Publications by authors named "Kehua Xu"

71 Publications

Correction: A "double-locked" probe for the detection of hydrogen sulfide in a viscous system.

Chem Commun (Camb) 2021 Jul;57(54):6693

College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Institutes of Biomedical Sciences, Shandong Normal University, Jinan 250014, People's Republic of China.

Correction for 'A "double-locked" probe for the detection of hydrogen sulfide in a viscous system' by Fanpeng Kong et al., Chem. Commun., 2021, DOI: 10.1039/d1cc01819a.
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http://dx.doi.org/10.1039/d1cc90224eDOI Listing
July 2021

A Mitochondrial-Targeting Near-Infrared Fluorescent Probe for Revealing the Effects of Hydrogen Peroxide And Heavy Metal Ions on Viscosity.

Anal Chem 2021 07 22;93(26):9244-9249. Epub 2021 Jun 22.

College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Normal University, Jinan 250014, P. R. China.

As an important cell organelle, the mitochondrion has special viscosities, while abnormal mitochondrial viscosity is closely related to many diseases. Hydrogen peroxide (HO) is an active molecule related to the cell microenvironment, and its influence on mitochondrial viscosity is still not clear, so further investigation is needed. In addition, since excessive accumulation of heavy metal ions would lead to cells' dysfunction, the study of effect of excessive heavy metal ions on mitochondrial viscosity has not been reported. Herein, we designed and synthesized a mitochondrial-targeting near-infrared fluorescent probe (Mito-NV) for real-time in situ imaging and analysis of mitochondrial viscosity. Furthermore, the probe revealed that HO can raise mitochondrial viscosity, while heavy metal ions reduce the viscosity. This work is of great significance for understanding the execution of mitochondrial functions and the occurrence and development of related diseases.
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http://dx.doi.org/10.1021/acs.analchem.1c01511DOI Listing
July 2021

A mitochondria-targeting near-infrared fluorescent probe for imaging hypochlorous acid in cells.

Talanta 2021 May 29;226:122152. Epub 2021 Jan 29.

College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Institute of Molecular and Nano Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Shandong Normal University, Jinan, 250014, PR China.

Hypochlorous acid (HOCl), as an important reactive oxygen species (ROS), plays an important role in various pathological and physiological processes. Therefore, it is of great significance to identify and detect HOCl in organisms. Herein, a mitochondria-targeting near-Infrared fluorescent probe (CVS) has been designed and synthesized for sensing HOCl. Under simulated physiological conditions, CVS can be instantly oxidized by HOCl to CVSO and the fluorescence signal is significantly enhanced. Additionally, CVS shows high selectivity toward HOCl over other ROS and owns low detection limit (94.7 nM) for HOCl. Moreover, CVS can be successfully applied to image HOCl in mitochondria of the HepG2 cells. Thus, CVS is a powerful tool for sensing HOCl and provides a perspective method for further study of the physiological and pathological functions related to HOCl.
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http://dx.doi.org/10.1016/j.talanta.2021.122152DOI Listing
May 2021

Real-time in situ monitoring of Lon and Caspase-3 for assessing the state of cardiomyocytes under hypoxic conditions via a novel Au-Se fluorescent nanoprobe.

Biosens Bioelectron 2021 Mar 5;176:112965. Epub 2021 Jan 5.

College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals, Shandong Normal University, Jinan, 250014, PR China.

Myocardial dysfunction caused by cardiomyocyte apoptosis under ischemic and hypoxic conditions is the pathological basis of most cardiovascular diseases. Current diagnosis of myocardial dysfunction still focuses on the symptomatic stage, usually after the occurrence of the irreversible remodelling and functional impairment. Thus, early stage identification of the apoptotic cardiomyocytes induced by hypoxia is highly significant for preventing the onset and delaying the progression of myocardial dysfunction. Herein, a novel Au-Se nanoprobe with strong anti-interference capability was developed for simultaneous real-time in situ monitoring the expression of Lon protease (Lon) and Caspase-3 with high-fidelity in living cardiomyocytes. As Lon upregulation plays a major role in the initiation of hypoxia-induced apoptosis and Caspase-3 is a marker protein for apoptosis, the nanoprobe has been successfully applied for imaging the activation of Lon-Caspase-3 apoptotic signalling pathway and assessing the state of cardiomyocytes under hypoxic conditions. Furthermore, combining with mitochondrial HO probe-MitoPY1, the nanoprobe was also used to confirm the synergistic effect of Lon and ROS on hypoxia-induced apoptosis of cardiomyocytes and evaluate the function of ROS scavenger on attenuating such apoptosis. This work proposed a promising strategy for early diagnosis, prevention and treatment of hypoxic-ischemic myocardial dysfunction.
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http://dx.doi.org/10.1016/j.bios.2021.112965DOI Listing
March 2021

Erratum: Ascorbic acid induced HepG2 cells' apoptosis via intracellular reductive stress: Erratum.

Theranostics 2021 1;11(4):1542. Epub 2021 Jan 1.

College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals, Shandong Normal University, Jinan 250014, P. R. China.

[This corrects the article DOI: 10.7150/thno.33783.].
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http://dx.doi.org/10.7150/thno.56023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7778605PMC
January 2021

Fishing out Methionine-Containing Proteins from Complex Biological Systems Based on a Non-Enzymatic Biochemical Reaction.

Nano Lett 2021 01 4;21(1):209-215. Epub 2020 Dec 4.

College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Institute of Molecular and Nano Science, Shandong Normal University, Jinan 250014, P. R. China.

Nowadays, it still remains a great challenge to develop a simple, fast, and low-toxic method for identification and separation of proteins from complex biological systems. Herein, a nanocomposite ([email protected]) was designed and synthesized to fish out methionine-containing proteins based on a non-enzymatic biochemical reaction, which couples amino groups of lysine with the -methyl group of methionine in the presence of HOBr. Peptides which contain four lysine residues (Lys-Lys-Lys-Lys-{Se-Cys}) linked to the [email protected] nanocomposites were used to capture methionine residues efficiently a S═N cross-linking. The methionine-containing protein was obtained by magnetic separation and released from the [email protected] nanocomposites with the influence of HSe. The HRMS and SDS-PAGE results confirmed the methionine-containing protein could be successfully fished out from a mixture solution. This work provides a useful strategy for recognition and separation of a category of proteins from complex biological systems.
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http://dx.doi.org/10.1021/acs.nanolett.0c03535DOI Listing
January 2021

Tricolor imaging of MMPs to investigate the promoting roles of inflammation on invasion and migration of tumor cells.

Talanta 2021 Jan 11;222:121525. Epub 2020 Aug 11.

College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Institute of Molecular and Nano Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Shandong Normal University, Jinan, 250014, PR China.

The expression levels of matrix metalloproteinases (MMPs) are closely related to the degree of inflammation which facilitates tumor cells' invasion and migration. A tricolor fluorescence nanoprobe based on high-fidelity gold-selenium (Au-Se) nanoplatform was designed and constructed for simultaneously imaging matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-7 (MMP-7) and matrix metalloproteinase-9 (MMP-9) to thoroughly investigate the tumor cells' invasion and migration behaviors under inflammation environment. The nanoprobe was assembled by attaching Au NPs with three different peptide substrates respectively labeled with fluorescein isothiocyanate (FITC), 5-carboxytetramethylrhodamine (5-TAMRA) and cyanine 5 (Cy5) via the Au-Se bond. The nanoprobe can specifically respond to MMP-2/7/9, thereby triggering the fluorophores' fluorescence that quenched previously by fluorescence resonance energy transfer (FRET) to realize the MMP-2/7/9's visualization in biological systems. Moreover, as the inflammation stimulated by different concentrations lipopolysaccharide (LPS), the expression of MMP-2/7/9 in SMMC-7721 cells was observed to be significantly enhanced by confocal laser scanning microscope (CLSM) imaging, and inflammation was further proved to intensify SMMC-7721 cells' invasion and migration by transwell invasion and migration experiments. Therefore, the nanoprobe can be used to monitor biomarkers to provide a visual system for the degree of invasion and migration of tumor cells in an inflammatory environment, and also offer a new strategy for the study of the correlation between various active biomacromolecules and specific intracellular pathways in cells.
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http://dx.doi.org/10.1016/j.talanta.2020.121525DOI Listing
January 2021

A differential study on oxidized/reduced ascorbic acid induced tumor cells' apoptosis under hypoxia.

Analyst 2020 Sep;145(19):6363-6368

College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals, Shandong Normal University, Jinan 250014, P. R. China.

The anticancer mechanism for reduced/oxidized ascorbic acid (AA/DHA) is of great significance for clinical cancer therapies. A pH controlled fluorescent nanocarrier was designed to targetably deliver AA and DHA into tumor cells for investigating their function in inducing intracellular apoptosis pathways. A fluorescent silicon nanoparticle with polymer coating serves as the pH controlled nanocarrier to deliver AA or DHA into HepG2 and B16-F10 cells for studying their biological functions. The intracellular apoptotic pathway was monitored through the Caspase-3 nanoprobe, while the changes of signal molecules H2O2 and NAD(P)H in the redox homeostasis system were monitored through the corresponding fluorescent probes. Under hypoxic conditions, AA can scavenge H2O2 in tumor cells and promote NAD(P)H accumulation, but DHA promotes the production of both H2O2 and NAD(P)H, indicating that the molecular mechanisms for inducing cancer cells' apoptosis are significantly different. AA leads to reductive stress by promoting the accumulation of NAD(P)H in tumor cells, but DHA enhances oxidative stress by increasing the H2O2 concentration in cells.
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http://dx.doi.org/10.1039/d0an01011aDOI Listing
September 2020

Hydrogen selenide, a vital metabolite of sodium selenite, uncouples the sulfilimine bond and promotes the reversal of liver fibrosis.

Sci China Life Sci 2021 Mar 1;64(3):443-451. Epub 2020 Sep 1.

College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Institute of Molecular and Nano Science, Shandong Normal University, Jinan, 250014, China.

Sodium selenite has alleviating effects on liver fibrosis; however, its therapeutic molecular mechanism remains unclear. Herein, hydrogen selenide, a major metabolite of NaSeO, was tested to uncouple the sulfilimine bond in collagen IV, the biomarker of liver fibrosis. A mouse model of liver fibrosis was constructed via a CCl-induced method, followed by the administration of 0.2 mg kg NaSeO via gavage three times per week for 4 weeks. Changes in HSe, NADPH, and HO levels were monitored in real time by using NIR-HSe, DCI-MQ-NADPH, and HO probes in vivo, respectively. HSe continuously accumulated in the liver throughout the NaSeO treatment period, but the levels of NADPH and HO decreased. The expression of collagen IV was analyzed through Western blot and liquid chromatography-mass spectrometry. Results confirmed that the sulfilimine bond of collagen IV in the fibrotic mouse livers could be broken by HSe with the NaSeO treatment. Therefore, the therapeutic effect of NaSeO on liver fibrosis could be mainly attributed to HSe that uncoupled the sulfilimine bond to induce collagen IV degradation. This study provided a reasonable explanation for the molecular mechanism of the in vivo function of NaSeO and the prevention of liver fibrosis by administering inorganic selenium.
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http://dx.doi.org/10.1007/s11427-019-1761-1DOI Listing
March 2021

Homotypic cell membrane-cloaked biomimetic nanocarrier for the accurate photothermal-chemotherapy treatment of recurrent hepatocellular carcinoma.

J Nanobiotechnology 2020 Apr 16;18(1):60. Epub 2020 Apr 16.

College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Institute of Molecular and Nano Science, Shandong Normal University, Jinan, 250014, People's Republic of China.

Background: Tumor recurrence in patients after surgery severely reduces the survival rate of surgical patients. Targeting and killing recurrent tumor cells and tissues is extremely important for the cancer treatment.

Results: Herein, we designed a nano-biomimetic photothermal-controlled drug-loading platform HepM-TSL with good targeting ability and immunocompatibility for the treatment of recurrent hepatocellular carcinoma. HepM-TSL can accurately target the recurrent tumor area with the aid of the cloaked homotypic cell membrane and release the chemotherapy drugs in a controlled manner. In vivo results have confirmed that HepM-TSL loaded with drugs and photosensitizer achieves the synergistic treatment of recurrent hepatocellular carcinoma with good therapeutic effect and slight side effects.

Conclusion: Accordingly, HepM-TSL provides a sound photothermal-chemotherapy synergistic strategy for the treatment of other recurrent cancers besides of recurrent hepatocellular carcinoma.
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http://dx.doi.org/10.1186/s12951-020-00617-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7164213PMC
April 2020

Reconstruction of nano-flares based on Au-Se bonds for high-fidelity detection of RNA in living cells.

Chem Commun (Camb) 2020 May 8;56(38):5178-5181. Epub 2020 Apr 8.

College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals, Shandong Normal University, Jinan 250014, P. R. China.

We have, for the first time, developed a Au-Se-DNA nanoprobe by upgrading the conventional Au-S bonds of nano-flares to more stable Au-Se bonds for high-fidelity imaging of target RNAs in living cells. The design concept is potentially introduced into various Au-DNA nanosensors that offer wide application prospects in research and clinical practice.
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http://dx.doi.org/10.1039/d0cc01213kDOI Listing
May 2020

Monitoring NAD(P)H by an ultrasensitive fluorescent probe to reveal reductive stress induced by natural antioxidants in HepG2 cells under hypoxia.

Chem Sci 2019 Sep 19;10(35):8179-8186. Epub 2019 Jul 19.

College of Chemistry, Chemical Engineering and Materials Science , Key Laboratory of Molecular and Nano Probes , Ministry of Education , Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong , Shandong Normal University , Jinan 250014 , P. R. China . Email: ; Email:

Reductive stress, the opposite of oxidative stress, represents a disorder in the redox balance state which is harmful to biological systems. For decades, the role of oxidative stress in tumor therapy has been the focus of attention, while the effects of reductive stress have been rarely studied. Here, we report the anti-cancer effects of reductive stress induced by three natural antioxidants (resveratrol, curcumin and celastrol). Considering the fact that the solid tumor microenvironment suffers from hypoxia, we performed cell experiments under hypoxic conditions. In order to observe the reductive stress, we first developed an ultrasensitive fluorescent probe (TCF-MQ) for specifically imaging NAD(P)H which is a marker of reductive stress. TCF-MQ responded to NAD(P)H rapidly and exhibited high sensitivity with a detection limit of 6 nM. With the help of TCF-MQ, we found that upon the treatment of HepG2 cells with pharmacological doses of three natural antioxidants under hypoxic conditions, high levels of NAD(P)H were produced before cell death. The excess NAD(P)H resulted in reductive stress instead of oxidative stress. In contrast, under normoxic conditions, there was no reductive stress involved in the process of cell death induced by three natural antioxidants. Therefore, we hypothesize that the mechanism of cancer cell death induced by natural antioxidants under hypoxia should be attributed to the reductive stress.
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http://dx.doi.org/10.1039/c9sc02020aDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6836941PMC
September 2019

An Au-Se nanoprobe for the evaluation of the invasive potential of breast cancer cells via imaging the sequential activation of uPA and MMP-2.

Analyst 2020 Feb;145(3):1008-1013

College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Shandong Normal University, Jinan 250014, P. R. China.

Urokinase-type plasminogen activator (uPA) has been shown to activate matrix metalloproteinase-2 (MMP-2) that leads to the migration and invasion of breast cancer cells. Overexpressed uPA and MMP-2 are regarded as signs of malignant tumors in clinical practice. Therefore, real-time monitoring of the sequential activation of these two signal molecules may have important implications for the evaluation of the invasive potential and tumor progression of breast cancer. However, due to the complicated intracellular environment, visualizing the dynamic changes of protein expression levels in living cells with a noninvasive method is still a great challenge. Here, a novel gold-selenium (Au-Se) fluorescent nanoprobe with excellent selectivity and strong anti-interference capability was designed for the simultaneous in situ imaging of uPA and MMP-2 and real-time monitoring of their changes in living cells. The imaging results demonstrated that the nanoprobe achieved a better prevention of glutathione interference compared to the conventional Au-S nanoprobe, thus it could be applied to actually reflect the expression level of uPA and MMP-2 in different breast cancer cells. Furthermore, the Au-Se nanoprobe could visually present the activation process of the two signal molecules, which play a dual role of insuring the invasiveness evaluation of breast cancer cells. Overall, our work offers a visual biomarker detection method for the judgment of the degree of breast cancer malignancy, and also provides an effective strategy to investigate the relationships among signal molecules of other signaling pathways in the future.
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http://dx.doi.org/10.1039/c9an01830aDOI Listing
February 2020

A fluorescent probe for simultaneously sensing NTR and hNQO1 and distinguishing cancer cells.

J Mater Chem B 2019 11 14;7(43):6822-6827. Epub 2019 Oct 14.

College of Chemistry, Chemical Engineering and Materials Science, Institute of Biomedical Sciences, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong normal University, Jinan 250014, P. R. China.

Identifying cancer at the cellular level during an early stage offers the hope of greatly improved outcomes for cancer patients. As potential cancer biomarkers, nitroreductase (NTR) and human quinine oxidoreductase 1 (hNQO1) are overexpressed in many type of cancer cells. Simultaneous detection of these two biomarkers would benefit diagnostic precision in related cancers without yielding false positive results. Herein, based on a dye generated in situ strategy, a dual-enzyme-responsive probe, CNN, was rationally designed and synthesized by installing p-nitrobenzene and trimethyl-locked quinone propionic acid groups, which are specific for NTR and hNQO1, respectively, into a single fluorophore. This probe is only activated in the presence of both NTR and hNQO1 and produces a large fluorescence response, enabling the detection of both endogenous NTR and hNQO1 activity in living cells. The imaging results indicate that the CNN probe differentiates cancer cells (HeLa, MDA-MB-231 and HepG2 cells) from normal liver HL-7702 cells owing to the existence of relatively high endogenous levels of both biomarkers in these cancer cells.
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http://dx.doi.org/10.1039/c9tb01581gDOI Listing
November 2019

Homotypic Cell Membrane-Cloaked Biomimetic Nanocarrier for the Targeted Chemotherapy of Hepatocellular Carcinoma.

Theranostics 2019 12;9(20):5828-5838. Epub 2019 Aug 12.

College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Institute of Molecular and Nano Science, Shandong Normal University, Jinan 250014, P. R. China.

Hepatocellular carcinoma (HCC) has been reported to be the third most common malignant tumor and has the highest rate of mortality. To increase the chemotherapy efficacy of HCC, a drug delivery system featured with desirable active targeting ability, delivery efficiency and immune evasion is in high demand. We have developed a drug nanocarrier by utilizing a homotypic cancer cell membrane for targeted chemotherapy of HCC. Structurally, the homotypic HepG2 cell membrane was used as the cloak, and a poly (lactic--glycolic acid) (PLGA) nanoparticle as the core, resulting in the nanocarrier . The nanoparticles exhibit excellent targeting ability toward HepG2 cells. Doxorubicin (Dox) carried by possesses high delivery efficiency and a remarkable therapeutic effect. In experiments, delivers Dox directly to the tumor lesion of nude mice, and tumor volume decreases by approximately 90% after treatment. We have developed a drug nanocarrier by utilizing a homotypic cancer cell membrane for targeted chemotherapy of HCC with excellent active targeting ability. This biomimetic platform not only effectively treats HCC but also provides a sound strategy for the treatment of other cancers changes in the corresponding homotypic cancer cell membrane.
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http://dx.doi.org/10.7150/thno.34837DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6735366PMC
August 2020

Ascorbic acid induced HepG2 cells' apoptosis intracellular reductive stress.

Theranostics 2019 31;9(14):4233-4240. Epub 2019 May 31.

College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals, Shandong Normal University, Jinan 250014, P. R. China.

: Destruction of the redox balance in tumor cells is of great significance for triggering their apoptosis in clinical applications. We designed a pH sensitive multifunctional drug nanocarrier with controllable release of ascorbic acid under hypoxic environment to induce tumor cells' apoptosis enhancing reductive stress, thereby dealing minimum damage to normal tissues. : A core-shell nanostructure of CdTe quantum dots with mesoporous silica coating was developed and functionalized with poly(2-vinylpyridine)-polyethylene glycol-folic acid, which achieves cancer cells' targeting delivery and reversibly pH controlled release of ascorbic acid both and . : The result demonstrated that ascorbic acid can indeed lead liver cancer cells' death with the increase of nicotinamide adenine dinucleotide phosphate, while normal cells not being affected. The molecular mechanism of apoptosis induced by ascorbic acid was firstly elucidated at cellular levels, and further confirmed investigations. : For the first time we proposed the concept for applying reductive stress into cancer treatments, which brings great advantage of toxicity free and less damage to normal tissues. In general, this technique has taken an important step in the development of a targeted tumor treatment system, providing perspectives for the design of medicines reductive stress, and offers new insights into future clinical mild-therapies.
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http://dx.doi.org/10.7150/thno.33783DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6592181PMC
July 2020

HSe Induces Reductive Stress in HepG2 Cells and Activates Cell Autophagy by Regulating the Redox of HMGB1 Protein under Hypoxia.

Theranostics 2019 28;9(6):1794-1808. Epub 2019 Feb 28.

College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Shandong Normal University, Jinan 250014, P. R. China.

Selenium has been shown to have chemotherapeutic effects against cancer. However, the anti-cancer mechanism of selenium is not fully understood, and the role of hydrogen selenide (HSe), which is a common metabolite of dietary selenium compounds, has not been elucidated due to the lack of detection methods. In this study, we revealed a new anti-cancer mechanism of selenite with the help of a HSe fluorescent probe. HepG2 cells were cultured under a simulated tumor hypoxic microenvironment. The HSe and HO levels were detected by fluorescent probes in living cells and in mice. Autophagic and apoptotic proteins were detected by Western blotting. The redox of HMGB1 protein were analyzed by non-reducing sodium dodecyl sulfate polyacrylamide gel electrophoresis. After pharmacological doses of NaSeO treatment of HepG2 cells under hypoxic conditions, high levels of HSe were produced before cell death. The HSe accumulation resulted in reductive stress instead of oxidative stress, which was induced by NaSeO treatment under normoxic conditions. Furthermore, HSe targeted the HMGB1 protein and induced cell autophagy. HSe could interrupt the disulfide bond in HMGB1 and promote its secretion. The reduced HMGB1 outside the cells stimulated cell autophagy by inhibiting the Akt/mTOR axis. Here, autophagy played a dual role, i.e., mild autophagy inhibited apoptosis, while excessive autophagy led to autophagy-associated cell death. These results show that HSe plays a key role during HepG2 cell death induced by selenite. Our findings reveal a new anti-cancer mechanism of selenite and provide a new research area for selenium studies.
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http://dx.doi.org/10.7150/thno.31841DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6485193PMC
March 2020

Enhanced oxygen sensing sensitivity by eliminating the protection of triplet phosphorescence.

Spectrochim Acta A Mol Biomol Spectrosc 2019 Jun 29;217:310-314. Epub 2019 Mar 29.

Condensed Matter Science and Technology Institute and Department of Physics, Harbin Institute of Technology, Harbin 150080, China.

High oxygen sensitivity (the slope of the Stern-Volmer plot reaches 0.73/μM) is achieved with a phosphorescence indicator, gadolinium-hematoporphyrin monomethyl ether (Gd-HMME), by decreasing the extent of its protection. In air-saturated solution, the phosphorescence quantum efficiency (QE) of Gd-HMME in a non-rigid microenvironment is lower than that in a rigid microenvironment. In contrast, when oxygen is removed, the QE of Gd-HMME in the non-rigid microenvironment was found to be same as that of Gd-HMME in the rigid microenvironment. This indicates that Gd-HMME is much more sensitive to oxygen in the non-rigid microenvironment. The oxygen sensitivity of Gd-HMME was found to increase as the rigidity of its microenvironment decreases. The oxygen response of Gd-HMME without any protection reaches 240 (0-374 μM oxygen), whereas that in the rigid microenvironment is only 3 in this range. The measurement precision of Gd-HMME without any protection is lower than that in the rigid microenvironment. These results indicate that the measurement of oxygen in different concentration ranges would require the rigidity of the microenvironment to be varied. Gd-HMME without any protection can be applied to detect oxygen as low as 0.1 μM. The detection limit of oxygen was evaluated to be as low as 20 nM based on Gd-HMME without any protection.
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http://dx.doi.org/10.1016/j.saa.2019.03.107DOI Listing
June 2019

Real-Time in Situ Visualizing of the Sequential Activation of Caspase Cascade Using a Multicolor Gold-Selenium Bonding Fluorescent Nanoprobe.

Anal Chem 2019 05 12;91(9):5994-6002. Epub 2019 Apr 12.

College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Institute of Molecular and Nano Science , Shandong Normal University , Jinan 250014 , People's Republic of China.

The caspase cascade is an ensemble of very important signaling molecules that plays a critical role in cell apoptosis. Real-time monitoring of the upstream and downstream activation relationships of the caspases in the signal pathway is of great significance for understanding the regulatory mechanisms of these signaling molecules in the development of various diseases. Herein, a multicolor fluorescent nanoprobe, GNP-Se-Casp, has been developed based on Au-Se bonding for real-time in situ monitoring caspase- (casp-) 3, 8, and 9 during cell apoptosis. In the real-time fluorescence imaging of apoptotic HeLa cells induced by staurosporine using GNP-Se-Casp, the fluorescence signals corresponding to casp-8 and casp-9 sequentially turn on, followed by the appearance of the fluorescence of casp-3, which visualizes the upstream and downstream relationships of casp-3, -8, and -9. Thus, GNP-Se-Casp is an effective tool for real-time in situ monitoring of caspase cascade activation in the apoptosis process of tumor cells. This design strategy is easily adaptable to in situ detection of other signal molecules, especially those with upstream and downstream activation relationships.
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http://dx.doi.org/10.1021/acs.analchem.9b00452DOI Listing
May 2019

An Aptamer-Based Near-Infrared Fluorescence Nanoprobe for Detecting and Imaging of Phospholamban Micropeptide in Cardiomyocytes.

ACS Sens 2019 03 28;4(3):733-739. Epub 2019 Feb 28.

College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong , Shandong Normal University , Jinan 250014 , P. R. China.

A growing body of evidence indicates that micropeptides encoded by long noncoding RNAs (lncRNAs) act independently or as regulators of larger proteins in fundamental biological processes, especially in the maintenance of cellular homeostasis. However, due to their small size and low intracellular expression, visual monitoring of micropeptides in living cells is still a challenge. In this work, we have designed and synthesized an aptamer-based near-infrared fluorescence nanoprobe for fluorescence imaging of phospholamban (PLN), which is an intracellular micropeptide that affects calcium homeostasis, and is closely associated with human heart failure in the clinic. The nanoprobe could respond specifically to PLN with excellent selectivity, high sensitivity, good nuclease stability, and biocompatibility, and it was successfully applied for imaging of changes in PLN levels in cardiomyocytes and in frozen sections of heart tissues. Further combined with clinical myocardial biopsy, we believe that the developed nanoprobe should be of great significance in later molecular pathology study of heart failure, which may help with diagnosis of early heart failure in the future. More importantly, for the first time nanoprobes were applied to visually monitor the changes of micropeptides in living cells and in frozen tissue sections, and the design concept of the aptamer-based nanoprobe can be extended to fluorescence detection of other micropeptides.
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http://dx.doi.org/10.1021/acssensors.9b00026DOI Listing
March 2019

Dynamic fluorescent imaging analysis of mitochondrial redox in single cells with a microfluidic device.

Biosens Bioelectron 2019 Mar 11;129:132-138. Epub 2019 Jan 11.

College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Institute of Molecular and Nano Science, Shandong Normal University, Jinan 250014, PR China. Electronic address:

The redox balance in cellular mitochondria is closely related to the physiological and pathological processes of the body. When exposed to external stimuli, the redox state in cells changes dynamically, and presents cell heterogeneity, which creates a need for techniques that can make dynamic and reversible visual analysis of redox in mitochondria at single-cell level. Here we describe a method for single-cell redox analysis based on a microfluidic device combing with a reversible fluorescent probe (Cy-O-ebselen), that enables online culture, labelling and dynamic fluorescent imaging analysis of mitochondrial redox (HO/GSH) change. Using this method, we further explored the dynamic changes of mitochondrial redox state after thermal stimulation or combined thermal-drug stimulation, and analysed the heterogeneous response of cells to external stimuli at the single cell level.
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http://dx.doi.org/10.1016/j.bios.2019.01.005DOI Listing
March 2019

Dicyanoisophorone-Based Near-Infrared-Emission Fluorescent Probe for Detecting NAD(P)H in Living Cells and in Vivo.

Anal Chem 2019 01 21;91(2):1368-1374. Epub 2018 Dec 21.

College of Chemistry, Chemical Engineering and Materials Science, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong , Shandong Normal University , Jinan 250014 , PR China.

NADH and NADPH are ubiquitous coenzymes in all living cells that play vital roles in numerous redox reactions in cellular energy metabolism. To accurately detect the distribution and dynamic changes of NAD(P)H under physiological conditions is essential for understanding their biological functions and pathological roles. In this work, we developed a near-infrared (NIR)-emission fluorescent small-molecule probe (DCI-MQ) composed of a dicyanoisophorone chromophore conjugated to a quinolinium moiety for in vivo NAD(P)H detection. DCI-MQ has the advantages of high water solubility, a rapid response, extraordinary selectivity, great sensitivity (a detection limit of 12 nM), low cytotoxicity, and NIR emission (660 nm) in response to NAD(P)H. Moreover, the probe DCI-MQ was successfully applied for the detection and imaging of endogenous NAD(P)H in both living cells and tumor-bearing mice, which provides an effective tool for the study of NAD(P)H-related physiological and pathological processes.
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http://dx.doi.org/10.1021/acs.analchem.8b03563DOI Listing
January 2019

Cyclic Regulation of the Sulfilimine Bond in Peptides and NC1 Hexamers via the HOBr/HSe Conjugated System.

Anal Chem 2018 08 9;90(15):9523-9528. Epub 2018 Jul 9.

College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals , Shandong Normal University , Jinan 250014 , People's Republic of China.

The sulfilimine bond (-S═N-), found in the collagen IV scaffold, significantly stabilizes the architecture via the formation of sulfilimine cross-links. However, precisely governing the formation and breakup process of the sulfilimine bond in living organisms for better life functions still remains a challenge. Hence, we established a new way to regulate the breaking and formation of the sulfilimine bond through hydrogen selenide (HSe) and hypobromous acid (HOBr), which can be easily controlled at simulated physiological conditions. This novel strategy provides a circulation regulation system to modulate the sulfilimine bond in peptides and NC1 hexamers, which can offer a substantial system for further study of the physiological function of collagen IV.
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http://dx.doi.org/10.1021/acs.analchem.8b02228DOI Listing
August 2018

Simultaneous Detection of Mitochondrial Hydrogen Selenide and Superoxide Anion in HepG2 Cells under Hypoxic Conditions.

Anal Chem 2018 07 19;90(13):8116-8122. Epub 2018 Jun 19.

College of Chemistry, Chemical Engineering and Materials Science, Institute of Biomedical Sciences, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals , Shandong Normal University , Jinan 250014 , People's Republic of China.

Previous studies proposed that sodium selenite (NaSeO) was reduced to hydrogen selenide (HSe) and that HSe subsequently reacted with oxygen to generate superoxide anion (O), resulting in tumor cell oxidative stress and apoptosis. However, under the hypoxic conditions of a solid tumor, the anticancer mechanism of sodium selenite remains unclear. To reveal the exact anticancer mechanism of selenite in the real tumor microenvironment, we developed a mitochondria-targeting fluorescent nanosensor, Mito-N-D-MSN, which was fabricated from mesoporous silica nanoparticles (MSNs) loaded with two small-molecule fluorescent probes and a triphenylphosphonium ion as a mitochondria-targeting moiety. With Mito-N-D-MSN, the fluctuations in the contents of mitochondrial hydrogen selenide (HSe) and superoxide anion (O) in HepG2 cells induced by NaSeO were investigated in detail under normoxic and hypoxic conditions. The results showed that the mitochondrial HSe content increased gradually, while the O content remained unchanged in HepG2 cells under hypoxic conditions, which indicated that the anticancer mechanism of selenite involves nonoxidative stress in the real tumor microenvironment.
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http://dx.doi.org/10.1021/acs.analchem.8b01345DOI Listing
July 2018

Targetable Mesoporous Silica Nanoprobes for Mapping the Subcellular Distribution of HSe in Cancer Cells.

ACS Appl Mater Interfaces 2018 May 10;10(20):17345-17351. Epub 2018 May 10.

College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals , Shandong Normal University , Jinan 250014 , P. R. China.

Hydrogen selenide, a highly active reductant, is believed as a key molecule in the cytotoxicity of inorganic selenium compounds. However, the detail mechanism has hardly been studied because the distribution of HSe in the subcellular organelles remains unclear. Herein, we exploited a series of novel targetable mesoporous silica nanoplatforms to map the distribution of HSe in cytoplasm, lysosome, and mitochondria of cancer cells. The subcellular targeting moiety-conjugated mesoporous silica nanoparticles were assembled with a near-infrared fluorescent probe (NIR-HSe) for detecting endogenous HSe in the corresponding organelles. The confocal fluorescence imaging of cancer cells induced by NaSeO found out a higher concentration of HSe accumulated only in mitochondria. Consequently, the HSe burst in mitochondria-triggered mitochondrial collapse that led to cell apoptosis. Hence, the selenite-induced cytotoxicity in cancer cells associates with the alteration in mitochondrial function caused by high level of HSe. These findings provide a new way to explore the tumor cell apoptosis signaling pathways induced by NaSeO, meanwhile, we propose a research strategy for tracking the biomolecules in the subcellular organelles and the correlative cellular function and related disease diagnosis.
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http://dx.doi.org/10.1021/acsami.8b02206DOI Listing
May 2018

Avoiding Thiol Compound Interference: A Nanoplatform Based on High-Fidelity Au-Se Bonds for Biological Applications.

Angew Chem Int Ed Engl 2018 05 9;57(19):5306-5309. Epub 2018 Apr 9.

College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for, Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals, Shandong Normal University, Jinan, 250014, P. R. China.

Gold nanoparticles (Au NPs) assembled through Au-S covalent bonds have been widely used in biomolecule-sensing technologies. However, during the process, detection distortions caused by high levels of thiol compounds can still significantly influence the result and this problem has not really been solved. Based on the higher stability of Au-Se bonds compared to Au-S bonds, we prepared selenol-modified Au NPs as an Au-Se nanoplatform (NPF). Compared with the Au-S NPF, the Au-Se NPF exhibits excellent anti-interference properties in the presence of millimolar levels of glutathione (GSH). Such an Au-Se NPF that can effectively avoid detection distortions caused by high levels of thiols thus offers a new perspective in future nanomaterial design, as well as a novel platform with higher stability and selectivity for the in vivo application of chemical sensing and clinical therapies.
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http://dx.doi.org/10.1002/anie.201712921DOI Listing
May 2018

Au-Se-Bond-Based Nanoprobe for Imaging MMP-2 in Tumor Cells under a High-Thiol Environment.

Anal Chem 2018 04 20;90(7):4719-4724. Epub 2018 Mar 20.

College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals , Shandong Normal University , Jinan 250014 , P. R. China.

The gold nanosensors based on the Au-S bond have been widely applied to biochemical detections. However, signal distortion caused by biothiols has been seldom mentioned and urgently needs to be solved. Herein, we designed a novel but easily assembled gold nanoprobe by coupling a selenol-modified peptide with FITC onto the gold nanoparticle's surface via an Au-Se bond for fluorescence imaging of a tumor marker matrix, metalloproteinases 2 (MMP-2). Compared to the Au-S probes, the Au-Se probes display high thermal stability and a very good anti-interference ability toward glutathione under simulated physiological conditions. More importantly, the Au-Se nanoprobe exhibits a high-fidelity fluorescent signal toward MMP-2, effectively avoiding interference caused by high levels of thiol compounds in vivo. In addition, in vivo experiments further proved that no significant signal intensity change for the tumor cells treated by the Au-Se probes was observed before and after eliminating glutathione. Hence, we believe such Au-Se probes with in vivo glutathione interfering resistance offer new routes and perspectives in biology and medicine in the future.
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http://dx.doi.org/10.1021/acs.analchem.7b05343DOI Listing
April 2018

High-Quantum-Yield Mitochondria-Targeting Near-Infrared Fluorescent Probe for Imaging Native Hypobromous Acid in Living Cells and in Vivo.

Anal Chem 2017 02 19;89(3):1787-1792. Epub 2017 Jan 19.

College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Institute of Molecular and Nano Science, Shandong Normal University , Jinan, Shandong 250014, P. R. China.

The discovery that hypobromous acid (HOBr) can regulate the activity of collagen IV has attracted great attention. However, HOBr as an important reactive small molecule has hardly ever been studied using a detection method suitable for organisms. Herein, a high-quantum-yield mitochondria-targeting near-infrared (NIR) fluorescent probe for HOBr, RhSN-mito, was designed. RhSN-mito was easily obtained by the Suzuki cross-coupling reaction. The test results show that RhSN-mito can rapidly respond to HOBr with ultrasensitivity and high selectivity. The achievement of ultrasensitivity lies in the high signal-to-noise ratio and the highest fluorescence quantum yield of the reaction product (Φ = 0.68) in the near-infrared region, as far as we know. RhSN-mito is successfully applied to image native HOBr in mitochondria of HepG2 cells and zebrafish. Thus, RhSN-mito is a powerful tool for detecting native HOBr in vivo and is expected to provide a method to further study the physiological and pathological functions related to HOBr.
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http://dx.doi.org/10.1021/acs.analchem.6b04094DOI Listing
February 2017

Highly Selective Fluorescent Probe for Imaging HSe in Living Cells and in Vivo Based on the Disulfide Bond.

Anal Chem 2017 01 15;89(1):688-693. Epub 2016 Dec 15.

College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Institute of Molecular and Nano Science, Shandong Normal University , Jinan, Shandong 250014, P. R. China.

Hydrogen selenide (HSe) is an important metabolite of dietary Se compounds and has been implicated in various pathological and physiological processes. The development of highly sensitive and selective methods for the sensing of HSe is therefore very important. Herein, we developed a fluorescent probe (hemicyanine (Hcy)-HSe) for detecting HSe based on a new HSe-specific receptor unit, 1,2-dithiane-4,5-diol. Hcy-HSe showed high selectivity toward HSe over thiols (RSH), hydrogen sulfide (HS), and selenocysteine (Sec) and was further exploited for the fluorescence imaging of HSe both in living cells and in vivo. Furthermore, with the aid of Hcy-HSe, we demonstrated that HSe can be generated and gradually accumulated in HepG2 cells under hypoxic conditions and in the solid tumor after treatment with NaSeO.
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http://dx.doi.org/10.1021/acs.analchem.6b03136DOI Listing
January 2017

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

Angew Chem Int Ed Engl 2016 10 15;55(41):12751-4. Epub 2016 Sep 15.

College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals, Shandong Normal University, Jinan, 250014, P.R. China.

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.
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http://dx.doi.org/10.1002/anie.201606285DOI Listing
October 2016