Fabiao Yu

A Near-IR Reversible Fluorescent Probe Modulated by Selenium for Monitoring Peroxynitrite and Imaging in Living Cells

We have developed a near-IR reversible fluorescent probe containing an organoselenium functional group that can be used for the highly sensitive and selective monitoring of peroxynitrite oxidation and reduction events under physiological conditions. The probe effectively avoids the influence of autofluorescence in biological systems and gave positive results when tested in both aqueous solution and living cells. Real-time images of cellular peroxynitrite were successfully acquired.

Reversible Near-Infrared Fluorescent Probe Introducing Tellurium to Mimetic Glutathione Peroxidase for Monitoring the Redox Cycles between Peroxynitrite and Glutathione in Vivo

The redox homeostasis between peroxynitrite and glutathione is closely associated with the physiological and pathological processes, e.g. vascular tissue prolonged relaxation and smooth muscle preparations, attenuation hepatic necrosis, and activation matrix metalloproteinase-2. We report a near-infrared fluorescent probe based on heptamethine cyanine, which integrates with telluroenzyme mimics for monitoring the changes of ONOO(-)/GSH levels in cells and in vivo. The probe can reversibly respond to ONOO(-) and GSH and exhibits high selectivity, sensitivity, and mitochondrial target. It is successfully applied to visualize the changes of redox cycles during the outbreak of ONOO(-) and the antioxidant GSH repair in cells and animal. The probe would provide a significant advance on the redox events involved in the cellular redox regulation.

A reversible fluorescence probe based on Se-BODIPY for the redox cycle between HClO oxidative stress and H2S repair in living cells

We have developed a new reversible fluorescence probe MPhSe-BOD for the redox cycle process between hypochlorous acid and hydrogen sulfide in solution and in living cells. Confocal microscopy imaging using RAW264.7 cell lines shows that the probe has good cell membrane permeability, and can monitor intracellular HClO/H(2)S redox cycles continuously.

Near-Infrared Fluorescent Probe for Imaging Mitochondrial Hydrogen Polysulfides in Living Cells and in Vivo

Hydrogen polysulfides (H2Sn, n > 1), derived from hydrogen sulfide (H2S), have attracted increasing attention in biochemical research, which may perform as the actual signaling molecules during cell signaling processes. Because of the closed biological and chemical relationship between H2S and H2Sn, it is of great value to develop sensitive and specific techniques to distinguish the intracellular level of H2Sn. To improve the understanding of the physiological and pathological roles played by H2Sn, we now develop a specific fluorescent probe Mito-ss for capturing H2Sn in cells and in vivo. When triggered by H2Sn, Mito-ss replies a turn-on fluorescence signal and exhibits a higher selectivity toward H2Sn than other abundant competing biothiols, such as glutathione, cysteine and H2S. The probe Mito-ss can also be applied to visual H2Sn in living cells, as well as in vivo, providing a potentially powerful approach for probing H2Sn in biological systems.

Substituent effects on the intramolecular charge transfer and fluorescence of bimetallic platinum complexes.

An investigation of a series of platinum-containing organometallic complexes for the study of fluorescence phenomena in organometallic chromophores controlled by the intramolecular charge transfer (ICT) is presented in this work. We report steady-state and time-resolved spectroscopic experiments as well as quantum chemistry calculations to investigate the substituent effects on the ICT and fluorescence emission. We demonstrate that the fluorescence maximum and lifetimes greatly depend on different substituents and the presence of bimetallic platinum donor. This work paves the way for an understanding of the fluorescence phenomena controlled by molecular ICT characters of these kinds of platinum-containing organometallic complexes.

A dual response near-infrared fluorescent probe for hydrogen polysulfides and superoxide anion detection in cells and in vivo

Intracellular reactive sulfur species play important roles in physiological and pathological processes. Emerging evidences suggest that sulfane sulfur instead of H2S is the actual signaling molecule in these processes. Sulfane sulfur can be generated as a result of the reaction between O2(·-) and H2S in mitochondria. Therefore, we develop a near-infrared mitochondria-targeting probe that allows multiresponse to O2(·-) and H2Sn successively for investigating this biosynthetic reaction. The probe exhibits highly selective fluorescent response to O2(·-) and H2Sn successively in presence of potential biological interferants. Fluorescent imaging studies and flow cytometry analysis of RAW264.7 cells elaborate that the probe can be used to reveal the continuous process of O2(·-) burst and H2Sn production in situ and in real-time. The mitochondria isolation indicates that the probe can specifically localize in mitochondria. Finally, the fluorescent probe has been successfully applied to detect O2(·-) and H2Sn in mice.

A fluorescent probe directly detect peroxynitrite based on boronate oxidation and its applications for fluorescence imaging in living cells

We present the design, synthesis, spectroscopy, and biological applications of PyBor, a new type of fluorescent probe for peroxynitrite detection in aqueous solution and living cells. The probe employs pyrene as the fluorophore, and is equipped with a chemically responsive unit boronate. The fluorescent probe can selectively detect peroxynitrite with fluorimetric determination and high-performance liquid chromatography analyses in aqueous solution and RAW264.7 cells intracellular free extracts. We also study our probe to time dependent peroxynitrite release from 3-morpholinylsydnonimine hydrochloride. Confocal microscopy experiments using mouse macrophage cell line RAW264.7 show that PyBor is able to detect the different intracellular peroxynitrite levels. In addition, we have performed quantum chemical calculations with TD-DFT/M06/TZVP level with COSMO solvation model basis sets using a suite of Gaussian 09 programs to provide insights into the structure optical properties of PyBor and PyOH.

Near-Infrared Fluorescence Probe for in Situ Detection of Superoxide Anion and Hydrogen Polysulfides in Mitochondrial Oxidative Stress

H2S plays important physiological and pathological roles in the cardiovascular system and nervous system. However, recent evidence imply that hydrogen polysulfides (H2Sn) are the actual signaling molecules in cells. Although H2Sn have been demonstrated to be responsible for mediating tumor suppressors, ion channels, and transcription factors, more of their biological effects are still need to be elaborated. On one hand, H2Sn have been suggested to be generated from endogenous H2S upon reaction with reactive oxygen species (ROS). On the other hand, H2Sn derivatives are proposed to be a kind of direct antioxidant against intracellular oxidative stress. This conflicting results should be attributed to the regulation of redox homeostasis between ROS and H2Sn. Superoxide anion (O2(•-)) is undoubtedly the primary ROS existing in mitochondria. We reason that the balance of O2(•-) and H2Sn are pivotal in physiological and pathological processes. Herein, we report two near-infrared fluorescent probes Hcy-Mito and Hcy-Biot for the detection of O2(•-) and H2Sn in cells and in vivo. Hcy-Mito is conceived to be applied in mitochondria, and Hcy-Biot is designed to target tumor tissue. Both of the probes were successfully applied for visualizing exogenous and endogenous O2(•-) and H2Sn in living cells and in tumor mice models. The results demonstrate that H2Sn can be promptly produced by mitochondrial oxidative stress. Flow cytometry assays for apoptosis suggest that H2Sn play critical roles in antioxidant systems.

A near-infrared ratiometric fluorescent probe for cysteine detection over glutathione indicating mitochondrial oxidative stress in vivo

We establish a near-infrared (NIR) ratiometric fluorescent probe Cy-NB for the selective detection of cysteine (Cys) over glutathione (GSH) and homocysteine (Hcy) in mitochondria to indicate oxidative stress. Heptamethine cyanine dye is chosen as the fluorophore of Cy-NB whose emission locates in NIR region. And p-nitrobenzoyl is employed as the fluorescent modulator due to its capability of selective-Cys response. Once triggered by Cys, the uncaged p-nitrobenzoyl rearranges the polymethine π-electron system of the fluorophore, which leads to a remarkable spectrum shifts in absorption and emission profiles. Taking advantage of these spectroscopic properties, we construct a ratiometric fluorescent signal for the detection of Cys with a detection limit of 0.2 µM within 5 min. Our probe Cy-NB can sensitively detect the mitochondrial Cys pool changes under different oxidative stress status in HepG2 cells. We also successfully employ Cy-NB to imaging Cys level changes in living mice. It suggests that mitochondrial Cys can be used as an oxidative stress biomarker with simple potential clinical applications. And our probe Cy-NB is of great potential for further utilizing in exploring the physiological function of Cys in biological systems.

A near-infrared fluorescent probe for the detection of hydrogen polysulfides biosynthetic pathways in living cells and in vivo

Hydrogen polysulfides (H2Sn, n > 1), derived from hydrogen sulfide (H2S), have been considered to be involved in cytoprotective processes and redox signaling. The emerging evidences imply that the actual signaling molecule is H2Sn rather than H2S. In this work, we present a near-infrared fluorescent probe BD-ss for the selective detection of H2Sn biosynthetic pathways in living cells and in vivo. The probe is constructed by equipping a bis-electrophilic H2Sn capture group p-nitrofluorobenzoate to a near-infrared fluorophore azo-BODIPY. BD-ss can provide a remarkable turn-on fluorescence response for assessing endogenous H2Sn formation ways in serum, in living cells and in vivo.