Adhesive Composite Hydrogel Patch Based on a Polyaspartamide Derivative to Treat Atopic Dermatitis

Transdermal patches offer significant advantages as a drug delivery system due to their ability to bypass first-pass metabolism, sustain drug release, and provide predetermined dose and application area. However, to be effective, transdermal patches must have optimal adhesion and drug-loading capacity. In this study, an adhesive composite hydrogel patch consisting of poly(N-2,3-dihydroxypropyl aspartamide) (PDHPA), a polyaspartamide derivative, and mesoporous silica nanoparticles (MSNs) are developed. To prepare the hydrogel, boric acid (BA) is utilized as a crosslinker to form reversible bonds between multiple hydroxyl groups in the polymer and BA. The PDHPA-BA hydrogel exhibits dynamic reversibility, self-healing properties, and a pH-dependent sol–gel transition. The addition of MSNs with abundant hydroxyl groups improves the mechanical performance, adhesion properties, and self-healing rate of the PDHPA-BA hydrogel. In addition, MSNs enable the loading of hydrophobic drugs, such as dexamethasone (Dex), onto the hydrogel. Using the Dex-loaded adhesive composite hydrogel as a transdermal patch, the severity of atopic dermatitis in a mouse model indicated by suppression of dermatitis score, epidermal thickness, number of mast cells, and serum interleukin-4 levels is successfully reduced. These results suggest that the composite hydrogel patch is a highly promising transdermal drug delivery system for effectively treating inflammatory skin diseases.