Nitrogen-phosphorus dual-doped auricularia auricula porous carbon as host for Li-S battery.

A nitrogen-phosphorus dual-doped porous spore carbon (NP-PSC) positive electrode matrix was prepared using native auricularia auricula as solid medium based on the principle of biomass rot. Yeast was introduce and cultured by the auricularia auricula solid medium. The freeze-drying and carbonization activation processes made the materials present a three-dimensional porous spore carbon aerogel properties. Yeast fermentation transformed auricularia auricula from blocky structure to porous structure and introduced nitrogen-phosphorus dual-doping. The physical and chemical properties of the prepared materials were characterized in detail. Electrochemical performance of NP-PSC in Li-S batteries was systematically investigated. Porous structure and heteroatom-doping improved the electrochemical performance, which is much superior to conventional activated carbon materials.

A benzothiophene-quinoline-based targetable fluorescent chemosensor for detection of viscosity and mitochondrial imaging in live cells.

Mitochondria are the sites of respiration in cells, and they participate in many indispensable biological processes. Because variations in mitochondrial viscosity can lead to dysfunctions of mitochondrial structure and function (and even induce malignant diseases), new sensors that can accurately monitor changes in mitochondrial viscosity are essential. To better investigate these changes, we report the development and evaluation of a novel benzothiophene-quinoline-based fluorescent chemosensor (BQL) that was designed especially for monitoring mitochondrial viscosity. BQL demonstrated a large Stokes shift (minimizing interference from autofluorescence) and a good response to viscosity (using the TICT principle). Moreover, BQL demonstrated little to no pH-dependency, polarity-dependency, or interference from other analytes. Thus, BQL has an excellent specificity for viscosity. BQL was used to monitor viscosity changes in mitochondria induced by ion carriers, and was used to report on viscosity in real time during mitophagy. To sum up, BQL provided a new approach for detecting viscosity in living cells and in vivo. BQL should prove to be an excellent tool for the analysis of viscosity changes in live cells.

Preparation of an N-S dual-doped black fungus porous carbon matrix and its application in high-performance Li-S batteries.

A nitrogen-sulfur dual-doped black fungus porous carbon (NS-FPC) matrix was prepared with natural black fungus as the carbon source and cysteine as the nitrogen-sulfur source. A black fungus-based solution was obtained by hydrothermal treatment. After further carbonization activation and combination with sulfur processing, the NS-FPC/S positive electrode materials were prepared. The uniform recombination of biomass carbon provides an efficient conductive framework for sulfur. The porous structure is conducive to the transport of electrolytes. Heteroatom doping can provide a more active site. The structure and composition analyses of the materials were carried out using X-ray diffraction (XRD). The electronic binding energy and bonding state were analyzed by X-ray photoelectron spectroscopy (XPS). The morphology was observed by scanning electron microscopy and transmission electron microscopy. The specific surface area and pore size distribution were analyzed using an N2 adsorption-desorption experiment. Sulfur loading was determined through thermogravimetric analysis. The electrochemical performance of NS-FPC/S in Li-S batteries was systematically investigated. The result shows that the NS-FPC/S electrode maintains more than 1,000 mAh g-1 reversible capacity after 100 cycles at 0.2 C current density, with a capacity retention of 85%. The cycle and rate performance are both considerably superior to those of traditional activated carbon materials.

Nitrogen/sulfur dual-doped micro-mesoporous hierarchical porous carbon as host for Li-S batteries.

A simple hydrothermal process employing sucrose and glutathione as the source of carbon and nitrogen-sulfur, respectively, a porous carbon/sulfur composite material doped with nitrogen and sulfur (NSPCS) was synthesized. The detailed structure information of the material was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The morphology information was investigated through Scanning Electron Microscope (SEM) methods. Structure of the pores and pore size distribution were investigated employing N2 adsorption-desorption isotherm. The material was treated Thermogravimetric analysis (TGA) in order to know the weight ratio of sulfur. The synthesized NSPCS composite produced high specific capacity, excellent rate performance and exceptionally good cycle stability when used as the positive electrode in Li-S batteries.

A neoteric dual-signal colorimetric fluorescent probe for detecting endogenous/exogenous hydrogen peroxide in cells and monitoring drug-induced hepatotoxicity.

Hydrogen peroxide (H2O2), one of the most important reactive oxygen species (ROS), can be generated endogenously in the liver and has been deemed as a biomarker for evaluating drug-induced liver injury (DILI). Therefore, it is highly crucial to construct an effective method for detecting H2O2 in the liver in order to evaluate DILI. Herein, a neoteric dual-signal colorimetric fluorescent probe XH-2 for sensing hydrogen peroxide was engineered and synthesized. Borate was grafted as a specific recognition group onto the fluorophore XH-1 (ΦF = 0.34) to establish a structurally unprecedented probe. The experimental results manifested that probe XH-2 (ΦF = 0.15) was able to detect hydrogen peroxide using a fluorescence method with an excellent linear range of 0-140 µM (R2 = 0.9974) and an especially low detection limit of 91 nM (λex/em = 570 nm/638 nm). In addition, the probe was capable of monitoring hydrogen peroxide in a colorimetric manner with the linear range of 0-110 µM (R2 = 0.9965). Furthermore, the specificity, applicability in serum (98.6-109.1%) and indirect detection of glucose make the probe XH-2 a superior probe. Based on its low cytotoxicity, the probe was successfully applied to monitor endogenous/exogenous hydrogen peroxide and quantitatively determine the concentration level of hydrogen peroxide at a range of 0-120 µM (R2 = 0.9859) in HepG2 cells. Ultimately, the probe could effectively monitor the level of hydrogen peroxide during DILI in HepG2 cells.

A novel water-soluble near-infrared fluorescent probe for monitoring mitochondrial viscosity.

Mitochondria, the main source of energy of cells, play a significant role in aerobic respiration process. Some stimulants can result in changes of mitochondrial microenvironments such as viscosity, pH and polarity. Abnormal changes of mitochondrial viscosity have been shown to relate to pathological activities and diseases. Therefore, it is critical to focus our attention on mitochondrial viscosity under different conditions. A novel organic water-soluble molecule called JLQL that could monitor viscosity was conveniently synthesized in two steps. The near-infrared sensor with maximum emission wavelength of 734.6 nm and the Stokes shift of 134.6 nm consisted of a fluorophore and a mitochondrial-targeting moiety as an acceptor group; the two were connected by a double bond. The fluorescence intensity of the sensor increased 175 times with the enhancement of viscosity of a PBS-glycerol system. The interference of other microenvironments such as pH and polarity and other interference analytes could be reduced. JLQL could sensitively and selectively differentiate different levels of mitochondrial viscosity induced by monensin or nystatin. Furthermore, the probe may provide an attractive way to monitor real-time changes of viscosity during mitophagy. Possessing the above properties, JLQL can potentially be employed as a powerful tool for the observation of mitochondrial viscosity.

Lysosome-targeted ratiometric fluorescent sensor for monitoring pH in living cells based on one-pot-synthesized carbon dots.

A hydrothermal method has been employed to synthesize a green and one-pot carbon dots-based sensor for ratiometric monitoring and imaging lysosomal pH in living cells. The carbon dots were directly functionalized by abundant amino groups during synthesis and exhibited dual emission bands at 439 and 550 nm under single-wavelength excitation of 380 nm without any additional modification. In addition to its small size, the established sensor had good biocompatibility. Owing to its abundant amino groups and good hydrophilicity, the sensor is able to target lysosome with high Pearson's colocalization coefficients (0.935 and 0.924) and responds to change of lysosomal pH in living cells. It also had excellent pH sensitivity and reversibility, and anti-interference capability, thus enabling sensing pH change in intracellular environment in real time, as demonstrated by successful monitoring of lysosomal pH changes during lysosomal alkalization, dexamethasone-induced stimulation, and stress in Michigan Cancer Foundation-7 cells (blue channel, excitation = 405 nm and emission = 419-459 nm bandpass; and yellow channel, excitation = 405 nm and emission = 530-570 nm bandpass). Graphical abstract.

A novel near-infrared fluorescent probe for intracellular detection of cysteine.

Cysteine (Cys) takes part in redox balance in cells as an antioxidant, and imbalance of Cys content in the body can cause a variety of diseases. It is very important to develop a new fluorescent chemosensor to specifically detect Cys intracellular. In this work, a novel NIR fluorescent probe was constructed based on 3-ethyl-1,1,2-trimethyl-1H-benzo[e]indol-3-ium iodide and 5-(4-hydroxyphenyl)furan-2-carbaldehyde. The probe could selectively detect Cys in the presence of homocysteine (Hcy), glutathione (GSH), and other interferences. It also had a number of advantages, including nucleolus-targeting ability, long fluorescence emission wavelength (685 nm), low detection limit (56 nM), and large Stokes shift (172 nm). The probe was employed to enable visualization of Cys in HepG2 cells, and due to its good response in viscous environment, the probe could also locate nucleoli intracellular.

A novel fluorescent probe for the localization of nucleoli developed via a chain reaction of endogenous cysteine in cells.

Nucleolus imaging is important for the understanding of gene expression, proliferation, and growth of cells. Traditional nucleoli localization mainly relies on the use of RNA fluorescent probes which are required in large amounts. These probes also have low selectivity, thus causing the generated images to have high background noise and the localization of nucleoli to become vague. In the present paper, a novel probe for nucleoli localization, BEB-A, which can specifically bind to RNA via the chain reaction of endogenous cysteine (Cys), was designed and developed. In addition to its mitochondria-targeting ability, the BEB-A probe could be used in the imaging of Cys in the cytoplasm, and its product, BEB-OH, could quickly penetrate into the cell nucleus to combine with nucleolar RNA to generate strong red fluorescence signals. The luminescence property and RNA-binding capability of the probe were also investigated via theoretical calculations and molecular docking simulations. This work presents a tool that can be applied to analyze the variation of Cys in mitochondria and RNA in cells.

A novel colorimetric and near-infrared fluorescence probe for detecting and imaging exogenous and endogenous hydrogen peroxide in living cells.

Hydrogen peroxide (H2O2), an important member of the family of reactive oxygen species (ROS), has a significant impact on cell signal transduction, energy conversion and immune responses of living organisms. Therefore, accurate detection of the content of H2O2 in living cells is of vital importance. In this paper, we report on the synthesis of a novel colorimetric and near-infrared fluorescent probe HAA, a heterocyclic aromatic amine with acetyl group for the specific detection of both exogenous and endogenous H2O2 in living cells. Our results show that the probe not only possesses high specificity and sensitivity, but also has advantages of low cytotoxicity and good biocompatibility. Theoretical computations elucidated the luminescence and quenching mechanism of HAA in the absence and presence of H2O2. In addition, HAA was applied to the determination of H2O2 in human serum and the imaging of endogenous H2O2 in living cells, during which it demonstrated excellent performance and good potential for future bioanalysis applications.

A novel highly sensitive and near-infrared fluorescent probe for detecting hypochlorite and its application in actual water sample and bioimaging.

Highly sensitive specific and ultrasensitive fluorescent probes are employed for tracking ClO⁻ for revealing its various cellular functions in living cells. In this work, a near-infrared fluorescence probe, XS-1, has been developed for tracking ClO⁻. The experimental results demonstrated that the probe, XS-1, could determine ClO⁻ at the linear range of 0-2 µM with a low detection limit of 72 nM (λex/em = 580/626 nm). XS-1 can specifically detect ClO⁻, which can be applied for determining the basal ClO⁻ and the fluctuation of exogenous ClO⁻ in living cells. For further confirming its practicability, the probe was applied for detecting the hypochlorite content in the actual water sample. The recovery rate (92.7%-102.9%) displayed satisfactory values in the tap water and 84 disinfectants. In addition, we carried out theoretical calculations for clarifying the luminescence mechanism of the system.

Development of a water-soluble near-infrared fluorescent probe for endogenous cysteine imaging.

We designed and synthesized a water-soluble near-infrared (NIR) fluorescent probe with the recognition unit of the cyanine-like structure and acrylate group. Through an aromatic ring nucleophilic substitution reaction based on sulfhydryl moiety, an off-on fluorescence response toward cysteine (Cys) was realized. The probe exhibited excellent spectral performance with an emission wavelength of 720nm and a detection limit of 0.20µM. The spectral properties, selectivity and anti-interference performance of the probe were systematically investigated. Density functional theory (DFT) calculations were conducted to clarify the luminescence mechanism of the probe. Furthermore, the probe was successfully applied to the detection of free Cys in human serum and the NIR imaging of endogenous Cys in living cells. Thus, the probe has a promising application prospect in clinical diagnosis and fluorescence imaging.