Bailey Karen A, Schultz Zachary D
Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States.
J Phys Chem B. 2016 Jul 14;120(27):6819-28. doi: 10.1021/acs.jpcb.6b04304. Epub 2016 Jun 28.
Multiplex coherent anti-Stokes Raman scattering correlation spectroscopy (CARS-CS) is shown as a label-free, chemically specific approach for monitoring the molecular mobility of particles in solution and at interfaces on the millisecond time scale. The CARS spectral range afforded by broadband excitation facilitates a quantitative measurement for the number of particles in the focal volume, whereas the autocorrelation of spectral data elucidates dynamic events, such as diffusion. The measured diffusion coefficients for polymer beads ranging from 100 nm to 1.1 μm in diameter are on the order of 10(-8)-10(-9) cm(2)/s, in good agreement with predicted Stokes-Einstein values. Diffusion at different interfaces shows particles are fastest in bulk medium, marginally slower at the liquid/glass interface, and 1.5-2 times slower rate at the air/liquid interface. Multivariate curve resolution analysis of distinct spectral features in multiplex CARS measurement distinguishes different composition lipid vesicles in a mixture diffusing through the focal volume. The observed diffusion is consistent with results obtained from single particle tracking experiments. This work demonstrates the utility of multiplex CARS correlation spectroscopy for monitoring particle diffusion from different chemical species across diverse interfaces.
多路相干反斯托克斯拉曼散射相关光谱法（CARS-CS）是一种无标记、具有化学特异性的方法，用于在毫秒时间尺度上监测溶液中和界面处粒子的分子迁移率。宽带激发提供的CARS光谱范围有助于对焦体积内的粒子数量进行定量测量，而光谱数据的自相关则阐明了诸如扩散等动态事件。直径从100 nm到1.1 μm的聚合物珠的测量扩散系数约为10^(-8)-10^(-9) cm^(2)/s，与预测的斯托克斯-爱因斯坦值高度吻合。在不同界面处的扩散表明，粒子在本体介质中最快，在液/玻璃界面处稍慢，在气/液界面处速率慢1.5-2倍。多路CARS测量中不同光谱特征的多元曲线分辨分析可区分混合溶液中通过焦体积扩散的不同组成的脂质囊泡。观察到的扩散与单粒子跟踪实验获得的结果一致。这项工作证明了多路CARS相关光谱法在监测不同化学物种在不同界面处的粒子扩散方面的实用性。
