共振光散射光谱研究噻嗪红R与牛血清白蛋白的作用及其分析应用

研究了噻嗪红R(Thiazine red R,TR)与牛血清蛋白(BSA)作用的共振光散射(RLS)光谱特征。考察了各种影响因素,并计算出了BSA与TR的结合比(质量之比)为1.25。结果表明,在优化条件下体系的RLS强度与蛋白质浓度在一定范围内具有良好的线性关系,据此建立了一种蛋白质测定的新方法。在最佳实验条件(TR,2.0×10-5mol/L;pH2.36)下,BSA的线性范围是0.01~5.0μg/mL,检出限为1.4ng/mL。该方法已用于合成样品及尿液的测定。     

Determination of dextrin based on its self-aggregation by resonance light scattering technique

A novel free-probe assay of dextrin was established based on the resonance light scattering (RLS) enhancement in aqueous solution due to the self-aggregation of dextrin. The RLS intensity was well proportional to the concentration of dextrin over the wide range 0.2-14 μg mL⁻¹ and a detection limit 0.02 μg mL⁻¹ was obtained in the optimum conditions. The effect factors such as pH, buffer medium, holding time, ionic strength and temperature were studied in detail. Little or no interference was presented in the detection when adding coexisting substances including various metal ions and some saccharine in the solution. The assay proposed owns the advantages of easy operation, rapidity, sensitivity and practicability. Three synthetic samples and three kinds of medicine samples were analyzed with satisfactory results.     

气体水合物膜生长动力学研究进展

由于大多数水合物客体不溶于水,水相与客体相界面首先形成一层气体水合物膜,气体水合物膜生长是水合物生长的主要形式,研究水合物膜生长规律对于理解水合物生长动力学及进一步开发促进和抑制水合物生长的应用技术具有重要意义.本文综述了近年来气体水合物膜生长形态、横向生长和增厚生长的理论和实验研究进展.首先介绍了不同客体-水体系(包括气/液界面、液/液界面和气-液-液体系)形成的水合物膜生长形态随实验条件的变化规律,然后分别从横向生长和增厚生长两方面总结了水合物膜生长的实验和模型方面的研究工作,阐述了常见的膜生长速率和膜厚度的测量方法,分析了水合物膜生长的传热和传质机理.同时展望了未来水合物膜生长研究的发展方向.     

Characterization of proteins separated by displacement chromatography using low angle laser light scattering photometry

Summary -Lactoglobulin A and B (-LACT) were separated by displacement chromatography (DSC) on an ionexchange column using dextran sulfate as the displacer. A LALLS photometer and a UV detector, in series, were used to determine the molecular weight (MW) of the proteins, on-line. The results indicate that both, -LACT A and B, were present as dimers in the buffer used for the mobile phase. The MWs of the proteins were about 6–8% higher than the theoretical MW of a dimer (37,000). Additional control studies have shown the presence of a high molecular weight species in both the proteins, which could possibly be an aggregate. This species was observed in the LALLS signal but was nearly absent in the UV signal. Our work has demonstrated the feasibility of interfacing LALLS with displacement chromatography for detecting impurities or aggregates which may be difficult to detect by conventional detectors used for chromatography.     

Speckle reduction in the small-angle light scattering technique using sample vibration

Experimental patterns obtained using the small-angle light scattering technique for thin-film polymer studies are fraught with speckles arising from the effect of interspherulitic interference. The presence of speckles hampers efforts in characterizing the spherulitic structure. Using a divergent beam increases the number of scattering sites and results in a reduction of the degree of speckling. Nevertheless, this decimates the ability of analyzing the pattern at low-scattering angles. Employing an expanded collimated beam produces the same effect but necessitates the use of specially designed optical components. This article outlines a novel technique that involves simple vibration of the polymer sample. Experimental results confirm its efficacy in reducing speckles without limiting the ability for analysis at low-scattering angles. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 937–943, 1997     

Progress in the development of techniques based on light scattering for single nanoparticle detection

Nanoparticles have recently attracted extensive attention in view of their great potential in biomedicine and bioanalytical ap- plications. Single particle detection via light scattering offers a simple and efficient approach for the size, size distribution, and concentration analysis of nanoparticles. In particular, intrinsic heterogeneity or rare events masked by ensemble averaging can be revealed. However, the sixth power dependence of Rayleigh scattering on particle size makes it very challenging to det...     

Femtosecond laser ablation: Visualization of the aerosol formation process by light scattering and shadowgraphic imaging

The shockwave propagation and aerosol formation during femtosecond laser ablation (fs-LA) of dielectric materials (Li₂B₄O₇, Y:ZrO₂) in ambient air were monitored using shadowgraphy and light scattering. Three independent shockwave fronts were observed originating from (i) the instantaneous compression of ambient gas during the initial stage of fs-LA, (ii) a secondary compression caused by material ejection, and (iii) an air breakdown well above the target surface. In addition, particle size distributions were found to be multimodal implying the co-existence of condensational growth and supplementary particle production pathways such as phase explosion or critical point phase separation (CPPS). As a consequence, fs-LA of Li₂B₄O₇ resulted in the formation of primary aggregates reaching diameters of > 10 μm. In contrast, aggregates formed during fs-LA of Y:ZrO₂ covered a size range < 1 μm. Our data, furthermore, indicate the existence of a breakdown channel in the ambient atmosphere being capable to carry plasmatic, i.e. non-condensed matter beyond the primary shockwave barrier which may occasionally causes a spatial separation of material released. Assuming the Taylor-Sedov model of explosion to be valid the over-all energy dissipated in acoustic transients was found to exceed values of 50%.     

Using light scattering to evaluate the separation of polydisperse nanoparticles

The analysis of natural and otherwise complex samples is challenging and yields uncertainty about the accuracy and precision of measurements. Here we present a practical tool to assess relative accuracy among separation protocols for techniques using light scattering detection. Due to the highly non-linear relationship between particle size and the intensity of scattered light, a few large particles may obfuscate greater numbers of small particles. Therefore, insufficiently separated mixtures may result in an overestimate of the average measured particle size. Complete separation of complex samples is needed to mitigate this challenge. A separation protocol can be considered improved if the average measured size is smaller than a previous separation protocol. Further, the protocol resulting in the smallest average measured particle size yields the best separation among those explored. If the differential in average measured size between protocols is less than the measurement uncertainty, then the selected protocols are of equivalent precision. As a demonstration, this assessment metric is applied to optimization of cross flow (V_x) protocols in asymmetric flow field flow fractionation (AF⁴) separation interfaced with online quasi-elastic light scattering (QELS) detection using mixtures of polystyrene beads spanning a large size range. Using this assessment metric, the V_x parameter was modulated to improve separation until the average measured size of the mixture was in statistical agreement with the calculated average size of particles in the mixture. While we demonstrate this metric by improving AF⁴V_x protocols, it can be applied to any given separation parameters for separation techniques that employ dynamic light scattering detectors.     

光化学催化动力学共振光散射法测定痕量铜

在高压汞灯照射下的H2SO4介质中,铜能强烈催化异丙醇还原钼酸铵生成钼同多蓝的光化学反应,生成的钼同多蓝在表面活性剂聚乙烯醇(PVA)存在下与罗丹明B能形成稳定的红紫色缔合物,导致共振瑞利散射峰(RRS)显著增强.据此建立了光化学催化动力学共振光散射法测定痕量铜的新方法.铜离子质量浓度在0.002～0.40 μg/mL范围内与RRS增强强度成良好的线性关系,方法的检出限为1.2 ng/mL.本方法具有高灵敏度和好的选择性,用于测定自来水和河水中的铜.     

刚果红共振光散射法测定蛋白质

本文研究了生物染料刚果红(Congo red)与人血清白蛋白(HSA)作用的共振光散射光谱,pH为4．35的溶液中,刚果红与人血清白蛋白作用导致在575m处共振光散射明显增强,且共振光散射信号值与蛋白质的浓度具有线性关系。     

Determination of deoxyribonucleic acids by a resonance light scattering technique and its application

For the first time, acetamiprid has been used to determine nucleic acid (DNA) using the resonance light scattering (RLS). The RLS of acetamiprid was greatly enhanced by DNA in the range of pH 1.6-1.8. A RLS peak at 313 nm was found, and the enhanced intensity of RLS at this wavelength was proportional to the concentration of DNA. The linear range of the calibration curve was 0-11.0 microg ml(-1) with the detection limit of 20 ng ml(-1). The nucleic acids in synthetic sample and in rice seedling extraction were determined satisfactorily. The interaction mechanism of acetamiprid and DNA is discussed. Mechanism studies show that the enhanced RLS is due to the aggregation of acetamiprid in the presence of DNA.     

Kinetics of hydrate formation using gas bubble suspended in water

An innovative experimental technique, which was devised to study the effects of temperature and pressure on the rate of hydrate formation at the surface of a gas bubble suspended in a stagnant water phase, was adapted in this work. Under such conditions, the hydrate-growth process is free from dynamic mass transfer factors. The rate of hydrate formation of methane and carbon dioxide has been systematically studied. The measured hydrate-growth data were correlated by using the molar Gibbs free energy as driving force. In the course of the experiments, some interesting surface phenomena were observed.     

结晶紫探针瑞利光散射技术测定安乃近

在弱碱性条件下,结晶紫与安乃近相互作用后,导致瑞利光散射增强,建立了一种简便、快速、灵敏及选择性好的测定安乃近的分析方法。在390 nm处的ΔIRLS最大,增强的瑞利散射光与0.06~0.40 mg·L-1范围的安乃近呈良好的线性关系,方法的检出限(3Sb/S)为0.017mg·L-1。该法用于市售安乃近药物中安乃近含量的测定,结果满意。     

Determination of lead in environmental water by a backward light scattering technique

An optical fiber assembly developed in our laboratory, which is based on detecting backward light scattering (BLS) signals, is now applied to detect the lead content in environmental samples. Due to effectively eliminating the interference of reflected light, this BLS signals based detection assembly can be used to determine analyte directly. In HAc-NaAc buffer medium (pH 4.8), the interaction of lead and sodium tetraphenylboron (TPB) in the presence of polyethylene glycol (PEG) yields large particles of ternary complex, resulting in strong enhanced backward light scattering (BLS) signals characterized at 371 nm. By measuring the BLS signals with the homemade optical fiber assembly coupled with a common spectrofluorometer, we found that the enhanced BLS intensity is proportional to lead content over the range of 0.03-1.0 μg ml⁻¹ with the limit of determination (LOD) of 2.6 ng ml⁻¹. Three artificial water samples containing various coexistent substances were detected with the recovery of 90.1-107.5%. Standard addition method was used to detect the lead content in drink tap water, and found that the lead is hardly to detect due to too low content. Prior enrichment should be made in order to detect river water samples, and it was found that the content of lead in Jialing River at Bebei Dock is about 14 ng ml⁻¹, identical to the results using inductively coupled plasma atomic emission spectrometry (ICP-AES).     

Another way to view the chain conformation broadening of the line-width distribution measured in dynamic light scattering

In dynamic laser light scattering (LLS), for a given polydisperse sample, a line-width distribution G(Γ) or the translational diffusion coefficient distribution G(D) can be obtained from the measured time correlation function. For rigid colloid particles, G(Γ) can be directly related to the hydrodynamic size distribution. However, for flexible polymer chains, G(Γ) depends not only on the chain length distribution, but also on the relaxation of the chain conformation; that is, even for a monodisperse polymer sample there still exists a chain conformation distribution. If the time scale of the chain conformation relaxation is comparable to that of the translational diffusion, such as in the case of a very long polymer chain, the conformation relaxation might lead to an additional broadening in G (Γ). This "conformation broadening" has been directly observed for the first time by comparing two G(Γ) s obtained from a poly(N-isopropyl-acrylamide) solution at～25℃ and～32℃ at which the solution is ther     

Interactions of norfloxacin with DNA and determination of DNA at nanogram levels based on the measurement of enhanced resonance light scattering

A novel assay of DNA at nanogram levels is presented that is based on the measurement of resonance light scattering (RLS) signals in the presence of norfloxacin. The characteristics of RLS spectra, the effective factors and the optimum conditions of the reaction have been investigated. In Britton-Robinson buffer (pH 5.87), norfloxacin has a maximum peak at 405.5 nm and the RLS intensity is greatly enhanced by trace amounts of DNA due to the interaction between norfloxacin and DNA. Mechanistic studies show that the binding of norfloxacin to DNA forms large particles, which result in the significant enhancement of RLS intensity. The enhanced intensity of RLS is proportional to the concentration of DNA in the range from 0.01–2.0 μg mL⁻¹ for yeast DNA, and from 0.02 to 2.3 μg mL⁻¹ for calf thymus DNA. The determination limit (3σ) is 0.7 ng mL⁻¹ for yeast DNA and 1.2 ng mL⁻¹ for calf thymus DNA, respectively. Synthetic samples were determined satisfactorily.     

Contribution to polymer nanoparticles analysis by laser light scattering

The applications of laser light scattering (LLS) to polymer physics and colloid science have been extensive and noteworthy, especially in particle-size analysis. The study presents an example of LLS application to the characterization of interpolymer complexation of poly(aspartic acid) with a vinylic polymer, by particle size and zeta potential evaluation. The LLS technique is complemented by oscillatory rheological data. The complexes have a potential biomedical application by bioactive substances attachment.     

Dynamic light scattering and small-angle neutron scattering studies on organogels formed with a gelator

Small-angle neutron scattering (SANS) and light scattering studies were carried out on an organogel consisting of a gelator, coded P-1, and dimethyl sulfoxide (DMSO). The gelator was made of an oligosiloxane stem and about eight branches of an amino acid derivative combined with a long alkyl chain. The amino acid part, N-n-pentanoyl-L -isoleucylaminooctadecane, was responsible for intermolecular association via hydrogen bonding between amide groups. After the complete dissolution of P-1 in DMSO at 85 °C, the solution was cooled, and the variations of the scattered light intensity were monitored as a function of the temperature. The scattered intensity increased drastically at about 40 °C when the P-1 concentration (C) was 3.5 g/L, and this indicated gel formation. The SANS results showed that the scattering intensity function was a monotonically decreasing function, regardless of C. A master relationship of the scattering intensity was obtained with respect to C. These scattering studies disclosed the following facts. First, gelation could be monitored as an abrupt increase in the intensity. Second, the gel was composed of randomly oriented bundlelike clusters. Third, the structure factor could be reduced by the gelator concentration, and this indicated the presence of a self-similar structure across the gelation threshold. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1841–1848, 2004     

维多利亚蓝B瑞利光散射技术测定阿魏酸

基于阿魏酸与维多利亚蓝B在中性介质中形成离子缔合物,导致瑞利光散射增强,建立了一种测定阿魏酸的分析方法。研究了离子缔合物反应的适宜条件,结果表明:在优化的条件下,阿魏酸浓度在5.60×10-7~1.34×10-5mol/L范围内与瑞利散射光的增强呈良好的线性关系,方法的检出限为3.26×10-7mol/L。已用于实际样品中阿魏酸的测定。