Development of a facile, versatile and scalable fabrication approach of solid, coated, and dissolving microneedle devices for transdermal drug delivery applications

Nowadays, microneedles as novel transdermal delivery systems are interested in scientists for biomedical applications. This work aims to present a Cascade Microneedle Molding Technique (CMMT) for the reusable fabrication of polydimethylsiloxane (PDMS) molds to produce microneedle devices. To produce a positive master mold from epoxy resin, a negative PDMS mold was first fabricated. PDMS can be molded, and microneedles can be fabricated using this epoxy mold in a scalable and cost-effective manner. These molds were used to manufacture solid, coated, and dissolving microneedles, which were characterized comprehensively. Microneedle morphology and geometry were evaluated using Scanning Electron Microscopy (SEM). The mechanical integrity and ability to insert the microneedle device into the skin were assessed using compression strength analysis and force -displacement measurements. Drug penetration through animal skin was evaluated for Rhodamine B (RhB) loaded microneedles. The depth of needle insertion was also visualized using histological analysis while the spatial distribution of released cargo was determined by using confocal microscopy. Taken together, CMMT offers a simple, rapid, cost-effective, and scalable method for mass-producing microneedles with remarkable properties compared to direct 3D printing or laser ablation.