Dos Santos Jordana Dias, Edwards Howell G M, de Oliveira Luiz Fernando Cappa
Núcleo de Espectroscopia e Estrutura Molecular, Departamento de Química, Universidade Federal de Juiz de Fora, Campus Universitario s/n, Martelos, Juiz de Fora, MG, 36036-330, Brazil.
School of Life Sciences, University of Bradford, Bradford, West Yorkshire, BD7 1DP, United Kingdom.
Heliyon. 2019 May 7;5(5):e01582. doi: 10.1016/j.heliyon.2019.e01582. eCollection 2019 May.
Human hair fibre is subjected to various structural modifications due to the application of chemicals such as dyes, shampoos and bleaches and/or physical procedures such as heating, and often more than one procedure is performed on the same hair. The present work aims to analyze the changes incurred in hair samples of two ethnic groups, namely Caucasian and Afro, before and after different treatments such as thermal, bleaching and straightening. In addition to observing the damage caused by each treatment separately, the study of samples that received all three treatments was carried out. For molecular structural characterization, the Raman vibrational spectroscopic technique was used and scanning electron microscopy (SEM) was used for morphological analysis of the hair fibres. This investigation has shown, through vibrational spectroscopy, that several important bonds have been modified, such as the S-S, C-S, C-C and S-O bonds as well as the secondary structures of proteins that have indergone changes in their conformation as a result of the treatment. Hair from the two ethnic groups showed small differences in relation to each applied treatment. Excessive heat generated a higher rate of Raman spectral band intensity changes when compared to the other treatments and it was observed that the action of several treatments on the same hair fibres resulted in even more pronounced structural changes. Finally, scanning electron microscopy showed that each treatment caused a different morphological deformation pattern on the capillary surface of the human hair.
由于使用了诸如染料、洗发水和漂白剂等化学物质以及诸如加热等物理过程，人类头发纤维会经历各种结构变化，而且通常在同一根头发上会进行不止一种处理。本研究旨在分析两个种族群体，即白种人和非洲裔群体的头发样本在热烫、漂白和拉直等不同处理前后所发生的变化。除了分别观察每种处理造成的损伤外，还对接受了所有三种处理的样本进行了研究。为了进行分子结构表征，使用了拉曼振动光谱技术，并使用扫描电子显微镜（SEM）对头发纤维进行形态分析。通过振动光谱分析，这项研究表明，一些重要的化学键发生了改变，如S-S、C-S、C-C和S-O键，以及蛋白质的二级结构，其构象因处理而发生了变化。两个种族群体的头发在每种应用处理方面显示出细微差异。与其他处理相比，过度加热产生的拉曼光谱带强度变化率更高，并且观察到几种处理对同一头发纤维的作用导致结构变化更加明显。最后，扫描电子显微镜显示，每种处理在人类头发的毛细管表面产生了不同的形态变形模式。
