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Scientists in Japan have developed a Raman spectroscopy technique that allows them to investigate the internal structure of even very dark hair for the first time. The work could have implications for understanding how hair changes as we grow older and may even have medical diagnostics applications. Understanding how hair changes as we grow older is not only useful from the cosmetic perspective but may also help medical science discover new diagnostic techniques for health problems that are a mere snip. However, revealing the internal structure of a shaft of very dark, or black hair is difficult because of the presence of confoundingly high levels of melanin pigment granules. These granules interfere with the keratin, hair protein, signals in the spectra. Now, Akio Kuzuhara and Nobuki Fujiwara of the Mandom Corporation, in Osaka, and Teruo Hori of Fukui University, Japan, have used Raman spectroscopy to investigate the differences in black hair from two groups of Japanese women, one group in their twenties, the other in their fifties. The team used samples of "virgin" hair, fresh from the follicle and allowed to grow just two millimetres from the scalp, before cutting for the study. "The key points of this method," explain the researchers, "are to cross-section hair samples to a thickness of 1.50 micrometres, to select points at various depths of the cortex with the fewest possible melanin granules." In addition, they "optimize laser power, cross slit width as well as total acquisition time," to obtain the clearest spectra. The researchers found that the reproducibility of the Raman bands, namely the alpha-helix content, the beta-sheet and/or random coil (beta/R) content, the disulfide (--SS--) content, and random coil content of two adjoining cross-sections of a single hair keratin fibre was "clearly good". Their results showed that disulfide content was much lower for Japanese females in their fifties than in their twenties. However, the alpha-helix and beta-sheet content did not change. In other words, the protein structures found in the hair remained stable despite aging whereas the disulfide bridges that bind individual fibres together within the hair were less common, presumably leading to more brittle hair and "split ends" among the older women. Related links:
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Raman close crops hair structure
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