Ratiometric and selective two-photon fluorescent probe based on PET-ICT for imaging Zn2+in living cells and tissues简

A two-photon fluorescent probe TPZn was developed for specific ratiometric imaging Zn2＋ in living cells and tissues. Significant ratiometric fluorescence change was based on photoinduced electron transfer and intramolecular charge transfer. The synthetic method of TPZn was simple. It was successfully used to selectively image Zn2＋ based on the higher binding affinity for Zn2＋ than for Cd2＋. TPZn was easily loaded into the living cell and tissues with high membrane permeability in a complex biological environment. TPZn could clearly visualize endogenous Zn2＋ by TP ratiometric imaging in hippocampal slices at a depth of 120 μm. Thus, TPZn is a useful tool to image of Zn2＋ in living cells and tissues without interference from Cd2＋.     

Development of an iminocoumarin-based zinc sensor suitable for ratiometric fluorescence imaging of neuronal zinc

Ratiometric imaging is a technique to reduce artifacts by minimizing the influence of extraneous factors on the fluorescence of a sensor and is particularly useful for cellular imaging studies. Here we characterized the iminocoumarin fluorophore as a new scaffold for sensors for ratiometric imaging. The iminocoumarin 4 showed a high quantum yield in aqueous media on excitation in the visible wavelength region, while its coumarin analogue showed little fluorescence. We therefore developed a novel fluorescence probe, ZnIC, for ratiometric imaging of Zn2+, using iminocoumarin as a fluorophore and (ethylamino)dipicolylamine as a Zn2+ chelator. ZnIC exhibited almost the same fluorescence properties as 4, and the emission spectrum of this probe was red-shifted on addition of Zn2+ under physiological conditions. ZnIC is selective for Zn2+ over other biologically important metal ions, such as Ca2+ and Mg2+, and has high affinity for Zn2+. To confirm the suitability of ZnIC for biological applications, we employed it for the ratiometric detection of changes in intracellular Zn2+ in cultured cells and in rat hippocampal slices. The results indicate that iminocoumarin is a useful fluorophore for fluorescence microscopic imaging and that ZnIC should be useful for studies on the biological functions of Zn2+.     

A ratiometric fluorescence probe for selective visual sensing of Zn2+

A simple ratiometric fluorescence probe based on vinylpyrrole end-capped bipyridine for the visual sensing of Zn2+ under aqueous physiological pH (6.8-7.4) is described. The fluorophores 3a-c showed strong emission around 537 nm in acetonitrile with a quantum yield of 0.4. In buffered (HEPES, pH 7.2) acetonitrile-water mixture (9:1 v/v), titration of transition metal salts to 3c showed strong quenching of the emission at 547 nm except in the case of Zn2+, which resulted in a red-shifted emission at 637 nm. Alkali and alkaline earth metal salts could not induce any considerable changes to the emission behavior of 3a-c. The binding of Zn2+ was highly selective in the presence of a variety of other metal ions. Though Cu2+ quenches the emission of 3c, in the presence of Zn2+, a red emission prevails, indicating the preference of 3c toward Zn2+. Job plot and Benesi-Hildebrand analysis revealed a 1:1 complexation between the probe and the metal ion. The selective visual sensing of Zn2+ with a red emission is ideally suited for the imaging of biological specimens.     

基于1,8-萘酰亚胺与罗丹明B间荧光共振能量转移的高选择性Hg2+比率荧光探针

以罗丹明B与1,8-萘二甲酰亚胺反应合成了1个高选择性Hg²⁺比率荧光探针(RN). 在甲醇/乙腈/4-羟基哌嗪乙磺酸缓冲溶液(pH=7.2, 体积比8:1:1)中, RN对Hg²⁺具有比色和比率荧光双重响应. 加入Hg²⁺后, RN的紫外-可见光谱在约556 nm处产生强吸收, 溶液由浅绿色变为橙色, 其它金属离子对RN的紫外-可见光谱几乎无影响. 无Hg²⁺存在时, RN的荧光光谱在540 nm处出现萘二甲酰亚胺荧光团的特征峰; 加入Hg²⁺后, 540 nm处的发射带逐渐消失, 同时在580 nm附近产生强荧光, 荧光颜色从绿色变为橙色. 这归因于从萘酰亚胺到开环罗丹明B的荧光共振能量转移(FRET), 探针RN对Hg²⁺的比率荧光响应具有高选择性, 不受其它共存金属离子的干扰.     

Fluorescence imaging of intracellular cadmium using a dual-excitation ratiometric chemosensor

We described here a coumarin-based dual-excitation ratiometric probe for cadmium, CadMQ. This fluorescence sensor has high quantum yields of 0.59 and 0.70 in the metal-free and Cd2+-bound forms, respectively, and has a dissociation constant of 0.16 nM for Cd2+. CadMQ is cell permeable and locates within the acidic compartments of the cells. We further show that CadMQ is a useful tool to ratiometrically probe the change in the intracellular Cd2+ levels with the use of two excited wavelengths.     

Highly sensitive fluorescent probes for zinc ion based on triazolyl-containing tetradentate coordination motifs

Two new 1,2,3-triazolyl-containing N4-tetradentate ligands show nanomolar affinity for Zn2+ under physiological conditions. Furthermore, they are easily derivatizable to afford fluorescent probes suitable for sensitive Zn2+ detection. Structural characterizations in both solid and solution states suggest that N3 and N2 in the 1,2,3-triazolyl moiety coordinate with Zn2+ in A and B to afford five-membered and six-membered coordination rings, respectively. The probes show sensitive fluorescence enhancement and ratiometric responses to Zn2+.     

表面活性剂增溶比率荧光Zn2+检测方法研究

合成了一种新的Zn2+荧光检测试剂8-(2-(十八氨基)乙酰氨基)喹啉(AQZ-18)。通过自发荧光的非离子表面活性剂OP-10增溶AQZ-18,获得了一个与Zn2+结合后在320 nm和505 nm分别有两个荧光发射峰的溶液体系。短波长荧光峰来自OP-10,荧光峰强度不随Zn2+浓度变化;长波长荧光峰来自AQZ-18,荧光峰强度随Zn2+浓度增加而增强。利用上述两个荧光峰强度随Zn2+浓度变化时的比值变化建立了一种新的比率荧光Zn2+检测方法。研究表明,Zn2+与AQZ-18形成1∶1型基态配合物,其表观结合常数为1.1×106L/mol。常见金属离子对Zn2+荧光检测无干扰,Zn2+浓度在0～1.1×10-5mol/L范围内与荧光强度变化的比值呈良好的线性关系,相关系数(r2)为0.996 2,检出限为55 nmol/L。该方法可用于水样中Zn2+的检测。     

Ratiometric and water-soluble fluorescent zinc sensor of carboxamidoquinoline with an alkoxyethylamino chain as receptor

A novel "naked-eye" and ratiometric fluorescent zinc sensor (AQZ) of carboxamidoquinoline with an alkoxyethylamino chain as receptor was designed and synthesized. AQZ shows good water solubility and high selectivity for sensing; about an 8-fold increase in fluorescence quantum yield and a 75 nm red-shift of fluorescence emission upon binding Zn2+ in buffer aqueous solution are observed. Moreover, AQZ can enter yeast cells and signal the presence of Zn2+.     

Photoinduced electron transfer (PET) based Zn2+ fluorescent probe: transformation of turn-on sensors into ratiometric ones with dual emission in acetonitrile

Ratiometric sensors for the detection of metal ions have gained increasing attention due to its self-calibration tendency for the environmental effects. In this context, we have synthesized and characterized a dual emitting ratiometric Zn(2+) probe (1) having acridinedione as a fluorophore and N,N-bis(2-pyridylmethyl)amine (BPA) as a receptor unit. Existence of two different conformation of the molecule with photoinduced electron transfer (PET) from amine moiety to the acridinedione fluorophore leads to dual emission, namely locally excited (425 nm) and anomalous charge transfer emission (560 nm) in aprotic solvents. In the presence of one equivalent of Zn(2+), a 15-fold fluorescence enhancement in the locally excited state together with the quenching of charge transfer emission is observed. The intensity changes at the two emission peaks allow a ratiometric detection of Zn(2+) under PET signaling mechanism. The utilization of PET process for the ratiometric fluorescence change will further signify the importance of PET mechanism in sensing action. Addition of Zn(2+) to 1 in acetonitrile/water mixtures shows a single emission peak with fluorescence enhancement.     

A novel,cell-permeable,fluorescent probe for ratiometric imaging of zinc ion

Zn(2+) plays important roles in various biological systems; as a result, the development of tools that can visualize chelatable Zn(2+) has attracted much attention recently. We report here newly synthesized fluorescent sensors for Zn(2+), ZnAF-Rs, whose excitation maximum is shifted by Zn(2+) under physiological conditions. Thus, these sensors enable ratiometric imaging, which is a technique to reduce artifacts by minimizing the influence of extraneous factors on the fluorescence of a probe. Ratiometric measurement can provide precise data, and some probes allow quantitative detection. ZnAF-Rs are the first ratiometric fluorescent sensors for Zn(2+) that enable quantitative analysis under physiological conditions. ZnAF-Rs also possess suitable K(d) for applications, and high selectivity against other biologically relevant cations, especially Ca(2+). Using these probes, changes of intracellular Zn(2+) concentration in cultured cells were monitored successfully. We believe that these probes will be extremely useful in studies on the biological functions of Zn(2+).     

A colorimetric and fluorometric dual-model assay for mercury ion by a molecule

The synthesis and sensing characteristics of a new class of colorimetric and fluorometric dual-modal probe for mercury ion are outlined. Judicious placement of two dithia-dioxa-aza macrocycles on the BODIPY chromophore generates this interesting molecule. A highly Hg2+-selective fluorescence enhancing property (>7-fold) in conjunction with a visible colorimetric change from purple to red-pink can be observed, leading to potential fabrication of both "naked-eye" and ratiometric fluorescent detection of Hg2+.     

A ratiometric fluorescent probe for oxalate based on alkyne-conjugated carboxamidoquinolines in aqueous solution and imaging in living cells

A novel ratiometric fluorescent probe for oxalic acid was designed and synthesized, based on the zinc-containing [DAQZ@2Zn(2+)] complex. It shows highly selective "on-off" fluorescence changes with a more than 20 nm blue shift in wavelength for oxalic acids in aqueous solution. Moreover, it can fluorescently respond to oxalic acid in living cells.     

Ratiometric fluorescence detection of a tag fused protein using the dual-emission artificial molecular probe

We have successfully developed a ratiometric detection system for protein of interest using the complementary recognition pair of the tetra-aspartate peptide tag and the SNARF-appended Zn(ii)-DpaTyr probe.     

N-(8-对氨基苯磺酰)胺基喹啉的合成及其荧光性质的研究

合成了一种Zn2+荧光探针N-(8-对氨基苯磺酰)胺基喹啉(HQAS),探讨了HQAS与Zn2+的键合比和配位模式,以及不同pH,其它金属离子对Zn2+检测的影响.研究结果显示:该探针与Zn2+形成配合物,使其荧光增强,键合比为2:1,pH 7.2时荧光强度增大9.4倍.大多数金属离子几乎不干扰Zn2+的检测,Cu2+...     

Development of a borondipyrromethene-based Zn2+ fluorescent probe: solvent effects on modulation sensing ability

A borondipyrromethene-based Zn(2+) fluorescent probe BODPAQ was designed and synthesized. The chelators in BODPAQ, 2,2'-dipicolylamine (DPA) and 8-aminoquinoline (AQ), coordinate to Zn(2+) in a synergic manner. As a result, BODPAQ displays high Zn(2+) selectivity with a dramatic enhanced emission accompanied by a notable hypsochromic shift due to the binary inhibition effect of PET and ICT mechanisms, enabling the detection of Zn(2+) by both ratiometric and normal turn-on fluorescence methods in acetonitrile. Interestingly, the sensitivity of BODPAQ towards Zn(2+) changes upon varying the compositions of buffer solutions. In 3-morpholinopropanesulfonic acid (MOPS) buffer aqueous solution (50% CH(3)CN), BODPAQ displays the highest sensitivity for Zn(2+), while in citrate-phosphate buffer, BODPAQ shows no response to Zn(2+).     

5,5-二乙烯基-2,2-联吡啶:可能的新型锌离子荧光探针(英文)

生物体系里微量元素锌在发育、新陈代谢和疾病的发生等多个领域扮演了重要的角色,定性和定量测量锌的含量将帮助我们理解锌的生物学意义。我们偶然发现5,5-二乙烯基-2,2-联吡啶(DVBP)在二氧六环里对锌离子呈现出类似比例计量型荧光探针的特性:即有2个荧光发射峰而且长波长峰随锌离子的增加按比例增长。但DVBP难溶于水而且2个荧光发射峰距离太近从而相互干扰,我们尝试利用硅氢反应将DVBP固定在多孔硅上制备感应锌离子的光极,我们发现多孔硅固相载体上的联吡啶通过与锌离子的螯合后荧光增强约8倍,比DVBP在溶液里与锌离子螯合后的荧光增强(约4.5倍)还要多,联吡啶对锌离子的荧光响应是一个值得继续探索的领域。     

A ratiometric fluorescent probe for thiols based on a tetrakis(4-hydroxyphenyl)porphyrin-coumarin scaffold

In this work, we have designed and synthesized the compound Ratio-HPSSC, based on a tetrakis(4-hydroxyphenyl)porphyrin-coumarin scaffold, as a new ratiometric fluorescent probe for thiols. The ratiometric probe Ratio-HPSSC is highly selective and sensitive to thiols. Importantly, the novel ratiometric probe exhibited a remarkable change in emission color from red to blue. This key feature allows Ratio-HPSSC to be employed for thiol detection by simple visual inspection. Furthermore, we have demonstrated that Ratio-HPSSC is suitable for ratiometric fluorescence imaging of thiols in living cells. We believe that the new ratiometric probe will find interesting applications in chemistry, biology, and medicine.     

A Zn2+-specific turn-on fluorescent probe for ratiometric sensing of pyrophosphate in both water and blood serum

A novel fluorescent sensor composed of a naphthalene functionalized tetraazamacrocycle ligand 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-3-methyl naphthalene (1) and Zn(2+) has been designed and prepared, which can be utilized for selective and ratiometric sensing of pyrophosphate (PPi) over other phosphate-containing anions in aqueous solution at physiological pH. Notably, the water soluble 1 itself also exhibits a selective enhanced fluorescent response to Zn(2+), and the complex 1-Zn(2+) thus formed eventually fulfils the synergic Zn(2+) coordination-altered strategy with PPi. Furthermore, the ratiometric sensing of 1-Zn(2+) towards PPi performed well even in blood serum milieu. Finally, the sensor 1-Zn(2+) was successfully employed to monitor a real-time assay of inorganic pyrophosphatase (PPase) by means of ratiometric fluorescent measurements for the first time.     

Ratiometric fluorescence detection of bleomycin based on proximity-dependent fluorescence conversion of DNA-templated silver nanoclusters

We design a ratiometric fluo rescent sensing platform for bleomycin(BLM) by using proximity-dependent DNA-templated silver nanoclusters(DNA-AgNCs) probe.This ratiometric sensing system is constructed with DNA-AgNCs as single fluorophore.The proposed strategy is based on the two following facts:(1) a covert DNA can approach and transform the DNA-AgNCs with green emission(G-DNA-AgNCs) into red emission through hybridization reaction.(2) The specific cleavage of the convert DNA by BLM in the presence of Fe(Ⅱ) inhibits the discoloration of G-DNA-AgNCs.Thus,benefiting from the specific recognition of BLM and unique properties of G-DNA-AgNCs,a hignly-sensitive ratiometric sensor for BLM has been successfully developed.The detection limit is as low as 30 pmol/L.This label-free fluorescence probe possesses advantages of convenient synthetic process and low cost.Moreover,this ratiometric method has been applied to the detection of BLM in human serum samples,illustrating a promising tool for analysis of BLM in cancer therapy.     

A highly selective pyrophosphate sensor based on ESIPT turn-on in water

Pyrophosphate (PPi) is a biologically important target. A binuclear system 3?2Zn is found to selectively recognize PPi, leading to a ratiometric fluorescent sensor at pH 7.4 in water. The binding event triggered a large fluorescence response (～100 nm bathochromic shift) by turning on the excited state intramolecular proton transfer (ESIPT). Detection of PPi released from a PCR experiment indicated that this new probe could be a useful tool in bioanalytical applications.