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11.
Chih‐Ching Huang Prof. Yu‐Lun Hung Yen‐Chun Shiang Tai‐Yuan Lin Prof. Yu‐Shen Lin Chao‐Tsen Chen Prof. Huan‐Tsung Chang Prof. 《化学:亚洲杂志》2010,5(2):334-341
We have employed mannose‐modified gold nanodots (Man–Au NDs) as a luminescence sensor for the detection of the thyroid‐cancer marker thyroglobulin (Tg) in homogeneous solutions. The luminescent Man–Au NDs are prepared through the reaction of 2.9 nm‐diameter gold nanoparticles (Au NPs) with 11‐mercapto‐3,6,9‐trioxaundecyl‐α‐D ‐mannopyranoside (Man‐RSH) under the irradiation of a light‐emitting diode (LED). We have found that the irradiation enhances the quantum yield (~11 %), alters the emission wavelength and lifetimes, and shortens the preparation time. A luminescence assay has been developed for Tg based on the competition between Tg and Man–Au NDs for the interaction with the concanavalin A (Con A). Because luminescence quenching of the Man–Au NDs by Con A is inhibited by Tg selectivity, we have obtained a highly sensitive and selective assay for Tg. 相似文献
12.
Wedge waves (WW) are guided acoustic waves propagating along the tip of a wedge, with energy tightly confined near the apex. This study is focused on exploring the dispersion behaviors of WW propagating along a bilinear wedge (BW). A BW is wedge with a cross section of two apex angles, compared with a linear wedge (LW) having a single apex angle. In the literature, many studies regarding to the dispersion behaviors of ASF modes are reported for LW, but not for BW. In this study, a combined experimental and numerical stidy is used to investigate the dispersion behavior of WW propagating in BW's. It is found out that WW in a BW is a result of mode coupling between the two WW's corresponding to simple wedges with the two apex angles of the BW. 相似文献
13.
Yang‐Wei Lin Wen‐Tsen Chen Huan‐Tsung Chang 《Rapid communications in mass spectrometry : RCM》2010,24(7):933-938
Surface‐assisted laser desorption/ionization mass spectrometry (SALDI‐MS) is applied to provide strong evidence for the chemical reactions of functionalized gold nanoparticles (Au NPs) with analytes – Hg2+ ions induced MPA?Au NPs aggregation in the presence of 2,6‐pyridinedicarboxylic acid (PDCA) and H2O2 induced fluorescence quenching of 11‐MUA?Au NDs. PDCA‐Hg2+‐MPA coordination is responsible for Au NPs aggregation, while the formation of 11‐MUA disulfide compounds that release into the bulk solution is responsible for H2O2‐induced fluorescence quenching. In addition to providing information about the chemical structures, SALDI‐MS is also selective and sensitive for the detection of Hg2+ ions and H2O2. The limits of detection (LODs) for Hg2+ ions and H2O2 by SALDI‐MS were 300 nM and 250 µM, respectively. The spot‐to‐spot variations in the two studies were both less than 18% (50 sample spots). Our results reveal that SALDI‐MS can be used to study analyte‐induced changes in the surface properties of nanoparticles. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
14.
A new general strategy to achieve chaos synchronization by variable strength linear coupling without another active control is proposed. They give the criteria of chaos synchronization for two identical chaotic systems and two different chaotic dynamic systems with variable strength linear coupling. In this method, the time derivative of Lyapunov function in series form is firstly used. Lorenz system, Duffing system, Rössler system and Hyper-Rössler system are presented as simulated examples. 相似文献
15.
Yi‐Ting Hsieh Wen‐Tsen Chen Iva Tomalová Jan Preisler Huan‐Tsung Chang 《Rapid communications in mass spectrometry : RCM》2012,26(12):1393-1398
We have developed a method for the determination of melamine (MEL), ammeline (AMN), and ammelide (AMD) by surface‐assisted laser desorption/ionization mass spectrometry (SALDI‐MS) using gold nanoparticles (Au NPs). The major peaks for MEL, AMN, and AMD at m/z 127.07, 128.05, and 129.04 are assigned to the [MEL + H]+, [AMN + H]+, and [AMD + H]+ ions. Because the three tested compounds adsorb weakly onto the surfaces of the Au NPs through Au–N bonding, they can be easily concentrated from complex samples by applying a simple trapping/centrifugation process. The SALDI‐MS method provides limits of detection of 5, 10, and 300 nM for MEL, AMN, and AMD, respectively, at a signal‐to‐noise ratio of 3. The signal variation for 150‐shot average spectra of the three analytes within the same spot was 15%, and the batch‐to‐batch variation was 20%. We have validated the practicality of this approach by the analysis of these three analytes in infant formula and grain powder. This simple and rapid SALDI‐MS approach holds great potential for screening of MEL in foods. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
16.
A dynamic adsorption model for surface-active materials at air/liquid interfaces with the consideration of aggregate dissolution effect was developed to investigate the dynamic surface tension behavior of aqueous surfactant dispersions. Two catanionic surfactants, cetylpyridinium dodecylsulfate (CP-DS) and dodecyltrimethylammonium dodecylsulfate (DTMA-DS), with low critical aggregation concentrations were chosen as model systems. Dynamic surface tensions of aqueous CP-DS and DTMA-DS systems were measured by a drop volume tensiometer. A model with diffusion-controlled or mixed-kinetic dynamic adsorption mechanisms considering the dissolution effect of dispersed aggregates was developed to simulate the dynamic surface tension data. An analysis by comparing the model predictions with experimental data demonstrated that the dynamic surface tension behavior of aqueous CP-DS and DTMA-DS dispersions could be described with a diffusion-controlled dynamic adsorption model taking the aggregate dissolution effect into account. 相似文献
17.
Relevance of phenolic diterpene constituents to antioxidant activity of supercritical CO(2) extract from the leaves of rosemary 总被引:1,自引:0,他引:1
Isolation of phenolic diterpene constituents from the freeze-dried leaves of Rosmarinus officinalis has been obtained by supercritical extraction with carbon dioxide. To determine the ideal conditions for the maximum yield of extract, nine different conditions using three levels of pressures (3000, 4000 and 5000 psi) in combination with three temperatures at 40, 60 and 80 degrees C, respectively, in combination with the analyses of the corresponding antioxidant activities and constituents which existed in extracts has been investigated. The antioxidant activity of each obtained extract was determined by using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals test. GC/MS method was used as an alternative to conventional HPLC method for the determination of the principal antioxidant constituents in extract, including phenolic diterpenes carnosic acid (CA) and carnosol (CAL). The confirmation of CA and CAL in extract was forward performed by subjecting HPLC isolates from extract into an ion trap mass spectrometer through an electrospray ionization (ESI) interface for MS/MS analysis. These results indicate that an ideal extraction process was obtained at 5000 psi and 80 degrees C with an extraction yield of 4.27% (w/w) and rich in phenolic antioxidants CA and CAL as contents of 35.23 and 0.46 mg g(-1) in extract, respectively. 相似文献
18.
Delineation of G‐Quadruplex Alkylation Sites Mediated by 3,6‐Bis(1‐methyl‐4‐vinylpyridinium iodide)carbazole‐Aniline Mustard Conjugates
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Chien‐Han Chen Tsung‐Hao Hu Tzu‐Chiao Huang Ying‐Lan Chen Prof. Yet‐Ran Chen Prof. Chien‐Chung Cheng Prof. Chao‐Tsen Chen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(48):17379-17390
A new G‐quadruplex (G‐4)‐directing alkylating agent BMVC‐C3M was designed and synthesized to integrate 3,6‐bis(1‐methyl‐4‐vinylpyridinium iodide)carbazole (BMVC) with aniline mustard. Various telomeric G‐4 structures (hybrid‐2 type and antiparallel) and an oncogene promoter, c‐MYC (parallel), were constructed to react with BMVC‐C3M, yielding 35 % alkylation yield toward G‐4 DNA over other DNA categories (<6 %) and high specificity under competition conditions. Analysis of the intact alkylation adducts by electrospray ionization mass spectroscopy (ESI‐MS) revealed the stepwise DNA alkylation mechanism of aniline mustard for the first time. Furthermore, the monoalkylation sites and intrastrand cross‐linking sites were determined and found to be dependent on G‐4 topology based on the results of footprinting analysis in combination with mass spectroscopic techniques and in silico modeling. The results indicated that BMVC‐C3M preferentially alkylated at A15 (H26), G12 (H24), and G2 (c‐MYC), respectively, as monoalkylated adducts and formed A15–C3M–A21 (H26), G12–C3M–G4 (H24), and G2–C3M–G4/G17 (c‐MYC), respectively, as cross‐linked dialkylated adducts. Collectively, the stability and site‐selective cross‐linking capacity of BMVC‐C3M provides a credible tool for the structural and functional characterization of G‐4 DNAs in biological systems. 相似文献
19.
Summary Graft copolymers were obtained by the interaction of polymethyl methacrylate with heterochain polyesters, their properties were studied and a hypothesis was put forward on their structure.The thermomechanical curves and x-ray pictures were obtained in the laboratories directed by G. L. Slonimskii and A. I. Kitaigorodskii, to whom we express our sincere thanks. 相似文献
20.
Dr. Yu‐Chen Lin Prof. Dr. Chao‐Tsen Chen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(7):2531-2538
A new metal‐ion‐responsive and fluorescent foldamer, OPLM8 , composed of eight lysine–coumarin–azacrown units, has been designed and synthesized. The flexible OPLM8 can be forced into a well‐defined helix structure only upon the addition of alkaline earth metal ions. The structural change is based on the crown ether moieties being positioned in the requisite arrangement along the peptide chain, that is, at i, i+4 spacing, such that the alkaline earth metal ions can mediate the formation of four sandwich complexes between them. Moreover, varying the chelator‐to‐metal‐ion ratio from 2:1 to 1:1 resulted in disassembly of the sandwich complexes leading to collapse of the helical structure to a random coil. These metal‐ion‐induced structural transitions could not only be monitored by the CD amplitude change but also easily probed by unique “OFF–OFF–ON” fluorescence intensity changes from 0.7‐fold to 14‐fold as the structure changed from the folded helix to a random coil. To further verify that the helix formation was indeed induced by metal‐ion complexation, two kinds of control octamers with only four metal‐ion chelators on the side chains were studied. One, which was capable of forming two sandwich complexes between the i and i+4 residues, displayed a negative Cotton couplet with the magnitude of its A value close to half that of OPLM8 , and the second had four metal‐ion chelators positioned in the same turn, and hence was incapable of forming intramolecular metal complexes and showed different induced CD signals. Collectively, the photospectroscopic data and the results of the control studies suggest that alkaline earth metal ions can efficiently promote the flexible octamer OPLM8 into a well‐organized helix by the formation of sandwich complexes between substituents at an i, i+4 spacing. 相似文献