Browsing by Author "Huang, Chin-Ping"

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A highly sensitive system for urea detection by using CdSe/ZnS core-shell quantum dots
(2007-03-15)
Huang, Chin-Ping
;
Li, Yaw-Kuen
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
An original and novel assay system with urease as a catalyst and CdSe/ZnS quantum dots (QDs) as an indicator has been developed for quantitative analysis of urea. By mixing urease and QDs, the determination of urea can be performed in a quantitative manner. The detection is based on the enhancement of QD photoluminescence (PL) intensity, which is correlated to the enzymatic degradation of urea. By controlling the buffer concentration and pH, PL enhancement due to the degradation of urea is linear in the urea concentration ranging from 0.01 to 100 mM. This property makes the urease/QDs system to be a promising urea-biosensing system. The newly developed system is a superior design and possesses many advantages, including its simple preparation, low cost, no enzyme immobilization required, high flexibility, and good sensitivity. (c) 2006 Elsevier B.V. All rights reserved.
A new approach for quantitative determination of glucose by using CdSe/ZnS quantum dots
(2008-03-14)
Huang, Chin-Ping
;
Liu, Shu-Wei
;
Chen, Teng-Ming
;
Li, Yaw-Kuen
;
應用化學系
Quantitative detection of glucose is an important issue in food industry, various biotechnological processes and medication of metabolic disorders. Many ways have been developed to approach this target. In this study, we demonstrated a simple assay system containing glucose oxidase (GOD) and CdSe/ZnS quantum dots (QDs) for specific and quantitative detection of glucose, The role of QDs functioned as an "indicator" to reveal the acidity change of the assay system resulting from the enzymatic oxidation of glucose. By controlling the initial buffer conditions of the assay system at 10 mM or 30 mM phosphate, pH 8.0, the quench ratio of PL intensity of QDs at 586 nm was found to be linear to the tested glucose in the range of 0.2-10 mM or 2-30 mM, respectively. The assay system also provides a convenient way to determine the glucose concentration by visuahzing the color change of QDs fluorescence. As compare to most of the existing methods, this newly developed system possesses many advantages, including simplicity, low cost, high flexibility, and good sensitivity. Furthermore, no complicated chemical modification and enzyme immobilization were needed in this system. (C) 2007 Elsevier B.V. All rights reserved.
Characterization and identification of essential residues of the glycoside hydrolase family 64 laminaripentaose-producing--1, 3-glucanase
(2011-08-01)
Shrestha, Keshab Lal
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Liu, Sheng-Wen
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Huang, Chin-Ping
;
Wu, Hsin-Mao
;
Wang, Wen-Ching
Laminaripentaose-producing -1,3-glucanase (LPHase) from Streptomyces matensis DIC-108 uniquely catalyzes the hydrolysis of -1,3-glucan to release laminaripentaose as the predominant product. For studying this novel enzyme, the gene of LPHase was reconstructed with polymerase chain reaction and over-expressed in Escherichia coli. The recombinant wild-type enzyme and various mutants were further purified to 90 homogeneity on an ion-exchange chromatograph. The catalysis of the recombinant LPHase is confirmed to follow a one-step single-displacement mechanism with (1)H-NMR spectrometry. To determine the amino-acid residues essential for the catalysis, more than ten residues, including five highly conserved residuesAsp(143), Glu(154), Asp(170), Asp(376) and Asp(377), were mutated. Among the mutants, E154Q, E154G, D174N and D174G significantly lost catalytic activity. Further investigation with chemical rescue using sodium azide on E154G and D174G confirmed that Glu(154) functions as the general acid whereas Asp(170) serves as the general base in a catalytic turnover. This work is the first report that provides direct information for the identification of the essential residues of GH-64 through kinetic examination.
Diversity of sugar acceptor of glycosyltransferase 1 from Bacillus cereus and its application for glucoside synthesis
(2016-05)
Chiu, Hsi-Ho
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Shen, Mo-Yuan
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Liu, Yuan-Ting
;
Fu, Yu-Lieh
;
Chiu, Yu-An
Glycosyltransferase 1 from Bacillus cereus (BcGT1) catalyzes the transfer of a glucosyl moiety from uridine diphosphate glucose (UDP-glucose) to various acceptors; it was expressed and characterized. The specificity of acceptors was found to be broad: more than 20 compounds classified into O-, S-, and N-linkage glucosides can be prepared with BcGT1 catalysis. Based on this work, we conclude that the corresponding acceptors of these compounds must possess the following features: (1) the acceptors must contain at least one aromatic or fused-aromatic or heteroaromatic ring; (2) the reactive hydroxyl or sulfhydryl or amino group can attach either on the aromatic ring or on its aliphatic side chain; and (3) the acceptors can be a primary, secondary, or even a tertiary amine. Four representative acceptors-fluorescein methyl ester, 17-beta-estradiol, 7-mercapto-4-methylcoumarin, and 6-benzylaminopurine-were chosen as a candidate acceptor for O-, S-, and N-glucosidation, respectively. These enzymatic products were purified and the structures were confirmed with mass and NMR spectra. As all isolated glucosides are beta-anomers, BcGT1 is confirmed to be an inverting enzyme. This study not only demonstrates the substrate promiscuity of BcGT1 but also showed the great application prospect of this enzyme in bioconversion of valuable bioactive molecules.
Infrared proximity sensor using organic light-emitting diode with quantum dots converter
(2012-11-01)
Chen, En-Chen
;
Yeh, Han-Cheng
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Chao, Yu-Chiang
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Meng, Hsin-Fei
;
Zan, Hsiao-Wen
An efficient visible-to-infrared conversion film is made by blending CdTe quantum dots (CdTe QDs) of 12 nm diameter in a polyvinylpyrrolidone 360 (PVP 360) polymer matrix cast by water solution. The solid-state photoluminescence quantum efficiency exceeds 10% with emission peak at 810 nm. Strong 810 emission is obtained by combining the quantum dot film and a green polyfluorene light-emitting diode. Color filter is used to remove residual light below 780 nm to make it entirely invisible. Infrared photo-detector is made by blending poly[5-(5-(2,5-bis(decyloxy)-4-methylphenyl)thiophen-2-yl)-2,3-bis(4-(2-ethylhexyloxy)phenyl)-7-(5-methylthiophen-2-yl)thieno[3,4-b]pyrazine] (PBDOTTP) with band-gap 1.2 eV and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM). The pixel contains one PD surrounded by four PLED on its four sides. The active areas of the five devices are all I cm by 1 cm and they are on the same plane. Infrared proximity sensor with photo-current over 300 nA at 10 cm object distance is achieved by detecting the reflected infrared signal. (C) 2012 Elsevier B.V. All rights reserved.
Interplay between Structure and Fluidity of Model Lipid Membranes under Oxidative Attack
(2010-12-02)
Tai, Wan-Yu
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Yang, Yi-Cyun
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Lin, Hui-Jen
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Huang, Chin-Ping
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Cheng, Yi-Lin
A proper regula:ion of membrane fluidity is critical for cellular activities such as communication between cells, mitosis, an :I endocytosis. Unsaturated lipids, a main component of biological membranes, are particularly susceptible to oxidative attack of reactive oxygen species. The oxidation of lipids can produce structural derangement of membranes and eventually alter the membrane fluidity. We have applied fluorescence correlation spectroscopy (FCS) and Raman spectroscopy to investigate the fluidity and structure of model membranes subject to oxidative attack. Hydrogen peroxide has little effect on the lateral fluidity of membranes. whereas hydroxyl radical causes a significantly increased fluidity. The latter is rationalized with the cleavage of the acyl chains of lipids caused by hydroxyl radical; this interpretation is founded on the diminished intensities of lines in Raman spectra associated with -CH(2) and C = C moieties in lipids and supported by mass-spectral measurements. The same approach provides a mechanistic account of the inhibitory capability of vitamins C and E against ate increased membrane fluidity resulting from an oxidative attack. Membranes with much cholesterol exhibit a novel resistance against altered membrane fluidity induced with oxidative attack; this finding has biological implications. Our approach combining FCS and Raman measurements reveals the interplay between the structure and fluidity of membranes and provides insight into the pathophysiology of cellular oxidative injury.
Preparation of High-Performance Water-Soluble Quantum Dots for Biorecognition through Fluorescence Resonance Energy Transfer
(2012-12-01)
Huang, Chin-Ping
;
Chao, Cheng-Fu
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Shen, Mo-Yuan
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Chen, Teng-Ming
;
Li, Yaw-Kuen
An improved method for the synthesis of high-performance and water-soluble quantum dots (QDs) involving the encapsulation of mercaptosuccinic acid coated QDs (MSA-QDs) with poly(diallyldimethylammonium chloride) (PDDA) followed by their direct photoactivation with fluorescent radiation near 295 K to yield PDDA-coated QDs (PDDA-QDs) has been demonstrated. The quantum yield (QY) of the PDDA-QDs was significantly improved from 0.6 (QY of MSA-QDs) to 48?%. By using this synthetic strategy, highly photoluminescent PDDA-QDs of varied size were readily prepared. The surface properties of PDDA-QDs and MSA-QDs were extensively characterized. The highly luminescent and positively charged PDDA-QDs serve as a useful and convenient tool for protein adsorption. With a ?5-3-ketosteroid isomerase adsorbed PDDA-QD complex, the biorecognition of steroids was demonstrated through the application of fluorescent resonance energy transfer.
Quantitative Determination of Triglyceride by Photoactivated CdSe/ZnS Quantum Dots Through Fluorescence Assay
(2008-07-01)
Huang, Chin-Ping
;
Li, Yaw-Kuen
;
Chen, Teng-Ming
;
應用化學系
;
Department of Applied Chemistry
The quantitative detection of triglycerides is an important issue for health inspection of metabolic disorders and for food and oil-refining industries. Many methods have been designed to approach this target, in which multiple reactions catalyzed by enzymes are normally coupled consecutively. In this study, we demonstrated a simple assay system containing lipase and photoactivated luminescent CdSe/ZnS quantum dots (QDs) for the quantitative detection of triglycerides. Photoactivated CdSe/ZnS QDs function as a sensitive "indicator" to reveal the minute acidity change of the assay system resulting from the enzymatic hydrolysis of triglycerides. By controlling the initial buffer condition of the assay system at 5, 10, or 20 mM phosphate buffer at pH 8.0, respectively, the quenching ratio of the QDs fluorescence intensity monitored at the maximum photoluminescence showed a linear correlation with the concentration of the examined triglyceride in the range of 0.02-6, 0.2-10, or 2-20 mM, respectively. The assay system also provides a convenient way to estimate triglyceride concentration by visualizing the color change of the QDs fluorescence. As compared to most of the existing methods, the system reported herein possessed many advantages, including simplicity, low cost, high flexibility, and high sensitivity. Furthermore, no complicated chemical modification or enzyme immobilization is needed.
Water-soluble germanium nanoparticles cause necrotic cell death and the damage can be attenuated by blocking the transduction of necrotic signaling pathway
(2011-12-15)
Ma, Yu-Hsin
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Huang, Chin-Ping
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Tsai, Jia-Shiuan
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Shen, Mo-Yuan
;
Li, Yaw-Kuen
Water-soluble germanium nanoparticles (wsGeNPs) with allyamine-conjugated surfaces were fabricated and emit blue fluorescence under ultraviolet light. The wsGeNP was physically and chemically stable at various experimental conditions. Cytotoxicity of the fabricated wsGeNP was examined. KIT assay demonstrated that wsGeNP possessed high toxicity to cells and clonogenic survival assay further indicated that this effect was not resulted from retarding cell growth. Flow cytometric analysis indicated that wsGeNP did not alter the cell cycle profile but the sub-G1 fraction was absent from treated cells. Results from DNA fragmentation and propidium iodide exclusion assays also suggested that apoptotic cell death did not occur in cells treated with wsGeNP. Addition of a necrosis inhibitor, necrostatin-1, attenuated cell damage and indicated that wsGeNP caused necrotic cell death. Cell signaling leads to necrotic death was investigated. Intracellular calcium and reactive oxygen species (ROS) levels were increased upon wsGeNP treatment. These effects can be abrogated by BAPTA-AM and N-acetyl cysteine respectively, resulting in a reduction in cell damage. In addition, wsGeNP caused a decrease in mitochondrial membrane potential (MMP) which could be recovered by cyclosporine A The cellular signaling events revealed that wsGeNP increase the cellular calcium level which enhances the production of ROS and leads to a reduction of MMP, consequentially results in necrotic cell death. (C) 2011 Elsevier Ireland Ltd. All rights reserved.