Stable Antimicrobial Activity Achieved via Immobilization of Quaternary Ammonium Chloride on Hair.

Dandruff and underarm malodor are caused by microorganisms. Personal hygiene products that contain various types of antimicrobial agents are available and are used for the prevention and alleviation of these conditions. However, their effects are not significant and often do not last long. Working toward a solution, hair was treated with thioglycolic acid, a reducing agent, and then with [2-(acryloyloxy)ethyl] trimethylammonium chloride to covalently bond and immobilize quaternary ammonium chloride (QAC) to hair shafts. Fourier transform infrared analysis confirmed the bonding of QAC. Time-kill assays were performed to evaluate the antimicrobial activities against two yeast strains responsible for dandruff, two bacterial strains responsible for underarm malodor, and two typical bacterial skin microflora strains. The time- kill assays revealed the antimicrobial effects of QAC against all tested microorganisms. Washing with detergents decreased the antimicrobial effects compared to hair not washed with detergent. This method could potentially replace personal hygiene products, such as shampoos and antiperspirants, which act as antimicrobial agents in the prevention and alleviation of dandruff and underarm malodor.