用于生物成像的近红外小分子荧光探针的研究进展

小分子荧光探针具有灵敏度高、生物相容性好、样品损伤小等优点，在疾病相关的生物分子检测领域显示出巨大潜力。但是，大部分的荧光探针发射波长短、斯托克斯位移较小，限制了其在生物成像中的应用。近年来，越来越多具有较长波长的近红外荧光探针被开发出来，用于疾病相关的生物分子的成像检测。对不同结构的荧光探针进行分类讨论，系统介绍了以花菁、半花菁、氧杂蒽和氟硼吡咯染料为荧光团的近红外探针的研究进展，简要概述近红外小分子荧光探针在对生物分子识别过程中的作用原理和生物成像领域的应用，这对荧光探针的性能提升和未来发展提出新的研究思路。     

基于半花菁染料荧光探针的应用及研究进展

半花菁是一个氮杂环阳离子和一个末端羟基、烷氧基或氨基通过π共轭桥连在一起的荧光染料,具有优异的光学性质和良好的稳定性,其独特的线粒体靶向能力以及近红外发射特性使以半花菁为骨架的荧光探针在荧光检测和识别方面发挥着重要的作用.本文综述了基于半花菁染料构建的荧光探针在识别各种离子、活性硫、生物酶等方面的研究及应用.     

基于醛基取代的氟硼二吡咯类荧光母体探针的合成及其应用

荧光探针具有灵敏度高、可实时检测、精准诊断与成像可视化等优点，被广泛应用于生物医药、信息存储、化学分析等领域。氟硼二吡咯（BODIPY）类荧光探针因其优异的光物理化学特性而被广泛设计与开发使用。该文综述了醛基取代的BODIPY荧光探针的分子设计策略和功能化应用，包括α位醛基BODIPY、β位醛基BODIPY、meso位醛基BODIPY和1,7-位醛基BODIPY的不同位点醛基调控的BODIPY荧光母体探针及其在阴离子检测、生物硫醇识别及细胞成像方面的研究进展。设计新型的醛基取代BODIPY荧光探针将在精准诊疗上具有巨大的发展空间。     

反应激活型酶荧光探针的研究进展

酶在维持生物体内稳态与生命活动的正常运行方面发挥着举足轻重的作用。某些特定酶含量及活性的异常与人类重大疾病的发生与发展密切相关。因此,生物体内特定酶的实时原位检测及可视化成像具有重要的意义。化学荧光探针具有选择性好、灵敏度高及高时空分辨率可视化成像等优点,近年来研究者设计合成了大量的可用于生物体系内酶识别与可视化成像的荧光探针。目前识别酶的荧光探针主要有两类：（1）基于酶对荧光探针分子中酶抑制剂基团的识别引起探针荧光信号的变化;（2）基于酶对荧光探针特异性催化反应来实现识别前后荧光信号的激活,称为反应激活型酶荧光探针。对反应激活型酶荧光探针的设计策略及4种重大疾病相关的生物标志酶（单胺氧化酶、β-半乳糖苷酶、硝基还原酶、γ-谷氨酰转肽酶）的识别可视化荧光探针研究进展进行了综述,对未来酶识别荧光探针的研究方向进行了展望。     

基于醛基取代的氟硼二吡咯类荧光母体探针的合成及其应用

荧光探针具有灵敏度高、可实时检测、精准诊断与成像可视化等优点,被广泛应用于生物医药、信息存储、化学分析等领域。氟硼二吡咯(BODIPY)类荧光探针因其优异的光物理化学特性而被广泛设计与开发使用。该文综述了醛基取代BODIPY荧光团的分子设计策略和功能化应用,包括α位醛基-BODIPY、β位醛基-BODIPY、meso位醛基-BODIPY和1,7-位醛基-BODIPY的不同位点醛基调控的BODIPY荧光母体探针及其在阴离子检测、生物硫醇识别及细胞成像等方面的研究进展。设计新型的醛基取代BODIPY探针,未来在精准诊疗上具有发展空间。     

香豆素类荧光传感器检测金属离子的研究进展

金属离子对自然环境和生物体的生长发育具有重要的影响,因此对环境中及生物体内的金属离子的识别和检测正日益受到人们广泛的关注。在不同的分析方法中,荧光分析法具有灵敏度高、选择性好和实时原位检测等优点,是实现环境中和生物体内金属离子识别和检测的良好工具。本文综述了近5年来香豆素类荧光传感器对一些重金属离子（Hg2+、Pb2+、Cd2+、Ni2+、Ag+）和一些具有重要生物学意义的过渡金属离子（Cu2+、Zn2+、Fe3+）的识别与检测及其应用进展情况,着重介绍了传感器分子的设计合成、识别机理、传感特性及其在环境分析和生物检测中的应用。随着金属离子检测要求的提高,未来香豆素类荧光传感器的设计将向着灵敏度更高、选择性更好、抗干扰性能更强的方向发展。此外,香豆素类传感器在生物检测中的应用研究有望得到进一步发展。     

对香豆素类荧光分子探针的认识

香豆素类荧光分子探针具有高灵敏性、选择性、分辨时间短等突出优点,因而在环境科学、医学、生物学等领域有重要应用。本文综述了香豆素类荧光探针在阴阳离子和中性分子识别检测中的分子设计、作用环境和应用效果,展望了该领域的发展方向。     

反应激活型酶荧光探针的研究进展

酶在维持生物体内稳态与生命活动的正常运行方面发挥着举足轻重的作用。某些特定酶含量及活性的异常与人类重大疾病的发生与发展密切相关。因此,生物体内特定酶的实时原位检测及可视化成像具有重要的意义。化学荧光探针具有选择性好、灵敏度高及高时空分辨率可视化成像等优点,近年来研究者设计合成了大量的可用于生物体系内酶识别与可视化成像的荧光探针。目前识别酶的荧光探针主要有两类:(1)基于酶对荧光探针分子中酶抑制剂基团的识别引起探针荧光信号的变化;(2)基于酶对荧光探针特异性催化反应来实现识别前后荧光信号的激活,称为反应激活型酶荧光探针。对反应激活型酶荧光探针的设计策略及4种重大疾病相关的生物标志酶(单胺氧化酶、β-半乳糖苷酶、硝基还原酶、γ-谷氨酰转肽酶)的识别可视化荧光探针研究进展进行了综述,对未来酶识别荧光探针的研究方向进行了展望。     

基于二氟化硼-二吡咯甲烷(BODIPY)类染料的次氯酸荧光探针的研究进展

次氯酸(HCl O)作为一种生物体内关键的活性氧物种(ROS),在多种正常的生化功能和异常病理过程中扮演着非常重要的角色。因此,识别与实时准确地监测细胞内次氯酸在活动位点的浓度变化对于生物学研究和临床诊断极其重要。而在所有的检测方法中,荧光探针法由于其灵敏度高、选择性好、易于操作、实时可视化检测、原位检测、无损检测、响应时间快速、所需试剂量小等优点而引起广大科研工作者的兴趣并将其用于生物体内次氯酸的检测及其生理功能的研究。重点综述了近年来基于BODIPY类染料的次氯酸荧光分子探针的设计合成、检测机理及其在生物成像上的应用研究进展。     

重金属离子荧光探针的应用及研究进展

荧光探针因具有高灵敏度、高选择性、使用便捷、成本低廉、样品不需要预处理等优点而备受关注,如今已成为一种重要的荧光传感分析方法。对荧光探针的识别机理、各种荧光探针分子在离子检测方面的应用作了简要介绍。介绍了卟啉类、罗丹明类、萘酰亚胺类、喹啉类、香豆素类和荧光纳米材料类等不同类型的荧光探针在重金属离子检测领域的研究与应用情况;阐述了重金属离子荧光探针的研究方向和前景,对其未来的发展趋势作了进一步的展望。     

Fluorescent probes and functional materials for biomedical applications

Due to their simplicity in preparation, sensitivity and selectivity, fluorescent probes have become the analytical tool of choice in a wide range of research and industrial fields, facilitating the rapid detection of chemical substances of interest as well as the study of important physiological and pathological processes at the cellular level. In addition, many long-wavelength fluorescent probes developed have also proven applicable for in vivo biomedical applications including fluorescence-guided disease diagnosis and theranostics (e.g., fluorogenic prodrugs). Impressive progresses have been made in the development of sensing agents and materials for the detection of ions, organic small molecules, and biomacromolecules including enzymes, DNAs/RNAs, lipids, and carbohydrates that play crucial roles in biological and disease-relevant events. Here, we highlight examples of fluorescent probes and functional materials for biological applications selected from the special issues “Fluorescent Probes” and “Molecular Sensors and Logic Gates” recently published in this journal, offering insights into the future development of powerful fluorescence-based chemical tools for basic biological studies and clinical translation.     

Near-Infrared Fluorescent Heptamethine Cyanine Dyes for COX-2 Targeted Photodynamic Cancer Therapy

We designed and synthesized two heptamethine cyanine-based theranostic probes that aimed to target COX-2 in cancer cells. One is I-IR799 - CXB , in which I-IR799 is conjugated to the COX-2-specific inhibitor, celecoxib, and another is I-IR799 - IMC , where the non-selective COX inhibitor, indomethacin, was used. I-IR799 is a heptamethine cyanine derivative that can be activated by near-infrared light for photodynamic therapy (PDT) purposes. I-IR799 - CXB and I-IR799 - IMC were tested for their cancer-targeting capacity and photodynamic efficiency toward hepatocellular carcinoma (HepG2) cells relative to normal liver cells, alpha mouse liver 12 (AML12) cells. Interestingly, after conjugation, I-IR799 - IMC exhibited better tumour targetability and PDT efficiency than I-IR799 - CXB .     

Bioluminescence Resonance Energy Transfer (BRET)-coupled Annexin V-functionalized Quantum Dots for Near-Infrared Optical Detection of Apoptotic Cells

Deregulation in apoptosis induces numerous diseases such as cancer, cardiovascular, and neurodegenerative diseases. Detection of apoptotic cells is crucial for understanding the mechanism of these diseases and for therapy development. Although optical imaging using visible-emitting fluorescent probes, such as FITC-labeled annexin V, is widely used for the detection of apoptotic cells, there are very limited probes that can be used in the near-infrared region (NIR) over 700 nm. Compared with visible light, NIR light is highly permeable in turbid biological samples and tissues. In addition, optical imaging in the NIR region shows low autofluorescence from biological samples, leading to clearer images with high signal to background ratios. Here, we report the synthesis of bioluminescence resonance energy transfer (BRET)-coupled annexin V-functionalized quantum dots (QDs) and their application to NIR optical detection of apoptotic cells.     

反应型荧光探针在检测金属离子中的研究进展

金属离子广泛存在于自然界中,与环境科学、生命科学、医学等领域有着密切的联系。一些金属离子如Hg²⁺、Fe³⁺、Cu²⁺、Zn²⁺、Al³⁺等,在生物体的生理和病理中扮演着重要角色,摄入过量或不足都会导致生理功能的紊乱,引发各种疾病。近几年来,反应型荧光探针因其高选择性和高灵敏性的特点得到了快速的发展。本文主要综述了近五年来反应型荧光探针在检测金属离子中的研究进展,主要介绍了各类探针分子的设计合成、传感机理、检测结果以及其在生物检测中的应用。指出反应型荧光探针的研究发展还处在初级阶段,该领域将会朝着灵敏度更高、反应时间更少、应用范围更广的方向发展,此外,反应型荧光探针在生物检测以及实际应用方面也有望得到进一步的应用发展。     

Fluorescent hydroxyapatite‐loaded biodegradable polymer nanoparticles with folate decoration for targeted imaging

The preparation of the luminescent hydroxyapatite (HAP)‐loaded biocompatible nanoparticles (NPs) for targeted imaging of cancer cells is described. Currently, cellular imaging using fluorescent probes is an important technique for the early diagnosis of cancer. Compared with the quantum dots, luminescent HAP is a new fluorescent material with many advantages such as low toxicity, biocompatibility, thermal stability, resistance to erosion, and low prices. Thus, luminescent HAP has enormous potential to be used as biological fluorescent probes. However, luminescent HAP is water‐insoluble, low sensitivity, which limit its application in the field of cellular imaging. Surface modification of NPs with targeting molecule was carried out to achieve its target function. Thus, novel fluorescent NPs with low toxicity, high sensitivity, and good photostability were prepared to be used for targeted imaging of cancer cells. This study initially explored the applications of luminescent HAP in the field of targeted cellular imaging. This NPs platform will be a promising tool for molecular imaging and medical diagnostics, especially the detection of cancer at its early stage. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4494–4501, 2013     

Recent Advances in the Development of Optical Imaging Probes for γ-Glutamyltranspeptidase

γ-Glutamyltranspeptidase (GGT) is a cell-membrane-bound protease that participates in cellular glutathione and cysteine homeostasis, which are closely related to many physiological and pathological processes. The accurate measurement of GGT activity is useful for the early diagnosis of diseases. In the past few years, many efforts have been made to build optical imaging probes for the detection of GGT activity both in vitro and in vivo. In this Minireview, recent advances in the development of various optical imaging probes for GGT, including activatable fluorescence probes, ratiometric fluorescence probes, and activatable bioluminescence probes, are summarized. This review starts from the instruction of the GGT enzyme and its biological functions, followed by a discussion of activatable fluorescence probes that show off–on fluorescence in response to GGT. GGT-activatable two-photon fluorescence imaging probes with improved imaging depth and spatial resolution are also discussed. Ratiometric fluorescence probes capable of accurately reporting on GGT levels through a self-calibration mechanism are discussed, followed by describing GGT-activatable bioluminescence probes that can offer a high signal-to-background ratio to detect GGT in living mice. Finally, current challenges and further perspectives for the development of molecular imaging probes for GGT are addressed.     

Design Strategies of Photoacoustic Molecular Probes

Photoacoustic (PA) probes have been developed very quickly and applied in broad areas in recent years. Most of them are constructed based on organic dyes with intrinsic near-infrared (NIR) absorption properties. To increase PA contrast and improve imaging resolution and the sensitivity of detection, various methods for the design of PA probes have been developed. This minireview mainly focuses on the development and design strategies of activatable small-molecule PA probes in four aspects: reaction-cleavage, metal ion chelation, photoswitch, and protonation-deprotonation. It highlights some key points of designing PA probes corresponding to their properties and applications. The challenges and perspectives for small-molecule PA probes are also discussed.     

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。     

氮杂氟硼荧（Aza-BODIPY）类荧光探针的研究进展

氮杂氟硼荧（Aza-BODIPY）作为BODIPYs改良型荧光团,具有摩尔吸光系数高、荧光光谱半峰宽窄、荧光寿命长、光稳定性好、荧光可调等优点,是优良的近红外比色及荧光探针候选母体,然而Aza-BODIPY也存在水溶性能差、应用领域待扩展等问题。本文主要综述了近年来各类以Aza-BODIPY为荧光团的探针种类及其应用：首先,简要概括了3种通用的Aza-BODIPY合成方法,包括从查尔酮出发合成Aza-BODIPY的O'Shea法、从2,4-二取代吡咯出发的Carreira法和Lukyanets的邻苯二腈与苯基溴化镁反应的稠环合成法;然后重点对pH、H₂O₂、NH₄⁺、F^-、Hg²⁺、CN^-、蛤毒素和Cys等探针的客体识别性能、识别机理和实际应用进行了总结。提出目前以Aza-BODIPY为母体设计合成的探针数量仍较少,将来的发展方向是通过结构修饰或改造来提高探针的水溶性能、拓宽其激发发射波长到近红外区、增加识别客体的种类和范围,在生物、环境等领域将具有重要的发展前景。     

Fabrication of SERS-fluorescence dual modal nanoprobes and application to multiplex cancer cell imaging

We report a highly sensitive optical imaging technology using surface-enhanced Raman scattering (SERS)-fluorescence dual modal nanoprobes (DMNPs). Fluorescence microscopy is a well-known imaging technique that shows specific protein distributions within cells. However, most currently available fluorescent organic dyes have relatively weak emission intensities and are rapidly photo-bleached. Thus more sensitive and stable probes are needed. In this work we develop DMNPs, which can be used for both SERS and fluorescence detection. SERS detection is a powerful technique that allows ultrasensitive chemical or biochemical analysis through unlimited multiplexing and single molecule sensitivity. Combining advantages of fluorescence and SERS allows these dual modal nanostructures to be used as powerful probes for novel biomedical imaging. In this work, the fabrication and characterization of the SERS-fluorescence DMNPs and application to biological imaging were investigated using markers CD24 and CD44, which are co-expressed in MDA-MB-231 breast cancer cells, as a model system. SERS imaging with DMNPs was found to be a powerful tool to determine the co-localization of CD24 and CD44 in the cell.