Developing Spectral Diffusion as a Nonlinear Optical Measurement of Interfacial Water.

Vibrational Spectroscopy;Ultrafast;Water Dynamice;Chemistry;Science;Biophysics

Osborne, Derek GlennVeatch, Sarah ;

University of Michigan

关键词: Vibrational Spectroscopy;    Ultrafast;    Water Dynamice;    Chemistry;    Science;    Biophysics;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/97877/dozzy_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Biological macromolecules have the ability to distort the hydrogen bonding network and orientational dynamics of their interfacial water. Experiments capable of measuring the dynamics of interfacial water are limited because measurements must have both ultrafast temporal resolution and site specific capabilities. To make significant progress in exploring the interfacial orientational dynamics of both hydration water and the biomolecules it solvates, we need new chemical probes as well as ultrafast, multidimensional optical techniques that we can interpret in terms of fundamental molecular dynamics. Here, we present a novel protocol to site specifically label a lipid membrane with a metal carbonyl that is sensitive to the orientational dynamics of the interfacial water by synthesizing a cholesterol group labeled with a chromium tricarbonyl motif which is then embedded in the lipid membrane. In this work we characterize the labeled cholesterol group with mass spectrometry and the location of the chromium tricarbonyl motif in the lipid membrane with multiple FTIR methods. In this work, we also develop new experimental approaches to accelerate the measurement of the key spectral diffusion observable of interest that can be linked to fast molecular motion in bulk, nanoconfined, and interfacial contexts to increase experimental throughput and ensure robust experimental trends. Additionally, using the compressed sensing data processing technique we demonstrate that the data acquisition of other ultrafast vibrational observables, such as chemical exchange and intramolecular vibrational energy redistribution, can be greatly accelerated. To test the robustness of these methods, we compare the measurements of these methods to those of established methods. Lastly, we confine a simple metal carbonyl in a β-cyclodextrin to calibrate how nanoconfinement will effect the spectral diffusion observable and found spectral diffusion to be dependent on the number of solvating alcohol molecules. We use both molecular dynamics and Monte Carlo simulations to isolate and confirm that the number of solvating molecules is indeed altering the spectral diffusion observable.