Abstract:

Chitosan (CS) and laponite (LAP) are both biocompatible materials, and modification can enrich them with enhanced bioactivity. This study investigated the preparation method of a composite antimicrobial material based on quaternized chitosan (QCS) and modified laponite, and its antimicrobial performance in shampoo. QCS was degraded via microwave-assisted hydrogen peroxide oxidation to enhance its solubility, and LAP was organically modified with cetyltrimethylammonium bromide (CTAB) to impart its Malassezia adsorption capability, resulting in positively charged organic LAP.  The successfully prepared QCS and CTAB-LAP composite materials were characterized and validated using Fourier-transform infrared spectroscopy, Zeta potential analysis, rotational rheometry, and scanning electron microscopy. Experimental results demonstrated that QCS of various molecular weights demonstrated excellent antimicrobial performance in aqueous media. The QCS and CTAB-LAP composite material exhibited a synergistic enhancement in antimicrobial effect. Optimal formulations for the composite antimicrobial agents in aqueous media and base shampoo were identified by varying the amount and ratio of the components. In aqueous solution, composite mixtures with mass ratios of 9:1, 5:5, and 1:9 achieved 100% antimicrobial efficacy after 10-fold dilution and 5 minutes of Malassezia strain contact. When added to base shampoo at a 9:1 ratio (total mass fraction 0.14%) and diluted 100-fold, the composite maintained significant antimicrobial efficacy, reaching up to 70% effectiveness compared to commercial chemical anti-dandruff products. This study highlights the potential of the QCS and CTAB-LAP composite for practical application in anti-dandruff shampoos and paves the way for the development of natural and eco-friendly antimicrobial materials.  

Key words: Quaternized chitosan, modified laponite, antimicrobial material, Malassezia, shampoo