDs) as a kind of nonisotopic biological labeling material have many unique fluorescent properties relative to conventional organic dyes and fluorescent proteins, such as composition- and size-dependent absorption and emission, a broad absorption spectrum, photostability, and single-dot sensitivity. These properties make them a promising stable and sensitive label, which can be used for long-term fluorescent tracking and subcellular location of genes and proteins. Here, a simple approach for the construction of QD-labeled DNA probes was developed by attaching thiol-ssDNA to QDs via a metal-thiol bond. The as-prepared QD-labeled DNA probes had high dispersivity, bioactivity, and specificity for hybridization. Based on such a kind of probe with a sequence complementary to multiple clone sites in plasmid pUC18, fluorescence in situ hybridization of the tiny bacterium Escherichia coli has been realized for the first time.     

A novel design method of ratiometric fluorescent probes based on fluorescence resonance energy transfer switching by spectral overlap integral

A ratiometric measurement, namely, simultaneous recording of the fluorescence intensities at two wavelengths and calculation of their ratio, allows greater precision than measurements at a single wavelength, and is suitable for cellular imaging studies. Here we describe a novel method of designing probes for ratiometric measurement of hydrolytic enzyme activity based on switching of fluorescence resonance energy transfer (FRET). This method employs fluorescent probes with a 3'-O,6'-O-protected fluorescein acceptor linked to a coumarin donor through a linker moiety. As there is no spectral overlap integral between the coumarin emission and fluorescein absorption, the fluorescein moiety cannot accept the excitation energy of the donor moiety and the donor fluorescence can be observed. After cleavage of the protective groups by hydrolytic enzymes, the fluorescein moiety shows a strong absorption in the coumarin emission region, and then acceptor fluorescence due to FRET is observed. Based on this mechanism, we have developed novel ratiometric fluorescent probes (1-3) for protein tyrosine phosphatase (PTP) activity. They exhibit a large shift in their emission wavelength after reaction with PTPs. The fluorescence quenching problem that usually occurs with FRET probes is overcome by using the coumarin-cyclohexane-fluorescein FRET cassette moiety, in which close contact of the two dyes is hindered. After study of their chemical and kinetic properties, we have concluded that compounds 1 and 2 bearing a rigid cyclohexane linker are practically useful for the ratiometric measurement of PTPs activity. The design concept described in this paper, using FRET switching by spectral overlap integral and a rigid link that prevents close contact of the two dyes, should also be applicable to other hydrolytic enzymes by introducing other appropriate enzyme-cleavable groups into the fluorescein acceptor.     

Syntheses of Novel Asymmetric Cyclopentanone Dyes and Measurement of Two－photon Absorption Cross－section

A simple synthesis route with a high yield of novel asymmetric cyclopentanone dyes 3a—3e and their highly two-photon up-converted fluorescences are reported. The dyes have good solubilities in most of ordi-nary solvents, a wide UV absorption wavelength range from 380—540 nm, and high fluorescence quantum yields. The two-photon absorption cross-sections of dyes 3a—M were measured in chloroform by a two-pho-ton induced fluorescence method. All of these properties of the new dyes make them suitable for being used as two-photon fluorescent probes.     

Thiourea- and Amino-Substituted Benzoxadiazole Dyes with Large Stokes Shifts as Red-Emitting Probe Monomers for Imprinted Polymer Layers Targeting Carboxylate-Containing Antibiotics

Bifunctional fluorescent molecular oxoanion probes based on the benzoxadiazole (BD) chromophore are described which integrate a thiourea binding motif and a polymerizable 2-aminoethyl methacrylate unit in the 4,7-positions of the BD core. Concerted charge transfer in this electron donor-acceptor-donor architecture endows the dyes with strongly Stokes shifted (up to >250 nm) absorption and fluorescence. Binding of electron-rich carboxylate guests at the thiourea receptor leads to further analyte-induced red-shifts of the emission, shifting the fluorescence maximum of the complexes to ≥700 nm. Association constants for acetate are ranging from 1–5×10⁵ M⁻¹ in acetonitrile. Integration of one of the fluorescent probes through its polymerizable moiety into molecularly imprinted polymers (MIPs) grafted from the surface of submicron silica cores yielded fluorescent MIP-coated particle probes for the selective detection of antibiotics containing aliphatic carboxylate groups such as enoxacin (ENOX) at micromolar concentrations in highly polar solvents like acetonitrile.     

Spectroscopic studies of a near-infrared absorbing pH sensitive aminodienone-carbocyanine dye system

Synthetic red and near-infrared absorbing dyes may be used as probe molecules in a large number of applications. Dyes exhibiting spectral changes with hydrogen ion concentration are useful as pH probes. Those dyes which have their absorption and fluorescence maxima in the long wavelength region of the visible spectral region are specially valuable because of decreased interference and semiconductor laser applications. In this paper we have evaluated an aminodienone dyes 1 which demostrates pH dependent absorption and fluorescence spectra as well as solvent polarity dependence. In organic solvents the long wavelength absorption band of the dye is in the reduced interference region. The absorption maximum is at 535 nm in neutral or alkaline solutions in methanol. The absorption spectra undergo a strong bathochromic shift in the presence of acids (lambda(max) = 709 nm) with a concomitant change in the fluorescence spectra. This pH sensitive dye was found to be specially especially useful for organic solvents. The analytical utility of this and similar near-infrared absorbing dyes is discussed.     

A unique class of near-infrared functional fluorescent dyes with carboxylic-acid-modulated fluorescence ON/OFF switching: rational design, synthesis, optical properties, theoretical calculations, and applications for fluorescence imaging in living animals

Fluorescence imaging is one of the most powerful techniques for monitoring biomolecules in living systems. Fluorescent sensors with absorption and emission in the near-infrared (NIR) region are favorable for biological imaging applications in living animals, as NIR light leads to minimum photodamage, deep tissue penetration, and minimum background autofluorescence interference. Herein, we have introduced a new strategy to design NIR functional dyes with the carboxylic-acid-controlled fluorescence on-off switching mechanism by the spirocyclization. Based on the design strategy, we have developed a series of Changsha (CS1-6) NIR fluorophores, a unique new class of NIR functional fluorescent dyes, bearing excellent photophysical properties including large absorption extinction coefficients, high fluorescence quantum yields, high brightness, good photostability, and sufficient chemical stability. Significantly, the new CS1-6 NIR dyes are superior to the traditional rhodamine dyes with both absorption and emission in the NIR region while retaining the rhodamine-like fluorescence ON-OFF switching mechanism. In addition, we have performed quantum chemical calculations with the B3LYP exchange functional employing 6-31G* basis sets to shed light on the structure-optical properties of the new CS1-6 NIR dyes. Furthermore, using CS2 as a platform, we further constructed the novel NIR fluorescent TURN-ON sensor 7, which is capable of imaging endogenously produced HClO in the living animals, demonstrating the value of our new CS NIR functional fluorescent dyes. We expect that the design strategy may be extended for development of a wide variety of NIR functional dyes with a suitable fluorescence-controlled mechanism for many useful applications in biological studies.     

Squaraine Dyes as Fluorescent Turn-on Probes for Mucins: A Step Toward Selectivity†

Mucins are a family of long polymeric glycoproteins which can be overexpressed in several types of cancers, and over recent years, great attention was addressed to identify mucins as an important biomarker of adverse prognosis. Fluorometric detection mediated by fluorescent probes could represent a winning strategy in the early diagnosis of different pathologies. Among promising biological fluorescent probes, squaraines are gaining particular attention, thanks to their sharp and intense absorption and emission in the NIR region. In this contribution, three squaraine dyes bearing different substituents and with different lipophilicity have been investigated for their ability to detect mucin. The turn-on response upon the addition of mucin has been investigated by means of absorbance and fluorescence spectroscopy. After a preliminary screening, the squaraine (S6) bearing bromine as a substituent and C4 aliphatic chains showed the highest fluorescence turn-on and highest affinity for mucin than albumin. To further highlight the selectivity of S6 for mucin, the fluorescence response has been evaluated in the presence of serum and site-specific proteins different than albumin. Absorption spectroscopy was used to characterize the binding mechanism of squaraine to mucin.     

Photophysical behavior of lipophilic xanthene dyes without the involvement of photoinduced electron transfer mechanism

The correlation of dibutyl-ether-ester of xanthene dye structures with their photophysical properties is discussed with respect to their capability as fluorescent probes based on ultraviolet–visible absorption, fluorescence spectra and fluorescence lifetimes measured in different solvents. It was found that the dibutyl-ether-ester of fluorescein is very weakly emissive in aprotic solvents, but fairly strong fluorescent in alcohols. The dependence of fluorescence quantum yield (Φ_f) and lifetime (τ_f) on solvent polarity suggests non-involvement of the intra-molecular photoinduced electron transfer (PeT) mechanism, suggested previously to account for the emission efficiency of fluorescein derivatives. The xanthene dyes intend to self-assemble in aprotic solvents, less polar solvents facilitate the aggregation while hydrogen bonding disfavor it. The formation of non-emissive H-aggregates is proposed to be responsible for their fluorescent behavior. The esterification showed stronger influences on the photophysics than the etherification, i.e. the former caused larger reduction of Φ_f owing to the internal conversion. The halogenation decreases the fluorescence quantum yield and lifetime of the xanthene dyes, owing to the enhancement of inter-system crossing process.     

官能化罗丹明基金属阳离子荧光探针

重金属离子对环境和生物体具有极强的生理毒性,故高选择性和高灵敏度的离子检测荧光探针的研究有着重要意义。荧光分子探针在表达分子间识别行为以及复杂的环境、生命体系的内状态信息方面具有优异的性能,已广泛深入的用于构建新型功能性探针分子。本文综述了近年来基于罗丹明的金属阳离子如Hg₂₊、Cu₂₊、Fe₃₊等荧光分子探针的研究进展,包括探针的结构特征、检测机理、检测水平,更重要的是其在环境检测、生物成像、分子器件等方面的新应用,并对荧光探针所面临的问题和发展前景做了分析。