Abstract:

With the increasing demand for hair beautification treatments such as dyeing and perming among consumers, hair damage has become increasingly prevalent, which in turn has driven market attention and demand for hair care products with repair efficacy. However, there currently lacks a unified evaluation standard for repair efficacy. This study aims to establish a comprehensive evaluation system for the repair efficacy of hair care products against chemical damage. In this study, we observed the cuticle morphology of hair fiber surface using scanning electron microscopy （SEM） and quantitatively analyzed the cross-sectional pore area. We also assessed the physical properties of hair bundles by measuring their coefficient of friction, combing work, number of broken hairs, and split ends using instrumental tests. Additionally, we analyzed the released amount of protein and cysteine content using UV and LC-MS/MS methods to investigate the chemical properties of hair bundles. By integrating these methods, we evaluated the repair effects of in vitro hair bundles subjected to chemical damage. The results indicate that after using hair masks, the hair cuticles show significant improvement, with a notable reduction in cross-sectional pore area. The coefficient of friction, dry combing work, number of broken hairs, number of split ends, the released amount of protein, and cysteine content are all significantly decreased, confirming the effectiveness of the repair products. This suggests that the efficacy evaluation method established in this study can effectively assess the repair efficacy of hair care products against chemical damage, providing a scientific and effective tool for the development and evaluation of hair care products. Overall, through SEM, physical property testing, and chemical property testing, this study provides a scientific basis for the evaluation method of repair efficacy against chemical damage in hair care products and establishes a comprehensive evaluation system.

Key words: in-vitro hair bundles, chemical damage, repairing, cross-sectional pore, cysteine