基于萘酰亚胺的次氯酸荧光探针的合成及细胞成像性能研究

以萘酰亚胺结构为荧光发色团,设计开发了一种含C=C双键的、具有分子内电荷转移(ICT)效应的新型水溶性优化的次氯酸荧光探针3-(2-氰基丙烯酸乙酯基)-4-羟基-N-正丙基-1,8-萘酰亚胺(NAEC).添加次氯酸后,探针分子NAEC中的C=C双键被氧化,生成醛基,探针NAEC原有的ICT效应被破坏,产生荧光信号.经核...     

A Ratiometric Fluorescent Probe for Gold and Mercury Ions

A fluorescent probe that displays a ratiometric fluorescence response towards gold and mercury ions has been devised. Emitting at a relatively longer wavelength, the conjugated form of the fluorescent dye transforms in the presence of the gold or mercury ions into a new dye, the molecular structure of which lacks the conjugation and consequently emits at a distinctly shorter wavelength.     

A Two-Photon Fluorescent Probe for the Visual Detection of Peroxynitrite in Living Cells and Zebrafish

Peroxynitrite (ONOO⁻), as an important reactive oxygen species (ROS), holds great potential to react with a variety of biologically active substances, leading to the occurrence of various diseases such as cancer and neurodegenerative diseases. In this work, we developed a novel mitochondria-localized fluorescent probe, HDBT-ONOO⁻, which was designed as a mitochondria-targeting two-photon fluorescence probe based on 1,8-naphthylimide fluorophore and the reactive group of 4-(bromomethyl)-benzene boronic acid pinacol ester. More importantly, the probe exhibited good biocompatibility, sensitivity, and selectivity, enabling its successful application in imaging the generation of intracellular and extracellular ONOO⁻. Furthermore, exogenous and endogenous ONOO⁻ products in live zebrafish were visualized. It is greatly expected that the designed probe can serve as a useful imaging tool for clarifying the distribution and pathophysiological functions of ONOO⁻ in cells and zebrafish.     

新型香豆素类氟离子荧光探针的合成及细胞成像研究

设计合成了一类基于分子内电荷转移（Intramolecular Charge Transfer,ICT）的香豆素类F^-荧光探针CS1,CS2和CS3,经¹H NMR,¹³C NMR,IR和HRMS表征了相应探针的结构,并解析了探针CS3的晶体结构.通过核磁和质谱实验验证了探针与F^-的作用机理是氟化物脱硅基.光谱分析实验结果显示,CS1,CS2和CS3均具有较好的选择性和灵敏度,且均能成功实现人乳腺癌细胞（MCF^-7）中F^-的检测.     

An ESIPT-Based Ratiometric Fluorescent Probe for Highly Sensitive and Rapid Detection of Sulfite in Living Cells

The novel ratiometric fluorescent probe HPQRB with an ESIPT effect based on Michael addition for highly sensitive and fast detection of sulfite in living HepG2 cells is reported. HPQRB can be easily synthesized by a two-step condensation reaction. HPQRB has a large emission shift (Δλ=116 nm), which is beneficial for fluorescence imaging research, and its sulfite-responsive site is based on a rhodamine-like structure with the emission peak at 566 nm, which decreases with increasing sulfite concentration. and its HPQ structure always has an ESIPT effect throughout the reaction process, keeping the emission peak at 450 nm as a self-reference. In particular, HPQRB has high selectivity for sulfite and responds quickly (within 30 s) with a low detection limit (44 nM). Furthermore, HPQRB has been successfully used for fluorescence imaging of sulfite in HepG2 cells, demonstrating the superior ability to detect sulfite under physiological conditions.     

Use of Selenium to Detect Mercury in Water and Cells: An Enhancement of the Sensitivity and Specificity of a Seleno Fluorescent Probe

Seleno fluorescent probe : An organoselenium fluorescent probe (FSe‐1) for mercury was designed based on the irreversible deselenation mechanism. FSe‐1 exhibits an ultrahigh selectivity and sensitivity for Hg²⁺ detection only for reactive selenium atom sites, due the strong affinity between Se and Hg. Furthermore, the new probe has been successfully used for imaging mercury ions in RAW 264.7 cells (a mouse macrophage cell line; see figure).

     

BODIPY-based Fluorescent Probe for Fast Detection of Hydrogen Sulfide and Lysosome-targeting Applications in Living Cells

Hydrogen sulfide (H₂S) is recognized as an endogenous gaseous signaling agent in many biological activities. Lysosomes are the main metabolic site and play a pivotal role in cells. Herein, we designed and synthesized two new fluorescent probes BDP-DNBS and BDP-DNP with a BODIPY core to distinguish H₂S. The sensing mechanism is based on the inhibition-recovery of the photo-induced electron transfer (PET) process. Through comparing the responsive behaviors of the two probes toward H₂S, BDP-DNBS showed a fast response time (60 s), low limit of detection (LOD, 51 nM), high sensitivity and selectivity. Moreover, the reaction mechanism was demonstrated by mass spectrometry and fluorescence off-on mechanism was proved by density functional theory (DFT). Significantly, confocal fluorescence imaging indicated that BDP-DNBS was successfully used to visualize H₂S in lysosomes in living HeLa cells.     

An Ultrasensitive Cyclization‐Based Fluorescent Probe for Imaging Native HOBr in Live Cells and Zebrafish

Bromine has been reported recently as being the 28^th essential element for human health. HOBr, which is generated in vivo from bromide, is a required factor in the formation of sulfilimine crosslinks in collagen IV. However, to date, no method for the specific detection of native HOBr in vivo has been reported. Herein, we develop a simple small molecular probe for imaging HOBr based on a specific cyclization catalyzed by HOBr. The probe can be easily synthesized in high yield through a Suzuki cross‐coupling reaction. The probe exhibits ultrahigh sensitivity at the picomole level, in addition to specificity for HOBr and real‐time response. Importantly, without Br^? stimulation, this probe reports native HOBr levels in HepG2 cells. Thus, the probe is a promising new tool for imaging endogenous HOBr and may provide a means for finding new physiological functions of HOBr in living organisms.     

A Multisite‐Binding Switchable Fluorescent Probe for Monitoring Mitochondrial ATP Level Fluctuation in Live Cells

Adenosine triphosphate (ATP), commonly produced in mitochondria, is required by almost all the living organisms; thus fluorescent probes for monitoring mitochondrial ATP levels fluctuation are essential and highly desired. Herein, we report a multisite‐binding switchable fluorescent probe, ATP‐Red 1 , which selectively and rapidly responds to intracellular concentrations of ATP. Live‐cell imaging indicated that ATP‐Red 1 mainly localized to mitochondria with good biocompatibility and membrane penetration. In particular, with the help of ATP‐Red 1 , we successfully observed not only the decreased mitochondrial ATP levels in the presence of KCN and starvation state, but also the increased mitochondrial ATP levels in the early stage of cell apoptosis. These results indicate that ATP‐Red 1 is a useful tool for investigating ATP‐relevant biological processes.     

Versatile Fluorescent Probes for Imaging the Superoxide Anion in Living Cells and In Vivo

The superoxide anion (O₂^.?) is widely engaged in the regulation of cell functions and is thereby intimately associated with the onset and progression of many diseases. To ascertain the pathological roles of O₂^.? in related diseases, developing effective methods for monitoring O₂^.? in biological systems is essential. Fluorescence imaging is a powerful tool for monitoring bioactive molecules in cells and in vivo owing to its high sensitivity and high temporal‐spatial resolution. Therefore, increasing numbers of fluorescent imaging probes have been constructed to monitor O₂^.? inside live cells and small animals. In this minireview, we summarize the methods for design and application of O₂^.?‐responsive fluorescent probes. Moreover, we present the challenges for detecting O₂^.? and suggestions for constructing new fluorescent probes that can indicate the production sites and concentration changes in O₂^.? as well as O₂^.?‐associated active molecules in living cells and in vivo.     

A Novel Phenoxazine-based Fluorescent Probe for the Detection of HOCl in Living Cells

Hypochlorous acid (HOCl), one of the reactive oxygen species (ROS), is a key microbicidal agent which is used for natural defense. However, it is also linked to varieties of human diseases owing to the overproduction of HOCl. Much effort has been made to exploit selective fluorescent sensors for the detection of HOCl, but most of them have some disadvantages such as short excitation wavelength, low selectivity, and slow response and so on. These restrict the biological application of the probes. In this work, BR-O was designed and synthesized on the base of phenoxazine for the detection of HOCl. BR-O exhibited a violent fluorescence enhancement in the presence of HOCl, showing excellent selectivity and high sensitivity. More importantly, the probe BR-O was capable of detecting exogenous and endogenous HOCl in living cells.     

Development of a Two‐Photon Fluorescent Probe for Imaging of Endogenous Formaldehyde in Living Tissues

Investigation of the physiological and pathological functions of formaldehyde (FA) are largely restricted by a lack of useful FA imaging agents, in particular, those that allow detection of FA in the context of living tissues. Herein, we present the rational design, synthesis, and photophysical property studies of the first two‐photon fluorescent FA probe, Na‐FA . Importantly, the highly desirable attributes of the probe Na‐FA (such as a very large turn‐on signal (up to 900‐fold), a low detection limit, and a very fast onset imparted by the unique design aspects of the probe), make it possible to monitor endogenous FA in living tissues for the first time. Furthermore, sodium bisulfite was identified as a simple and convenient inhibitor of FA within biological environments.     

A Naphthalimide‐Based Fluorescence “Turn‐On” Probe for the Detection of Pb2+ in Aqueous Solution and Living Cells

An easily available naphthalimide‐based fluorescent probe NPA for Pb²⁺ detection was successfully developed. NPA exhibited an obvious fluorescence turn‐on response toward Pb²⁺ in aqueous solution and in living cells. Moreover, a series of model compounds were rationally designed and synthesized in order to explore the sensing mechanism and binding mode of NPA with Pb²⁺.     

Small Molecular Fluorescent Probes for Imaging of Viscosity in Living Biosystems

Viscosity, as a vital microenvironment parameter, is tightly associated with multitudinous cellular processes and diseases. Recently, precise visualization of viscosity has started to arouse more and more interest. However, owing to the complicated character, it is still a huge challenge to directly observe viscosity in living systems. In this regard, mounting fluorescence probes are being increasingly fabricated to map viscosity inside live cells and small animals. In this minireview, the viscosity-sensitive small molecular fluorescent probes used in bioimaging are comprehensively summarized, mainly focusing on the last three years. Moreover, the current challenges and opportunities for the development of viscosity-specific fluorescent probes will be discussed.     

Assembly of Water-soluble AIE-active Fluorescent Organic Nanoparticles for Ratiometric Detection of Hypochlorite in Living Cells

Hypochlorous acid (HOCl) plays a crucial role in many physiological processes and is widely used as bleach, deodorant and fungicide. In this work, we designed an amphiphilic hydrazone fluorescent molecule THG-1 containing hydrophilic sugar units and hydrophobic tetraphenylethylene unit for ratiometric detection of HOCl with high sensitivity and excellent selectivity based on HOCl-triggered hydrolyzation reaction and aggregation-induced emission (AIE) effect. The detection mechanism was verified by liquid chromatograph mass spectrometry experiments and scanning electron microscope (SEM) tests. Contrast experiments revealed that the numbers of lactose unit and hydrazone linker were essential for assembly of THG-1 and detection of HOCl. In addition, THG-1 was successfully used for imaging of exogenous and endogenous HOCl in living cells.