40 results on '"Fang WANG"'
Search Results
2. Ultrasensitive Photoelectrochemical Biosensor Based on Novel Z-Scheme Heterojunctions of Zn-Defective CdS/ZnS for MicroRNA Assay
- Author
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Xiankang Niu, Yan Zhao, Fang Wang, Jinghua Wu, Fengli Qu, and Weihong Tan
- Subjects
MicroRNAs ,Zinc ,Limit of Detection ,Zinc Compounds ,Biosensing Techniques ,Electrochemical Techniques ,Sulfides ,Analytical Chemistry - Abstract
The sensitive and accurate detection of microRNA (miRNA) has meaningful values for clinical diagnosis application as an early stage of tumor markers. Herein, a novel photoelectrochemical (PEC) biosensor was developed for the ultrasensitive and highly selective detection of microRNA-122 (miRNA-122) based on a direct Z-scheme heterojunction of Zn vacancy-mediated CdS/ZnS (CSZS-V
- Published
- 2021
3. Highly Selective Electrochemical Detection of 5-Formyluracil Relying on (2-Benzimidazolyl) Acetonitrile Labeling
- Author
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Zilin Chen, Jing Ren, Chen Chen, Guangrong Zou, Jing Tang, and Fang Wang
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Streptavidin ,Acetonitriles ,Hydroquinone ,Metal Nanoparticles ,Benzoquinone ,Combinatorial chemistry ,Analytical Chemistry ,chemistry.chemical_compound ,Biotin ,chemistry ,Polynucleotide ,Covalent bond ,Click chemistry ,Nucleic acid ,Gold ,Uracil - Abstract
The identification of formylpyrimidines in DNA is crucial for a better understanding of epigenetics. Although many techniques have been explored to detect their content, more accurate methods of formylpyrimidine determination are still required due to the relatively lower sensitivity or lack of selectivity in current methods. Herein, an electrochemical method based on the covalent bonding of the azido derivative of (2-benzimidazolyl) acetonitrile (azi-BIAN) and the aldehyde group of 5-formyluracil (5fU) was proposed for the selective detection of 5fU in the presence of 5-formylcytosine (5fC) and apyrimidinic (AP) sites. Target DNA containing 5fU was first treated with azi-BIAN and then incubated with DBCO-PEG4-Biotin to introduce a biotin group by copper-free click chemistry. Next, the sulfhydryl group was attached to the 5' end of above DNA through T4 polynucleotide kinase-catalyzed reaction. Subsequently, the labeled DNA was assembled onto the AuNPs-modified glassy carbon electrode (AuNPs/GCE) through Au-S bonds, and the streptavidin-horseradish peroxidase conjugate (SA-HRP) was further immobilized onto the surface of the above electrode by specific recognition between biotin and streptavidin. Finally, HRP catalyzed hydroquinone oxidation to benzoquinone to enhance the current signal, which was related to the amount of 5fU in nucleic acids. This method demonstrated a good linear relationship with 5fU concentrations ranging from 0.1 to 10 nM. Moreover, the level of 5fU in γ-irradiated nucleic acids was also successfully detected, indicating that the combination of molecule-depended chemical recognition and electrochemical sensing is a promising method for the selective and sensitive detection of 5fU.
- Published
- 2021
4. Construction of a Polarity-Switchable Photoelectrochemical Biosensor for Ultrasensitive Detection of miRNA-141
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Dan Su, Fang Wang, Fengli Qu, Changtong Lu, Xiankang Niu, and Weihong Tan
- Subjects
Photocurrent ,Detection limit ,Bioanalysis ,Chemistry ,business.industry ,Polarity (physics) ,Biosensing Techniques ,Electrochemical Techniques ,Photoelectric effect ,Analytical Chemistry ,MicroRNAs ,Limit of Detection ,Quantum dot ,Clinical diagnosis ,Quantum Dots ,Biomarkers, Tumor ,Humans ,Optoelectronics ,business ,Biosensor - Abstract
As an early-stage tumor biomarker, microRNA (miRNA) has clinical application potential and its sensitive and accurate detection is significant for early tumor diagnosis. In this study, a photoelectrochemical (PEC) biosensing platform was fabricated for ultrasensitive miRNA-141 detection, which is based on a photocurrent polarity-switchable system using CdS quantum dots (QDs) in the presence of a 5,10,15,20-tetrakis (4-aminophenyl)-21H,23H-porphine (Tph-2H)-coated glassy carbon electrode (GCE). As an excellent photoactive material, Tph-2H has a narrow band gap that effectively gathers photoelectrons under visible light irradiation and improves the transfer ability of photogenerated electrons. Further, the detection sensitivity of miRNA-141 could be significantly improved by combining an enzyme-assisted recycle amplification reaction and a magnetic bead-based separation strategy. The proposed photocurrent polarity-switchable PEC biosensor could efficiently eliminate the false-positive or false-negative signals and achieve a wide linear response range from 1 fM to 1 nM with a low detection limit of 0.33 fM for miRNA-141, providing a potentially alternative solution for detecting other biomarkers in bioanalysis and clinical diagnosis.
- Published
- 2021
5. Hydralazine as a Versatile and Universal Matrix for High-Molecular Coverage and Dual-Polarity Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging
- Author
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Fang Wang, Yanwen Chen, Weiwei Tang, Bin Li, and Andrew Gordon
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Chemistry ,Lasers ,010401 analytical chemistry ,Analytical chemistry ,Proteins ,Hydralazine ,010402 general chemistry ,Mass spectrometry ,Lipids ,01 natural sciences ,Small molecule ,Mass spectrometry imaging ,0104 chemical sciences ,Analytical Chemistry ,Solvent ,Mice ,Matrix (mathematics) ,Matrix-assisted laser desorption/ionization ,Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization ,Desorption ,Animals ,Macromolecule - Abstract
Few matrices have the potential to be universally applicable for imaging vast endogenous compounds ranging from micro to macromolecules. In this article, we present hydralazine (HZN) as a versatile and universal matrix for matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) of a wide range of endogenous compounds between 50.0 and 20,000.0 Da. HZN was prepared from its hydrochloride by alkalizing HZN·HCl with ammonia to enhance the optical absorptivity at the preferred MALDI UV laser wavelength. To further improve its performance for MALDI MS, HZN was doped with NH4OH or TFA, resulting in matrix superior performance for imaging biologically relevant compounds in the negative and positive-ion modes, respectively. The analyte-matrix interaction was also enhanced by the optimized matrix solvent and the deposition amount. Compared with conventional matrices such as 2,5-dihydroxybenzoic acid, α-cyano-4-hydroxycinnamic acid, and 9-aminoacridine (9-AA), the HZN matrix provided higher sensitivity, broader molecular coverage, and improved signal intensities. Its broad acquisition range makes it versatile for imaging small molecular metabolites and lipids, as well as proteins. In addition, HZN was applied successfully for the visualization of tissue-specific distributions and changes of small molecules, lipids, and proteins in the kidney and liver sections of obese ob/ob and diabetic db/db mice. The use of the HZN matrix shows great potential application in the field of pathological research.
- Published
- 2021
6. Self-Replication-Assisted Rapid Preparation of DNA Nanowires at Room Temperature and Its Biosensing Application
- Author
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Cuisong Zhou, Yong Guo, Guixiu Dong, Ruoxing Liao, Jianyuan Dai, Dan Xiao, Hongli Shi, Fang Wang, Yunran Qiu, and Hongfei He
- Subjects
Nanowires ,010401 analytical chemistry ,Temperature ,Nanowire ,Biosensing Techniques ,DNA ,010402 general chemistry ,01 natural sciences ,DNA sequencing ,0104 chemical sciences ,Analytical Chemistry ,chemistry.chemical_compound ,Adenosine Triphosphate ,chemistry ,Self-replication ,Biophysics ,Dna assembly ,Biosensor ,Adenosine triphosphate ,Dna strand displacement - Abstract
A rapid room-temperature DNA nanowires preparation strategy on the basis of self-replicating catalyzed hairpin assembly (SRCHA) was reported. In this system, three hairpin probes (P1, P2, and P3) were well-designed and partially hybridize to each other, and two split trigger DNA sequences were integrated into P1 and P3, respectively. When the SRCHA was initiated by the trigger DNA, a series of DNA assembly steps based on the toehold-mediated DNA strand displacement were activated, and the Y shaped DNA (P1-P2-P3) was formed. In that case, the two split trigger DNA sequences will come into close-enough proximity to form the trigger DNA replicas, which can initiate the additional SRCHA reaction cycles for DNA nanowire preparation, and eventually a rapid room-temperature DNA nanowires preparation strategy without need of fuel strands was successfully developed. Furthermore, the prepared DNA nanowires have been used to develop a rapid and signal amplified sensing platform for sensitive adenosine triphosphate (ATP) detection.
- Published
- 2019
7. Discrimination of saccharides with a fluorescent molecular imprinting sensor array based on phenylboronic acid functionalized mesoporous silica
- Author
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Jin, Tan, He-Fang, Wang, and Xiu-Ping, Yan
- Subjects
Carbohydrates -- Identification and classification ,Carbohydrates -- Measurement ,Chemical detectors -- Materials ,Chemistry - Abstract
A fluorescent indicator-displacement molecular imprinting sensor array based on phenylboronic acid functionalized mesoporous silica was developed for discriminating saccharides. D-Fructose imprinted material (FruIM), D-xylose imprinted material (XylIM) together with a control blank nonimprinted material (NIM) were synthesized as the elements of the imprinting sensor array. Spectrofluorimetric titrations of the three materials with eight selected saccharides were carried out, and Stern--Volmer quenching constants ([K.sub.sv]) of NIM, FruIM, and XylIM with the eight selected saccharides were obtained to investigate the interaction of the materials with saccharides. The present approach couples molecular imprinting technique to indicator-displacement strategy with the use of one conventional saccharide receptor (phenylbotonic acid) and one commercially available fluorescent dye (Alizarin Red S., ARS) as the indicator, and allows identifying two template saccharides (D-fructose and D-xylose) plus eight nontemplate saccharides (D-arabinose, D-glucose, D-galactose, D-mannose, L-sorbose, D-ribose, L-rhamnose and sucrose). The principal component analysis (PCA) plot shows a clear discrimination of the I0 tested saccharides at 100 mM and the first principal component possesses 94.8% of the variation. Besides, the developed saccharide imprinted sensor array is successfully applied to discriminating three brands of orange juice beverage.
- Published
- 2009
8. Noninvasive and Accurate Detection of Hereditary Hearing Loss Mutations with Buccal Swab Based on Droplet Digital PCR
- Author
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Xiurui Zhu, Fang Wang, Yang Wenjun, Tao Deng, Guo Yong, Junmin Pan, Gao Huafang, Nan Wang, Dongyang Kang, Liu Baoxia, and Zhu Lingxiang
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Adult ,Male ,0301 basic medicine ,Genotype ,Hearing loss ,DNA Mutational Analysis ,Buccal swab ,Deafness ,Polymerase Chain Reaction ,Specimen Handling ,Analytical Chemistry ,law.invention ,Young Adult ,03 medical and health sciences ,Neonatal Screening ,0302 clinical medicine ,law ,medicine ,Humans ,Digital polymerase chain reaction ,Genetic Testing ,Child ,Polymerase chain reaction ,Genetic testing ,Detection limit ,medicine.diagnostic_test ,Chemistry ,Infant, Newborn ,DNA ,Molecular biology ,Heteroplasmy ,030104 developmental biology ,030220 oncology & carcinogenesis ,Mutation ,Female ,medicine.symptom - Abstract
Hereditary hearing loss is a common clinical neurosensory disorder in humans and has a high demand for genetic screening. Current screening techniques using peripheral blood or dried blood spots (DBSs) are invasive. Therefore, this study aims to develop a noninvasive and accurate detection method for eight hotspot deafness-associated mutations based on buccal swab and droplet digital PCR (ddPCR). First, this method was evaluated for analytic performance including specificity, detection limit, dynamic range using plasmid DNA. The specificity was 100% and the detection limit was 5 copies. The dynamic range of this ddPCR-based method was from 10 to 105 copies/μL. Next, the method was found to accurately quantify mitochondrial gene heteroplasmy rate as low as 1% for both m.1494C > T and m.1555A > G sites. Then, we demonstrated that buccal swab was a reliable sample. DNA can be extracted and accurately quantified after a buccal swab had been stored for 90 days at either room temperature or −20 °C. Finally, cli...
- Published
- 2018
9. Turning Nonspecific Interference into Signal Amplification: Covalent Biosensing Nanoassembly Enabled by Metal-Catalyzed Cross-Coupling
- Author
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Fang Wang, Haiyun Liu, Mei Yan, Jinghua Yu, Shenguang Ge, and Hao Li
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chemistry.chemical_classification ,Cathepsin ,Chemistry ,010401 analytical chemistry ,Peptide ,010402 general chemistry ,01 natural sciences ,Cathepsin B ,0104 chemical sciences ,Analytical Chemistry ,Coupling (electronics) ,Biochemistry ,Interference (communication) ,Covalent bond ,Biophysics ,Biosensor ,Electrochemical potential - Abstract
In this work, a new method of protein detection in complicated samples is proposed. This method employs probe-target recognition to induce cross-linking among the probe, the target, and the nonspecific proteins in the complicated sample as a means to convert interference into effective signal amplification. This also eliminates the necessity of multistep signal amplification in a separate solution system. On the basis of this strategy, a simple and robust assay for the activity of serum cathepsin B is established. Peptide probes immobilized on a sensing slide can recognize cathepsin B, and this can induce thiol-alkyne covalent coupling between the probe and cathepsin B. Meanwhile, applying electrochemical potential scanning to this sensing surface, Cu binding fragments of the probe peptide can be released into the solution phase to act as an electrochemical catalyst for oxidative dityrosine cross-linking among all proteins including the captured cathepsin B and the nonspecific proteins. A continuous nanoassembly covalently anchored on the sensing surface can gradually form, allowing violent detergent rinsing to remove residual interference. Using this method, not only sensitivity in the picomolar range can be achieved for serum analysis, the results of the analysis can also reliably discriminate benign and cancerous ovarian conditions. These results may suggest prospective application of this method in early screening of cancer in the future.
- Published
- 2017
10. Fluorescence Anisotropy as a Reliable Discrimination of Ligand-Asymmetric and Symmetric Mn-Doped ZnS Quantum Dots
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Yu Zhang, He-Fang Wang, and Lin Miao
- Subjects
Masking (art) ,Photoluminescence ,Ligand ,Chemistry ,technology, industry, and agriculture ,Analytical chemistry ,02 engineering and technology ,equipment and supplies ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensation reaction ,01 natural sciences ,0104 chemical sciences ,Analytical Chemistry ,Dynamic light scattering ,Quantum dot ,PEG ratio ,Physical chemistry ,0210 nano-technology ,Fluorescence anisotropy - Abstract
We presented a novel fluorescence anisotropy (FA) method for the noninvasive, effective, simple, and convenient discrimination of the symmetric and asymmetric distribution of the ligands on Mn-doped ZnS quantum dots (QDs). The symmetric or asymmetric distribution of mercaptopropionic acid (MPA) and NH2-polyethylene glycol-CH3 (PEG-m, MW 2000) was controlled by the condensation reaction of the carboxyl of MPA and the amino of PEG-m with or without the masking by the amino-functionalized silica nanoparticles. The ligand-asymmetric Janus-QDs were obtained with the masking, whereas the ligand-symmetric PEG-QDs were gained without masking. The FA values of the QDs could not only distinguish the ligand symmetric PEG-QDs from the ligand asymmetric Janus-QDs but also discriminate the QDs with a different PEG-m amount. Besides, the FA assay also has superiority over the dynamic light scattering (DLS) and photoluminescence (PL) methods in discriminating the interaction of Janus-QDs or PEG-QDs with protamine (the se...
- Published
- 2016
11. Mn-Doped ZnS Quantum Dot Imbedded Two-Fragment Imprinting Silica for Enhanced Room Temperature Phosphorescence Probing of Domoic Acid
- Author
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He-Fang Wang and Li Dan
- Subjects
Manganese ,Analyte ,Kainic Acid ,Temperature ,Molecularly imprinted polymer ,Analytical chemistry ,Hydrogen-Ion Concentration ,Sulfides ,Silicon Dioxide ,Photochemistry ,Analytical Chemistry ,Molecular Imprinting ,chemistry.chemical_compound ,Hydrolysis ,Template ,chemistry ,Zinc Compounds ,Quantum dot ,Luminescent Measurements ,Quantum Dots ,Imprinting (psychology) ,Derivatization ,Phosphorescence ,Shellfish - Abstract
A novel strategy was presented to construct the enhanced molecularly imprinted polymer (MIP)-based room temperature phosphorescence (RTP) probe by combining the RTP of Mn-doped ZnS quantum dots (Mn-ZnS QDs) and two-fragment imprinting. Two fragments or structurally similar parts of the target analytes were used as the dummy templates. Polyethyleneimine capped Mn-ZnS (PEI-Mn-ZnS) QDs, offering the binding sites to interact with the carboxyl groups of templates, were imbedded into MIPs by the hydrolysis of tetraethoxysilane. The rebinding of the target analytes to their fragments' cavities (recognition sites) modulated the selective aggregation of Mn-ZnS QDs in QDs-MIPs and resulted in the RTP enhancement. This new method was suitable for the selective enhanced RTP detection of nonphosphorescent analytes without any derivatization and inducers. The proposed methodology was applied to construct the high selective enhanced MIP-based RTP probe for domoic acid (DA) detection. The RTP enhancement of two-fragment imprinting silica was about 2 times of one-fragment imprinting silica and 4 times of the nonimprinting silica. The two-fragment imprinting silica exhibited the linear RTP enhancement to DA in the range of 0.25-3.5 μM in buffer and 0.25-1.5 μM in shellfish sample. The precision for 11 replicate detections of 1.25 μM DA was 0.65% (RSD), and the limit of detection was 67 nM in buffer and 2.0 μg g(-1) wet weight (w/w) in shellfish sample.
- Published
- 2013
12. Magnetic Separation-Assistant Fluorescence Resonance Energy Transfer Inhibition for Highly Sensitive Probing of Nucleolin
- Author
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Qian Liu, He-Fang Wang, Zhangyong Hong, and Yan-Ran Li
- Subjects
Quenching (fluorescence) ,Chemistry ,Polymers ,Magnetic Phenomena ,Stacking ,RNA-Binding Proteins ,Carbocyanines ,Photochemistry ,Phosphoproteins ,Acceptor ,Fluorescence ,Analytical Chemistry ,Cell Line ,Hydrophobic effect ,Förster resonance energy transfer ,Spectrometry, Fluorescence ,Fluorescence Resonance Energy Transfer ,MCF-7 Cells ,Humans ,Pyrroles ,Phosphorescence ,Magnetite Nanoparticles ,Nucleolin - Abstract
For the widely used "off-on" fluorescence (or phosphorescence) resonance energy transfer (FRET or PRET) system, the separation of donors and acceptors species was vital for enhancing the sensitivity. To date, separation of free donors from FRET/PRET inhibition systems was somewhat not convenient, whereas separation of the target-induced far-between acceptors has hardly been reported yet. We presented here a novel magnetic separation-assistant fluorescence resonance energy transfer (MS-FRET) inhibition strategy for highly sensitive detection of nucleolin using Cy5.5-AS1411 as the donor and Fe3O4-polypyrrole core-shell (Fe3O4@PPY) nanoparticles as the NIR quenching acceptor. Due to hydrophobic interaction and π-π stacking of AS1411 and PPY, Cy5.5-AS1411 was bound onto the surface of Fe3O4@PPY, resulting in 90% of fluorescence quenching of Cy5.5-AS1411. Owing to the much stronger specific interaction of AS1411 and nucleolin, the presence of nucleolin could take Cy5.5-AS1411 apart from Fe3O4@PPY and restore the fluorescence of Cy5.5-AS1411. The superparamagnetism of Fe3O4@PPY enabled all separations and fluorescence measurements complete in the same quartz cell, and thus allowed the convenient but accurate comparison of the sensitivity and fluorescence recovery in the cases of separation or nonseparation. Compared to nonseparation FRET inhibition, the separation of free Cy5.5-AS1411 from Cy5.5-AS1411-Fe3O4@PPY solution (the first magnetic separation, MS-1) had as high as 25-fold enhancement of the sensitivity, whereas further separation of the nucleolin-inducing far-between Fe3O4@PPY from the FRET inhibition solution (the second magnetic separation, MS-2) could further enhance the sensitivity to 35-fold. Finally, the MS-FRET inhibition assay displayed the linear range of 0.625-27.5 μg L(-1) (8.1-359 pM) and detection limit of 0.04 μg L(-1) (0.05 pM) of nucleolin. The fluorescence intensity recovery (the percentage ratio of the final restoring fluorescence intensity to the quenched fluorescence intensity of Cy5.5-AS1411 solution by 0.09 g L(-1) Fe3O4@PPY) was enhanced from 36% (for nonseparation) to 56% (for two magnetic separations). This is the first accurate evaluation for the effect of separating donor/acceptor species on the FRET inhibition assay.
- Published
- 2015
13. Conjugation of Glucose Oxidase onto Mn-Doped ZnS Quantum Dots for Phosphorescent Sensing of Glucose in Biological Fluids
- Author
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Xiu-Ping Yan, He-Fang Wang, Peng Wu, and Yu He
- Subjects
Blood Glucose ,Analytical chemistry ,Biosensing Techniques ,Sulfides ,Photochemistry ,Analytical Chemistry ,Nanomaterials ,Glucose Oxidase ,Enzyme Stability ,Quantum Dots ,Humans ,Glucose oxidase ,Thermal stability ,Manganese ,Quenching (fluorescence) ,Bioconjugation ,biology ,Chemistry ,Temperature ,Water ,Solutions ,Zinc Compounds ,Quantum dot ,Luminescent Measurements ,biology.protein ,Phosphorescence ,Biosensor - Abstract
Integrating various enzymes with nanomaterials provides various nanohybrids with new possibilities in biosensor applications. Furthermore, the enzymatic activity and stability are also improved due to the large surface area of nanomaterials. Here we report the conjugation of glucose oxidase (GOD) onto phosphorescent Mn-doped ZnS quantum dots (QDs) using 1-ethyl-3-(3-dimethylaminopropy)carbodiimide (EDC)/N-hydroxysuccinimide (NHS) as coupling reagents for glucose biosensing based on the effective quenching of the room temperature phosphorescence (RTP) of Mn-doped ZnS QDs by the H(2)O(2) generated from GOD-catalyzed oxidation of glucose. The obtained bioconjugate not only provided improved enzymatic performance with Michaelis-Menten constant of 0.70 mM but also favored biological applications because the phosphorescent detection mode avoided the interference from autofluorescence and scattering light from the biological matrix. In addition, the GOD-conjugated Mn-doped ZnS QDs showed better thermal stability in the temperature range of 20-80 degrees C. The GOD-Mn-doped ZnS QDs based RTP sensor for glucose gave a detection limit of 3 microM and two linear ranges from 10 microM to 0.1 mM and from 0.1 to 1 mM. The developed biosensor was successfully applied to the determination of glucose in real serum samples without the need for any complicated sample pretreatments.
- Published
- 2010
14. Surface Molecular Imprinting on Mn-Doped ZnS Quantum Dots for Room-Temperature Phosphorescence Optosensing of Pentachlorophenol in Water
- Author
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Tian-Rong Ji, He-Fang Wang, Yu He, and Xiu-Ping Yan
- Subjects
Detection limit ,chemistry.chemical_compound ,Chemistry ,Quantum dot ,Molecularly imprinted polymer ,Analytical chemistry ,Molecular imprinting ,Derivatization ,Phosphorescence ,Zinc sulfide ,Analytical Chemistry ,Pentachlorophenol - Abstract
A new type of molecularly imprinted polymer (MIP)-based room-temperature phosphorescence (RTP) optosensor was developed by anchoring the MIP layer on the surface of Mn-doped ZnS quantum dots (QDs) via a surface molecular imprinting process. The synergetic combination of the RTP property of the Mn-doped ZnS QDs and the merits of the surface imprinting polymers not only improves the RTP selectivity of the Mn-doped ZnS QDs but also makes the MIP-based RTP optosensor also applicable to selective detecting of those nonphosphorescent analytes without the need for any inducers and derivatization. The new MIP-based RTP sensing protocol was applied to detect trace pentachlorophenol (PCP) in water samples without the interference of autofluorescence and scattering light of matrixes. The detection limit for PCP was 86 nM, and the precision for five replicate detections of 0.4 microM PCP was 2.8% (relative standard deviation). The recovery of spiked PCP in river water samples ranged from 93% to 106%.
- Published
- 2009
15. Exploring Mn-Doped ZnS Quantum Dots for the Room-Temperature Phosphorescence Detection of Enoxacin in Biological Fluids
- Author
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Xiu-Ping Yan, He-Fang Wang, and Yu He
- Subjects
Enoxacin ,chemistry.chemical_classification ,Manganese ,Quenching (fluorescence) ,Biomolecule ,Fluorescence spectrometry ,Analytical chemistry ,Sulfides ,Photochemistry ,Zinc sulfide ,Fluorescence ,Anti-Bacterial Agents ,Analytical Chemistry ,chemistry.chemical_compound ,Microscopy, Electron, Transmission ,chemistry ,Zinc Compounds ,Quantum dot ,Luminescent Measurements ,Quantum Dots ,medicine ,Phosphorescence ,medicine.drug - Abstract
While most research works focus on the development of quantum dots (QDs)-based fluorescence sensors, much less attention is paid to the phosphorescence properties of QDs and their potential for phosphorescence detection. In this work, the phosphorescence property of Mn-doped ZnS QDs is explored to develop a novel room-temperature phosphorescence (RTP) method for the facile, rapid, cost-effective, sensitive, and selective detection of enoxacin in biological fluids. The Mn-doped ZnS QDs-based RTP method reported here does not need the use of deoxidants and other inducers and allows the detection of enoxacin in biological fluids without interference from autofluorescence and the scattering light of the matrix. The Mn-doped ZnS QDs offer excellent selectivity for detecting enoxacin in the presence of the main relevant metal ions in biological fluids, biomolecules, and other kinds of antibiotics. Quenching of the phosphorescence emission due to the addition of enoxacin at 1.0 microM is unaffected by 5000-fold excesses of Na (+) and 10000-fold excesses of K (+), Mg (2+), and Ca (2+). Amino acids such as tryptophan, histidine, and l-cysteine at 1000-fold concentration of enoxacin do not affect the detection of enoxacin. Glucose does not affect the detection at 10000-fold concentration of enoxacin. Typical coadministers (mainly other types of antibiotics) such as ceftezole, cefoperazone, oxacillin, and kalii dehydrographolidi succinas are permitted at 50-, 10-, 100-, and 50-fold excesses, respectively, without interference with the detection of enoxacin. The precision for 11 replicate detections of 0.4 microM enoxacin is 1.8% (RSD). The detection limit for enoxacin is 58.6 nM. The recovery of spiked enoxacin in human urine and serum samples ranges from 94 to 104%. The developed Mn-doped ZnS QDs-based RTP method is employed to monitor the time-dependent concentration of enoxacin in urine from a healthy volunteer after the oral medication of enoxacin. The investigation provides evidence that doped QDs are promising for RTP detection in further applications.
- Published
- 2008
16. Quantifying nanosheet graphene oxide using electrospray-differential mobility analysis
- Author
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Hsin Chia Ho, Yen Chih Lai, De Hao Tsai, Rong-Ming Ho, Jui Ting Tai, Hsiao Fang Wang, and Jian He Yang
- Subjects
Electrospray ,Spectrometry, Mass, Electrospray Ionization ,Graphene ,Analytical chemistry ,Oxide ,Oxides ,Stability (probability) ,Analytical Chemistry ,law.invention ,Nanostructures ,chemistry.chemical_compound ,Colloid ,chemistry ,Microscopy, Electron, Transmission ,Transmission electron microscopy ,law ,Microscopy ,Graphite ,Nanosheet - Abstract
We report a high-resolution, traceable method to quantify number concentrations and dimensional properties of nanosheet graphene oxide (N-GO) colloids using electrospray-differential mobility analysis (ES-DMA). Transmission electron microscopy (TEM) was employed orthogonally to provide complementary data and imagery of N-GOs. Results show that the equivalent mobility sizes, size distributions, and number concentrations of N-GOs were able to be successfully measured by ES-DMA. Colloidal stability and filtration efficiency of N-GOs were shown to be effectively characterized based on the change of size distributions and number concentrations. Through the use of an analytical model, the DMA data were able to be converted into lateral size distributions, showing the average lateral size of N-GOs was ∼32 nm with an estimated thickness ∼0.8 nm. This prototype study demonstrates the proof of concept of using ES-DMA to quantitatively characterize N-GOs and provides traceability for applications involving the formulation of N-GOs.
- Published
- 2015
17. Glucose oxidase-catalyzed growth of gold nanoparticles enables quantitative detection of attomolar cancer biomarkers
- Author
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Xiaoyuan Chen, Dingbin Liu, Zhongliang Wang, Jie Yang, A. R. Hight Walker, He-Fang Wang, Xinglu Huang, Gang Niu, and Zhantong Wang
- Subjects
Metal Nanoparticles ,Enzyme-Linked Immunosorbent Assay ,Catalysis ,Article ,Analytical Chemistry ,Glucose Oxidase ,Antigen ,Microscopy, Electron, Transmission ,Limit of Detection ,medicine ,Biomarkers, Tumor ,Glucose oxidase ,Detection limit ,Immunoassay ,Chromatography ,medicine.diagnostic_test ,biology ,Chemistry ,Molecular biology ,Orders of magnitude (mass) ,Colloidal gold ,biology.protein ,Cancer biomarkers ,Naked eye ,Gold - Abstract
Ultrasensitive and quantitative detection of cancer biomarkers is an unmet challenge because of their ultralow concentrations in clinical samples. Although gold nanoparticle (AuNP)-based immunoassays offer high sensitivity, they were unable to quantitatively detect targets of interest most likely due to their very narrow linear ranges. This article describes a quantitative colorimetric immunoassay based on glucose oxidase (GOx)-catalyzed growth of 5 nm AuNPs that can detect cancer biomarkers from attomolar to picomolar levels. In addition, the limit of detection (LOD) of prostate-specific antigen (PSA) of this approach (93 aM) exceeds that of commercial enzyme-linked immunosorbent assay (ELISA) (6.3 pM) by more than 4 orders of magnitude. The emergence of red or purple color based on enzyme-catalyzed growth of 5 nm AuNPs in the presence of target antigen is particularly suitable for point-of-care (POC) diagnostics in both resource-rich and resource-limited settings.
- Published
- 2014
18. Aminophenylboronic-acid-conjugated polyacrylic acid-Mn-doped ZnS quantum dot for highly sensitive discrimination of glycoproteins
- Author
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Li-Jia Sang and He-Fang Wang
- Subjects
chemistry.chemical_classification ,Glycan ,Manganese ,Chromatography ,biology ,Chemistry ,Polyacrylic acid ,Acrylic Resins ,Sulfides ,Horseradish peroxidase ,Boronic Acids ,Analytical Chemistry ,chemistry.chemical_compound ,Microscopy, Electron, Transmission ,Transferrin ,Zinc Compounds ,Quantum Dots ,Spectroscopy, Fourier Transform Infrared ,biology.protein ,Biophysics ,Glucose oxidase ,Glycoprotein ,Fluorescence anisotropy ,Avidin ,Glycoproteins - Abstract
Discrimination of glycoproteins with different glycans is a significant but difficult issue. We presented here a new strategy for strengthening the discrimination of glycoproteins by introducing a new signaling channel, fluorescence polarization (FP), into a "single probe with three signaling channels" sensor array. The single probe was aminophenylboronic-acid-conjugated poly(acrylic acid)-Mn-doped ZnS quantum dots, and the three signaling channels were FP, room temperature phosphorescence and light scattering. Ten glycoproteins, including ovalbumin, fibrinogen, transferrin, horseradish peroxidase, vascular endothelial growth factor, immunoglobulin G, avidin, hyaluronidase, cellulase R-10, and glucose oxidase, were involved for evaluating the discriminating capability. The introduction of the FP signaling channel improved the discriminating power of the sensor array, so that the 10 glycoproteins at 0.15 μM could be well discriminated both in PBS buffer and in the presence of human serum sample. The identification accuracy of the unknown samples was 96.25% (77 out of 80) at the 0.15 μM level and 97.50% (78 out of 80) at the 0.2 μM level. The integration of the signaling patterns with different responsive principles was demonstrated as the promising way to enhance the discrimination power of the single-probe-based sensor arrays.
- Published
- 2014
19. Noninvasive and Accurate Detection of Hereditary Hearing Loss Mutations with Buccal Swab Based on Droplet Digital PCR.
- Author
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Fang Wang, Lingxiang Zhu, Baoxia Liu, Xiurui Zhu, Nan Wang, Tao Deng, Dongyang Kang, Junmin Pan, Wenjun Yang, Huafang Gao, and Yong Guo
- Published
- 2018
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20. Chiral Separations by Nonaqueous Capillary Electrophoresis
- Author
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Morteza G. Khaledi and Fang Wang
- Subjects
Formamide ,chemistry.chemical_classification ,Cyclodextrins ,Time Factors ,Chromatography ,Cyclodextrin ,Electrophoresis, Capillary ,Trimipramine ,Analytical Chemistry ,Electrophoresis ,chemistry.chemical_compound ,Capillary electrophoresis ,Models, Chemical ,chemistry ,Stability constants of complexes ,medicine ,Urea ,Amine gas treating ,Mathematical Computing ,medicine.drug - Abstract
This paper reports successful chiral separations of pharmaceutical racemic amines by nonaqueous capillary electrophoresis (NACE) using beta- and gamma-cyclodextrins (CDs) and various derivatives of beta-CDs. The results in three organic solvents, formamide (FA), N-methylformamide (NMF), and N,N-dimethylformamide (DMF) were compared to those in pure water and in 6 M urea in water systems. The binding constants of trimipramine, mianserin, and thioridazine with beta-CD were determined in the following five solvent systems: water, 6 M urea in water, FA, NMF, and DMF. The binding constants decreased systematically from approximately 10(4) in water to approximately 10 in FA and approximately 10(-2) in DMF. As a result, the optimum CD concentration in the aqueous media is in the high micromolar range, while that in the FA is around 100 mM. In the aqueous media, the occurrence of the optimum at very low concentrations and the rapid changes in enantioselectivity with CD concentration would make it difficult to develop methods based on trial and error. Nevertheless, it is shown that, even under nonoptimum concentrations of the chiral selector, other experimental parameters such as ionic strength, addition of tetraalkylammonium (TAA+), and temperature can be adjusted to achieve acceptable resolutions. This, however, is often achieved at the expense of longer analysis times. In addition, the effects of apparent pH (pH*) and type of cyclodextrin on chiral separations in NACE are studied. The application of negatively charged beta-CD in FA is also reported. Chiral separation of trimipramine was achieved at lower concentration of anionic CD due to the additional Coulombic interactions.
- Published
- 1996
21. Room-temperature phosphorescent discrimination of catechol from resorcinol and hydroquinone based on sodium tripolyphosphate capped Mn-doped ZnS quantum dots
- Author
-
He-Fang Wang, Ye-Yu Wu, and Xiu-Ping Yan
- Subjects
Detection limit ,Catechol ,Manganese ,Hydroquinone ,Ligand ,Sodium ,Catechols ,Temperature ,chemistry.chemical_element ,Resorcinol ,Resorcinols ,Sulfides ,Photochemistry ,Analytical Chemistry ,Hydroquinones ,chemistry.chemical_compound ,chemistry ,Quantum dot ,Polyphosphates ,Zinc Compounds ,Luminescent Measurements ,Quantum Dots ,Phosphorescence - Abstract
A room-temperature phosphorescence (RTP) strategy was developed for direct, additive-free discrimination of catechol from resorcinol and hydroquinone based on sodium tripolyphosphate capped Mn-doped ZnS quantum dots (STPP-Mn-ZnS QDs). The RTP response of STPP-Mn-ZnS QDs to the three isomers was pH-dependent, and the greatest difference in the RTP response to the isomers was observed at pH 8.0: catechol enhanced the RTP intensity of the QDs, while resorcinol and hydroquinone had little effect on the RTP intensity of the QDs. The enhanced RTP intensity of 1 μM catechol was not affected by the coexistence of 30 μM resorcinol and 50 μM hydroquinone at pH 8.0. The detection limit of this RTP method was 53 nM catechol, and the precision was 3.2% (relative standard deviation) for five replicate detections of 1 μM catechol. The discrimination mechanism was ascribed to the weak bonded ligand of STPP-Mn-ZnS QDs and the different interaction between the three isomers and STPP-Mn-ZnS QDs. The strong binding of catechol to Zn resulted in the extraction of Zn from the surface of STPP-Mn-ZnS QDs and the generation of holes that were trapped by Mn(2+) to form Mn(3+). Catechol also promoted the reduction of Mn(3+) into Mn(2+) excited state, thus ultimately inducing the enhanced RTP response of STPP-Mn-ZnS QDs.
- Published
- 2012
22. Metal-organic-framework-based tandem molecular sieves as a dual platform for selective microextraction and high-resolution gas chromatographic separation of n-alkanes in complex matrixes
- Author
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Zhi-Yuan Gu, He-Fang Wang, Na Chang, and Xiu-Ping Yan
- Subjects
Detection limit ,Analyte ,Chromatography ,Chromatography, Gas ,Tandem ,Extraction (chemistry) ,Analytical chemistry ,Molecular sieve ,Analytical Chemistry ,Hexane ,chemistry.chemical_compound ,Petroleum ,chemistry ,Metals ,Alkanes ,Hexanes ,Nanoparticles ,Metal-organic framework ,Nonane ,Organic Chemicals ,Solid Phase Microextraction - Abstract
Metal-organic frameworks (MOFs) were employed to design tandem molecular sieves as a dual platform for selective solid-phase microextraction (SPME) and high-resolution gas chromatographic (GC) separation of target analytes in complex matrixes. An elegant combination of a ZIF-8-coated fiber for SPME with a ZIF-8-coated capillary for GC allows selective extraction and separation of n-alkanes from complex matrixes such as petroleum-based fuel and biological fluids. The proposed tandem ZIF-8 molecular sieves not only offered good enhancement factors from 235 (hexane) to 1212 (nonane), but also exhibited wide linearity with 3 orders of magnitude for the tested linear alkanes. The limits of detection for the linear alkanes ranged from 0.46 ng L(-1) (nonane) to 1.06 ng L(-1)(hexane). The relative standard deviations of retention time, peak area, peak height, and half peak width for five replicate determinations of the tested n-alkanes at 30 ng L(-1) were 0.02-0.26%, 1.9-8.6%, 1.4-6.0%, and 1.3-7.2%, respectively. The developed tandem ZIF-8 molecular sieves were further used for the determination of linear alkanes in petroleum-based fuel and human serum. The large diversity in structure and pore size allows various combinations of MOFs for designing an MOF-based tandem molecular sieve platform to achieve different selectivities in extraction and chromatographic separation and to solve headache problems in complex real sample analysis.
- Published
- 2011
23. In situ hydrothermal growth of metal-organic framework 199 films on stainless steel fibers for solid-phase microextraction of gaseous benzene homologues
- Author
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Xiu-Ping Yan, Yan Li, Xiaoyan Cui, Dong-Qing Jiang, He-Fang Wang, and Zhi-Yuan Gu
- Subjects
Detection limit ,chemistry.chemical_compound ,chemistry ,Xylene ,Analytical chemistry ,Sample preparation ,Metal-organic framework ,Fiber ,Benzene ,Solid-phase microextraction ,Microanalysis ,Analytical Chemistry ,Nuclear chemistry - Abstract
Metal-organic frameworks (MOFs) have received great attention due to their fascinating structures and intriguing potential applications in various fields. Herein, we report the first example of the utilization of MOFs for solid-phase microextraction (SPME). MOF-199 with unique pores and open metal sites (Lewis acid sites) was employed as the coating for SPME fiber to extract volatile and harmful benzene homologues. The SPME fiber was fabricated by in situ hydrothermal growth of thin MOF-199 films on etched stainless steel wire. The MOF-199-coated fiber not only offered large enhancement factors from 19,613 (benzene) to 110,860 (p-xylene), but also exhibited wide linearity with 3 orders of magnitude for the tested benzene homologues. The limits of detection for the benzene homologues were 8.3-23.3 ng L(-1). The relative standard deviation (RSD) for six replicate extractions using one SPME fiber ranged from 2.0% to 7.7%. The fiber-to-fiber reproducibility for three parallel prepared fibers was 3.5%-9.4% (RSD). Indoor air samples were analyzed for the benzene homologues using the SPME with the MOF-199-coated fiber in combination with gas chromatography-flame ionization detection. The recoveries for the spiked benzene homologues in the collected indoor air samples were in the range of 87%-106%. The high affinity of the MOF-199-coated fiber to benzene homologues resulted from the combined effects of the large surface area and the unique porous structure of the MOF-199, the pi-pi interactions of the aromatic rings of the analytes with the framework 1,3,5-benzenetricarboxylic acid molecules, and the pi-complexation of the electron-rich analytes to the Lewis acid sites in the pores of MOF-199.
- Published
- 2009
24. Discrimination of saccharides with a fluorescent molecular imprinting sensor array based on phenylboronic acid functionalized mesoporous silica
- Author
-
He-Fang Wang, Jin Tan, and Xiu-Ping Yan
- Subjects
Orange juice ,Chromatography ,Xylose ,Fluorescence spectrometry ,Fructose ,Mesoporous silica ,Silicon Dioxide ,Fluorescence ,Combinatorial chemistry ,Boronic Acids ,Analytical Chemistry ,Molecular Imprinting ,chemistry.chemical_compound ,Kinetics ,chemistry ,Titration ,Phenylboronic acid ,Molecular imprinting ,Biosensor ,Fluorescent Dyes - Abstract
A fluorescent indicator-displacement molecular imprinting sensor array based on phenylboronic acid functionalized mesoporous silica was developed for discriminating saccharides. D-Fructose imprinted material (FruIM), D-xylose imprinted material (XylIM) together with a control blank nonimprinted material (NIM) were synthesized as the elements of the imprinting sensor array. Spectrofluorimetric titrations of the three materials with eight selected saccharides were carried out, and Stern-Volmer quenching constants (K(SV)) of NIM, FruIM, and XylIM with the eight selected saccharides were obtained to investigate the interaction of the materials with saccharides. The present approach couples molecular imprinting technique to indicator-displacement strategy with the use of one conventional saccharide receptor (phenylboronic acid) and one commercially available fluorescent dye (Alizarin Red S., ARS) as the indicator, and allows identifying two template saccharides (D-fructose and D-xylose) plus eight nontemplate saccharides (D-arabinose, D-glucose, D-galactose, D-mannose, L-sorbose, D-ribose, L-rhamnose and sucrose). The principal component analysis (PCA) plot shows a clear discrimination of the 10 tested saccharides at 100 mM and the first principal component possesses 94.8% of the variation. Besides, the developed saccharide imprinted sensor array is successfully applied to discriminating three brands of orange juice beverage.
- Published
- 2009
25. Characterization of a thermally induced irreversible conformational transition of amylose tris(3,5-dimethylphenylcarbamate) chiral stationary phase in enantioseparation of dihydropyrimidinone acid by quasi-equilibrated liquid chromatography and solid-state NMR
- Author
-
Ivan Santos, Karl T. Mueller, Fang Wang, Jean Wyvratt, Robert M. Wenslow, and Thomas Dowling
- Subjects
Tris ,chemistry.chemical_compound ,Conformational change ,Ethanol ,Chromatography ,Solid-state nuclear magnetic resonance ,Chemistry ,Amylose ,Phase (matter) ,Trifluoroacetic acid ,Enantiomer ,Analytical Chemistry - Abstract
A thermally induced irreversible conformational transition of amylose tris(3,5-dimethylphenylcarbamate) (i.e., Chiralpak AD) chiral stationary phase (CSP) in the enantioseparation of dihydropyrimidinone (DHP) acid racemate was studied for the first time by quasi-equilibrated liquid chromatography with cyclic van't Hoff and step temperature programs and solid-state ((13)C CPMAS and (19)F MAS) NMR using ethanol and trifluoroacetic acid (TFA)-modified n-hexane as the mobile phase. The conformational transition was controlled by a single kinetically driven process, as evidenced by the chromatographic studies. Solid-state NMR was used to study the effect of the temperature on the conformational change of the solvated phase (with or without the DHP acid enantiomers and TFA) and provided some viable structural information about the CSP and the enantiomers.
- Published
- 2003
26. Magnetic Separation-Assistant Fluorescence Resonance Energy Transfer Inhibition for Highly Sensitive Probing of Nucleolin.
- Author
-
Yan-Ran Li, Qian Liu, Zhangyong Hong, and He-Fang Wang
- Published
- 2015
- Full Text
- View/download PDF
27. Quantifying Nanosheet Graphene Oxide Using Electrospray-Differential Mobility Analysis.
- Author
-
Jui-Ting Tai, Yen-Chih Lai, Jian-He Yang, Hsin-Chia Ho, Hsiao-Fang Wang, Rong-Ming Ho, and De-Hao Tsai
- Published
- 2015
- Full Text
- View/download PDF
28. Glucose Oxidase-Catalyzed Growth of Gold Nanoparticles Enables Quantitative Detection of Attomolar Cancer Biomarkers.
- Author
-
Dingbin Liu, Jie Yang, He-Fang Wang, Zhongliang Wang, Xinglu Huang, Zhantong Wang, Gang Niu, Walker, A. R. Hight, and Xiaoyuan Chen
- Published
- 2014
- Full Text
- View/download PDF
29. Mn-Doped ZnS Quantum Dot Imbedded Two-Fragment Imprinting Silica for Enhanced Room Temperature Phosphorescence Probing of Domoic Acid.
- Author
-
Li Dan and He-Fang Wang
- Subjects
- *
OPTICAL properties of quantum dots , *OPTICAL properties of zinc sulfide , *PHOSPHORESCENCE , *DOMOIC acid , *MOLECULAR imprinting , *SILICA , *MOLECULAR probes , *MANGANESE - Abstract
A novel strategy was presented to construct the enhanced molecularly imprinted polymer (MIP)-based room temperature phosphorescence (RTP) probe by combining the RTP of Mn-doped ZnS quantum dots (Mn-ZnS QDs) and two-fragment imprinting. Two fragments or structurally similar parts of the target analytes were used as the dummy templates. Polyethyleneimine capped Mn-ZnS (PEI-Mn-ZnS) QDs, offering the binding sites to interact with the carboxyl groups of templates, were imbedded into MIPs by the hydrolysis of tetraethoxysilane. The rebinding of the target analytes to their fragments' cavities (recognition sites) modulated the selective aggregation of Mn-ZnS QDs in QDs-MIPs and resulted in the RTP enhancement. This new method was suitable for the selective enhanced RTP detection of nonphosphorescent analytes without any derivatization and inducers. The proposed methodology was applied to construct the high selective enhanced MIP-based RTP probe for domoic acid (DA) detection. The RTP enhancement of two-fragment imprinting silica was about 2 times of one-fragment imprinting silica and 4 times of the nonimprinting silica. The two-fragment imprinting silica exhibited the linear RTP enhancement to DA in the range of 0.25-3.5 μM in buffer and 0.25-1.5 μM in shellfish sample. The precision for 11 replicate detections of 1.25 μM DA was 0.65% (RSD), and the limit of detection was 67 nM in buffer and 2.0 μg g-1 wet weight (w/w) in shellfish sample. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
30. Room-Temperature Phosphorescent Discrimination of Catechol from Resorcinol and Hydroquinone Based on Sodium Tripolyphosphate Capped Mn-Doped ZnS Quantum Dots.
- Author
-
He-Fang Wang, Ye-Yu Wu, and Xiu-Ping Yan
- Subjects
- *
PHOSPHORIMETRY , *CATECHOL , *OPTICAL properties of quantum dots , *OPTICAL properties of zinc sulfide , *DOPED semiconductors , *RESORCINOL , *HYDROQUINONE , *SODIUM tripolyphosphate - Abstract
A room-temperature phosphorescence (RTP) strategy was developed for direct, additive-free discrimination of catechol from resorcinol and hydroquinone based on sodium tripolyphosphate capped Mn-doped ZnS quantum dots (STPP-Mn-ZnS QDs). The RTP response of STPP-Mn-ZnS QDs to the three isomers was pH-dependent, and the greatest difference in the RTP response to the isomers was observed at pH 8.0: catechol enhanced the RTP intensity of the QDs, while resorcinol and hydroquinone had little effect on the RTP intensity of the QDs. The enhanced RTP intensity of 1 μM catechol was not affected by the coexistence of 30 μM resorcinol and 50 μM hydroquinone at pH 8.0. The detection limit of this RTP method was 53 nM catechol, and the precision was 3.2% (relative standard deviation) for five replicate detections of 1 μM catechol. The discrimination mechanism was ascribed to the weak bonded ligand of STPP-Mn-ZnS QDs and the different interaction between the three isomers and STPP-Mn-ZnS QDs. The strong binding of catechol to Zn resulted in the extraction of Zn from the surface of STPP-Mn-ZnS QDs and the generation of holes that were trapped by Mn2+ to form Mn3+. Catechol also promoted the reduction of Mn3+ into Mn2+ excited state, thus ultimately inducing the enhanced RTP response of STPP-Mn-ZnS QDs. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
31. Ultrasensitive Detection of Bacteria by Microchip Electrophoresis Based on Multiple-Concentration Approaches Combining Chitosan Sweeping, Field-Amplified Sample Stacking, and Reversed-Field Stacking.
- Author
-
Zhi-Fang Wang, Shuang Cheng, Shu-Li Ge, Huan Wang, Qing-Jiang Wang, Pin-Gang He, and Yu-Zhi Fang
- Subjects
- *
ESCHERICHIA coli , *DETECTION of microorganisms , *ANALYTICAL biochemistry , *MICROCHIP electrophoresis , *CAPILLARY electrophoresis , *BACTERIAL pollution of water research - Abstract
In this paper we describe an on-chip multiple-concentration method combining chitosan (CS) sweeping, reversed-field stacking, and field-amplified sample stacking for highly efficient detection of bacteria. Escherichia coli was selected as a model bacterium to investigate the efficiency of this multiple-concentration method. CS was the most suitable sweeping agent for microchip electrophoresis, replacing the usually used cetyltrimethylammonium bromide for capillary electrophoresis. The additive taurine had a synergistic effect by enhancing the interaction between CS and the surface of the bacteria, thus improving the analysis sensitivity. All steps of the concentration method and related mechanisms are described and discussed in detail. A concentration enhancement factor of approximately 6000 was obtained using this concentration method under optimal conditions as compared to using no concentration step, and the detection limit of E. coli was 145 CFU/mL. The multiple-concentration methodology was also applied for the quantification of bacteria in surface water, and satisfactory results were achieved. The application of this methodology showed that the concentration enhancement of bacteria clearly conferred advantageous sensitivity, speed, and sample volume compared to established methods. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
32. Turn-on Room Temperature Phosphorescence Assay of Heparin with Tunable Sensitivity and Detection Window Based on Target-Induced Self-Assembly of Polyethyleneimine Capped Mn-Doped ZnS Quantum Dots.
- Author
-
Huan Yan and He-Fang Wang
- Subjects
- *
PHOSPHORESCENCE , *HEPARIN , *QUANTUM theory , *SENSITIVITY analysis , *LIGANDS (Chemistry) , *CARDIOVASCULAR surgery - Abstract
Room-temperature phosphorescence (RTP) turn-on assay of heparin with tunable sensitivity and detection window was demonstrated on the basis of the target induced self-assembly of polyethyleneimine capped Mn-doped ZnS (PEI-Mn-ZnS) QDs. The proposed method can cover the whole therapeutic dosing concentration range in postoperation and long-term therapy (0.2–1.2 U/mL, 1.7–10 μM) and cardiovascular surgery (2–8 U/mL, 17–67 μM) in 10 mM Tris–HCl (pH 7.4) buffer and can be applied for heparin determination in 100-fold diluted human serum samples. The tunable sensitivity and detection window was ascribed to the tunable particle size and ligand loading amount of PEI-Mn-ZnS QD arising from the chain length (or molecule weight) and feed amount of PEI. The chain length of PEI exhibited significant effect on the particle size and ligand loading amount and ultimately had important influence on both the sensitivity and detection window. The feeding amount of PEI, however, greatly affected the ligand loading amount alone and, in turn, affected only the detection window. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
33. Metal-Organic-Framework-Based Tandem Molecular Sieves as a Dual Platform for Selective Microextraction and High-Resolution Gas Chromatographic Separation of n-Alkanes in Complex Matrixes.
- Author
-
Na Chang, Zhi-Yuan Gu, He-Fang Wang, and Xiu-Ping Yan
- Published
- 2011
- Full Text
- View/download PDF
34. Conjugation of Glucose Oxidase onto Mn-Doped ZnS Quantum Dots for Phosphorescent Sensing of Glucose in Biological Fluids.
- Author
-
Peng Wu, Yu He, He-Fang Wang, and Xiu-Ping Yan
- Published
- 2010
- Full Text
- View/download PDF
35. In Situ Hydrothermal Growth of Metal-Organic Framework 199 Films on Stainless Steel Fibers for Solid-Phase Microextraction of Gaseous Benzene Homologues.
- Author
-
Xiao-Yan Cui, Zhi-Yuan Gu, Dong-Qing Jiang, Yan Li, He-Fang Wang, and Xiu-Ping Yan
- Published
- 2009
- Full Text
- View/download PDF
36. Temperature-Programmed Natural Convection for Micromixing and Biochemical Reaction in a Single Microfluidic Chamber.
- Author
-
Sung-Jin Kim, Fang Wang, Burns, Mark A., and Kurabayashi, Katsuo
- Subjects
- *
CHEMICAL reactions , *CHEMICAL processes , *POLYMERASE chain reaction , *AMPLIFIED fragment length polymorphism , *POLYMERIZATION - Abstract
Micromixing is a crucial step for biochemical reactions in microfluidic networks. A critical challenge is that the system containing micromixers needs numerous pumps, chambers, and channels not only for the micromixing but also for the biochemical reactions and detections. Thus, a simple and compatible design of the micromixer element for the system is essential. Here, we propose a simple, yet effective, scheme that enables micromixing and a biochemical reaction in a single microfluidic chamber without using any pumps. We accomplish this process by using natural convection in conjunction with alternating heating of two heaters for efficient micromixing, and by regulating capillarity for sample transport. As a model application, we demonstrate micromixing and subsequent polymerase chain reaction (PCR) for an influenza viral DNA fragment. This process is achieved in a platform of a microfluidic cartridge and a microfabricated heating- instrument with a fast thermal response. Our results will significantly simplify micromixing and a subsequent bio- chemical reaction that involves reagent healing in microfluidic networks. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
37. Surface Molecular Imprinting on Mn-Doped ZnS Quantum Dots for Room-Temperature Phosphorescence Optosensing of Pentachlorophenol in Water.
- Author
-
He-Fang Wang, Yu He, Tian-Rong Ji, and Xiu-Ping Yan
- Subjects
- *
PENTACHLOROPHENOL , *CHLOROPHENOLS , *IMPRINTED polymers , *QUANTUM dots , *DERIVATIZATION , *CHEMICAL reactions , *LIGHT scattering , *LUMINESCENCE , *MOLECULAR imprinting , *POLYMERIZATION - Abstract
A new type of molecularly imprinted polymer (MIP)-based room-temperature phosphorescence (RTP) optosensor was developed by anchoring the MIP layer on the surface of Mn-doped ZnS quantum dots (QDs) via a surface molecular imprinting process. The synergetic combination of the RTP property of the Mn-doped ZnS QDs and the merits of the surface imprinting polymers not only improves the RTP selectivity of the Mn-doped ZnS QDs but also makes the MIP-based RTP optosensor also applicable to selective detecting of those nonphosphorescent analytes without the need for any inducers and derivatization. The new MIP-based RTP sensing protocol was applied to detect trace pentachlorophenol (PCP) in water samples without the interference of autofluorescence and scattering light of matrixes. The detection limit for PCP was 86 nM, and the precision for five replicate detections of 0.4 μM PCP was 2.8% (relative standard deviation). The recovery of spiked PCP in river water samples ranged from 93% to 106%. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
38. Exploring Mn-Doped ZnS Quantum Dots for the Room-Temperature Phosphorescence Detection of Enoxacin in Biological Fluids.
- Author
-
Yu He, He-Fang Wang, and Xiu-Ping Yan
- Subjects
- *
QUANTUM dots , *FLUID mechanics , *ANTIBIOTICS , *MICROBIAL metabolites , *AMINO acids , *ORAL drug administration - Abstract
While most research works focus on the development of quantum dots (QDs)-based fluorescence sensors, much less attention is paid to the phosphorescence properties of QDs and their potential for phosphorescence detection. In this work, the phosphorescence property of Mn-doped ZnS QDs is explored to develop a novel room-temperature phosphorescence (RTP) method for the facile, rapid, cost-effective, sensitive, and selective detection of enoxacin in biological fluids. The Mn-doped ZnS QDs-based RIP method reported here does not need the use of deoxidants and other inducers and allows the detection of enoxacin in biological fluids without interference from autofluorescence and the scattering light of the matrix. The Mn-doped ZnS QDs offer excellent selectivity for detecting enoxacin in the presence of the main relevant metal ions in biological fluids, biomolecules, and other kinds of antibiotics. Quenching of the phosphorescence emission due to the addition of enoxacin at 1.0 μM is unaffected by 5000-fold excesses of Na+ and 10000-fold excesses of K+, Mg2+, and Ca2+. Amino acids such as tryptophan, histidine, and L-cysteine at 1000-fold concentration of enoxacin do not affect the detection of enoxacin. Glucose does not affect the detection at 10000-fold concentration of enoxacin. Typical coadministers (mainly other types of antibiotics) such as ceftezole, cefoperazone, oxacillin, and kalii dehydrographolidi succinas are permitted at 50-, 10-, 100-, and 50-fold excesses, respectively, without interference with the detection of enoxacin. The precision for 11 replicate detections of 0.4 μM enoxacin is 1.8% (RSD). The detection limit for enoxacin is 58.6 nM. The recovery of spiked enoxacin in human urine and serum samples ranges from 94 to 104%. The developed Mn-doped ZnS QDs-based RTP method is employed to monitor the lime-dependent concentration of enoxacin in urine from a healthy volunteer after the oral medication of enoxacin. The investigation provides evidence that doped QDs are promising for RTP detection in further applications. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
39. Characterization of a Thermally Induced Irreversible Conformational Transition of Amylose Tris(3,5-dimethylphenylcarbamate) Chiral Stationary Phase in Enantioseparation of Dihydropyrimidinone Acid...
- Author
-
Fang Wang, Wenslow Jr., Robert M., Dowling, Thomas M., Mueller, Karl T., Santos, Ivan, and Wyvratt, Jean M.
- Subjects
- *
CHROMATOGRAPHIC analysis , *ENANTIOMERS , *NUCLEAR magnetic resonance - Abstract
A thermally induced irreversible conformational transition of amylose tris(3,5-dimethyiphenylcarbamate) (i.e., Chiralpak AD) chiral stationary phase (CSP) in the enantioseparation of dihydropyrimidinone (DHP) acid racemate was studied for the first time by quasi-equilibrated liquid chromatography with cyclic van't Hoff and step temperature programs and solid-state ([SUP13]C CPMAS and [SUP19]F MAS) NMR using ethanol and trifluoroacetic acid (TFA)-modified n-hexane as the mobile phase. The conformational transition was controlled by a single kinetically driven process, as evidenced by the chromatographic studies. Solid-state NMR was used to study the effect of the temperature on the conformational change of the solvated phase (with or without the DHP acid enantiomers and TFA) and provided some viable structural information about the CSP and the enantiomers. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
40. Chiral separations by nonaqueous capillary electrophoresis.
- Author
-
Fang Wang and Khaledi, Morteza G.
- Subjects
- *
NONAQUEOUS solvents , *CAPILLARY electrophoresis , *CYCLODEXTRINS in pharmaceutical technology - Abstract
Reports on successful chiral separations of pharmaceutical racemic amines by nonaqueous capillary electrophoresis (NACE) using beta and gamma-cyclodextrins (CDs) and various derivatives of beta-CDs. Determination of binding constants of some basic pharmaceutical racemates in different solvents.
- Published
- 1996
- Full Text
- View/download PDF
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