Biocompatible microneedles with engineered indentation design fabricated via vat photopolymerization for enhanced transdermal drug delivery

The advancement of microneedle technology offers a promising alternative to conventional drug delivery methods by enhancing drug loading efficiency, controlled release, and patient comfort. In this study, we developed a high-resolution microneedle array fabricated via vat photopolymerization using a biocompatible UV-curable polymer. Engineered indentations were introduced to increase the surface area, enhancing drug loading capacity and improving drug uptake. Additionally, the microneedles were mounted on a mechanically adaptive substrate designed to accommodate dynamic movements and conform to curved or flexible surfaces. Mechanical characterization demonstrated that the microneedle patch withstood up to 46.8 ± 2 % strain without failure while maintaining penetration efficiency in rat skin. Drug release analysis showed an initial burst phase within the first 60 h, followed by a sustained release profile. The optimized microneedle design with a 0.25 mm indentation achieved a drug loading efficiency of 27.5 ± 0.6 % and a cumulative release of 37.6 ± 0.7 % after 25 h. These findings highlight the potential of biomimetic structural modifications and vat photopolymerization in advancing microneedle-based transdermal drug delivery, offering a minimally invasive, efficient, and patient-friendly alternative to conventional drug administration.