发光ZnSalen配合物在分子荧光成像中的应用进展

荧光分子探针的设计、合成以及应用是分子荧光成像领域重要的化学问题.本文从Znsalen配合物的基本性质出发,概述了Znsalen配合物结构与功能的关系,特别是其发光性质与分子结构及分子聚集状态的相关性及应用.针对Znsalen配合物的发光性质,展示了其应用于分子荧光成像和活细胞中分子事件监测的研究进展.这些最新研究表明,Znsalen配合物探针的细胞毒性低(利于活细胞成像)、发光效率高(适用于单、双光子成像)、发光可调(通过配体的修饰和分子聚集状态的调节),有望作为一类重要的发光金属荧光探针实现在分子荧光成像中的应用.     

稀土有机配合物发光研究的新进展

本文描述了稀土有机配合物发光学基础研究及有关应用研究的国内外动态。评述了近十年来稀土-β二酮配合物发光研究的新进展及在工农业、科技方面的应用。对八十年代后期发展起来的稀土生物荧光标记、稀土离子在生物大分子结构探针研究方面也给予了综合报道。此外,对稀土-高分子有机配合物、低价态稀土-有机配合物发光研究的概况做了介绍。最后,本文还展望了稀土-有机配合物发光研究的发展趋势.     

单细胞核酸编码扩增成像分析

单细胞成像可在单细胞水平观测目标物位置、 确定目标物含量, 在生命科学与临床医学研究领域应用广泛. 核酸编码扩增技术利用特定分子反应将待测目标识别转化为核酸条码的扩增, 具有探针种类多、 易编程、 反应条件温和及信号放大效率高等特点, 在单细胞低丰度、 高灵敏、 多目标物成像中优势显著, 为理解细胞状态、 探索生命过程提供了新思路. 本文综合评述了核酸编码扩增在单细胞荧光成像领域的研究进展, 以目标物的编码方式为分类依据, 系统阐述了固定细胞原位成像和活细胞成像中不同目标物编码与扩增成像方式的区别, 并对活细胞成像中多重检测面临的问题以及未来发展前景进行了展望.     

水溶性超分子荧光探针对多菌灵的识别及细胞成像

基于八元瓜环(Q[8])可使吖啶橙(AD)的荧光降低的性质制备了荧光探针2AO@Q[8],当在该探针中加入多菌灵后荧光强度又逐渐增强,利用此超分子配合物的荧光效应,构建了一种能够检测多菌灵的超分子荧光探针.研究结果表明,该探针在水溶液中对多菌灵具有良好的选择性,在一定浓度范围内其线性关系良好,检出限为8. 14×10~(-8)mol/L.细胞成像结果显示,该探针在前列腺癌细胞中对多菌灵具有良好的响应,可用于生物细胞内多菌灵的识别检测.     

发光金属Salen配合物作为检测细胞内微黏度的荧光成像探针

细胞内微黏度是描述细胞状态的重要物理参数,与物质转运和信号转导等一系列扩散控制的生理过程密切相关.构筑对细胞内微黏度响应灵敏的荧光探针是原位实时检测细胞状态的重要手段之一.我们设计含有D-π-A推拉电子结构N,N'-双水杨醛缩乙二胺类配体(N,N'-thiophene-3,4-bis-4'-(diethylamino)-salicylimine,Salen)的Zn~(2+)和Al~(3+)配合物,考察了其光物理性质,发现该类配合物具有对溶液黏度依赖的荧光增强性质.同时,相比于配合物ZnSalen,[AlSalen]~+Cl~-具有检测灵敏度高、荧光成像信号增强倍数高等优点.利用激光扫描共聚焦荧光成像和荧光寿命成像,[AlSalen]~+Cl~-同样表现出在培养温度降低或细胞自噬下的荧光增强和发光寿命延长等变化,显示其作为检测细胞内微黏度荧光探针的潜在应用价值.     

可逆识别Hg~(2+)荧光探针的合成及活细胞中成像的应用

以罗丹明B与邻苯二甲酰氯为原料缩合反应得到新化合物T1,通过荧光光谱法研究了化合物与金属离子的识别特性.结果表明荧光探针T1能对Hg2+进行快速、选择性、可逆的识别,且常见金属离子对其干扰较小.探针的荧光强度与Hg2+浓度(4×10-8~9×10-8 mol/L)呈现较好的线性关系.探针在HepG2活细胞中的荧光显微成像表明T1可应用于生物体的检测.     

一种Hg~(2+)荧光探针的合成及其在活细胞成像中的应用（英文）

设计合成了一个新的罗丹明席夫碱类荧光探针1,其结构经~1H NMR、~(13)C NMR、MS和X射线单晶衍射的验证.通过紫外-可见光谱法和荧光光谱法研究了探针1在乙醇-水(V/V=7/3,HEPES 10 mmol/L,p H=7.0)中对Hg~(2+)的识别性能.探针1通过显著的荧光增强来识别Hg~(2+),并具有良好的选择性和抗干扰能力.通过Job’s plot和MS证明了探针1和Hg~(2+)形成1∶1的配合物.探针1的荧光强度与Hg~(2+)浓度(0~50μmol/L)呈良好的线性关系,可以定量地检测该范围内的Hg~(2+).在MGC-803活细胞中的荧光显微成像表明,探针1可检测生物体内的Hg~(2+).     

用于细胞成像的双氰基二苯代乙烯衍生物双光子荧光银离子探针

双光子荧光显微成像兼具诸如近红外激发、暗场成像、避免荧光漂白和光致毒、定靶激发、高横向分辨率与纵向分辨率、降低生物组织吸光系数及降低组织自发荧光干扰等特点,显著地优于单光子荧光显微成像,为生命科学研究提供了更为便利的工具.因此双光子荧光探针适合于生物检测与成像.制备了衍生于二苯代乙烯的双光子荧光银离子探针,此探针以拥有异常大的双光子吸收截面(6TPA)的4-甲基-2,5-二氰基-4'-氨基二苯乙烯(DCS)作为双光子荧光母体,以6-芳基-3,9-二硫-6-氮杂癸烷(TAU)为Ag+配体.探针显示了大的δTPA(在MeCN中,950 GM)、对银离子有高的灵敏性与选择性、强的双光子荧光(790 nm激光激发时).探针的络合常数为IgK=5.76±0.05.探针能选择性地检测和成像活细胞中的游离Ag+,可用于细胞中微量Ag+的分析检测与成像.此探针为开发理想的双光子荧光探针提供了可供借鉴的平台.     

荧光纳米探针用于细胞器pH检测的研究进展

pH稳态对于维持活细胞细胞器的正常功能具有重要作用.细胞器内pH稳态被打破会导致细胞器功能的紊乱,进而引发癌症、神经退行性疾病等相关疾病.因此,在活细胞水平上定量测定pH并对其波动进行实时监测对于理解相关疾病的发生机制非常重要.基于非侵入、高时空分辨率成像的优势,荧光探针非常适合用于活细胞内pH的检测.本综述总结了近些年利用不同种类荧光纳米探针对不同细胞器进行pH成像的研究工作,并对荧光纳米探针应用面临的机遇与挑战进行了展望.     

磷光寿命法研究稀土配合物的跨膜传输

从分子水平研究细胞与稀土离子及其配合物的作用机制和跨膜行为以及在细胞内作用的靶分子是阐明稀土生物效应的基础理论问题，研究这一问题对指导稀土的应用意义重大．要实现解决这一科学家梦寐以求的本质问题，关键是要寻求切实可行的有效的研究方法．室温磷光光谱分子探针技术在研究动物组织和细胞方面的应用发展非常迅速，由于氧在各种组织中分布的差异，因而对探针分子的磷光碎灭影响不同．曾经有人用把外吩配合物为磷光探针研究了细胞组织的病变行为’‘－‘’．本文选用的探针为稀土钦离子，通过测定稀土钦离子的磷光寿命，可以观察稀…     

A new class of macrocyclic lanthanide complexes for cell labeling and magnetic resonance imaging applications

Lanthanide complexes have wide applications in biochemical research and biomedical imaging. We have designed and synthesized a new class of macrocyclic lanthanide chelates, Ln/DTPA-PDA-C(n), for cell labeling and magnetic resonance imaging (MRI) applications. Two lipophilic Gd3+ complexes, Gd/DTPA-PDA-C(n) (n = 10, 12), labeled a number of cultured mammalian cells noninvasively at concentrations as low as a few micromolar. Cells took up these agents rapidly and showed robust intensity increases in T1-weighed MR images. Labeled cells showed normal morphology and doubling time as control cells. In addition to cultured cells, these agents also labeled primary cells in tissues such as dissected pancreatic islets. To study the mechanism of cellular uptake, we applied the technique of diffusion enhanced fluorescence resonance energy transfer (DEFRET) to determine the cellular localization of these lipophilic lanthanide complexes. After loading cells with a luminescent complex, Tb/DTPA-PDA-C10, we observed DEFRET between the Tb3+ complex and extracellular, but not intracellular, calcein. We concluded that these cyclic lanthanide complexes label cells by inserting two hydrophobic alkyl chains into cell membranes with the hydrophilic metal binding site facing the extracellular medium. As the first imaging application of these macrocyclic lanthanide chelates, we labeled insulin secreting beta-cells with Gd/DTPA-PDA-C12. Labeled cells were encapsulated in hollow fibers and were implanted in a nude mouse. MR imaging of implanted beta-cells showed that these cells could be followed in vivo for up to two weeks. The combined advantages of this new class of macrocyclic contrast agents ensure future imaging applications to track cell movement and localization in different biological systems.     

Cationic Biphotonic Lanthanide Luminescent Bioprobes Based on Functionalized Cross-Bridged Cyclam Macrocycles

Cationic lanthanide complexes are generally able to spontaneously internalize into living cells. Following our previous works based on a diMe-cyclen framework, a second generation of cationic water-soluble lanthanide complexes based on a constrained cross-bridged cyclam macrocycle functionalized with donor-π-conjugated picolinate antennas was prepared with europium(III) and ytterbium(III). Their spectroscopic properties were thoroughly investigated in various solvents and rationalized with the help of DFT calculations. A significant improvement was observed in the case of the Eu³⁺ complex, while the Yb³⁺ analogue conserved photophysical properties in aqueous solvent. Two-photon (2P) microscopy imaging experiments on living T24 human cancer cells confirmed the spontaneous internalization of the probes and images with good signal-to-noise ratio were obtained in the classic NIR-to-visible configuration with the Eu³⁺ luminescent bioprobe and in the NIR-to-NIR with the Yb³⁺ one.     

Time-resolved long-lived luminescence imaging method employing luminescent lanthanide probes with a new microscopy system

Superior fluorescence imaging methods are needed for detailed studies on biological phenomena, and one approach that permits precise analyses is time-resolved fluorescence measurement, which offers a high signal-to-noise ratio. Herein, we describe a new fluorescence imaging system to visualize biomolecules within living biological samples by means of time-resolved, long-lived luminescence microscopy (TRLLM). In TRLLM, short-lived background fluorescence and scattered light are gated out, allowing the long-lived luminescence to be selectively imaged. Usual time-resolved fluorescence microscopy provides fluorescence images with nanosecond resolution and has been used to image interactions between proteins, protein phosphorylation, the local pH, the refractive index, ion or oxygen concentrations, etc. Luminescent lanthanide complexes (especially europium and terbium trivalent ions (Eu3+ and Tb3+)), in contrast, have long luminescence lifetimes on the order of milliseconds. We have designed and synthesized new luminescent Eu3+ complexes for TRLLM and also developed a new TRLLM system using a conventional fluorescence microscope with an image intensifier unit for gated signal acquisition and a xenon flash lamp as the excitation source. When the newly developed luminescent Eu3+ complexes were applied to living cells, clear fluorescence images were acquired with the TRLLM system, and short-lived fluorescence was completely excluded. By using Eu3+ and Tb3+ luminescent complexes in combination, time-resolved dual-color imaging was also possible. Furthermore, we monitored changes of intracellular ionic zinc (Zn2+) concentration by using a Zn2+-selective luminescent Eu3+ chemosensor, [Eu-7]. This new imaging technique should facilitate investigations of biological functions with fluorescence microscopy, complementing other fluorescence imaging methodologies.     

Novel antennae for the sensitization of near infrared luminescent lanthanide cations

Near Infrared (NIR) luminescence is useful for many applications ranging from lasers, telecommunication to biological imaging. We have a special interest for applications in biological media since NIR photons have less interference with such samples. NIR photons can penetrate relatively deeply in tissues and cause less damage to biological samples. The use of NIR luminescence also results in improved detection sensitivity due to low background emission. The lower scattering of NIR photons results in improved image resolution. NIR emitting lanthanide compounds are promising for imaging because of their unique properties such as sharp emission bands, long luminescence lifetimes and photostability. Here, we review our efforts to develop novel sensitizers for NIR emitting lanthanides. We have employed two global strategies: (1) monometallic lanthanide complexes based on derivatives of salophen, tropolonate, azulene and pyridine; and (2) polymetallic lanthanide compounds based on nanocrystals, metal-organic frameworks and dendrimers complexes.     

1-Azathioxanthone Appended Lanthanide(III) DO3A Complexes That Luminesce Following Excitation at 405 nm**

Since the pioneering report by Selvin, we have been fascinated by the potential of using lanthanide luminescence in bioimaging. The uniquely narrow emission lines and long luminescence lifetimes both provide the potential for background free images together with full certainty of probe localization. General use of lanthanide based bioimaging was first challenged by low brightness, and later by the need of UV (<405 nm) excitation sources not present in commercial microscopes. Here, we designed three lanthanide-based imaging probes based on a known motif to investigate the limitations of 405 nm excitation. These were synthesized, characterized, investigated on dedicated as well as commercial microscopes, and the photophysics was explored in detail. It was proven without doubt that the lanthanide complexes enter the cells and luminesce internally. Even so, no lanthanide luminescence were recovered on the commercial microscopes. Thus, we returned to the photophysical properties that afforded the conclusion that – despite the advances in light sources and photodetectors – we need new designs that can give us brighter lanthanide complexes before bioimaging with lanthanide luminescence becomes something that is readily done.     

Pyridine-based lanthanide complexes combining MRI and NIR luminescence activities

A series of novel triazole derivative pyridine-based polyamino-polycarboxylate ligands has been synthesized for lanthanide complexation. This versatile platform of chelating agents combines advantageous properties for both magnetic resonance (MR) and optical imaging applications of the corresponding Gd(3+) and near-infrared luminescent lanthanide complexes. The thermodynamic stability constants of the Ln(3+) complexes, as assessed by pH potentiometric measurements, are in the range log K(LnL)=17-19, with a high selectivity for lanthanides over Ca(2+), Cu(2+), and Zn(2+). The complexes are bishydrated, an important advantage to obtain high relaxivities for the Gd(3+) chelates. The water exchange of the Gd(3+) complexes (k(ex)(298)=7.7-9.3×10(6) s(-1)) is faster than that of clinically used magnetic resonance imaging (MRI) contrast agents and proceeds through a dissociatively activated mechanism, as evidenced by the positive activation volumes (ΔV(≠)=7.2-8.8 cm(3) mol(-1)). The new triazole ligands allow a considerable shift towards lower excitation energies of the luminescent lanthanide complexes as compared to the parent pyridinic complex, which is a significant advantage in the perspective of biological applications. In addition, they provide increased epsilon values resulting in a larger number of emitted photons and better detection sensitivity. The most conjugated system PheTPy, bearing a phenyl-triazole pendant on the pyridine ring, is particularly promising as it displays the lowest excitation and triplet-state energies associated with good quantum yields for both Nd(3+) and Yb(3+) complexes. Cellular and in vivo toxicity studies in mice evidenced the non-toxicity and the safe use of such bishydrated complexes in animal experiments. Overall, these pyridinic ligands constitute a highly versatile platform for the simultaneous optimization of both MRI and optical properties of the Gd(3+) and the luminescent lanthanide complexes, respectively.     

Gadolinium(III) complexes as MRI contrast agents: ligand design and properties of the complexes

Magnetic resonance imaging is a commonly used diagnostic method in medicinal practice as well as in biological and preclinical research. Contrast agents (CAs), which are often applied are mostly based on Gd(III) complexes. In this paper, the ligand types and structures of their complexes on one side and a set of the physico-chemical parameters governing properties of the CAs on the other side are discussed. The solid-state structures of lanthanide(III) complexes of open-chain and macrocyclic ligands and their structural features are compared. Examples of tuning of ligand structures to alter the relaxometric properties of gadolinium(III) complexes as a number of coordinated water molecules, their residence time (exchange rate) or reorientation time of the complexes are given. Influence of the structural changes of the ligands on thermodynamic stability and kinetic inertness/lability of their lanthanide(III) complexes is discussed.     

Azulene-moiety-based ligand for the efficient sensitization of four near-infrared luminescent lanthanide cations: Nd3+, Er3+, Tm3+, and Yb3+

The ML(4) complexes formed by reaction between the bidentate azulene-based ligand diethyl 2-hydroxyazulene-1,3-dicarboxylate (HAz) and several lanthanide cations (Pr(3+), Nd(3+), Gd(3+), Ho(3+), Er(3+), Tm(3+), Yb(3+), and Lu(3+)) have been synthesized and characterized by elemental analysis, FT-IR vibrational spectroscopy and electrospray ionization mass spectroscopy. Spectrophotometric titrations have revealed that four Az(-) ligands react with one lanthanide cation to form the ML(4) complex in solution. Studies of the luminescence properties of these ML(4) complexes demonstrated that Az(-) is an efficient sensitizer for four different near-infrared emitting lanthanide cations (Nd(3+), Er(3+), Tm(3+), and Yb(3+)); the resulting complexes have high quantum yield values in CH(3)CN. The near-infrared emission arising from Tm(3+) is especially interesting for biologic imaging and bioanalytical applications since biological systems have minimal interaction with photons at this wavelength. Hydration numbers, representing the number of water molecules bound to the lanthanide cations, were obtained through luminescence lifetime measurements and indicated that no molecules of water/solvent are bound to the lanthanide cation in the ML(4) complex in solution. The four coordinated ligands protect well the central luminescent lanthanide cation against non-radiative deactivation from solvent molecules.     

Cationic iridium(III) complexes for phosphorescence staining in the cytoplasm of living cells

Two cationic iridium(III) complexes with bright green and red emissions were demonstrated as phosphorescent dyes for living cell imaging. In particular, their exclusive staining in cytoplasm, low cytotoxicity and reduced photobleaching, as well as cell membrane permeability, make the two complexes promising candidates for the design of specific bioimaging agents.     

Luminescence imaging microscopy and lifetime mapping using kinetically stable lanthanide(III) complexes

The sensitised luminescence from stable lanthanide complexes (1 and 2) bearing a phenanthridine antenna has been used to generate time-resolved images of silica particles. The millisecond order luminescent lifetime of these complexes is utilised to demonstrate time-gated imaging of the sample from a fluorescent background and to facilitate lifetime mapping over the area of the sample.