Publications by authors named "Zhaoyang Wu"

57 Publications

Organic Nanoparticles-Assisted Low-Power STED Nanoscopy.

Nano Lett 2021 Apr 13;21(8):3487-3494. Epub 2021 Apr 13.

Beijing Key Laboratory for Optical Materials and Photonic Devices, Capital Normal University, Beijing 100048, China.

Stimulated emission depletion (STED) nanoscopy plays a key role in achieving sub-50 nm high spatial resolution for subcellular live-cell imaging. To avoid re-excitation, the STED wavelength has to be tuned at the red tail of the emission spectrum of fluorescent probes, leading to high depletion laser power that might damage the cell viability and functionality. Herein, with the highly emissive silica-coated core-shell organic nanoparticles (CSONPs) enabling a giant Stokes shift of 150 nm, ultralow power STED is achieved by shifting the STED wavelength to the emission maximum at 660 nm. The stimulated emission cross section is increased by ∼20-fold compared to that at the emission red tail. The measured saturation intensity and lateral resolution of our CSONP are 0.0085 MW cm and 25 nm, respectively. More importantly, long-term (>3 min) dynamic super-resolution imaging of the lysosomal fusion-fission processes in living cells is performed with a resolution of 37 nm.
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http://dx.doi.org/10.1021/acs.nanolett.1c00161DOI Listing
April 2021

Defatted Seeds of as a Potential Functional Food Ingredient for Diabetes.

Foods 2021 Mar 5;10(3). Epub 2021 Mar 5.

Key Laboratory of Public Health Safety of Hebei Province, College of Public Health, Hebei University, Baoding 071002, China.

The defatted seeds of (DSOB) are a by-product of evening primrose oil production that are currently not effectively used. In this study, α-glucosidase inhibition, aldose reductase inhibition, antioxidant capacity, polyphenol composition, and nutritional value (carbohydrates, proteins, minerals, fat, organic acid, and tocopherols) of DSOB were evaluated using the seeds of (SOB) as a reference. DSOB was an excellent inhibitor of α-glucosidase (IC = 3.31 μg/mL) and aldose reductase (IC = 2.56 μg/mL). DSOB also showed considerable antioxidant capacities (scavenging of 2,2-diphenyl-1-picrylhydrazyl, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid, nitric oxide, peroxynitrite, and hydroxyl radicals). DSOB was a reservoir of polyphenols, and 25 compounds in DSOB were temporarily identified by liquid chromatography coupled with electrospray ionization-quadrupole time of flight-mass spectrometry analysis. Moreover, the carbohydrate, protein, and mineral content of DSOB were increased compared to that of SOB. DSOB contained large amounts of fiber and low levels of sugars, and was rich in calcium and iron. These results imply that DSOB may be a potential functional food ingredient for diabetes, providing excellent economic and environmental benefits.
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http://dx.doi.org/10.3390/foods10030538DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8002154PMC
March 2021

Stimulated emission depletion microscopy for biological imaging in four dimensions: A review.

Microsc Res Tech 2021 Mar 13. Epub 2021 Mar 13.

Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, China.

Stimulated emission depletion (STED) microscopy allows high lateral and axial resolution, long term imaging in living cells. Here we review recent technical advances in STED microscopy, with emphasis on resolution and measurement range of XYZt four dimensions. Different STED technical advances and novel STED probes are discussed with their respective application in biological subcellular imaging. This review may serve as a practical guide for choosing a suitable approach to the advanced STED super-resolution imaging.
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http://dx.doi.org/10.1002/jemt.23750DOI Listing
March 2021

Epidermal growth factor receptor promotes tumor progression and contributes to gemcitabine resistance in osteosarcoma.

Acta Biochim Biophys Sin (Shanghai) 2021 Mar;53(3):317-324

Department of Orthopedics, The First Affiliated Hospital of Fujian Medical University, Fuzhou 350005, China.

Osteosarcoma (OS) is the most common type of primary malignant tumors that originate in the bone. Resistance to chemotherapy confers a poor prognosis on OS patients. Dysregulation of the epidermal growth factor receptor (EGFR) signaling has been reported in sarcomas. However, the functional contribution of EGFR hyperactivation to the tumor biology and chemoresistance remains largely unexplored in OS. In this study, we aimed to investigate the role of EGFR in OS progression and in the response of OS to gemcitabine treatment. The EGFR expression was found to be upregulated in fibroblastic OS cell lines. EGFR knockdown suppressed OS cell proliferation, migration, and invasion in vitro and tumor formation in vivo. Conversely, EGFR overexpression promoted the growth and motility of OS cells. In terms of mechanism, the levels of phospho-Akt and phospho-ERK were decreased upon EGFR knockdown but increased as a result of EGFR overexpression, implying a possible involvement of PI3K/Akt and ERK pathways in mediating the effects of EGFR on OS cells. Moreover, the level of phospho-EGFR was increased in OS cells when exposed to gemcitabine treatment. A more profound proliferative inhibition and a higher rate of apoptosis were obtained in OS cells via inducing cell cycle arrest at G1 phase upon gemcitabine treatment combined with EGFR knockdown, as compared to gemcitabine alone. On the contrary, EGFR overexpression counteracted the growth-inhibiting and pro-apoptotic effects of gemcitabine in OS cells. The present study suggests that EGFR promotes tumor progression and contributes to gemcitabine resistance in OS.
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http://dx.doi.org/10.1093/abbs/gmaa177DOI Listing
March 2021

Pretreatments for enhancing sewage sludge reduction and reuse in lipid production.

Biotechnol Biofuels 2020 Dec 14;13(1):204. Epub 2020 Dec 14.

Department of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen, People's Republic of China.

Background: Converting wastewater sludge to lipid is considered as one of the best strategies of sludge management. The current problem of lipid production from wastewater sludge is the low yield (0.10-0.16 g lipid/g dry sludge) due to the low availability of easily uptaken materials (such as soluble monosaccharide and oligosaccharide) in sludge to oleaginous microorganism (Rhodotorula glutinis, Trichosporon oleaginosus, Lipomyces starkeyi). Pretreatments are efficient methods to improve sludge bioavailability. This study is aimed to achieve high lipid production from sludge and high sludge reduction.

Results: In this study, it was observed that the soluble chemical oxygen demand (SCOD) had significantly increased after different pretreatment. The SCOD in the supernatant was increased from 32.64 to 180.25 mg/L, 924.16 mg/L, 1029.89 mg/L and 3708.31 mg/L after acidic (pH 2 for 2 h), alkaline (pH 12 for 2 h), microwave irradiation (15 min with 5 min interval), and ultrasonication (30 min at 450 W and 20 kHz frequency with 5 s on and 2 s off mode) pretreatment, respectively. Pretreatments have also increased the release of total nitrogen (TN) and total phosphorus (TP) from solids. The sludge after different pretreatments were used as a medium for lipid production, and the highest lipid content (36.67% g/g) was obtained in the fermentation with ultrasonication pretreatment sludge, and the sludge reduction was 63.10%. For other pretreatments, the lipid content and sludge reduction were 18.42% and 32.63% in acid pretreatment case, 21.08% and 36.44% in alkaline pretreatment case, and 26.31% and 43.03% in microwave pretreatment case, respectively.

Conclusion: It was found that ultrasonication pretreatment was the most efficient way to increase the sludge biodegradability (SCOD) and to release TN and TP from solid phase to liquid phase. Pretreated sludge for lipid production achieved significant improvement in lipid yield and sludge reduction. Lipids produced from pretreated sludge were transesterified to biodiesel and the analysis showed that biodiesel had a similar composition as commercial biodiesel. The study reveals that pretreatment on sludge is a promising method for enhancing biological sludge management efficiency.
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http://dx.doi.org/10.1186/s13068-020-01844-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7734850PMC
December 2020

Ratiometric sensors with selective fluorescence enhancement effects based on photonic crystals for the determination of acetylcholinesterase and its inhibitor.

J Mater Chem B 2020 12;8(48):11001-11009

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China.

Ratiometric fluorescent sensors are powerful tools for quantitative analyses. However, gold nano-clusters (AuNCs) as typical fluorophores in ratiometric sensors have some disadvantages, such as low luminous efficiency. In this study, a highly sensitive ratiometric fluorescence sensor was fabricated by the combination of AuNCs and fluorescein (FL), and the photonic crystals (PhCs) were used to selectively enhance the fluorescence intensity of AuNCs. This fluorescence sensor was used for the sensitive detection of acetylcholinesterase (AChE) and its inhibitor paraoxon. AChE can catalyze the hydrolysis of acetylthiocholine (ATCh) to form thiocholine (TCh), which can induce the fluorescence quenching of AuNCs while having no obvious influence on the fluorescence intensity of FL. AChE can be determined in the range from 0.1 to 25 mU mL-1 with a limit of detection (LOD) of 0.027 mU mL-1, and paraoxon can be determined in the range of 0.06 to 60 ng mL-1 with a LOD 0.025 ng mL-1. This method, as a new way to selectively improve the fluorescence signal of one of the fluorophores in the ratiometric sensor, would be a promising strategy for the sensitive determination of AChE and its inhibitor.
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http://dx.doi.org/10.1039/d0tb02197kDOI Listing
December 2020

A two-dimensional photonic crystal hydrogel biosensor for colorimetric detection of penicillin G and penicillinase inhibitors.

Analyst 2021 Jan 19;146(2):502-508. Epub 2020 Nov 19.

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China.

A simple penicillinase functionalized two-dimensional photonic crystal hydrogel (2DPPCH) biosensor was developed for colorimetric detection of penicillin G and penicillinase inhibitors. The penicillinase can specifically recognize penicillin G and catalyze it to produce penicilloic acid, which decreases the pH of the hydrogel microenvironment and shrinks the pH-sensitive hydrogel. The particle spacing decrease of the 2D photonic crystal array induced by the hydrogel shrinkage further causes a blue-shift in the diffraction wavelength. While the hydrolysis reaction is repressed upon treatment with clavulanate potassium (a kind of penicillinase inhibitor), no significant change in the diffraction wavelength is found. The detection of targets can be achieved by measuring the Debye diffraction ring diameter or observing the structural color change in the visible region. The lowest detectable concentrations for penicillin G and clavulanate potassium are 1 μM and 0.1 μM, respectively. Moreover, the 2DPPCH is proved to exhibit high selectivity and an excellent regeneration property, and it shows satisfactory performance for penicillin G analysis in real water samples.
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http://dx.doi.org/10.1039/d0an01946aDOI Listing
January 2021

Low-angle-dependent CdS@SiO photonic crystal hydrogel material for visual detection and removal of uranyl ions.

Mikrochim Acta 2020 08 1;187(8):476. Epub 2020 Aug 1.

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, People's Republic of China.

A low-angle-dependent photonic crystal hydrogel (LAD-PCH) material was developed to simultaneously detect and remove uranyl ions (UO). Different from traditional SiO photonic crystal hydrogel with the problem of angle dependency, the LAD-PCH material overcomes the restriction of observation direction. The LAD-PCH is a composite material with the photonic crystal array of 180-nm monodisperse CdS@SiO particles embedded into the functional hydrogel. As one UO can bind to multiple carboxyl groups and amide groups, the functional hydrogel fabricated by acrylic acid and acrylamide will shrink after chelating. These changes in the hydrogel volume alter the array spacing and trigger a blue shift of diffraction wavelength and naked-eye visual color changes of LAD-PCH. The color can vary from orange-red to orange, yellow, green, and cyan, corresponding to the determination range of 100 pM-100 μM. The LAD-PCH material detects UO sensitively as the lowest detectable concentration is about 100 pM, and removes UO high-efficiently as the maximum adsorption capacity of U(VI) is about 1010 mg g at 298 K. This LAD-PCH material is convenient and has potential to simultaneously monitor and remove UO from uranium-polluted water. Schematic representation of the low-angle-dependent photonic crystal hydrogel (LAD-PCH) material for UO detection and removal: The structural colors of LAD-PCH material overcome the restriction of observation angles. After the ligands complex with UO, the networks of LAD-PCH show different degrees of shrinkage; these volume changes of hydrogel trigger obvious naked-eye visual color changes of LAD-PCH.
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http://dx.doi.org/10.1007/s00604-020-04456-8DOI Listing
August 2020

Smart soft photonic dressing toward fast drug release and visualized self-monitoring.

J Colloid Interface Sci 2020 Nov 16;580:681-689. Epub 2020 Jul 16.

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, People's Republic of China. Electronic address:

Stimuli-responsive microgel have shown great promise in drug delivery material applications. However, it still remains an unresolved problem to establish method that can monitor the degree of drug release in situ and real-time. Here, taking advantage of thermo-sensitive and fast responsive ability of the soft nanoparticles, and inspired by the excellent mechanical properties of polyurethane, a novel materials is presented, which combines the soft particles and polyacrylamide-co-polyurethane acrylate for the first time, the generation of multifunctional material based on soft photonic crystals with tunable structure color and drug delivery capability is reported. As proof-of-concept, BSA was selected as model of protein-based drug, the smart materials exhibit different optical properties during the release of BSA. Consequently, the cumulative release amount of the BSA can be sensitively evaluated by measuring the reflection peak position, and shows a property of self-monitoring. Our strategy is a straightforward way to propose simple smart drug delivery materials whose cumulative release of drug and reflection peak can be tuned through the judicious choice of the temperature, and it has been proved that this is a promising way to construct visualized self-monitoring drug delivery systems using soft colloidal crystal films as stimuli-responsive and drug carrier substrates.
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http://dx.doi.org/10.1016/j.jcis.2020.07.069DOI Listing
November 2020

Mitochondrial dynamics quantitatively revealed by STED nanoscopy with an enhanced squaraine variant probe.

Nat Commun 2020 07 24;11(1):3699. Epub 2020 Jul 24.

Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, 100871, China.

Mitochondria play a critical role in generating energy to support the entire lifecycle of biological cells, yet it is still unclear how their morphological structures evolve to regulate their functionality. Conventional fluorescence microscopy can only provide ~300 nm resolution, which is insufficient to visualize mitochondrial cristae. Here, we developed an enhanced squaraine variant dye (MitoESq-635) to study the dynamic structures of mitochondrial cristae in live cells with a superresolution technique. The low saturation intensity and high photostability of MitoESq-635 make it ideal for long-term, high-resolution (stimulated emission depletion) STED nanoscopy. We performed time-lapse imaging of the mitochondrial inner membrane over 50 min (3.9 s per frame, with 71.5 s dark recovery) in living HeLa cells with a resolution of 35.2 nm. The forms of the cristae during mitochondrial fusion and fission can be clearly observed. Our study demonstrates the emerging capability of optical STED nanoscopy to investigate intracellular physiological processes with nanoscale resolution for an extended period of time.
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http://dx.doi.org/10.1038/s41467-020-17546-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7382495PMC
July 2020

A responsive photonic crystal film sensor for the ultrasensitive detection of uranyl ions.

Analyst 2020 Aug 8;145(16):5624-5630. Epub 2020 Jul 8.

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China.

As an effective nuclear energy resource, uranium plays an important role in industry and energy but the wastes of uranium also cause radioactive contamination, which is harmful to the environment and the human body. Herein, a responsive photonic crystal (PC) film sensor for the ultrasensitive and label-free detection of uranyl ions (UO) has been proposed, which is easy to construct and does not need to be combined with a hydrogel. The PC film is not pH-sensitive because it is obtained by the self-assembly of methyl methacrylate-acrylonitrile co-polymeric nanospheres (PMMA-AN). These nanospheres were modified with amidoxime groups, which have a good coordination ability with UO. The bindings between nanospheres and UO change the refractive index and disturb the face-centered cubic structure of the film, which leads to a decrease in the diffraction peak intensity of the PC film. The sensor works in the concentration range of 10 pM to 100 μM for UO determination and the decreased intensities of the diffraction peaks are linearly correlated with the logarithm of UO concentration in the range from 1 nM to 100 μM. Moreover, the sensor shows good selectivity for UO and can also perform the determination of UO in a real sample. The responsive PC film sensor shows great potential in the label-free and ultrasensitive detection of UO.
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http://dx.doi.org/10.1039/d0an00443jDOI Listing
August 2020

Photonic crystal enhanced gold-silver nanoclusters fluorescent sensor for Hg ion.

Anal Chim Acta 2020 Jun 8;1114:50-57. Epub 2020 Apr 8.

State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, PR China.

Luminescent nanoclusters (NCs) have attracted much attention because of their good photostability and low toxicity, however, the low quantum yield is still a deficiency, and many increasing efforts are being devoted to enhance the luminescence intensity of NCs. In this paper, a method of enhancing the fluorescent signal of gold-silver nanoclusters (AuAgNCs) by photonic crystals (PhCs) was proposed. The fluorescent intensity of AuAgNCs on PhCs can be enhanced 8.0-fold in comparison to the control sample without PhCs. Furthermore, a novel fluorescence sensor of AuAgNCs based on PhCs is used for the sensitive and selective detection of Hg ion in the aqueous solution, the detection limit is 0.35 nM due to the PhCs enhancement effect for the fluorescence. This proposed method may not only develop a highly sensitive method for determination of Hg ion, but also expand the application of AuAgNCs in ultra-trace analysis.
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http://dx.doi.org/10.1016/j.aca.2020.04.011DOI Listing
June 2020

Alkyne/Ruthenium(II) Complex-Based Ratiometric Surface-Enhanced Raman Scattering Nanoprobe for In Vitro and Ex Vivo Tracking of Carbon Monoxide.

Anal Chem 2020 01 17;92(1):924-931. Epub 2019 Dec 17.

Department of Chemistry , University of California-Riverside , Riverside , California 92521 , United States.

Here, we report a surface-enhanced Raman scattering (SERS) nanosensor for real-time ratiometric detection of carbon monoxide (CO) based on a ligand displacement mechanism. This nanoprobe consists of a gold-silver (Au-Ag) alloy nanoparticle core as the highly active SERS substrate, an alkyne/ruthenium(II) (alkyne/Ru(II)) complex immobilized on the surface as the CO-sensing element, and a porous silica shell to improve the stability and biocompatibility of the particle. Displacement of the alkyne ligand by CO results in a decrease of the alkyne vibrations and an increase of the metal carbonyl complex signals, thus allowing the effective ratiometric detection of CO in real-time. The great potential of this assay for CO detection is validated in clean buffer environments, live cells, and tissue slices.
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http://dx.doi.org/10.1021/acs.analchem.9b03769DOI Listing
January 2020

Sensing of cocaine using polarized optical microscopy by exploiting the conformational changes of an aptamer at the water/liquid crystal interface.

Mikrochim Acta 2019 10 26;186(11):724. Epub 2019 Oct 26.

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, People's Republic of China.

Liquid crystals (LCs) have the ability to transduce and amplify a molecular stimulus into optical signals due to their elastic and birefringence properties. An aptamer-based LC sensor for cocaine is described here. 3-Morpholinopropanesulfonic acid with amphipathic structure was used to establish recognition sites at a water/LC interface for the detection of cocaine. The cocaine-binding aptamer is formed at the interface. The conformation of the aptamer undergoes a change on binding cocaine, and this triggers the LCs anchoring transition from homeotropic to planar. Binding can also be detected by polarized optical microscopy. The fluorescence spectroscopy and circular dichroism results are used to prove that the conformation of aptamer changed from a hairpin structure to a special three-way junction structure on binding of cocaine at the interface. The assay works in the 1 nM to 10 μM cocaine concentration range and is specific. Graphical abstract Schematic representation of aptamer-based liquid crystal (LC) biosensor for the detection of cocaine. In this interface biosensing system, after the aptamer binding with cocaine, the conformation of aptamer at the aqueous/LC interface was changed from a hairpin structure to a special three-way junction structure. This triggered the Liquid crystals (LCs) anchoring transition from homeotropic to planar and the sign-on optical signal could be obtained by polarizing optical microscope (POM) in real-time.
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http://dx.doi.org/10.1007/s00604-019-3855-1DOI Listing
October 2019

Ratiometric SERS biosensor for sensitive and reproducible detection of microRNA based on mismatched catalytic hairpin assembly.

Biosens Bioelectron 2019 Oct 22;143:111619. Epub 2019 Aug 22.

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China.

MicroRNAs (miRNAs) serve as significant regulators in a variety of diseases and have been emerging as a class of promising biomarkers for early cancer diagnosis. Herein, an enzyme-free surface-enhanced Raman scattering (SERS) platform was proposed for sensitive and reliable detection of target miRNA-21 using a corrective internal standard (IS)-based ratiometric SERS probe coupled with mismatched catalytic hairpin assembly (CHA) amplification. The 4-aminothiophenol (4-ATP) was used as IS molecule and modified on the surface of silver nanoparticles decorated silicon wafer. In principle, the presence of miRNA-21 could cyclically trigger the allosteric effects of mismatched CHA amplification and the 3'-R6G labeled hairpin probe 1 (H1) was opened. Then, the hairpin probe 2 (H2) hybridized with H1 to form H1-H2 complex and the released miRNA-21 was free to participate in the next cycle of CHA reaction. Meanwhile, the H1-H2 complex could hybridize with the capture DNA on the SERS chip, making the Raman tag of R6G close to the surface of SERS substrate, and the intensity of SERS signal from R6G labels increase while that from 4-ATP remain relatively unchanged. Benefiting from outstanding performances of the ratiometric SERS strategy and enzyme-free CHA amplification system, this platform exhibits sensitivity toward miRNA-21 with a limit of detection of 3.5 fM and a broad dynamic range from 10 fM to 100 nM. More importantly, this proposed method presents an excellent reliable SERS analysis with the correction of IS. The developed strategy holds a potential alternative tool for miRNA detection in biomedical research and early clinical diagnosis.
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http://dx.doi.org/10.1016/j.bios.2019.111619DOI Listing
October 2019

Ultra-sonication for controlling the formation of disinfection by-products in the ClO pre-oxidation of water containing high concentrations of algae.

Environ Geochem Health 2020 Mar 15;42(3):849-861. Epub 2019 May 15.

INRS Eau, Terre et Environnement, 490, rue de la Couronne, Québec, G1K 9A9, Canada.

Eutrophication has become great concern in recent years due to the fact that rivers, lakes, and reservoirs are the main drinking water source. Studies have been performed to enhance the removal of algae with ClO pre-oxidation, but there was high potential in the formation of chlorite and chlorate. In this study, ultra-sonication was employed to assist algae removal and control disinfection by-products formation in ClO pre-oxidation processes. It was found that solo ultra-sonication for 10 min (algae removal 86.11 ± 2.16%) could achieve similar algae removal efficiency as that with solo ClO (0.5 mg/L) pre-oxidation for 10 min (algae removal 87.10 ± 3.50%). In addition, no formations of chlorite and chlorate were detected in solo ultra-sonication process. Five-minutes ultra-sonication followed by 5-min 0.5 mg/L ClO treatment (total treatment time 10 min; algae removal 93.55 ± 3.22%) provided a better performance on algae removal compared to the solo ClO (0.5 mg/L) pre-oxidation for 10 min. Moreover, chlorite was undetectable. It suggests that the utilization of ultra-sonication in ClO pretreatment for algae removal has highly prevented the formations of chlorite and chlorate.
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http://dx.doi.org/10.1007/s10653-019-00312-8DOI Listing
March 2020

Nanoconjugates of Ag/Au/Carbon Nanotube for Alkyne-Meditated Ratiometric SERS Imaging of Hypoxia in Hepatic Ischemia.

Anal Chem 2019 04 13;91(7):4529-4536. Epub 2019 Mar 13.

Department of Chemistry , University of California-Riverside , Riverside , California 92521 , United States.

We report a ratiometric surface-enhanced Raman scattering (SERS) nanoprobe for imaging hypoxic living cells or tissues, using azo-alkynes assembled on a single-walled carbon nanotube (SWCNT) surface-functionalized with Ag/Au alloy nanoparticles (SWCNT/Ag/AuNPs). Under a hypoxic condition, azobenzene derivatives preassembled on the surface of the nanostructures are reduced stepwise by various reductases and eventually removed from the surface of the SWCNT/Ag/AuNPs, resulting in the loss of characteristic alkyne Raman bands at 2207 cm. Using 2D-band of SWCNTs at 2578 cm as the internal standard, we are able to determine the hypoxia level based on the ratio of two peak intensities ( I/ I) as demonstrated by the successful detection in different cell lines and rat liver tissue samples derived from hepatic ischemia surgery. By combining the outstanding anti-interference property of alkynes as SERS reporters and the distinct Raman responses of alkynes and SWCNTs in complex systems, this novel ratiometric SERS strategy holds promise in becoming a very useful tool for in vitro and in vivo monitoring of hypoxia in research and clinical settings.
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http://dx.doi.org/10.1021/acs.analchem.8b05487DOI Listing
April 2019

Molecularly imprinted photonic hydrogel sensor for optical detection of L-histidine.

Mikrochim Acta 2018 11 21;185(12):557. Epub 2018 Nov 21.

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, People's Republic of China.

A molecularly imprinted photonic hydrogel (MIPH) is described for the optical determination of L-histidine (L-His). The inverse opal structure of MIPH was obtained by placing silica particles (230 nm) in molecularly imprinted polymer on a glass slide. After being fully etched by hydrofluoric acid, this inverse opal structure brings about a high specific surface and plentiful binding sites for L-His. If L-His is absorbed by the modified MIPH, its average effective refraction coefficient is increased. This causes the Bragg diffraction peak to be red-shifted by about 34 nm as the concentration of L-His increases from 0 to 100 nM. Much smaller diffraction peak shifts are obtained for other amino acids. The detection limit of this method is 10 pM. The response time towards L-His is as short as 60 s. In addition, the sensor can be recovered by treatment with 0.1 M acetic acid/methanol. It was applied to the determination of L-His in drinks sample. Graphical abstract After absorbing L-histidine, the average effective refractive index of this molecularly imprinted photonic hydrogel (MIPH) is increased, and the Bragg diffraction peak is shifted. The shift of the diffraction peak can be used for the detection of L-His.
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http://dx.doi.org/10.1007/s00604-018-3080-3DOI Listing
November 2018

Alkyne-based surface-enhanced Raman scattering nanoprobe for ratiometric imaging analysis of caspase 3 in live cells and tissues.

Anal Chim Acta 2018 Dec 8;1043:115-122. Epub 2018 Sep 8.

Institute of Chemical Biology and Nanomedicine, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China. Electronic address:

Surface-enhanced Raman scattering (SERS) still faces a big challenge in bioanalysis due to the biological background interference and the poor reproducibility of the Raman signal. Accordingly, herein a novel surface-enhanced Raman scattering (SERS) nanoprobe is prepared via the co-assembly of 3-(4-(phenylethynyl)benzylthio) propanoic acid (PEB) tagged-peptides and 4-thiol phenylacetylene (TPA) on gold nanorods, and used for the measurement of caspase 3, as a biomarker. A key advantage of this system is the lack of background alkyne signals throughout the cell. The two alkyne-bearing molecules produce distinct SERS signal but the PEB signal decreases in response to the peptide-cleavage activity of caspase 3, thereby allowing the ratiometric detection of analytes. Under the optimized conditions, the ratiometric peak intensity of I/I dynamically increased with increasing caspase 3 concentration in the range from 12.5 to 500 ng/mL, with a detection limit of 1.99 ng/mL based on a signal-to-noise ratio of S/N = 3. The nanoprobe has been successfully applied in a live cell imaging assay of caspase 3 and in an ischemia-reperfusion surgery-treated rat living tissue model.
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http://dx.doi.org/10.1016/j.aca.2018.09.009DOI Listing
December 2018

Internal standard-based SERS aptasensor for ultrasensitive quantitative detection of Ag ion.

Talanta 2018 Aug 9;185:30-36. Epub 2018 Mar 9.

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, People's Republic of China.

A ratiometric surface-enhanced Raman scattering (SERS) aptasensor based on internal standard (IS) methods was proposed for the ultrasensitive and reproducible quantitative detection of silver ion (Ag) with Au@Ag core-shell nanoparticle (Au@Ag NP) substrate. In principle, the thiolated 5'-Rox C-containing labeled aptamer probe (Rox-aptamer) is firstly immobilized on the SERS substrate surface and then hybridizes with the complementary DNA (cDNA) to form a rigid double-stranded DNA (dsDNA), in which the Rox Raman labels is used to produce the Raman signal. Furthermore, the pyridine is employed as an IS element to provide the ratiometric determination of target. In the presence of Ag, the Rox-aptamer is turned into the cytosine (C)-Ag-C mediated hairpin structure, which remarkably reduces the distance between the Rox labels and the Au@Ag NP surface responsible for a measurable 'turn-on' signal change of Rox. This IS-based ratiometric SERS aptasensor exhibits a limit of detection of 50 pM for Ag with a linear detection range from 0.1 to 100 nM and the shortcoming of irreproducibility of SERS signal could be overcome. The proposed method provides a simple, robust, and rapid approach for the sensitive and reproducible quantitative detection of Ag, and it could also be used for the detection of other metal ions which exhibits specific interactions with natural or synthetic bases.
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http://dx.doi.org/10.1016/j.talanta.2018.03.014DOI Listing
August 2018

Novel ratiometric surface-enhanced raman spectroscopy aptasensor for sensitive and reproducible sensing of Hg.

Biosens Bioelectron 2018 Jan 19;99:646-652. Epub 2017 Aug 19.

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China.

It is important to precisely monitor mercury (II) ions (Hg) for environment protection and human health monitoring. Although many strategies have been developed in the past decades, there still remains a challenge for developing an ultrasensitive, simple and reliable approach to detect Hg. Herein, we report a ratiometric surface-enhanced Raman scattering (SERS) aptasensor by employing aptamer-modified Au@Ag core-shell nanoparticles (Au@Ag NPs) as highly functional sensing probes, allowing for ultrasensitive detection of Hg. In principle, the thiolated 5'-Cy3 labeled aptamer probe (Cy3-aptamer) is firstly immobilized on the SERS substrate surface and then hybridizes with the 5'-Rox labeled complementary DNA (cDNA) to form a rigid double-stranded DNA (dsDNA), in which the Cy3 and Rox Raman labels are used to produce the ratiometric Raman signals. In the presence of Hg, the aptamer DNA turns into the thymine (T)-Hg-T mediated hairpin structure, leading to the dissociation of dsDNA. As a result, the Rox labels are away from the Au@Ag NP SERS substrate while Cy3 labels are close to it. Therefore, the intensity of SERS signal from Cy3 labels increases while that from Rox labels decreases. The ratio between the Raman intensities of Cy3 labels and Rox labels is linear with Hg concentrations in the range from 0.001 to 1.0nM, and the limit of detection is estimated to be 0.4pM. The proposed strategy provides a new rapid, simple and reliable approach for sensitive detection of Hg and may create a universal methodology for developing analogous aptasensors for a wide range of other analytes determination.
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http://dx.doi.org/10.1016/j.bios.2017.08.041DOI Listing
January 2018

Novel Aptasensor Platform Based on Ratiometric Surface-Enhanced Raman Spectroscopy.

Anal Chem 2017 03 22;89(5):2852-2858. Epub 2017 Feb 22.

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University , Changsha, Hunan, China.

A novel aptasensor platform has been developed for quantitative detection of adenosine triphosphate (ATP) based on a ratiometric surface-enhanced Raman scattering (SERS) strategy. The thiolated 3'-Rox-labeled complementary DNA (cDNA) is first immobilized on the gold nanoparticle (AuNP) surface and then hybridizes with the 3'-Cy5-labeled ATP-binding aptamer probe (Cy5-aptamer) to form a rigid double-stranded DNA (dsDNA), in which the Cy5 and Rox Raman labels are used to produce the ratiometric Raman signals. In the presence of ATP, the Cy5-aptamer is triggered the switching of aptamer to form the aptamer-ATP complex, leading to the dissociation of dsDNA, and the cDNA is then formed a hairpin structure. As a result, the Rox labels are close to the AuNP surface while the Cy5 labels are away from. Therefore, the intensity of SERS signal from Rox labels increases while that from Cy5 labels decreases. The results show that the ratio between the Raman intensities of Rox labels and Cy5 labels is well linear with the ATP concentrations in the range from 0.1 to 100 nM, and the limit of detection reaches 20 pM, which is much lower than that of other methods for ATP detection and is also lower than that of SERS aptasensor for ATP detection. The proposed strategy provides a new reliable platform for the construction of SERS biosensing methods and has great potential to be a general method for other aptamer systems.
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http://dx.doi.org/10.1021/acs.analchem.6b04010DOI Listing
March 2017

Identification of -(2-Phenoxyethyl)imidazo[1,2-]pyridine-3-carboxamides as New Antituberculosis Agents.

ACS Med Chem Lett 2016 Dec 11;7(12):1130-1133. Epub 2016 Oct 11.

Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College , Beijing 100050, China.

A series of imidazo[1,2-]pyridine carboxamides (IPAs) bearing an -(2-phenoxyethyl) moiety was designed and synthesized as new antitubercular agents. Seven 2,6-dimethyl IPAs demonstrated excellent activity (MIC: 0.025-0.054 μg/mL) against the drug susceptive H37Rv strain and two clinically isolated multidrug-resistant strains. Compound displayed acceptable safety and pharmacokinetic properties, opening a new direction for further development.
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http://dx.doi.org/10.1021/acsmedchemlett.6b00330DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5150680PMC
December 2016

Sensitive inkjet printing paper-based colormetric strips for acetylcholinesterase inhibitors with indoxyl acetate substrate.

Talanta 2017 Jan 4;162:174-179. Epub 2016 Oct 4.

State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China.

A new paper-based biosensing approach has been developed for sensitive and rapid detection of acetylcholinesterase (AChE) inhibitors. The biosensing zone of the paper strip is constructed with an inkjet printing method, and the biomolecule AChE is immobilized into two layers of biocompatible sol-gel-derived silica ink with a "sandwich" form. Indoxyl acetate (IDA) is used as a chromogenic substrate, which is colorless and can be catalytically hydrolyzed into blue-colored indigo dipolymer. When the enzymatic activity of AChE is inhibited after incubation with organophosphate pesticides (OPs), there is a decreased hydrolysis of IDA accompanying with a drop in color intensity. Paraoxon and trichlorfon are used as the representative OPs in the assay. Due to the low solubility and high molar absorption coefficient of the IDA dipolymer product, the paper-based strip can form a neat blue sensing zone and shows obviously improved sensitivity with a limit of detection (LOD) of 0.01ngmL paraoxon and 0.04ngmL trichlorfon (S/N=3) and the LODs for visual detection are 0.03ngmL for paraoxon and 0.1ngmL for trichlorfon comparing with the previously reported colorimetric methods. The concentrations of paraoxon in apple juice samples are also detected, and the results are in accord well with these results from high-performance liquid chromatography, showing great potential for on-site detection of OPs in practical application. The developed assay can be used to qualitatively and semiquantitatively estimate with naked eyes and quantitatively assess OPs through image analysis.
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http://dx.doi.org/10.1016/j.talanta.2016.10.011DOI Listing
January 2017

Label-Free Photonic Crystal-Based β-Lactamase Biosensor for β-Lactam Antibiotic and β-Lactamase Inhibitor.

Anal Chem 2016 09 30;88(18):9207-12. Epub 2016 Aug 30.

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University , Changsha 410082, People's Republic of China.

A simple, label-free, and visual photonic crystal-based β-lactamase biosensor was developed for β-lactam antibiotic and β-lactamase inhibitor in which the penicillinase (a β-lactamase) was immobilized on the pH-sensitive colloidal crystal hydrogel (CCH) film to form penicillinase colloidal crystal hydrogel (PCCH) biosensing film. The hydrolysis of penicillin G (a β-lactam antibiotic) can be catalyzed by penicillinase to produce penicilloic acid, leading to a pH decrease in the microenvironment of PCCH film, which causes the shrink of pH-sensitive CCH film and triggers a blue-shift of the diffraction wavelength. Upon the addition of β-lactamase inhibitor, the hydrolysis reaction is suppressed and no clear blue-shift is observed. The concentrations of β-lactam antibiotic and β-lactamase inhibitor can be sensitively evaluated by measuring the diffraction shifts. The minimum detectable concentrations for penicillin G and clavulanate potassium (a β-lactamase inhibitor) can reach 1 and 0.1 μM, respectively. Furthermore, the proposed method is highly reversible and selective, and it allows determination of penicillin G in fish pond water samples.
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http://dx.doi.org/10.1021/acs.analchem.6b02457DOI Listing
September 2016

A novel logic gate based on liquid-crystals responding to the DNA conformational transition.

Analyst 2016 05;141(10):2870-3

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China.

Described herein is a novel liquid crystal (LC)-based DNA logic gate constructed via employing the reorientation of LCs triggered by metal-ion-mediated DNA probe conformational changes.
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http://dx.doi.org/10.1039/c6an00504gDOI Listing
May 2016

Synthesis, antimycobacterial and antibacterial activity of 1-(6-amino-3,5-difluoropyridin-2-yl)fluoroquinolone derivatives containing an oxime functional moiety.

Bioorg Med Chem Lett 2016 May 14;26(9):2262-7. Epub 2016 Mar 14.

Beijing Key Laboratory of Drug Resistance Tuberculosis Research, Department of Pharmacology, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing Chest Hospital, Capital Medical University, Beijing 101149, China. Electronic address:

A series of novel 1-(6-amino-3,5-difluoropyridin-2-yl)fluoroquinolone derivatives containing an oxime functional moiety were synthesized and evaluated for their biological activity. Our results reveal that compounds 9a-9c have considerable activity against both of MTB H37Rv ATCC 27294 (MICs: 3.81-7.13 μg/mL) and methicillin-sensitive Staphylococcus aureus strains (MICs: <0.008-0.5 μg/mL).
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http://dx.doi.org/10.1016/j.bmcl.2016.03.050DOI Listing
May 2016

Label-free liquid crystal biosensor for L-histidine: A DNAzyme-based platform for small molecule assay.

Biosens Bioelectron 2016 May 31;79:650-5. Epub 2015 Dec 31.

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.

We have developed a novel DNAzyme-based liquid crystal (LC) biosensor with high sensitivity for L-histidine, which is based on L-histidine-mediated formation of DNA duplexes by cleaving DNAzyme using L-histidine, resulting in a remarkable optical signal. Firstly, an optimal amount of capture probe is bound to the glass slide, which changes the surface topology as little as possible and shows a zero-background for the sensing system. When the DNAzyme molecule is cleaved by the target, L-histidine, a partial substrate strand is produced, which in turn can hybridize with the capture probe, forming a DNA duplex. The DNA duplexes induce LC molecules to undergo a homeotropic-to-tiled transition, obtaining a remarkable optical signal. The results show that the DNAzyme-based LC biosensor is highly sensitive to L-histidine with a detection limit of 50 nM. Compared with previously reported multi-step amplified methods, this newly designed assay system for L-histidine has no amplified procedures with comparable sensitivity. This method is an unprecedented example of DNAzyme-based LC biosensor for small molecules, which has potential to offer a DNAzyme-based LC model used in various targets.
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http://dx.doi.org/10.1016/j.bios.2015.12.107DOI Listing
May 2016

Immobilization of Ni-Pd/core-shell nanoparticles through thermal polymerization of acrylamide on glassy carbon electrode for highly stable and sensitive glutamate detection.

Anal Chim Acta 2015 Oct 11;896:137-42. Epub 2015 Sep 11.

State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China. Electronic address:

The preparation of a persistently stable and sensitive biosensor is highly important for practical applications. To improve the stability and sensitivity of glutamate sensors, an electrode modified with glutamate dehydrogenase (GDH)/Ni-Pd/core-shell nanoparticles was developed using the thermal polymerization of acrylamide (AM) to immobilize the synthesized Ni-Pd/core-shell nanoparticles onto a glassy carbon electrode (GCE). The modified electrode was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Electrochemical data showed that the prepared biosensor had remarkably enhanced electrocatalytic activity toward glutamate. Moreover, superior reproducibility and excellent stability were observed (relative average deviation was 2.96% after continuous use of the same sensor for 60 times, and current responses remained at 94.85% of the initial value after 60 d). The sensor also demonstrated highly sensitive amperometric detection of glutamate with a low limit of detection (0.052 μM, S/N = 3), high sensitivity (4.768 μA μM(-1) cm(-2)), and a wide, useful linear range (0.1-500 μM). No interference from potential interfering species such as l-cysteine, ascorbic acid, and l-aspartate were noted. The determination of glutamate levels in actual samples achieved good recovery percentages.
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http://dx.doi.org/10.1016/j.aca.2015.09.005DOI Listing
October 2015

Synthesis and antitumor activity of 5-(5-halogenated-2-oxo-1H-pyrrolo[2,3-b]pyridin-(3Z)-ylidenemethyl)-2,4-dimethyl-1H-pyrrole-3-carboxamides.

Bioorg Med Chem Lett 2015 Jul 15;25(14):2782-7. Epub 2015 May 15.

Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.

We report herein the design and synthesis of a series of novel 5-halogenated-7-azaindolin-2-one derivatives containing a 2,4-dimethylpyrrole moiety. Nine target compounds with ⩾70% inhibition against MCF-7 at 30 μM were further evaluated for their in vitro antitumor activity against seven human cancer cell lines by SRB assay. Results reveal that some compounds have potent antitumor activity, and the most active 13c7 (IC50s: 4.49-15.39 μM) was found to be more active than Sunitinib (IC50s: 4.70->30 μM) against all of the tested cancer cell lines.
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http://dx.doi.org/10.1016/j.bmcl.2015.05.017DOI Listing
July 2015