DSC-investigations of alpha-keratins and the specific effects of chemical treatments on human hair
January 2006
The study investigated the effects of chemical treatments on human hair using differential scanning calorimetry (DSC) to analyze the thermal stability of alpha-keratins. It was found that the denaturation temperature of hair increased with the cross-link density of the matrix, influenced by cystine. European human hair subjected to oxidative (bleaching) and reductive (perm-waving) treatments showed that both intermediate filaments (IFs) and IF-associated proteins (IFAPs) were similarly affected by bleaching, while reductive damage was more pronounced in IFs. The study revealed that oxidative treatments led to a decrease in denaturation temperature from 158°C to 138°C after seven treatments and a 40% reduction in native alpha-helix content. The kinetic analysis suggested that the matrix's viscosity plays a crucial role in controlling the denaturation process, with oxidative treatments potentially affecting the crystalline structure of IFs inhomogeneously.