Light-emitting diode-induced fluorescence detection of native proteins in capillary electrophoresis

A continuous-wave 280 nm light-emitting diode (LED) was used as the excitation source for native fluorescence detection of proteins in CE. The operating current and temperature of the LED were optimized in order to achieve high luminescence power. It was found that a forward current of 30 mA and a temperature of approximately 5 degrees C gave the best S/N. By using a set of two ball lenses to focus light from the LED, we achieved a spot of approximately 200 mum with a power of 0.1-0.2 mW on the detection window. Fluorescence was collected with a ball lens at 90 degrees angle through a bandpass filter onto a photomultiplier tube. In CZE an LOD of 20 nM for conalbumin was reached. In capillary gel electrophoresis all eight proteins from a commercial standard kit were detected with high S/N. For a 10 microg/mL total protein mixture, S/N was better than 3 for all proteins in solution. Further improvement in LOD should be possible on utilization of an LED with higher luminescence power.     

X-射线荧光分析散射幂函数法原理及其应用I·RhKα相干散射平方法

本文发现6~40号元素对能量为20keV的X_射线的质量吸收系数和质量相干散射系数之间呈二次幂函数关系,并据此提出了X_射线荧光定量分析校正基体效应的新方法——RhKa相干散射平方法.用国家标准物质GBW对该原理进行了验证.本法用于硅酸盐地质样品中微量元素的测定取得令人满意的结果.     

Markov processes in single molecule fluorescence

This article examines the current status of Markov processes in single molecule fluorescence. For molecular dynamics to be described by a Markov process, the Markov process must include all states involved in the dynamics and the first-passage time (FPT) distributions out of those states must be describable by a simple exponential law. The observation of non-exponential FPT distributions or other evidence of non-Markovian dynamics is common in single molecule studies and offers an opportunity to expand the Markov model to include new dynamics or states that improve understanding of the system.     

Self-assembly, optical behavior, and permeability of a novel capsule based on an azo dye and polyelectrolytes

A novel capsule composed of an azo dye, Congo red (CR), and different polymers, including poly(styrenesulfonate, sodium salt) (PSS), poly(allylamine hydrochloride) (PAH), and poly(diallyldimethylammonium chloride) (PDDA), have been successfully fabricated by the layer-by-layer self-assembly technique. The stepwise linear deposition process was monitored by means of UV-visible absorption measurements. The formation of hollow capsules was verified by confocal laser scanning microscopy (CLSM) and scanning force microscopy (SFM). The resulting hollow PSS/PAH/CR/PDDA capsules displayed a sensitive response to visible light. Optical changes of the hollow capsules prior to and after the photoreaction were investigated in detail by means of UV-visible spectroscopy, CLSM, and SFM. It was found that the photochemical reaction of the assembled hollow capsules depends strongly on the matrix. Qualitative results on the permeability of the hollow capsule walls with CR as one component indicate that the permeability of the walls can be easily photo-controlled at varying irradiation time intervals without addition of external chemicals.     

聚乙二醇在高真空条件下的单链弹性

在过去二十年间，高分子的单链弹性已经得到了广泛的研究.然而由于环境和高分子之间往往有着复杂的相互作用，实验中很难得到高分子在严格无扰状态下的单链弹性（即本征弹性）.为此，利用单分子力谱技术研究了高真空条件下聚乙二醇（PEG）的单链弹性.结果表明，由于高真空条件下溶剂分子的干扰被消除，PEG在这一准无扰状态下呈现其本征弹性.在非极性有机溶剂中，由于溶剂分子和PEG之间只有微弱的范德华力作用，PEG表现出和高真空中基本一致的弹性.然而，在不同环境中，力曲线的低力区（F<100 pN）存在着细微的差异.这一现象可归因于不同条件下基底与PEG链之间的吸附力不同.采用的高真空力谱可用于研究其他高分子单链在准无扰状态下的本征弹性.     

碱性体系在线氢化物发生—原子荧光光谱法测定痕量铋

提出了一种碱性体系在线氢化物发生－原子荧光光谱法测定痕量铋的分析方法。设计了在线氢化物发生系统流路及操作程序，研究了碱性体系氢化物发生的各项最佳条件。方法操作简便快速，能有效地消除过渡元素的严重化学干扰。应用于黄铜标样中痕量铋的直接测定，获得满意结果。     

Complexation of Al(III) by 8-Hydroxyquinoline and Drastic Fluorescence Enhancement in Reverse Micelles

Complexation of Al^IIIby 8-hydroxyquinoline and fluorescence behavior of the quinolinate(s) were studied in reverse micellar systems at low water content, and compared to aqueous media. Two surfactants were used: one was cationic (CTAC: cetyltrimethylammonium chloride) and the other was anionic (AOT: sodium bis(2-ethylhexyl)sulfosuccinate). The results obtained in the CTAC/dichloromethane system (W= [H₂O]/[surfactant] = 0.9) showed that complexation occurred very likely in the oil phase and no micellar effect was observed. On the contrary, in the presence of AOT, specific micellar effects were observed due to the presence of the anionic polar heads: stabilization of the positively charged 1:1 and 1:2 chelates, at the expense of the neutral water-insoluble 1:3 chelate which is formed in aqueous solutions under similar conditions;drastic fluorescence enhancement factorsof 120 and 100 in AOT/heptane (W= 1.5) and AOT/dichloromethane (W= 1.6), respectively. Such factors have never been reported so far in either hydroorganic or direct micellar systems. In return, the length of time for the production of the complex(es) is increased because of the microheterogeneity of the medium and the small sizes of the water pools.     

八—4—(四氢糠氧基)双酞菁衍生物钕(Ⅲ)、铕(Ⅲ)的合成和LB膜的气敏性

八—４—（四氢糠氧基）双酞菁衍生物钕（Ⅲ）、铕（Ⅲ）的合成和ＬＢ膜的气敏性张引＊辛春梅王丹（吉林省教育学院化学系，长春１３００２２）梁冰洁＊＊陈文启席时权（中科院长春应用化学研究所，长春１３００２２）关键词：希土双酞菁衍生物ＬＢ膜气敏性荧光性紫外可见...     

Optimization of Ormosil Films for Optical Sensor Applications

Recent work has indicated that Ormosil films, fabricated from organically modified precursors, produce better sensor performance for some specific applications, compared to films fabricated from conventional sol-gel precursors such as TEOS or TMOS. This paper aims to compare film properties and sensor behavior for films fabricated from tetraethoxysilane (TEOS) and tetramethoxysilane (TMOS) silica precursors and both methyltrimethoxysilane (MTMS) and methyltriethoxysilane (MTES) organically modified precursors. Microstructural differences, for example, porosity changes due to the different precursor backbone structures, are interrogated by monitoring oxygen gas and aqueous-phase sensor response. Oxygen sensing using these films is enabled by incorporating in the films an oxygen-sensitive ruthenium dye whose fluorescence is quenched in the presence of oxygen. Film properties such as thickness, thickness stabilization time, as well as sensor response, are discussed in terms of relative hydrolysis and condensation behavior for the different precursors. Film hydrophobicity, an issue which has been identified as being of crucial importance for optimum dissolved oxygen sensor response, is discussed and contact angle measurements are used to investigate the degree of hydrophobicity for different film types. The main motivation for this work is film optimization for optical gas-phase and dissolved oxygen sensors.     

Preparation, characterization, and application of multistimuli-responsive microspheres with fluorescence-labeled magnetic cores and thermoresponsive shells

Novel functional microspheres with multistimuli-responsive properties have been prepared and characterized. The as-prepared microspheres respond to an external magnetic field, environmental temperature, and ultraviolet radiation. The in vitro drug-loading efficiency and drug-release behavior of these microspheres demonstrated that they could be used as drug carriers for drug controlled release. The results of in vivo distribution investigations of these microspheres showed that they exhibit a high magnetic-targeting effect, which holds promise for applications in various fields such as magnetic drug targeting and tissue labeling, among others.