Dissolving Microneedle Patches Integrating Optical Clearing and Photothermal Agents for Improved Photothermal Disinfection

Photothermal disinfection is an emerging and efficient therapeutic method for treating various infections. However, the therapeutic efficacy is hindered by the poor tissue penetration of light. While tissue optical clearance technology can enhance light transmission, the stratum corneum impedes the delivery of clearing agents to deeper tissues. Herein, dissolving microneedle (DMN) patches incorporating optical clearing and photothermal agents are developed for improved photothermal disinfection. Such DMN patches are obtained using sucrose as the optical clearing agent and polydopamine (PDA) nanoparticles as photothermal agents in poly(vinyl alcohol) (PVA) DMN matrix. After treatment with the composite DMN, the light transmittance of the pigskin increased by 4.75 times. The composite DMNs deliver PDAs to the subsurface of skin while improving the optical clearing effect, raising the temperature of the subsurface of pigskin to 45 °C under near-infrared (NIR) light irradiation with a wavelength of 808 nm. In treating a deep infection model (pigskin coverage) established on mouse skin, the composite DMNs significantly improve the wound recovery rate. This approach is expected to be a general strategy for enhancing the anti-infective efficacy of photothermal disinfection and shows great potential for improving the clinical application of various phototherapies.