Noninvasive, in-vivo, near infrared vibrational spectroscopic study of lipid and aqueous phases of skin and near surface tissues

We report the use of near infrared vibrational spectroscopy to noninvasively probe the in-vivo lipid and aqueous phases of skin and near surface tissues under conditions of thermal and chemical modulation. We demonstrate thermally induced order-disorder transitions in lipids that can be directly compared to well known behavior of in-vitro samples of phospholipid bilayers and bulk fatty acids. We show reversible chemical modification of aqueous phase proteins which are also directly comparable to well known phenomena involving in-vitro proteins. The results of these studies demonstrate the capacity for noninvasively probing live human tissues on the molecular level using near infrared vibrational spectroscopy. This capacity suggests numerous potential applications ranging from assessing the efficacy of cosmetics, skin care treatments and transdermal therapeutic agents/treatments to serving as a diagnostic of various skin ailments, e.g. melanoma.