Vibrational Nanospectroscopy of Biosubstrate Surfaces and Molecular Films

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The project entails the imaging and spectroscopy of a variety of biologically/commercially relevant substrates before and after treatment with model chemical treatments relevant to hair and personal care products. These are to include treated and untreated hair and skin models, both as real substrates such as microtomed hair cross sections and model systems. The model systems to be investigated comprise but will not be limited to biolipid membranes (both as monolayers and as bilayers) composed primarily of DPPC and DPPE, which will be investigated as model lipid membrane systems relevant to both the personal care field and as fundamental academic studies.Imaging will be carried out on the departmental Nano-IR2 instrument comprising of an atomic force microscope with associated mid IR laser (AFM-IR) for sub diffraction limited spectroscopy and spectral mapping with additional spectral mapping carried out on a confocal Raman microscope. Mapping studies aim to elucidate the localisation of different surface chemistries both on the large scale, circa 1 micron and also at the nanoscale at circa 40nm. The structure and conformational ordering of the films is to be determined through the use of Sum Frequency Generation spectroscopy (SFG) with the ancillary usage of polarization modulation reflection adsorption spectroscopy (PMIRRAS) and attenuated total internal reflectance (ATR) spectroscopy. Further development of the ATR investigation is planned via the use of polarization modulated ATR in order to minimise the contribution from the liquid phase when studying hydrated lipid bilayer systems.