Dual-Function Microneedle Patch for Retinyl Acetate Delivery and Lactate Sensing in Skincare Management.

Closed-loop skin health management that integrates real-time diagnostic feedback with on-demand therapeutic delivery remains a critical unmet challenge in precision dermatology. Here, a smart core-shell microneedle (MN) patch is developed for bidirectional skin intervention: simultaneous delivery of retinyl acetate (RA) therapy and in situ monitoring of interstitial fluid (ISF) lactate as a metabolic biomarker. RA is first encapsulated in hydroxypropyl-β-cyclodextrin (HPβCD) inclusion complexes via a rapid ultrasonic method to enhance solubility and stability. The MN patch features a mechanically robust polyvinyl alcohol/sodium hyaluronate (PVA/SH) shell for effective stratum corneum penetration and a hyaluronic acid-based core loaded with RA@HPβCD, type I collagen, and chitosan for synergistic anti-aging and anti-acne effects. The MN patch delivers RA to remodel the dermal matrix while continuously extracting ISF, enabling on-site quantitative analysis of lactate as a metabolic feedback indicator of skin status-elevated lactate signals skin hypoxia or inflammation, prompting timely RA action. This integrated platform thereby establishes a closed-loop system coupling therapeutic intervention with diagnostic assessment. This smart MN patch offers a promising strategy for precision skin care and holds potential for managing diverse dermatological conditions requiring dynamically adjustable therapy.