Hyaluronic acid-based bilayer microneedles integrating a polydopamine-indocyanine green nanoplatform and curcumin for near-infrared-activated antibacterial therapy.

Skin and soft tissue infections (SSTIs) present a significant clinical challenge due to persistent bacterial colonization that exacerbates oxidative stress and impairs tissue repair. To address this, we developed a novel bilayer microneedle system (PI@Cur MN) combining polydopamine (PDA)-stabilized indocyanine green (ICG) at the tips with a Curcumin (Cur)-loaded backing layer, enabling synergistic photodynamic (PDT) and photothermal (PTT) antimicrobial therapy coupled with antioxidant functionality. The PDA-encapsulated ICG nanoparticles (PI) in microneedle tips demonstrated targeted near-infrared (NIR, 808 nm) responsiveness, achieving rapid bacterial eradication through concurrent PTT-induced hyperthermia and PDT-generated reactive oxygen species (ROS), with 99.89 % and 99.74 % reduction against Staphylococcus aureus and MRSA, respectively. Meanwhile, the backing layer containing curcumin remained on the skin surface as a drug reservoir. After the needle was inserted, it enabled a sustained release of Cur, which provided long-lasting antioxidant and anti-inflammatory effects. This multifunctional platform integrates multimodal antibacterial action, oxidative stress alleviation, and minimally invasive drug delivery, offering a clinically promising solution for managing SSTIs and promoting infected wound healing.