Polarized Raman microspectroscopy on intact human hair

摘要

Polarization -resolved Raman microspectroscopy with near-infrared laser excitation was applied to intact human hair in order to non-invasively investigate the conformation and orientation of the polypeptide chains. By varying the orientation of the hair shaft relative to the polarization directions of the laser/analyzer, a set of four polarized Raman spectra is obtained: this allows to simultaneously determine both the secondary structure oJ hair proteins and the orientation of the polypeptide strands relative to the axis of the hair shaft. For the amide I band, results from a quantitative analysis of the polarized Raman spectra are compared with theoretically expected values for fibers with uniaxial symmetry. Based on the polarization behavior of the amide I band and further vibrational bands, a partial ordering of α-he-lical polypeptide strands parallel to the hair shaft can be concluded. We suggest that this microspectroscopic ap- proach may be used for human hair diagnostics by de- ing structural or orientalional alterations of keratins.