Tryptophan fluorescence in hair-examination of contributing factors.

Various types of hair, including white (unpigmented), Piedmont (yellow-colored), blonde, brown, curly black of African origin, straight black of Chinese origin, and chemically processed (bleached) hair, were studied by using fluorescence spectroscopy. Fluorescence measurements were obtained by using a single- or double-grating fluorescence spectrophotometer and a bifurcated fiber optics accessory to measure the spectra directly from the surface of the hair. The results have shown that all types of hair share similar fluorescence characteristics, as recorded by excitation at 290 nm, 320 nm, 350 nm, and 380 nm, with emissions that could be ascribed to chromophores such as tryptophan (Trp), N-formylkynurenine, kynurenine, and 3-hydroxykynurenine.

Measurements of hair volume by laser stereometry.

A three-dimensional laser stereometer was constructed utilizing an x-y two-dimensional translational stage and a laser device, which provides distance information in the z-direction. The distance data is obtained by triangulation of the reflecting red laser beam from the surface of the measured object, in this case hair. Since hair fiber assemblies do not have a continuous solid surface, each z-dimension reading is obtained as an average of measurements obtained from multiple reflections corresponding to fibers at various depths below the outermost hair surface.

Alteration of skin mechanics by thin polymer films.

Background/purpose: High molecular weight polymers such as proteins and polysaccharides have been commonly employed in cosmetic practice to induce skin tightness. The effect is perceived by users as an increase in skin tightness (firmness) accompanied by skin smoothing and elimination of wrinkles and lines. The aim of the study was to assess whether high molecular weight synthetic polymers, in the form of simple skin treatment formulations, could modify mechanical properties of natural skin as well as artificial skin models.