ROS-Scavenging Hyperbranched Polymer Dot Nanozymes Combined with Fractional CO2 Laser Microchannels for Hair Follicle Regeneration.

PURPOSE: Topical nanomaterials for hair regeneration are limited by poor follicular penetration, while the regenerative window opened by fractional laser injury is transient and accompanied by rep air-constraining oxidative stress. We investigated whether fractional CO2 laser-generated microchannels could unlock the nanozyme activity of hyperbranched polymer dots (HPD) and accelerate hair follicle regeneration. PATIENTS AND METHODS: HPD (3-5 nm), synthesized by A2+B3 condensation polymerization and displaying concentration-dependent scavenging of hydroxyl radicals, hydrogen peroxide, and superoxide anions, were tested in telogen-synchronized female C57BL/6 mice. Laser energy and spot density were optimized for microchannel formation and tissue tolerability. Five groups (n = 6) received vehicle, 5% minoxidil, HPD, laser alone, or laser plus HPD; laser was applied once on Day 1 and topical treatment daily through Day 15. Outcomes were hair coverage, skin pigmentation, optical coherence tomography (OCT), hematoxylin-eosin histomorphometry, and Ki67 and β-catenin immunofluorescence at Days 8, 11, and 15. RESULTS: Optimized irradiation (30 mJ, 196 spots cm-2, 6.5% coverage) produced reproducible microchannels reaching ~191 μm into the perifollicular dermis without ulceration. Combined treatment outperformed all comparators, increasing hair coverage 16.58-fold versus control by Day 10 (p = 0.0313), follicle length 2.96-fold by Day 11 (p = 0.0001), Ki67⁺ cells 30.49-fold (p < 0.0001), and β-catenin 9.32-fold (p < 0.0001), both still elevated at Day 15. OCT showed more complete microchannel closure with HPD than laser alone. Follicle number per cross-sectional field was highest after combined treatment but did not differ significantly from control (1.91-fold, p = 0.1016). CONCLUSION: Laser microchannels act as both delivery portals and regenerative triggers, while HPD scavenges post-injury reactive oxygen species and sustains Wnt/β-catenin activation, producing a greater-than-additive acceleration of hair follicle regeneration exceeding minoxidil. This reflects activation and accelerated growth of existing follicles rather than de novo neogenesis, and offers a drug-free platform for regenerative dermatology.