STRUCTURE OF WATER, PROTEINS, AND LIPIDS IN INTACT HUMAN SKIN, HAIR, AND NAIL

Raman spectroscopy is a nondestructive analytical method for determini ng the structure and conformation of molecular compounds. It does not require sample preparation or pretreatment, Recently, near-infrared Fo urier transform Raman spectroscopy has emerged as being specially suit ed for investigations of biologic material, In this study, we obtained near-infrared Fourier transform Raman spectra of intact human skin, h air, nail, and stratum corneum, We disclosed major spectral difference s in conformational behavior of lipids and proteins between normal ski n, hair, and nail, The amide I and III band location indicated that th e majority of proteins in all samples have the same secondary alpha-he lix structure, Positions of (S-S) stretching bands of proteins reveale d a higher stability of the disulfide bonds in the hair and the nail, Analysis of vibrations of protein -CH groups showed that in the hair a nd the nail the proteins are apparently highly folded, interacting wit h the surroundings only to a small degree, The position of lipid speci fic peaks in spectra of hair, nail, and stratum corneum suggested a hi ghly ordered, lamellar crystalline lipid structure, A greater lipid fl uidity was found in whole skin, Assessment of the structure of water c lusters revealed that mainly bound water is present in the human skin, stratum corneum, and nail, In conclusion, structural changes of water , proteins, and lipids in intact skin and skin appendages may be analy zed by Raman spectroscopy, This technique may be used in the future in a noninvasive analysis of structural changes in molecular compounds i n the skin, hair, and nail associated with different dermatologic dise ases.