pH协同血清白蛋白对单个活态人红细胞作用的拉曼光谱研究

红细胞是维持生命最重要的细胞之一,pH是影响其结构功能的重要因素。 结合人血液中存在血清白蛋白,且可能会对红细胞起作用的特点,在模拟人体内血液中血清白蛋白与血红蛋白摩尔比值的条件下,研究pH协同血清白蛋白对单个活态人红细胞的形态,细胞膜变形能力及胞内血红蛋白结构变化的影响。 结果显示,不同pH下,红细胞的表面形态、 膜变形能力的变化规律与其胞内血红蛋白结构的变化有关：在pH 4.14,4.76,10.18时,红细胞胞内血红蛋白螺旋结构的减少、 疏水性氨基酸的暴露,血红素珠蛋白结合状态的改变,影响了血红蛋白结构的稳定性,从而导致红细胞的结构发生变化,其形态、 膜变形能力与正常值相比,变化结果显著。 而在pH 6.51和7.80下,血红蛋白的拉曼谱结果并未发现有上述变化情况,胞内血红蛋白的结构没有发生改变,红细胞的形态、 膜变形能力也接近于正常值。 在pH 5.49和8.76下,红细胞的表面形态和膜变形能力都有不同程度的变差,但其胞内血红蛋白的结构并没有改变,提示红细胞的形态和变形能力的改变可能是可逆的。 结果表明,pH协同血清白蛋白的作用下,血清白蛋白能对红细胞起保护作用,增强红细胞调节、 缓冲环境pH变化的能力。 研究结果全面地揭示了在模拟人体内血液中血清白蛋白与血红蛋白摩尔比值的情况下,红细胞结构功能的变化情况,不仅有助于阐明红细胞在有关生理、 病理状态下的结构与功能的变化,而且对其临床表现与有关防治对策都有重要的指导意义。     

非正常形态红细胞对拉曼光谱判别的影响

血红细胞对环境敏感,细胞形态很容易发生改变,皱缩甚至形成棘形。文章应用光镊拉曼光谱技术俘获、收集来自健康个体和地中海贫血患者的正常形态、一般皱缩和棘形红细胞的拉曼光谱,从平均光谱、主成分分析等方法分析不同形态红细胞的光谱差异与胞内Hb的变化,及其对光谱诊断分析的影响。结果发现,在正常的生理环境下,红细胞发生皱缩甚至形成棘形细胞并不影响光谱判别分析。     

血液的超声研究

对血液超声性质的研究,超声生物物理学界和医学界一直表现出极大的兴趣。本文研究表明:红细胞压缩性与其血红蛋白质含量成反比。在血液的由细胞级结构引起的超声衰减中,红细胞超声吸收的贡献为主,红细胞相对血浆运动的粘滞损耗小于15%,而红细胞超声散射损耗则可略而不计。血液凝固状态的变化伴有超声参量的明显改变,用超声技术检测血液凝固比传统的粘滞法有较大的优越性。血液凝固使其超声衰减增大,但衰减的频率关系无明显变化。血液凝固使其超声背向散射和非线性参量B/A值明显增大。这些研究结果对发展超声医学具有十分重要的现实意义。     

离体血红细胞的活性衰变规律研究

采用光镊技术研究了离体血红细胞的动力学过程即细胞活性的变化规律。当光镊中的半导体激光器发出的高斯光束照射红细胞使其发生形变并反转,待细胞保持动态平衡后切断激光光路,得到形变血红细胞的自由回复时间,该时间长短与细胞活性相关联。通过对比被小功率He-Ne激光器持续照射和正常离体血液的活性衰变规律,结果表明,细胞活性均呈现出规律性的变化,波动之后逐渐减弱并最终趋向死亡。被激光持续照射的红细胞活性衰变较缓,即激光照射的作用延缓了红细胞的衰弱。研究结果能为细胞的活性和动力学分析提供参考,为血液疾病的临床检测和激光临床治疗提供帮助。     

基于血红细胞特征体积模型匹配的慢速血流检测

针对微血管中血流速度慢、血红细胞数量少的特点,采用同步移相显微干涉术实时测量血红细胞的相位,建立血红细胞特征体积模型,对多帧相位图进行特征血红细胞匹配,以实现慢速血流检测。利用牛红细胞阿氏液制备了流速在0.1～1.0 mm/s内可控,内径为100μm的微血管模型,搭建了基于微偏振阵列的同步移相显微干涉实验装置,通过实验验证了所提慢速血流检测方法的可行性,血流速度的测量误差不超过±11.2%。     

基于同步移相显微干涉的血红细胞形貌测量方法

血红细胞的形貌特征是医学领域对多种疾病进行预防和诊断的一项重要指标,提出一种同步移相显微干涉法实现对血红细胞形貌的动态测量。搭建了透射式显微干涉成像系统,测量了100 μm内径模拟微血管内、名义直径为7 μm～8 μm、高度最大值为2 μm的新西兰兔血红细胞,针对血红细胞所处的微血管环境提出了基于微血管相位相减的血红细胞形貌提取方法和成像放大率校正方法,实验得到模拟微血管内的血红细胞平均直径7.757 μm和平均最高高度2.022 μm,验证了本方法具有在体定量测量血红细胞形貌的潜力。     

一种基于异硫氰酸荧光素的pH纳米传感器制备

无创且实时检测微观环境的pH变化在医疗等领域具有重要的研究价值,本文通过灵活简单的共沉淀方法制备了一种基于pH敏感分子异硫氰酸荧光素(FITC)的荧光pH纳米传感器,FITC的荧光强度随pH值增加发生明显变化,当pH值从3变至9时,荧光强度增大约38倍,基于FITC荧光强度变化可实现对pH的灵敏检测,pKa值为6.07。该荧光pH纳米传感器具有小粒径、高灵敏度、良好的可逆性和生物相容性,在细胞等微环境pH检测方面将具有良好的应用前景。     

人血红细胞傅里叶变换红外和近红外拉曼光谱

通过人血红细胞傅里叶变换近红外拉曼光谱和红外光谱研究,基本上确定了人血红细胞中特征官能团的归属, 发现不同拉曼频移的拉曼信号强度随激发光功率呈非线性变化规律。近红外激光拉曼光谱结合红外光谱信息,可作为研究人血红细胞结构的有效测试手段。     

新型快速显微多道分光光度技术对血红蛋白的光谱分析

用新型快速显微多道分光光度(MMSP)技术,在生理环境(pH、温度、氧分压和渗透压)改变下,对单个活态人血红细胞内血红蛋白分子的吸收光谱进行监测。发现生理环境的改变,引起血红蛋白吸收光谱曲线540,575 nm特征吸收峰的峰高、峰位和峰形发生了不同程度的变化。MMSP技术提示血红蛋白分子的结构、浓度和功能与上述生理环境密切相关。     

咪唑类氮氧自由基的ESR波谱的酸度相关性─pH自旋探针应用研究之一(英文)

根据咪唑类氮氧自由基的结构特性合成了一系列的pH自旅探针,其ESR波谱参数均在一定范围内与介质的酸性呈明显的相关性．可望为较精确地测量化学胶束、细胞等微观体系的pH值开辟一个新的途径．本文研究了灵敏变化的pH范围与取代基的关系,得到了5种自旅探针的ESR参数-pH曲线、pKa值以及Hanmmett相关图,分析了如何通过改变取代基合成出不同pH变化范围并适用于不同生物和化学体系的pH自旅探针,最终达到付诸应用的目的．     

Study of optical and nanostructural metal-induced changes in erythrocyte membranes by scattering and atomic force microscopy

The surface topography of erythrocyte membranes is studied by atomic force microscopy. Differences in fine structure of membranes are found. The structure of profiles of erythrocyte membranes modified by metals is smoother compared to unmodified erythrocytes. The autocorrelation function of irregularity pro-files of erythrocyte membranes and its parameter (the correlation length) are informative parameters of the action of toxic metals on the erythrocyte membrane surface. The content of metal in an erythrocyte membrane is determined from optical investigations of a suspension of membranes subjected to the action of lead and zinc ions. It is revealed that the luminescence of erythrocyte membranes is enhanced compared to reference data. The absorption spectra of erythrocyte membranes in the range 325–740 nm are calculated from the diffuse transmission and reflection coefficients of samples taking into account their luminescence. The possibility of determining the content of metals in erythrocyte membranes from optical measurements is demonstrated.     

Analysis of Anionic Polymer Dispersant Behavior in Dense Silicon Nitride and Carbide Suspensions Using an AFM

The paper focuses on the interaction mechanism caused by anionic polymer dispersants in dense silicon nitride and silicon carbide suspensions. An atomic force microscope (AFM) was used to determine the relationship between the macroscopic suspension viscosity and the microscopic structure adsorbing of a polymer dispersant at the solid/liquid interface. The surface interactions within the suspensions were analyzed under various dispersant pH values and additive conditions. The addition of an anionic polymer dispersant decreased the viscosity of silicon nitride and silicon carbide suspension and increased the electrosteric repulsive force on the non-oxide surface in solution at pH > 6, which was the isoelectric point of the materials. Based on the above results, we estimated the adsorption mechanism of anionic polymer dispersants on each solid surface in solution under relatively high pH conditions.     

Electroporative Adjustment of pH in Living Yeast Cells: Ratiometric Fluorescence pH Imaging

A number of vital cell functions including modulation of signaling pathways and regulation of the cellular transport critically depends on the cytoplasmic pH. Many pathological cellular changes are related to the abnormal cytosolic pH as well. Reliable and well-calibrated methods for quantification of the cytosolic pH are therefore of high importance. The pH calibration is particularly difficult in walled cells since standard methods fail. In this report we evaluated the new electroporative calibration method of the cytosolic pH in yeasts by the fluorescence microscopy. The calibration was done on living cells using pyranine as a ratiometric pH-sensitive probe. The probe was electroporatively delivered to the cytosol. We have shown that unlike the measurements in suspension the fluorescence microscopy reveals cell subpopulations with different sensitivity to the pH calibration. While the majority of the cells were well calibrated, there was found subpopulation of uncalibrated cell as well as singular cells exhibiting anomalous pH calibration due to the staining of acidic organelles. Resolution of cell subpopulations helps to achieve better pH calibration compared to the calibration in cuvette on a cell suspension.     

用时间分辨光谱研究红细胞悬液的荧光发射

实验获得了激光照射红细胞悬液的荧光光谱,并分别监测不同荧光峰值波长处强度随时间的衰变过程,测试了其相应的荧光寿命。结果表明,在波长为407nm的激光照射下,红细胞悬液向外发射中心波长分别位于596,628,692nm的荧光光谱,各荧光峰对应衰变过程的平均荧光寿命分别为1.97,13.31,14.58ns。利用荧光强度和吸收率的加和性表示了混合物的总吸收率和总荧光发射强度,通过理论计算获得了红细胞悬液中锌卟啉、原卟啉和其他游离物参与荧光发射的相对含量和相对强度在不同荧光峰位的变化关系,进一步解释了不同峰位处荧光发射强度和平均荧光寿命的变化原因。     

Effect of the External Refractive Index on Fluorescence Kinetics of Perylene in Human Erythrocyte Ghosts

Fluorescence kinetics of perylene molecules in hemoglobin-free human erythrocyte membranes is investigated as a function of the refractive index of the external medium varied by adjusting the concentration of sorbitol or sucrose in an aqueous suspension of erythrocyte ghosts. It has been found that the fluorescence of perylene in erythrocyte ghosts decays nonexponentially, with the mean decay time decreasing from 7.13 to 5.70 ns with an increase in the refractive index of the suspension from 1.333 to 1.442. An analysis of the dependence made it possible to obtain an estimate of the second-rank orientational order parameter of perylene in the human erythrocyte membrane «P ₂ (cos)» = 0.32 ... 0.43, which bears witness of considerable ordering of perylene molecules along acyl chains of phospholipids constituting the membrane. Good correspondence of the order parameter with the value of the steady-state emission anisoptropy of perylene in erythrocyte ghosts suggests that acyl chains of phospholipids in the human erythrocyte membrane are predominantly oriented along the normal to its surface.     

Investigation of erythrocyte membrane damage under the action of γ radiation in a wide dose range using electroporation

Human erythrocyte membrane damage under the impact of γ radiation on blood suspension is studied in a wide dose range (2–1000 Gy, irradiation dose rate 2.75 Gy/min). It is shown that the irradiation in the absorbed dose range from 600 Gy and higher results in hemolysis of erythrocytes immediately (or within several hours) after irradiation, and the value of the hemolysis rate constant increases with increasing absorbed dose. For finding hidden membrane damage occurring several hours after irradiation with smaller doses, the suspension was affected by a high voltage pulsed electric field (PEF). It is shown that, for an absorbed dose range from 2 to ～350 Gy, no noticeable increase in the erythrocyte hemolysis rate was observed after the action of PEF on the suspension, as compared to the nonirradiated suspension. This testifies that, in this dose range, the degree of membrane damage is small and practically independent of absorbed dose value. For doses from 400 to ～550 Gy, a noticeable increase in the hemolysis rate after the action of PEF growing with increasing absorbed dose was observed.     

磁性ICF靶丸的化学镀工艺制备与表征

 采用化学镀工艺在ICF聚苯乙烯靶丸表面包覆了一层磁性的Ni-P合金镀层，并分别用扫描电子显微镜、能谱仪、X射线衍射仪以及振动样品磁强计对其形貌、组成、结构和磁性能进行了表征。结果表明：通过化学镀工艺制备的Ni-P合金镀层厚度约为4 μm，且为非晶结构，并具有一定的磁性；该磁性ICF靶丸可望用来进行磁悬浮实验研究。最后，对聚苯乙烯靶丸表面磁性涂层的制备机理进行了讨论。     

Electrodeposited cobalt films: hcp versus fcc nanostructuring and magnetic properties

The crystallographic structure and morphology of electrodeposited cobalt films on Au(111) is found to be very sensitive on the electrolyte pH value and on the overpotential applied during deposition. The samples, 2 to 500 nm thick, where characterized by nuclear magnetic resonance (NMR), atomic force microscopy (AFM) and electron diffraction. The latter technique shows that the Co films grow in registry with the gold underlayer, reproducing the Au(111) texture. During the first stage of growth and depending on overpotential and pH value, either continuous hcp Co films or hcp Co islands are formed. Only the latter growth mode leads to an out of plane magnetization with 100% of remanence. Increasing the thickness, fcc Co becomes the prevailing phase. Eventually the fcc to hcp ratio saturates at the same value regardless the overpotential. The thickness for which the equilibrium fcc to hcp ratio is obtained as well as the sample structure and morphology before saturation, depend strongly on the overpotential value. In any case, the predominance of the fcc Co phase leads to an in plane magnetization of the thick samples. This study opens up new opportunities of engineering the properties of electrodeposited cobalt films. Received 29 February 2000 and Received in final form 3 July 2000     

Determination of Particle Size Distribution by Laser Diffraction of Doped‐CeO2 Powder Suspensions: Effect of Suspension Stability and Sonication

The particle size distributions (PSDs) of metal oxide powders are often determined by analyzing suspensions of powders using laser diffraction (e.g. Malvern MasterSizer 2000). Particle agglomeration can effectively bias the resulting distribution towards “unrealistic” particle sizes. Solutions to avoid this problem must be found if a particle distribution based on the elemental or primary particle sizes is desired. In this work, the particle size distribution of doped‐CeO₂ powders was studied. These powders show a crystalline single phase structure of controlled stoichiometry as determined by X‐ray diffraction and ICP analysis. The apparent size distribution was found to be a strong function of suspension stability. Dispersant agents (PBTCA and phosphonoacetic acid) and suspension pH affected stability as characterized by zeta potential measurements. Sonication of the suspensions further enhanced particle de‐agglomeration. Finally, only the combined effect of a dispersant agent, pH adjustment of the suspension and sonication provided a primary particle size distribution. The results presented in this work can be used in the analysis of similar ceramic powders in which strong particle agglomeration is present.