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61.
Fast and sensitive DNA analysis using changes in the FRET signals of molecular beacons in a PDMS microfluidic channel 总被引:3,自引:0,他引:3
Jung J Chen L Lee S Kim S Seong GH Choo J Lee EK Oh CH Lee S 《Analytical and bioanalytical chemistry》2007,387(8):2609-2615
A new DNA hybridization analytical method using a microfluidic channel and a molecular beacon-based probe (MB-probe) is described.
A stem-loop DNA oligonucleotide labeled with two fluorophores at the 5′ and 3′ termini (a donor dye, TET, and an acceptor
dye, TAMRA, respectively) was used to carry out a fast and sensitive DNA analysis. The MB-probe utilized the specificity and
selectivity of the DNA hairpin-type probe DNA to detect a specific target DNA of interest. The quenching of the fluorescence
resonance energy transfer (FRET) signal between the two fluorophores, caused by the sequence-specific hybridization of the
MB-probe and the target DNA, was used to detect a DNA hybridization reaction in a poly(dimethylsiloxane) (PDMS) microfluidic
channel. The azoospermia gene, DYS 209, was used as the target DNA to demonstrate the applicability of the method. A simple
syringe pumping system was used for quick and accurate analysis. The laminar flow along the channel could be easily controlled
by the 3-D channel structure and flow speed. By injecting the MB-probe and target DNA solutions into a zigzag-shaped PDMS
microfluidic channel, it was possible to detect their sequence-specific hybridization. Surface-enhanced Raman spectroscopy
(SERS) was also used to provide complementary evidence of the DNA hybridization. Our data show that this technique is a promising
real-time detection method for label-free DNA targets in the solution phase.
Figure FRET-based DNA hybridization detection using a molecular beacon in a zigzag-shaped PDMS microfluidic channel 相似文献
62.
63.
Wan-Keun Kim Kyung A Sung Keun-Hwan Oh Min-Ju Choo Kuk Young Cho Ki-Yun Cho Jung-Ki Park 《Electrochemistry communications》2009,11(8):1714-1716
A new concept of in situ pore generation to reduce water flooding in cathode catalyst layer (CCL) of polymer electrolyte membrane fuel cell (PEMFC) is proposed with the introduction of water soluble poly(ethylene glycol) (PEG) as a porogen to CCL based on sulfonated poly(ether ether ketone) (sPEEK). In this new type of CCL, PEG is directly removed by water produced during the cathode reaction. The new CCL exhibited much higher cell performance especially in mass transport limitation region compared to the pristine sPEEK-CCL. In addition, the presence of PEG in the new CCL lowered the glass transition temperature of the sPEEK binder, and it could improve the transference of catalyst layer onto the polymer electrolyte membrane. 相似文献
64.
Singlet molecular oxygen, O2(1Σ), is one of the important intermediate species in the atmospheres of Earth, Mars, and Venus. To elucidate the chemistry of this excited molecular oxygen, a series of kinetic measurements have been undertaken using the flow-discharge/optical-emission technique. By monitoring the characteristic emission (762 nm for 1Σ), the quenching rates for several important molecules have been obtained at room temperature. The following table summarizes measurements.
The error limits represent one standard deviation. The systematic error is estimated to be about 15%. For CO2 and O3 molecules, the quenching rate constants were also measured in the temperature range of 245–362 K. In both reactions, negligible temperature dependences (with the activation energy less than 0.6 kcal/mole) were observed. 相似文献
Quencher | Rate Constants (cm3/s) |
---|---|
CH2 | (4.6 ± 0.5) × 10?13 |
H2 | (7.0 ± 0.3) × 10?13 |
N2 | (1.7 ± 0.1) × 10?15 |
Cl2 | (4.5 ± 0.8) × 10?16 |
CO | (4.5 ± 0.5) × 10?15 |
O3 | (2.2 ± 0.3) × 10?11 |
2,3 DBM-2 | (6.0 ± 0.1) × 10?13 |
65.
A discharge-flow apparatus with resonance fluorescence and chemiluminescence detection has been used to monitor O2(b 1σ) production from several reactions of the HO2 radical at 300 K and 1-torr total pressure. O2(b), HO2, and OH were observed when F atoms were added to H2O2 in the gas phase. Signal strengths of O2(b) were proportional to initial concentrations of H2O2 and HO2. These observations were analyzed by using a simple three step mechanism and a more complete computer simulation with 22 reaction steps. The results indicate that the F + HO2 reaction yields O2(b) with an efficiency of (3.6 ± 1.4) × 10?3. By monitoring [O2(b)] and [HO2] upon addition of an excess second reactant to HO2, O2(b) yields from the reactions of HO2 with O, Cl, D, H, and OH were found to be <1 × 10?2, <5 × 10?4, <2 × 10?3, <8 × 10?3, and <1 × 10?3, respectively. Yields of O2(b) from the HO2 ± HO2 reaction were found to be less than 3 × 10?2. 相似文献
66.
Kwang-Duk Ahn Jong-Hee Kang Kynug Wook Yoo Dong Joon Choo 《Macromolecular Symposia》2007,254(1):46-53
Summary: Photocured coatings promise enhanced performance, higher productivity and an improved environmental impact on the favorable reduction or near elimination of volatile organic compounds. Increasing interest in the photocuring industry has been imposed on the “photoinitiator-free photopolymerization [PIFP]” system based on the electron-donor-acceptor [EDA] concept, which commonly employs a mixture of a vinyl ether monomer (donor) and an N-substituted maleimide or bismaleimide monomer (acceptor). The PIFP systems employing silicon-containing maleimides together with vinyl ether monomers were firstly investigated and their photoreactions resulted in quite fast curing comparable to the conventional acrylate- based photocurable systems. 相似文献
67.
Dong Kyu Lim Nguyen Phuoc Long Sanghan Choo Changyeun Mo Ziyuan Dong Giyoung Kim 《Analytical letters》2017,50(16):2519-2529
Milling is an influential factor that affects the nutritional components in rice. However, the alteration of rice constituents by milling has not been thoroughly examined. In this study, rice with various degrees of milling was analyzed by gas chromatography–mass spectrometry and high-performance liquid chromatography–mass spectrometry. Principal component analysis and partial least square-discriminant analysis were performed to characterize the nutritional components that have significant changes during milling. The concentrations of sugars and sugar alcohols decreased while the phospholipids increased in accordance with the milling degree. These results provide a contrast to the common idea that brown rice is nutritionally superior to white rice. In conclusion, the knowledge of nutritional alterations related to milling may benefit rice production and consumption. 相似文献
68.
69.
Chan Woo Jung Ghulam Jalani Juhui Ko Jaebum Choo Dong Woo Lim 《Macromolecular rapid communications》2014,35(1):56-65
Anisotropic microarchitectures with different physicochemical properties have been developed as advanced materials for challenging industrial and biomedical applications including switchable displays, multiplexed biosensors and bioassays, spatially‐controlled drug delivery systems, and tissue engineering scaffolds. In this study, anisotropic biohybrid microparticles (MPs) spatio‐selectively conjugated with two different antibodies (Abs) are first developed for fluorescence‐based, multiplexed sensing of biological molecules. Poly(acrylamide‐co‐acrylic acid) is chemically modified with maleimide‐ or acetylene groups to introduce different targeting biological moieties into each compartment of anisotropic MPs. Modified polymer solutions containing two different fluorescent dyes are separately used for electrohydrodynamic co‐jetting with side‐by‐side needle geometry. The anisotropic MPs are chemically stabilized by thermal imidization, followed by bioconjugation of two different sets of polyclonal Abs with two individual compartments via maleimide‐thiol coupling reaction and Huisgen 1,3‐dipolar cycloaddition. Finally, two compartments of the anisotropic biohybrid MPs are spatio‐selectively associated with the respective monoclonal Ab‐immobilized substrate in the presence of the antigen by sandwich‐type immunocomplex formation, resulting in their ordered orientation due to the spatio‐specific molecular interaction, as confirmed by confocal laser scanning microscopy. In conclusion, anisotropic biohybrid MPs capable of directional binding have great potential as a new fluorescence‐based multiplexing biosensing system.
70.
Bioorthogonal Cleavage and Exchange of Major Histocompatibility Complex Ligands by Employing Azobenzene‐Containing Peptides 下载免费PDF全文
Joanna A. L. Choo Dr. Sock Yue Thong Jiawei Yap Dr. Wim J. E. van Esch Dr. Manfred Raida Dr. Rob Meijers Dr. Julien Lescar Dr. Steven H. L. Verhelst Dr. Gijsbert M. Grotenbreg 《Angewandte Chemie (International ed. in English)》2014,53(49):13390-13394
Bioorthogonal cleavable linkers are attractive building blocks for compounds that can be manipulated to study biological and cellular processes. Sodium dithionite sensitive azobenzene‐containing (Abc) peptides were applied for the temporary stabilization of recombinant MHC complexes, which can then be employed to generate libraries of MHC tetramers after exchange with a novel epitope. This technology represents an important tool for high‐throughput studies of disease‐specific T cell responses. 相似文献