Engineering cellulose acetate microneedle coated with zinc-phenolic imidazolium poly(ionic liquids) for atopic dermatitis treatment

Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by impaired epidermal barrier function, immune dysregulation, and microbial colonization, particularly by Staphylococcus aureus ( S. aureus ). Current topical therapies are often limited by poor dermal penetration, systemic absorption, and long-term side effects. Microneedle (MN) patches have emerged as a promising transdermal delivery platform due to their minimally invasive nature and ability to bypass the stratum corneum. In this study, we developed a non-dissolvable cellulose acetate (CA) MN patch coated with zinc-phenolic imidazolium poly(ionic liquids) coating for AD treatment. The MN patches, fabricated using CA as the backbone, were respectively coated with poly(vinylbutylimidazolium dihydroxyphenylpropionic acid) (PVD) coordinated with Zn 2+ (PVD@Zn) or ZnO nanoparticles (PVD@ZnO), exhibiting favorable mechanical strength, sustained coatings release, potent antibacterial activity against S. aureus , cell migration, and anti-inflammatory property‌ (such as reactive oxygen species (ROS) scavenging capacity and inflammatory factors down regulation). In vivo evaluations demonstrated enhanced biocompatibility, antibacterial activity, reduced inflammation, and promotion of skin barrier recovery. The multifunctional coated MN patches represented a rational strategy for synergistic antibacterial and anti-inflammatory therapy, offering a safe and effective approach for managing AD and other inflammatory skin conditions.