ИСТИНА

Appearance and quality of hair depend on the conformation of structural proteins – keratins. Under the influence of UV spectral part of the solar light, hair become pale and lose mechanical strength. It is known that the UV irradiation causes cleavage of inter- and intramolecular disulfide bonds. In this work, we employ confocal Raman microspectroscopy to evaluate the effect of UV radiation on S-S and C-S bonds in the vicinity of hair surface and in the central part of hair (medulla). We study the slices of silver hair from one healthy donor. Hair diameter is about 50 mkm. The samples are divided into two parts. One of them is used as a control. The other one is irradiated with the help of an IPL-K150 UV lamp during 2 hours. The wavelength of the most high-frequency emission band of the lamp is about 250 nm. To measure Raman spectra, we use a Thermo Scientific Raman DXR confocal microscope. The spectra are processed as described in. Raman microspectroscopy is an efficient tool in the study of the structure of various biological objects. Raman spectra of proteins exhibit several conformation-sensitive bands: amide I (1640 cm-1), amide III (1270 cm-1), tyrosine doublet (830 and 855 cm-1), bands of the disulfide bridges (510, 525, and 540 cm-1), and several bands assigned to the vibrations of tryptophan residues (e.g., 1361 cm-1). It is shown that UV irradiation of hair leads to a decrease in the number of S-S and C-S bonds and the corresponding increase in the number of S-H bonds. In addition, the content of S-S bonds in the external part of irradiated hair is less than the content in the central part. This work is supported in part by Lomonosov Moscow State University Program of Development.