Engineering of a Microneedle-Based Drug Delivery System via a Reaction-Diffusion Process

Microneedle-based transdermal drug delivery has emerged as a promising alternative to conventional hypodermic injection owing to its minimally invasive nature, improved patient compliance, and ability to bypass the gastrointestinal tract and first-pass metabolism. However, conventional micromolding techniques often require prolonged fabrication times and repeated centrifugation steps for multilayer structures, which may reduce the stability and bioactivity of encapsulated therapeutics. To address these limitations, we propose a rapid fabrication strategy for multilayer hydrogel microneedles based on a reaction–diffusion process using photocurable prepolymers.
The fabrication mechanism exploits the competition between UV-induced photopolymerization and oxygen diffusion, enabling the formation of well-defined multilayer microneedles within a short processing time without repeated molding or centrifugation. Poly(vinyl alcohol) (PVA) and poly(ethylene glycol) diacrylate (PEGDA) were employed as the hydrogel matrix. PVA gradually dissolves upon contact with interstitial fluid, creating diffusion pathways for drug release, whereas PEGDA forms a crosslinked network that maintains the structural integrity and provides sufficient mechanical strength for reliable skin penetration. By adjusting the composition of the PVA/PEGDA prepolymer solution, the crosslinking density and hydrogel properties can be readily tuned, allowing controlled modulation of drug release kinetics.
This reaction–diffusion-based fabrication strategy provides a simple, rapid, and versatile platform for producing hydrogel microneedles while minimizing processing-induced drug degradation. The proposed system demonstrates the potential of PVA/PEGDA hydrogel microneedles as an efficient transdermal drug delivery platform with tunable release behavior and excellent biocompatibility.