Mass producible and biocompatible microneedle patch and functional verification of its usefulness for transdermal drug delivery.

The key issues in the development of a microneedle patch as a tool for transdermal drug delivery are safety and delivery performance in addition to economical production. In this paper, novel fabrication methods for an inexpensive microneedle patch made of biocompatible polymer are reported, along with functional verifications for the fabricated microneedle patch through animal models. We combined the merits of in-line microneedles, i.e., easy and economical production, with the superior performance of two-dimensionally arrayed microneedles. One-dimensionally fabricated microneedles were assembled to make two-dimensionally arrayed patches to attain our goal. First, we fabricated strips with one-dimensionally arrayed microneedles through deep X-ray lithography on polymethylmethacrylate or another negative photoresist, SU-8, with sharply reduced exposure time. Second, we assembled microneedle strips to make two-dimensionally arrayed microneedles, which we utilized further for fabrication of molding masters. Finally, we prepared microneedle patches made of polycarbonate by hot embossing with these masters. We then demonstrated the actual delivery of exogenous materials through application on skin via animal experiments, and we found no detectable side effects such as inflammation or allergic reactions at the site of application.