A fluorescence resonance energy transfer probe for sensing pH in aqueous solution

A fluorescence resonance energy transfer (FRET) sensor, which has a FRET donor and an acceptor attached to each chain end of pH-sensitive polysulfonamide, is synthesized and its pH sensitivity is examined in terms of the FRET efficiency. This polymeric sensor exhibits an instantaneous conformation change from coil to globule at a specific pH, which results in the drastic on-and-off FRET efficiency. To detect a specific pH region, sulfadimethoxine and sulfamethizole are selected among various sulfonamides since their pK_a values are in the physiological pH. For tuning the emission color arising from FRET, 7-hydroxy-4-bromomethyl coumarin and coumarin 343 are used as a FRET donor and an acceptor, respectively, for a blue-to-green FRET sensor, and fluorescence amine isomer I and rhodamine B are used for a green-to-red FRET sensor. Each sensor shows a distinct color change from the emission wavelength of FRET donor to the emission wavelength of FRET acceptor, which well explains their feasibility as a useful optical sensor.     

A highly selective wavelength-ratiometric and colorimetric probe for cysteine

Based on the nucleophilic aromatic substitution reaction mechanism, a new highly selective probe for cysteine (Cys), N-butyl-4-bromo-3-nitro-1,8-naphthalimide (1), was designed and synthesized. The probe displayed a remarkable (58 nm) red-shift in the absorption spectra and the color changes from colorless to yellow upon reaction with Cys. The probe could detect Cys quantitatively in the range of 0-0.9 mM by both normal and ratiometric absorption spectrometry methods. Moreover, 1 could also serve as a “naked-eye” probe for Cys with a minimum detectable concentration of approximately 50 μM.     

基于罗丹明B的有机荧光探针合成及Cu~(2+)检测

基于罗丹明B合成了两种有机荧光探针用来检测Cu~(2+)。以罗丹明B与3-甲氧基苯酰肼、水杨酰肼为原料合成了两种探针,命名为Rh1、Rh2,分别与Cu~(2+)以及其它金属离子溶液反应,观察溶液的颜色变化,分别测定其紫外及荧光吸收光谱。Rh1、Rh2加入铜离子溶液后,溶液由无色到粉红色的显著颜色变化,与其它金属离子比较在400～700nm有较明显的紫外-可见吸收和荧光增强。两种荧光探针能够有效的跟Cu~(2+)结合,从紫外-可见吸收光谱和荧光光谱可以看出此探针显示出选择性的、敏感的荧光增强反应,表现出对Cu~(2+)良好的选择性。     

Depolymerized phosphorus-doped polymeric carbon nitride: A mercury (II) ion fluorescent probe

The fluorescence quenching effect of polymeric carbon nitride-based materials can be efficiently applied to the rapid detection of Hg²⁺. Herein, we chose dicyandiamide and sodium hypophosphite as precursors to prepare bulk phosphorous-doped polymeric carbon nitride through thermal polycondensation, and then a one-step hydrothermal treatment caused the depolymerization of the bulk products and the formation of the nanorod-like structures. The depolymerization resulted in the good aqueous colloidal stability of the polymeric carbon nitride-based derivative, and phosphorus-doping significantly improved its fluorescence. More terminal amino and abundant surface hydroxyl groups led to the enhanced selective fluorescence quenching of Hg²⁺ by the depolymerized products. Therefore, the depolymerized phosphorous-doped polymeric carbon nitride with a fluorescence quantum yield of 23.2% showed excellent Hg²⁺ detection capability. The limit of detection of the depolymerized polymeric carbon nitride to Hg²⁺ can reach 0.74 nmol L^?1. And the depolymerized products also showed good accuracy in the Hg²⁺ detection of shrimp samples. This work broadens the scope of polymeric carbon nitride-based heavy metal ion fluorescent probes, and provides a new roadmap for the highly selective determination of Hg²⁺.     

基于1,8-萘酰亚胺-罗丹明的FRET机理阳离子探针研究进展

综述了近年来以1,8-萘酰亚胺-罗丹明为母体的FRET机理阳离子探针的研究进展.介绍了Hg2＋,Al3＋,Fe3＋,Sn4＋,Cr3＋和H＋荧光探针的设计合成、性质及其应用,并对今后的研究方向作简要的展望.     

比率型过氧化氢荧光探针的合成及成像应用

采用6-甲氧基苯并噻唑-2-羟基喹啉作为双光子荧光团、硼酸酯作为过氧化氢（H2O2）识别基团，合成比率型检测H2O2的双光子荧光探针{6-甲氧基-2-[6-(4,4,5,5-四甲基-1,3,2-二氧硼杂环戊烷-2-基)喹啉-2-基]苯并[d]噻唑}（MQH2O2）。利用荧光光谱和双光子荧光光谱对探针进行H2O2响应能力的评估，结果显示探针具有良好的H2O2比率响应（30 min内比率信号增强约25.4倍、检出限低至38.6 nmol/L）和双光子性质（最大双光子荧光活性截面为150 GM）。通过双光子共聚焦成像完成了细胞和大脑组织成像，结果表明该探针能够实现脑卒中诱导细胞氧化应激的原位成像分析。     

Rhodamine-based fluorescent sensor for mercury in buffer solution and living cells

A novel fluorescent sensor based on thiooxorhodamine B has been prepared to detect Hg²⁺ in aqueous buffer solution. It demonstrates high selectivity for sensing Hg²⁺ with about 383-fold enhancement in fluorescence emission intensity and micromolar sensitivity (K_d = 7.5 × 10⁻⁶ mol L⁻¹) in comparison with alkali and alkaline earth metal ions (K⁺, Na⁺, Mg²⁺, Ca²⁺) and other transition metal ions (Mn²⁺, Ni²⁺, Co²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Ag⁺, Pb²⁺, Cr³⁺, Fe³⁺). Meanwhile the distinct color changes and rapid switch-on fluorescence also provide ‘naked eyes’ detection for Hg²⁺ over a broad pH range. Moreover, such sensor is cell-permeable and can visualize the changes of intracellular mercury ions in living cells using fluorescence microscopy.     

用于检测氟离子的荧光探针的制备

设计合成了基于萘胺为荧光团的的氟离子荧光探针。通过核磁表征了荧光探针的结构。研究了该探针在加入F-前后吸收光谱和发射光谱的变化。结果表明,随着F-的加入,探针有明显的荧光增强。另外,探针具有良好的选择性,加入其他阴离子不影响其光谱性质。以上性能证明,该探针有望应用于检测F-的荧光传感器。     

Fluorescent Gold Nanoprobes for the Sensitive and Selective Detection for Hg

A simple, cost-effective yet rapid and sensitive sensor for on-site and real-time Hg²⁺ detection based on bovine serum albumin functionalized fluorescent gold nanoparticles as novel and environmentally friendly fluorescent probes was developed. Using this probe, aqueous Hg²⁺ can be detected at 0.1 nM in a facile way based on fluorescence quenching. This probe was also applied to determine the Hg²⁺ in the lake samples, and the results demonstrate low interference and high sensitivity.     

A highly selective and sensitive fluorescence chemosensor based on optically active polybinaphthyls for Hg

The chiral polymer was synthesized by the polymerization of 4,7-diethynylbenzo[2,1,3]-thiadiazole (M-1) with (R)-6,6′-dibutyl-3,3′-diiodo-2,2′-bis(diethylaminoethoxy)-1,1′-binaphthyl (R-M-1) via Pd-catalyzed Sonogashira reaction. The chiral polymer has orange fluorescence due to the extended π-electronic structure between binaphthyl unit and benzo[2,1,3]thiadiazole (BT) group via ethynyl bridge. The responsive optical properties of the polymer on various metal ions were investigated by fluorescence spectra. The fluorescence of the chiral polymer can produce the pronounced enhancement as high as 1.8-fold upon addition of 1:2 molar ratio of Hg²⁺. Compared with other cations, such as K⁺, Mg²⁺, Pb²⁺, Co²⁺, Ni²⁺, Ag⁺, Cd²⁺, Cu²⁺, Zn²⁺, Mn²⁺ and Fe³⁺, Hg²⁺ can produce the pronounced fluorescence response of the polymer. The result indicates this kind of chiral polybinaphthyls incorporating diethylamino and benzo[2,1,3]thiadiazole (BT) moieties as receptors exhibits highly sensitive and selective behavior for Hg²⁺ detection.     

A ratiometric fluorescent sensor for zinc(II) with high selectivity

Spectroscopic studies revealed that the compound [N,N′-di(quinoline-2-methylene) -1,2-phenylenediimine] (1) exhibited a rather high selectivity toward Zn²⁺ over other metal ions, even Cd²⁺. In acetonitrile, the red shift of fluorescent emission from 396 nm to 426 nm upon zinc binding is due to the formation of a 1:1 metal/ligand complex.     

A highly selective ratiometric fluorescent sensor for Hg2+ based on 1,8‐naphthalimide

A sulfur probe based on 1,8‐naphthalimide was designed and synthesised, and its sensing behaviour towards a mercury ion was investigated by fluorescence spectroscopy. The probe showed higher selective recognition towards Hg²⁺ than towards other metal ions in methanol solution. Compared with 4‐amino‐substituted naphthalimide derivatives, the probe exhibited different fluorescent characteristics for sensing Hg²⁺. The novel, reaction‐based probe is recommended for selective recognition of Hg²⁺ with significant fluorescence change.     

A highly selective fluorescent sensor for Hg based on the water-soluble poly(p-phenyleneethynylene)

The conjugated polymer P-1 could be synthesized by the polymerization of 4,7-diethynyl-benzo[2,1,3]thiadiazole (M-1) and 1,4-bis[3′-(N,N-diethylamino)-1′-oxapropyl]-2,5-diiodobenzene (M-2) via Pd-catalyzed Sonogashira reaction. The water-soluble conjugated polyelectrolyte P-2 could be obtained by the reaction of P-1 with ethyl bromide. Both P-1 and P-2 can emit orange fluorescence. The responsive optical properties of P-1 and P-2 on Hg²⁺ were investigated by fluorescence spectra. Hg²⁺ can lead to nearly complete fluorescence quenching of P-1. On the contrary, Hg²⁺ can show the most pronounced fluorescence enhancement response of P-2 in aqueous solution without interference from those coexistent ions, such as K⁺, Mg²⁺, Pb²⁺, Co²⁺, Ni²⁺, Ag⁺, Cd²⁺, Cu²⁺, Fe³⁺ and Zn²⁺. The results also exhibit that this kind of water-soluble conjugated polyelectrolyte can be used as a highly sensitive and selective fluorescence sensor for Hg²⁺ detection in water.     

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.     

基于1,8-萘酰亚胺检测细胞内肼的荧光探针

以对氨基酚和3-溴肉桂酸为原料,以4-溴-1,8-萘酰亚胺为荧光母体设计合成了一例用于检测细胞内肼的荧光探针NH1。该探针能够对肼产生特异性响应。利用1H NMR、MS对NH1进行了结构确证。在体外测试中,探针NH1最大发射波长处（λem=535 nm）的荧光强度随着肼含量的增加而逐渐增强,并且具有良好的线性关系（R2=0.99）,检测限为0.23 μmol/L。该探针有着良好的选择性和抗干扰能力,在广泛pH范围内（4.5~10.5）均能够特异性检测肼。该探针能够染色到细胞内对细胞内的肼进行检测。     

基于吲哚半花菁结构的比值式pH荧光探针

设计合成了一种基于半花菁类结构的比值式pH荧光探针,能快速响应pH值的变化,对常见金属离子具有较好的抗干扰能力。在pH 5.4~7.2范围内,随着pH值升高,探针紫外可见吸收光谱最大吸收波长由422 nm红移至525 nm。激发波长为430 nm时,荧光发射峰峰高之比(I513 nm/I553 nm)与pH值的变化有良好的线性关系,可用于检测生物体内pH的变化。HeLa细胞毒性试验表明,该探针具有较低的细胞毒性。     

新型罗丹明类荧光标记探针的研究(Ⅰ)--氨基标记产物的质子化互变异构

罗丹明B-N-琥珀酰亚胺酯可用于生命体系物质氨基标记的新型荧光探针。研究了标记产物在不同的pH介质中的紫外一可见及荧光光谱特性，结合质子化互变异构机理，对互变异构现象与光谱变化的相关性进行了考察，确认了仲酰胺在中性和碱性条件下形成无荧光性的螺环内酰胺结构。     

Thermochromic microgels and core‐shell microgels based on fluorescence resonance energy transfer

Microgels exhibiting thermochromic behavior based on fluorescence resonance energy transfer (FRET) are prepared. The FRET microgels consist of poly(N‐isopropylacrylamide) (PNiPAm) networks with fixed fluorescein and rhodamine moieties and exhibits volume phase transition (VPT) at 34–35°C. A critical decrease in their sizes during the VPT enhances the efficiency of FRET between fluorescein as a donor and rhodamine as an acceptor. Therefore, emission from fluorescein (523 nm) and that of rhodamine (579 nm) is dominant at temperatures below and above the VPT temperature, respectively, when fluorescein is excited. We also prepare thermochromic core‐shell FRET microgel exhibiting two‐step color change. The microgels consist of a PNiPAm core and a poly(N‐isopropylacrylamide‐co‐N,N‐diethylacrylamide) shell and exhibit dual temperate‐responsiveness at 19 and 33°C. The fluorescence spectrum of the microgels also changes in two steps at these temperatures. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

A carboxylic acid‐functionalized polyfluorene as fluorescent probe for protein sensing

A new water‐soluble fluorescent conjugated polyelectrolyte, poly[9,9‐bis(3′‐butyrate)fluoren‐2,7‐yl] sodium (BBS‐PF), was studied as a fluorescent probe for protein sensing. The conjugated polyelectrolyte BBS‐PF shows high fluorescence sensitivity to cytochrome c, lysozyme, and bovine serum albumin (BSA). The Stern–Volmer constant (K_sv) in cytochrome c was measured to be as high as 6.1 × 10⁷ L/mol, approximately twice as that of the other two. Interestingly, it is found that BSA slightly enhances the fluorescence of BBS‐PF rather than quenches the fluorescence at its micromolar concentrations. The excitation spectra confirm that the interaction of BBS‐PF with the proteins could be different. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

氟代指示剂在核磁共振检测细胞内钙离子中的应用

细胞内游离Ca^2 在生理功能中起重要作用,本文简介了利用^19F NMR测定细胞内游离Ca^2 浓度的方法,该方法所具有的优越性以及氟代指示剂的改进和应用。