Prüger B, Eppmann P, Donath E, Gimsa J
Institute of Biology, Humboldt University, Berlin, Germany.
Biophys J. 1997 Mar;72(3):1414-24. doi: 10.1016/S0006-3495(97)78788-5.
Common dynamic light scattering (DLS) methods determine the size and zeta-potential of particles by analyzing the motion resulting from thermal noise or electrophoretic force. Dielectric particle spectroscopy by common microscopic electrorotation (ER) measures the frequency dependence of field-induced rotation of single particles to analyze their inherent dielectric structure. We propose a new technique, electrorotational light scattering (ERLS). It measures ER in a particle ensemble by a homodyne DLS setup. ER-induced particle rotation is extracted from the initial decorrelation of the intensity autocorrelation function (ACF) by a simple optical particle model. Human red blood cells were used as test particles, and changes of the characteristic frequency of membrane dispersion induced by the ionophore nystatin were monitored by ERLS. For untreated control cells, a rotation frequency of 2 s-1 was induced at the membrane peak frequency of 150 kHz and a field strength of 12 kV/m. This rotation led to a decorrelation of the ACF about 10 times steeper than that of the field free control. For deduction of ERLS frequency spectra, different criteria are discussed. Particle shape and additional field-induced motions like dielectrophoresis and particle-particle attraction do not significantly influence the criteria. For nystatin-treated cells, recalculation of dielectric cell properties revealed an ionophore-induced decrease in the internal conductivity. Although the absolute rotation speed and the rotation sense are not yet directly accessible, ERLS eliminates the tedious microscopic measurements. It offers computerized, statistically significant measurements of dielectric particle properties that are especially suitable for nonbiological applications, e.g., the study of colloidal particles.
常见的动态光散射（DLS）方法通过分析热噪声或电泳力引起的运动来确定颗粒的大小和zeta电位。通过普通显微镜电旋转（ER）进行的介电颗粒光谱法测量单个颗粒场诱导旋转的频率依赖性，以分析其固有介电结构。我们提出了一种新技术，即电旋转光散射（ERLS）。它通过零差DLS装置测量颗粒集合中的ER。通过简单的光学颗粒模型从强度自相关函数（ACF）的初始去相关中提取ER诱导的颗粒旋转。人红细胞用作测试颗粒，通过ERLS监测离子载体制霉菌素诱导的膜色散特征频率的变化。对于未处理的对照细胞，在150 kHz的膜峰频率和12 kV/m的场强下诱导出2 s-1的旋转频率。这种旋转导致ACF的去相关比无场对照陡约10倍。为了推导ERLS频谱，讨论了不同的标准。颗粒形状以及介电泳和颗粒间吸引力等额外的场诱导运动对这些标准没有显著影响。对于制霉菌素处理的细胞，介电细胞特性的重新计算显示离子载体诱导内部电导率降低。虽然绝对旋转速度和旋转方向尚未直接获得，但ERLS消除了繁琐的显微镜测量。它提供了对介电颗粒特性的计算机化、具有统计学意义的测量，特别适用于非生物应用，例如胶体颗粒的研究。
