Smart Light-Activated Microneedles with Copper-Doped Prussian Blue for Targeted Propionibacterium acnes Eradication

Acne is a chronic inflammatory skin disease primarily caused by an infection with Propionibacterium acnes, which compromises skin integrity and impairs patients’ quality of life. Conventional antibiotic treatments face challenges, including bacterial resistance and poor lesion penetration. To address these limitations, we developed copper-doped Prussian Blue (CuPB) hyaluronic acid (HA) microneedles (MNs) (Cu₁₀PB-HA@MNs). This nonantibiotic system combines photothermal therapy (PTT) and photodynamic therapy (PDT) for dual antibacterial and reparative effects. Cu²⁺ doping enhances PB’s plasmon resonance, achieving rapid heating (exceeding 50 °C in 3 min) while reducing its band gap to facilitate charge carrier transfer and electron–hole (e^–/h⁺) separation. Under the acne microenvironment, these photoexcited carriers generate reactive oxygen species (ROS) via oxygen/water reactions. The optimized PTT/PDT system demonstrates exceptional antibacterial efficacy (99.76% against P. acnes, 99.65% against Staphylococcus aureus (S. aureus)). Additionally, photothermally released HA, Cu, and Fe ions stimulate collagen deposition, accelerating skin regeneration. The Cu₁₀PB-HA@MN platform offers a simple yet effective therapeutic strategy for treating acne.