In vivo Raman spectroscopy of biochemical changes in human skin by cosmetic application

The skin aging process is mainly accelerated by external agents such as sunlight, air humidity and surfactants action. Changes in protein structures and hydration during the aging process are responsible for skin morphological variations. In this work the human skin was investigated by in vivo Raman spectroscopy before and after the topical applications of a cosmetic on 17 healthy volunteers (age 60 to 75). In vivo Raman spectra of the skin were obtained with a Spectrometer SpectraPro- 2500i (Pi-Acton), CCD detector and a 785 nm laser excitation source, collected at the beginning of experiment without cream (T0), after 30 (T30) and 60 (T60) days using the product. The primary changes occurred in the following spectral regions: 935 cm -1 (νCC), 1060 cm -1 (lipids), 1174 to 1201 cm -1 (tryptofan, phenylalanine and tyrosine), 1302 cm -1 (phospholipids), 1520 to 1580 cm -1 (C=C) and 1650 cm -1 (amide I). These findings indicate that skin positive effects were enhanced by a continuous cream application.