Betaine-stabilized Poly(lipoic acid) Adhesive Patch for Oral Ulcer Treatment

Oral ulcers, a prevalent oral mucosal condition, involve epithelial discontinuity, tissue fluid loss, reactive oxygen species accumulation, and bacterial infection. Dynamic saliva flow and physical friction from food residues further aggravate the damage and delay healing. To address this problem, we developed a stable PolyLA-based adhesive patch by combining α -lipoic acid (LA) and betaine (BET) using a simple one-step solvent evaporation method, referred to as PolyLA/BET. The carboxylate and tertiary ammonium groups on BET formed multiple hydrogen bonds with PolyLA, effectively inhibiting the depolymerization of LA. PolyLA/BET firmly adheres to oral tissues via hydrogen bonding mediated by surface carboxyl groups. Moreover, zwitterionic structure of BET enabled the patch to absorb and retain water. Upon hydration, the patch maintains structural stability while acquiring flexibility and adhesiveness, which are essential characteristics for durable sealing and the formation of a stable moist wound healing microenvironment. The patch also sustained the release of LA, providing antioxidant and antibacterial activities. In a rat oral ulcer model, PolyLA/BET outperformed the commercial patch in promoting wound healing.