Xu Wang

Bio: Xu Wang is an academic researcher from Shandong Normal University. The author has contributed to research in topics: Immunoassay & Medicine. The author has an hindex of 34, co-authored 69 publications receiving 3447 citations. Previous affiliations of Xu Wang include Tsinghua University.

A Near-Infrared Neutral pH Fluorescent Probe for Monitoring Minor pH Changes: Imaging in Living HepG2 and HL-7702 Cells

Abstract: A near-neutral pH near-infrared (NIR) fluorescent probe utilizing a fluorophore-spacer- receptor molecular framework that can modulate the fluorescence emission intensity through a fast photoinduced electron-transfer process was developed. Our strategy was to choose tricarbocyanine (Cy), a NIR fluorescent dye with high extinction coefficients, as a fluorophore, and 4′-(aminomethylphenyl)-2,2′:6′,2′′-terpyridine (Tpy) as a receptor. The pH titration indicated that Tpy-Cy can monitor the minor physiological pH fluctuations with a pKa of ∼7.10 near physiological pH, which is valuable for intracellular pH researches. The probe responds linearly and rapidly to minor pH fluctuations within the range of 6.70−7.90 and exhibits strong dependence on pH changes. As expected, the real-time imaging of cellular pH and the detection of pH in situ was achieved successfully in living HepG2 and HL-7702 cells by this probe. It is shown that the probe effectively avoids the influence of autofluorescence and native cellular s...

Small-Molecule Fluorescent Probes for Imaging and Detection of Reactive Oxygen, Nitrogen, and Sulfur Species in Biological Systems

Abstract: Intracellular redox homeostasis provides broad implications in physiological and pathological fields. The disruption of redox homeostasis is closely associated with some human diseases, such as cancer, neurodegenerative diseases, cardiovascular diseases, diabetes mellitus, and gastrointestinal diseases.1-6 Therefore, cells possess an elaborate regulation system to maintain their redox balance and the large or significant redox state changes can be buffered by the redox-active molecules.7,8 These molecules experience interreaction and interconversion to facilitate the dynamic balance of intracellular redox state, among which three types of representative molecules should be mentioned, including reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive sulfur species (RSS).

A near-infrared ratiometric fluorescent probe for rapid and highly sensitive imaging of endogenous hydrogen sulfide in living cells

Abstract: We describe the design and synthesis of a cyanine-based near-infrared ratiometric fluorescent probe, HS–Cy, for H2S detection, which features rapid response, high sensitivity, and mitochondria targeting. After a rapid quenching at 780 nm by initial nucleophilic addition on the aldehyde group, HS–Cy experienced a polymethine π-electron conjugation modulation triggered by a second nucleophilic addition on the ester, releasing the cyanine fluorophore which underwent tautomerism from enol form to ketone form. Therefore, gradual emergence of a new peak at 625 nm was observed, constructing a ratiometric signal for H2S with a detection limit of 5.0–10 nM, which is the most sensitive among the reported H2S-sensing fluorescent probes. HS–Cy was proven to selectively locate into mitochondria with faster trapping kinetics towards H2S. Based on this, the endogenously generated H2S in human A549 cells was ratiometrically detected and imaged by HS–Cy.

High specific and ultrasensitive isothermal detection of microRNA by padlock probe-based exponential rolling circle amplification.

Abstract: In this paper, a padlock probe-based exponential rolling circle amplification (P-ERCA) assay is developed for highly specific and sensitive detection of microRNA (miRNA). The padlock probe is composed of a hybridization sequence to miRNA and a nicking site for nicking endonuclease. Using the miRNA as a template, specific ligation to the padlock probe and linear rolling circle reaction (LRCA) are achieved under isothermal conditions. After multiple nicking reactions, many copies of short DNA products are successively produced and then used as triggers in next circle amplification. Thus, a small amount of miRNAs are converted to a large number of triggers to initiate the rolling circle amplification reaction, and circular exponential signal amplification is achieved. This padlock probe-based exponential rolling circle amplification assay exhibits a remarkable sensitivity of 0.24 zmol using optimized sequences of the padlock probe. The target-dependent circularization of the padlock probe and the ligation re...

Two-photon fluorescent probe for revealing drug-induced hepatotoxicity via mapping fluctuation of peroxynitrite

Abstract: Drug-induced injury has attracted increasing attention in public health issues. Among them, hepatotoxicity has been regarded as the leading clinical problem caused by drug toxicity. However, owing to the complexity of the involved pathophysiological mechanisms and the lack of noninvasive, straightforward, and real-time tools, drug-induced hepatotoxicity has rarely been predicted satisfactorily. In this paper, by utilizing the reactive species peroxynitrite (ONOO−) as a biomarker, we present a two-photon fluorescent probe, TP-KA, holding rapid response, high specificity and sensitivity towards ONOO−, to investigate drug (acetaminophen and tolcapone)-related liver injury and the remediate effect of N-acetyl cysteine (NAC). With the support of TP-KA, we obtained direct and visual evidence of the upregulation of ONOO− during drug challenge both in live cells and mice, which was accompanied by liver tissue injury and tyrosine nitration. These findings demonstrate that ONOO− is a good and appropriate biomarker of hepatotoxicity, and nitrosative stress may be necessary for acetaminophen and tolcapone to exert their toxicity. Moreover, TP-KA can be employed as a powerful tool to pre-detect drug-induced organism injury and study the effect of antidotes.

Luminescent chemodosimeters for bioimaging.

Abstract: Yuming Yang,†,§ Qiang Zhao,‡,§ Wei Feng,† and Fuyou Li*,† †Department of Chemistry and State Key Laboratory of Molecular Engineering of Polymers and Institutes of Biomedical Sciences, Fudan University, Shanghai 200433, P. R. China ‡Key Laboratory for Organic Electronics and Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, Nanjing 210046, P. R. China.

Fluorescent chemosensors based on spiroring-opening of xanthenes and related derivatives.

Abstract: Fluorescent Chemosensors Based on Spiroring-Opening of Xanthenes and Related Derivatives Xiaoqiang Chen, Tuhin Pradhan, Fang Wang, Jong Seung Kim,* and Juyoung Yoon* Departments of Chemistry and Nano Science and of Bioinspired Science (WCU), Ewha Womans University, Seoul 120-750, Korea State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing University of Technology, Nanjing 210009, China Department of Chemistry, Korea University, Seoul 136-701, Korea

Far-red to near infrared analyte-responsive fluorescent probes based on organic fluorophore platforms for fluorescence imaging

Abstract: The long wavelength (far-red to NIR) analyte-responsive fluorescent probes are advantageous for in vivo bioimaging because of minimum photo-damage to biological samples, deep tissue penetration, and minimum interference from background auto-fluorescence by biomolecules in the living systems. Thus, great interest in the development of new long wavelength analyte-responsive fluorescent probes has emerged in recent years. This review highlights the advances in the development of far-red to NIR fluorescent probes since 2000, and the probes are classified according to their organic dye platforms into various categories, including cyanines, rhodamine analogues, BODIPYs, squaraines, and other types (240 references).