Monodispersed sodium hyaluronate microcapsules for transdermal drug delivery systems

This study presents an alternative to cross-linking for the preparation of monodispersed polymer microcapsules made from water-soluble and biocompatible sodium hyaluronate (SH). Water was removed from monodispersed drug-containing SH droplets by creating an osmotic pressure difference, causing the droplets to thicken and solidify into microcapsules. The fabricated microcapsules were water-soluble and could be stored in oil for at least one month without dissolution, thereby retaining the contained drug. In addition, we used SH microcapsules to prepare biodegradable microneedles (MNs), one of the materials for transdermal drug delivery systems (TDDSs), by embedding the microcapsules in a poly(lactic-co-glycolic acid) copolymer, which was molded into a needle shape. The MNs embedded with drug-containing microcapsules released the drug over time based on the amount of microcapsules contained and were capable of penetrating the stratum corneum of the skin. These findings show the application potential of these monodispersed SH microcapsules for TDDSs, while avoiding the common issues associated with cross-linking, such as toxicity and bursting. This novel material exhibits potential for use in pharmaceutics and cosmetics.