Impact of Hydrogen Peroxide on Hair Fiber and Follicle Integrity: A Study Combining FTIR-ATR, Mechanical Strength and Immunostaining of Proteins Related to Melanogenesis

Author: Samara Eberlin

Published at: September 15, 2025

The cosmetic use of hydrogen peroxide can lead to degradation of protein chains at the hair fiber matrix level due to oxidative effects on –S-S– and SO₃– groups that compose human hair. Also, accumulation of H₂O₂ can degrade melanin and damage melanocytes. This study aimed to evaluate the degradation caused by H₂O₂ in hair fiber and follicles using (FTIR-ATR), combined with hair fiber mechanical resistance testing and immunolabeling of melanogenesis associated proteins. Natural Asian, Caucasian, and Curly hair strands were exposed 1 hour to 3.5% H₂O₂ Young’s modulus and Force at 20% deformation were measured, cystine/amid area ratio and disulfide bridges were quantified from FTIR-ATR spectra. Measurements were taken 5 cm above the strand section submerged in peroxide, highlighting the agent's capillary action and damage displacement. Additionally, follicles obtained from microdissection were cultured and exposed to 3.5% H₂O₂, followed by histological analysis and CKIT and MITF immunolabeling. Hair strands exposed to peroxide damage showed a reduction in Young’s modulus and Force at 20% specific deformation compared to natural hair, following an increasing order of damage: Caucasian, Asian, and Curly. The average cystine/amid area ratio of damaged strands was higher than that of natural hair. Similarly, the area of disulfide bonds in exposed hair strands showed a decrease compared to natural hair, following the same increasing order of damage. Additionally, in the follicles, H₂O₂ exposure caused reductions in MITF and C-kit markings compared to the unexposed group. The cystine/amid area ratio reflects the oxidation level of hair disulfide bonds, with a higher ratio indicating greater fiber damage. Lower disulfide bond area values further confirm bond degradation. This highlights that peroxide-induced damage extends beyond the immersed hair portion, potentially reaching follicles and the hair bulb. This finding is supported by the reduction in hair strand resistance caused by oxidative damage to the cortical matrix, with an increasing order of damage: Caucasian, Asian, and Curly. Also, the images obtained highlighted a reduction in MITF and C-KIT proteins, affecting melanogenesis by disrupting regulatory points and signaling pathways in melanocytes.