基于硼酸及硼酸酯的细胞器靶向过氧化氢荧光探针的研究进展

过氧化氢(H2O2)是活性氧(reactive oxygen species,ROS)的重要组成部分,是氧代谢的重要产物,与许多生物过程有关。但是,H2O2的异常产生与许多疾病密切相关,例如细胞损伤、炎症疾病和癌症。为了更好地了解H2O2在亚细胞水平上的作用,科研工作者已经开发了许多H2O2荧光探针,用于在不同细胞器中对H2O2进行成像。硼酸盐由于对H2O2的高选择性和敏感性而被用作H2O2的识别基团。综述中重点介绍基于硼酸盐与线粒体、内质网、溶酶体、高尔基体和细胞核靶向能力的H2O2荧光探针的代表性实例。包含其分子结构、细胞器靶向设计策略、荧光行为及其生物学应用。     

线粒体靶向型离子荧光探针的研究进展

线粒体在细胞的能量代谢过程中发挥着关键作用。线粒体内含有各种生物活性物质,它们在人体各种生理和病理过程中发挥着重要作用。综述了近年来有机单、双光子线粒体靶向型离子荧光探针的研究现状,重点介绍了荧光探针的设计机理、识别机理、特点以及生物应用,并对该类探针的未来发展趋势进行了展望。     

线粒体靶向型离子荧光探针的研究进展

线粒体在细胞的能量代谢过程中发挥着关键作用。线粒体内含有各种生物活性物质，它们在人体各种生理和病理过程中发挥着重要作用。综述了近年来有机单、双光子线粒体靶向型离子荧光探针的研究现状，重点介绍了荧光探针的设计机理、识别机理、特点以及生物应用，并对该类探针的未来发展趋势进行了展望。     

线粒体内活性硫有机荧光小分子探针研究进展

该文综述了近年来有机单、双光子线粒体内H_2S、SO_2、巯基、多硫化氢及苯硫酚活性硫物种(RSS)荧光探针研究现状,重点讨论了荧光探针选择性、灵敏度、识别机理、细胞毒性以及生物监测成像等方面的性能,并提出这类荧光探针存在的问题以及未来的发展趋势,旨在为构建新型线粒体荧光探针和进一步剖析线粒体内RSS的细胞学功能提供重要的理论和实践意义。     

用于检测次氯酸的线粒体靶向荧光探针研究进展

次氯酸是一种来源于线粒体的活性氧，在各种生理和病理过程中起着重要的作用。但是，当细胞中的HOCl浓度超过正常值时范围，它会导致机体损伤和一系列疾病。因此，近年来开发设计了一系列能实时识别和监测线粒体中的次氯酸水平的荧光探针，这有助于更好地了解生物体健康状况和HOCl起到的生理作用和病理过程。主要介绍了近几年HOCl荧光探针的应用和发展，根据靶向线粒的基团类别，分别介绍了三苯基膦类荧光探针，半花菁类荧光探针，氟硼吡咯类荧光探针。     

香豆素类荧光探针研究进展

香豆素类化合物不仅具有广发的生物活性,同时香豆素类化合物具有荧光强度高、溶解性和细胞渗透性好及易于合成的优点。因此,香豆素类化合物也是优良的荧光团之一。综述了近几年利用香豆素片段为荧光团,对待测物进行荧光成像研究的荧光探针,同时对这些荧光探针的设计、机理及特点进行了概述。     

用于溶酶体定位的比率型次氯酸根探针的构建及应用研究

以常见荧光团罗丹明和萘酰亚胺设计并合成了一例用于比率型识别次氯酸根的荧光探针。结果表明,探针能够对次氯酸根实现高效专一的比率型选择,能够克服其他分析物的干扰。溶液体系荧光发射强度比率值(F_(590 nm)/F_(542 nm))在次氯酸钠浓度为0～1μmol/L范围内呈现良好的线性,其对次氯酸根的最低检出限为1.3×10~(-8) mol/L。探针可以定位于亚细胞器溶酶体中识别次氯酸根,并且能够应用于自来水等实际样品中检测次氯酸根。     

新型近红外荧光探针成像细胞肺纤维化过程粘度变化

肺纤维化是一种致命疾病，患病率不断上升。肺纤维化的非放射性和无创性早期诊断可以改善预后，但却是艰巨的挑战。粘度的异常是肺纤维化的典型微环境特征。最近，粘度的精准可视化检测引起了人们的广泛兴趣。然而，由于其特性复杂，直接观察生物系统中的粘度仍然是一个巨大的挑战。线粒体粘度波动与肺纤维化、糖尿病、神经退行性疾病、癌症等多种疾病有关。在这里，报告了一种新型小分子荧光探针NIR-V-BR,用于检测线粒体粘度变化。NIR-V-BR对粘度变化具有近红外发射、优异的水溶性、良好的光稳定性、良好的膜通透性和低细胞毒性。共定位实验表明NIR-V-BR探针具有良好的线粒体靶向能力。NIR-V-BR成功应用于成像活细胞线粒体中粘度变化。最重要的是，NIR-V-BR探针荧光成像实验表明肺纤维化细胞中粘度水平升高。这些结果表明，NIR-V-BR将为生物医学诊断和成像应用提供新的机会。     

Fe3+荧光探针的研究进展

综述了近几年来用于Fe~(3+)检测的荧光探针研究进展。重点介绍了以香豆素、罗丹明、氟硼二吡咯(BODIPY)作为荧光团的Fe~(3+)荧光探针,及部分其它类型铁离子荧光探针的结构和设计原理,概述了Fe~(3+)荧光探针在检测过程中的优点,并展望了Fe~(3+)荧光探针的研究和发展方向。     

有机线粒体内HClO/ClO~-荧光探针研究进展

基于荧光探针与线粒体内HClO/ClO~-的识别机理,介绍了近年来有机单、双光子线粒体内HClO/ClO~-荧光探针的研究现状,并对其未来发展方向进行了展望。     

Differently Tagged Probes for Protein Profiling of Mitochondria

The mitochondrion is one of the most important organelles in the eukaryotic cell. Characterization of the mitochondrial proteome is a prerequisite for understanding its cellular functions at the molecular level. Here we report a proteomics method based on mitochondrion-targeting groups and click chemistry. In our strategy, three different mitochondrion-targeting moieties were each augmented with a clickable handle and a cysteine-reactive group. Fluorescence-based bioimaging and fractionation experiments clearly showed that most signals arising from the labels were localized in the mitochondria of cells, as a result of covalent attachment between probe and target proteins. The three probes had distinct profiling characteristics. Furthermore, we successfully identified more than two hundred mitochondrial proteins. The results showed that different mitochondrion-targeting groups targeted distinct proteins with partial overlap. Most of the labeled proteins were localized in the mitochondrial matrix and inner mitochondrial membrane. Our results provide a tool for chemoproteomic analysis of mitochondrion-related proteins.     

One Scaffold,Different Organelle Sensors: pH-Activable Fluorescent Probes for Targeting Live Microglial Cell Organelles**

Targeting live cell organelles is essential for imaging, understanding, and controlling specific biochemical processes. Typically, fluorescent probes with distinct structural scaffolds are used to target specific cell organelles. Here, we have designed a modular one-step synthetic strategy using a common reaction intermediate to develop new lysosomal, mitochondrial, and nucleus-targeting pH-activable fluorescent probes that are all based on a single boron dipyrromethane scaffold. The divergent cell organelle targeting was achieved by synthesizing probes with specific functional group changes to the central scaffold resulting in differential fluorescence and pK_a. Specifically, we show that the functional group transformation of the same scaffold influences cellular localization and specificity of pH-activable fluorescent probes in live primary microglial cells with pK_a values ranging from ∼3.2–6.0. We introduce a structure-organelle-relationship (SOR) framework to target nuclei ( NucShine ), lysosomes ( LysoShine ), and mitochondria ( MitoShine ) in live microglia. This work will result in future applications of SOR beyond imaging to target and control organelle-specific biochemical processes in disease-specific models.     

Visualizing biochemical activities in living cells through chemistry

The development of molecular probes to visualize cellular processes is an important challenge in chemical biology. One possibility to create such cellular indicators is based on the selective labeling of proteins with synthetic probes in living cells. Over the last years, our laboratory has developed different labeling approaches for monitoring protein activity and for localizing synthetic probes inside living cells. In this article, we review two of these labeling approaches, the SNAP-tag and CLIP-tag technologies, and their use for studying cellular processes.     

Motility Plays an Important Role in the Lifetime of Mammalian Lipid Droplets

The lipid droplet is a kind of organelle that stores neutral lipids in cells. Recent studies have found that in addition to energy storage, lipid droplets also play an important role in biological processes such as resistance to stress, immunity, cell proliferation, apoptosis, and signal transduction. Lipid droplets are formed at the endoplasmic reticulum, and mature lipid droplets participate in various cellular processes. Lipid droplets are decomposed by lipase and lysosomes. In the life of a lipid droplet, the most important thing is to interact with other organelles, including the endoplasmic reticulum, mitochondria, peroxisomes, and autophagic lysosomes. The interaction between lipid droplets and other organelles requires them to be close to each other, which inevitably involves the motility of lipid droplets. In fact, through many microscopic observation techniques, researchers have discovered that lipid droplets are highly dynamic organelles that move quickly. This paper reviews the process of lipid droplet motility, focusing on explaining the molecular basis of lipid droplet motility, the factors that regulate lipid droplet motility, and the influence of motility on the formation and decomposition of lipid droplets. In addition, this paper also proposes several unresolved problems for lipid droplet motility. Finally, this paper makes predictions about the future research of lipid droplet motility.     

Recent advances of small-molecule fluorescent probes for detecting biological hydrogen sulfide

H₂S is well-known as a colorless,acidic gas,with a notoriously rotten-egg smell.It was recently revealed that H₂S is also an endogenous signaling molecule that has important biological functions,however,most of its physiology and pathology remains elusive.Therefore,the enthusiasm for H₂S research remains.Fluorescence imaging technology is an important tool for H₂S biology research.The development of fluorescence imaging technology has realized the study of H₂S in subcellular organelles,facilitated by the development of fluorescent probes.The probes reviewed in this paper were categorized according to their chemical mechanism of sensing and were divided into three groups:H₂S reducibility-based probes,H₂S nucleophilicity-based probes,and metal sulfide precipitation-based probes.The structure of the probes,their sensing mechanism,and imaging results have been discussed in detail.Moreover,we also introduced some probes for hydrogen polysulfides.     

Regulation of Endoplasmic Reticulum–Mitochondria Tethering and Ca2+ Fluxes by TDP-43 via GSK3β

Mitochondria–ER contacts (MERCs), tightly regulated by numerous tethering proteins that act as molecular and functional connections between the two organelles, are essential to maintain a variety of cellular functions. Such contacts are often compromised in the early stages of many neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). TDP-43, a nuclear protein mainly involved in RNA metabolism, has been repeatedly associated with ALS pathogenesis and other neurodegenerative diseases. Although TDP-43 neuropathological mechanisms are still unclear, the accumulation of the protein in cytoplasmic inclusions may underlie a protein loss-of-function effect. Accordingly, we investigated the impact of siRNA-mediated TDP-43 silencing on MERCs and the related cellular parameters in HeLa cells using GFP-based probes for MERCs quantification and aequorin-based probes for local Ca²⁺ measurements, combined with targeted protein and mRNA profiling. Our results demonstrated that TDP-43 down-regulation decreases MERCs density, thereby remarkably reducing mitochondria Ca²⁺ uptake after ER Ca²⁺ release. Thorough mRNA and protein analyses did not highlight altered expression of proteins involved in MERCs assembly or Ca²⁺-mediated ER–mitochondria cross-talk, nor alterations of mitochondrial density and morphology were observed by confocal microscopy. Further mechanistic inspections, however, suggested that the observed cellular alterations are correlated to increased expression/activity of GSK3β, previously associated with MERCs disruption.     

Recent Advances in Small Molecule-Based Intracellular pH Probes

Intracellular pH plays an important role in many biological and pathological processes. Small-molecule based pH probes are found to be the most effective for pH sensing because of ease of preparation, high sensitivity, and quick response. They have many advantages such as small perturbation to the functions of the target, functional adaptability, cellular component-specific localization, etc. The present review highlights the flurry of recent activity in the development of such probes. The probes are categorized based on the type of fluorophore used like quinoline, coumarin, BODIPY, rhodamine, indolium, naphthalimide, etc., and their analytical performance is discussed.     

Nanomagnetism reveals the intracellular clustering of iron oxide nanoparticles in the organism

There are very few methods to investigate how nanoparticles (NPs) are taken up and processed by cells in the organism in the short and long terms. We propose a nanomagnetism approach, in combination with electron microscopy, to document the magnetic outcome of iron oxide-based P904 NPs injected intravenously into mice. The NP superparamagnetic properties are shown to be modified by cell internalization, due to magnetic interactions between NPs sequestered within intracellular organelles. These modifications of magnetic behaviour are observed in vivo after NP uptake by resident macrophages in spleen and liver or by inflammatory macrophages in adipose tissue as well as in vitro in monocyte-derived macrophages. The dynamical magnetic response of cell-internalized NPs is theoretically and experimentally evidenced as a global signature of their local organization in the intracellular compartments. The clustering of NPs and their magnetism become dependent on the targeted organ, on the dose administrated and on the time elapsed since their injection. Nanomagnetism probes the intracellular clustering of iron-oxide NPs and sheds light on the impact of cellular metabolism on their magnetic responsivity.