Digital light processing 3D-printed PEGDA microneedle patches for sustained transdermal carbamazepine delivery

Microneedles (MNs) have emerged as a promising platform for transdermal drug delivery by overcoming the barrier properties of the stratum corneum while minimizing pain and improving patient compliance. In this study, digital light processing (DLP) three-dimensional printing was employed to fabricate PEGDA-based MN arrays for the controlled transdermal delivery of carbamazepine (CBZ). The influence of UV light intensity, layer exposure time, post-curing temperature and exposure time on the printability and mechanical properties of printed PEGDA and PEGDA/PEG 200 formulations was systematically investigated to identify optimal fabrication and post-curing conditions. Mechanical characterization demonstrated that curing at 50 °C for 45 min provided the most favourable balance between compressive modulus and ultimate strength for the PEGDA formulation. Three MN designs with different needle geometries and densities were fabricated and evaluated. The 300 and 300 MT designs exhibited significantly greater fracture resistance than the 200 μm design and possessed margins of safety exceeding unity, confirming their suitability for skin insertion. Ex-vivo porcine skin studies demonstrated successful penetration without structural deformation, while SEM analysis confirmed preservation of needle integrity following insertion. Drug incorporation reduced mechanical strength however did not compromise insertion performance. Both MN designs achieved sustained CBZ release over the experimental period, with release kinetics influenced by needle density and polymer composition. Cytocompatibility studies using HaCaT keratinocytes demonstrated good biocompatibility of the post-cured materials, whereas uncured resins exhibited pronounced cytotoxicity. Overall, the results demonstrate that DLP-fabricated PEGDA/PEG 200 MNs possess adequate mechanical robustness, controlled drug delivery capability, and favourable cytocompatibility, highlighting their potential as customizable platforms for sustained transdermal drug delivery.