Influence of Surface Functional Groups on the Hair Growth-Promoting Activities of Nanochitins: An In Vitro Analysis

Four types of nanochitins with similar fibril morphology but varying surface groups or charge densities were developed to assess their impact on hair growth. All nanochitin types were biocompatible, with partially deacetylated nanochitin (DNCh) showing the highest survival rate, indicating superior biocompatibility. Changes in nanochitin concentration did not affect the survival rate of Human Carcinoma T cells (HaCaT). All nanochitin could regulate Vascular Endothelial Growth Factor (VEGF) and Fibroblast Growth Factor-7 (FGF-7) secretion, potentially promoting angiogenesis and dermal repair-related biological processes, with hydrochloric acid hydrolyzed nanochitin (HNCh) having the strongest pro-secretory effect, increasing VEGF levels by 30.0%. Moreover, all four types of nanochitin effectively promote hair growth in mice; DNCh and phosphoric acid hydrolyzed nanochitin (PNCh) groups demonstrated superior therapeutic outcomes, with earlier emergence of dense hair shafts compared to HNCh and amphoteric nanochitin (ANCh) groups, while ANCh demonstrated the most balanced and optimal overall effect.