Probing Deuteration-Induced\nPhase Separation in Supported\nLipid Monolayers using Hyperspectral TERS Imaging

In\nthis study, we investigate the impact of deuteration\non the\nformation of phase-separated domains in supported lipid monolayers\nusing hyperspectral Tip-Enhanced Raman Spectroscopy (TERS) imaging.\nThe intricate organization of biological membranes plays a crucial\nrole in cellular functions. Various factors that influence domain\nformation have been identified in previous studies such as lipid tail\nlength and cholesterol concentration. Deuterium labeling of lipids\nhas proven useful for probing cellular structures and dynamics, but\nits impact on lipid phase separation remains underexplored. By examining\n1:1 mixed monolayers of dipalmitoylphosphatidylcholine (DPPC) and\ndeuterated DPPC on Au(111) surfaces, we reveal partial segregation\nof domains rich in deuterated and nondeuterated lipids. This study\naddresses a gap in knowledge by examining the impact of deuteration\non lipid tail behavior, offering new insights into how even subtle\nstructural modifications can influence phase behavior. Furthermore,\nit demonstrates that TERS can be a powerful, nondestructive, and label-free\nnanoanalytical tool for analyzing lipid membranes and advance the\nfield of membrane biophysics.