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181.
Liang Cui Yanling Song Guoliang Ke Zhichao Guan Huimin Zhang Ya Lin Yishun Huang Dr. Zhi Zhu Prof. Chaoyong James Yang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(32):10442-10451
Recently, the binding ability of DNA on GO and resulting nuclease resistance have attracted increasing attention, leading to new applications both in vivo and in vitro. In vivo, nucleic acids absorbed on GO can be effectively protected from enzymatic degradation and biological interference in complicated samples, making it useful for targeted delivery, gene regulation, intracellular detection and imaging with high uptake efficiencies, high intracellular stability, and very low toxicity. In vitro, the adsorption of ssDNA on GO surface and desorption of dsDNA or well‐folded ssDNA from GO surface result in the protection and deprotection of DNA from nucleic digestion, respectively, which has led to target‐triggered cyclic enzymatic amplification methods (CEAM) for amplified detection of analytes with sensitivity 2–3 orders of magnitude higher than that of 1:1 binding strategies. This Concept article explores some of the latest developments in this field. 相似文献
182.
Prof. Pil Seok Chae Andrew C. Kruse Dr. Kamil Gotfryd Rohini R. Rana Kyung Ho Cho Prof. Søren G. F. Rasmussen Hyoung Eun Bae Richa Chandra Prof. Ulrik Gether Prof. Lan Guan Prof. Brian K. Kobilka Prof. Claus J. Loland Dr. Bernadette Byrne Prof. Samuel H. Gellman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(46):15645-15651
Integral membrane proteins play central roles in controlling the flow of information and molecules across membranes. Our understanding of membrane protein structures and functions, however, is seriously limited, mainly due to difficulties in handling and analysing these proteins in aqueous solution. The use of a detergent or other amphipathic agents is required to overcome the intrinsic incompatibility between the large lipophilic surfaces displayed by the membrane proteins in their native forms and the polar solvent molecules. Here, we introduce new tripod amphiphiles displaying favourable behaviours toward several membrane protein systems, leading to an enhanced protein solubilisation and stabilisation compared to both conventional detergents and previously described tripod amphiphiles. 相似文献
183.
Addition of nitroalkanes into n‐alkanes can lower the activation barriers of free‐radical production and accelerate the decomposition of n‐alkanes at relatively low temperatures. Four initial decomposition mechanisms of the n‐butane/nitroethane binary mixture were proposed for the promoting effect and considered theoretically at the B3LYP, BB1K, BMK, MPW1K, and M06‐2X levels with MG3S basis set. Energetics above was compared to high‐level CBS‐QB3 and G4 calculations. Calculated results confirm the feasibility of the four initial decomposition pathways: (I) the C? NO2 bond rupture of nitroethane to produce ethyl and ·NO2, (II) HONO elimination from nitroethane followed by decomposition to ·OH and ·NO, (III) rearrangement of nitroethane to ethyl nitrite which further dissociates into CH3CH2O· and ·NO, and (IV) direct hydrogen‐abstraction of nitroethane with n‐butane. 相似文献
184.
Yong Guan Huanyao Zhang Anna Zheng Dafu Wei Jian Hu Zhenzhen Wang Xiang Xu 《先进技术聚合物》2019,30(7):1555-1563
Recently, silicone rubber (VMQ) was extensively used in household articles and medical devices. To develop a kind of safe and long‐term antimicrobial VMQ was of great significance. In this work, a kind of vinyl‐contained polyhexamethylene guanidine hydrochloride (VPHMG) was synthesized and used as antimicrobial additive for VMQ. With the increasing of VPHMG addition, the mechanical properties and antimicrobial properties of VMQ‐VPHMG were significantly improved. In particular, the antimicrobial rates against Escherichia coli and Staphylococcus aureus were higher than 99.99% as for 4 wt% of VPHMG addition. Moreover, the surface concentration of VPHMG as well as the antimicrobial rates revealed almost unchanged after being extracted by water and methanol. All the results indicated the vinyl‐contained VPHMG vulcanization and therefore provided the permanent antimicrobial performance for VMQ. 相似文献
185.
Chao Ma Huida Guan Zhengcai Ju Shuping Li Gang Deng Yunpeng Zhang Qiyan Lin Xuemei Cheng Li Yang Zhengtao Wang Changhong Wang 《Journal of separation science》2019,42(8):1550-1563
Notoginsenoside Fc, a protopanaxadiol‐type saponin, shows multi‐pharmacological activities. Chemical stability evaluation plays a crucial role in drug development. In this study, the forced degradation behavior of Notoginsenoside Fc was investigated under hydrolytic and oxidative conditions. A specific ultra high performance liquid chromatography with quadrupole time‐of‐flight mass spectrometry was developed for the separation, identification, and characterization of the degradation products of Notoginsenoside Fc. Fifty potential degradation products were formed via deglycosylation, dehydration, hydration, isomerization, side‐chain cleaving, oxidation, and superoxidation. Notoginsenoside Fc was subjected to different pH solutions, temperatures, and time periods to assess its stability. A sensitive ultra high performance liquid chromatography‐tandem mass spectrometry was developed for the quantification of Notoginsenoside Fc, notoginsenoside ST‐4, notoginsenoside Ft1, and relative quantification of notoginsenoside Ft2, 20(R)‐notoginsenoside Ft2, notoginsenoside SFt3, and notoginsenoside SFt4. The assay was linear over the concentration range (R2 > 0.997) with the lowest limit of quantification of 0.02 μg/mL for Notoginsenoside Fc, Notoginsenoside ST‐4, and Notoginsenoside Ft1. The intra‐day precision, inter‐day precision, and accuracy of the three analytes were within accepted levels. The degradation kinetics of Notoginsenoside Fc in pH 1 and 3 solutions fits to first‐ and second‐order kinetics, respectively. The degradation of Notoginsenoside Fc is pH‐, temperature‐, and time‐dependent. 相似文献
186.
Sainan Zhang Zhengcai Ju Huida Guan Lu Yu Zhengtao Wang Yuqing Zhao 《Biomedical chromatography : BMC》2019,33(11)
Notoginsenoside R1 (NGR1), a diagnostic protopanaxatriol‐type (ppt‐type) saponin in Panax notoginseng, possesses potent biological activities including antithrombotic, anti‐inflammatory, neuron protection and improvement of microcirculation, yet its pharmacokinetics and metabolic characterization as an individual compound remain unclear. The aim of this study was to investigate the exposure profile of NGR1 in rats after oral and intravenous administration and to explore the metabolic characterization of NGR1. A simple and sensitive ultra‐fast liquid chromatographic–tandem mass spectrometric method was developed and validated for the quantitative determination of NGR1 and its major metabolites, and for characterization of its metabolic profile in rat plasma. The blood samples were precipitated with methanol, quantified in a negative multiple reaction monitoring mode and analyzed within 6.0 min. Validation parameters (linearity, precision and accuracy, recovery and matrix effect, stability) were within acceptable ranges. After oral administration, NGR1 exhibited dose‐independent exposure behaviors with t1/2 over 8.0 h and oral bioavailability of 0.25–0.29%. A total of seven metabolites were characterized, including two pairs of epimers, 20(R)‐notoginsenoside R2/20(S)‐notoginsenoside R2 and 20(R)‐ginsenoside Rh1/20(S)‐ginsenoside Rh1, with the 20(R) form of saponins identified for the first time in rat plasma. Five deglycometabolites were quantitatively determined, among which 20(S)‐notoginsenoside R2, ginsenoside Rg1, ginsenoside F1 and protopanaxatriol displayed relatively high exploration, which may partly explain the pharmacodynamic diversity of ginsenosides after oral dose. 相似文献
187.
Dr. Muhammad Ehsan Dr. Yang Du Jonas S. Mortensen Dr. Parameswaran Hariharan Qianhui Qu Lubna Ghani Dr. Manabendra Das Anne Grethen Prof. Bernadette Byrne Prof. Georgios Skiniotis Prof. Sandro Keller Prof. Claus J. Loland Prof. Lan Guan Prof. Brian K. Kobilka Prof. Pil Seok Chae 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(49):11545-11554
Amphipathic agents are widely used in various fields including biomedical sciences. Micelle-forming detergents are particularly useful for in vitro membrane-protein characterization. As many conventional detergents are limited in their ability to stabilize membrane proteins, it is necessary to develop novel detergents to facilitate membrane-protein research. In the current study, we developed novel trimaltoside detergents with an alkyl pendant-bearing terphenyl unit as a hydrophobic group, designated terphenyl-cored maltosides (TPMs). We found that the geometry of the detergent hydrophobic group substantially impacts detergent self-assembly behavior, as well as detergent efficacy for membrane-protein stabilization. TPM-Vs, with a bent terphenyl group, were superior to the linear counterparts (TPM-Ls) at stabilizing multiple membrane proteins. The favorable protein stabilization efficacy of these bent TPMs is likely associated with a binding mode with membrane proteins distinct from conventional detergents and facial amphiphiles. When compared to n-dodecyl-β-d -maltoside (DDM), most TPMs were superior or comparable to this gold standard detergent at stabilizing membrane proteins. Notably, TPM-L3 was particularly effective at stabilizing the human β2 adrenergic receptor (β2AR), a G-protein coupled receptor, and its complex with Gs protein. Thus, the current study not only provides novel detergent tools that are useful for membrane-protein study, but also suggests a critical role for detergent hydrophobic group geometry in governing detergent efficacy. 相似文献
188.
189.
本文用顶空气相色谱法,以GDX-101为固定相,测定了延生护宝液中甲醇残留量,方法的回收率在85.9%-101.6%之间,变异系数0.3%,最小检出量1.0mg/L。 相似文献
190.
高效液相色谱法测定血浆中7种灭鼠剂 总被引:12,自引:0,他引:12
建立了血浆中7种缓效灭鼠剂的反相高效液相色谱分析方法,选择了样品提取与测定条件,考察了有关化合物对测定的影响,在色谱工作站上建立了灭鼠剂的紫餐吸收光谱库,根据吸收光谱与tR值进行库检索,提出了定性的准确度。方法的线性范围为2-10μL/L血浆,最低检测浓度为1μL/mL血浆。 相似文献