Membrane filtration: An unconventional route for fabrication of the flexible and dissolvable, polymer microneedle patches

Utilization of dissolvable, polymer microneedles (MNs) for transdermal drug delivery offers many advantages such as being painless to patients, biocompatibility, biodegradability, and active and controlled drug release. There are many different approaches for fabrication of such MNs; however, most of them still suffer from tedious procedures, stringent fabrication conditions, expensive equipment, or substantially long processing time. In this work, we applied membrane filtration to fabricate dissolvable, polymer MNs. The polydimethylsiloxane mold having pyramidal wells with through holes was constructed and placed on top a filter membrane. The polymer solution was then dispensed on top of the mold, followed by turning on the vacuum for filtration. It was found that, when using 22% polyvinylpyrrolidone (PVP) solution with molecular weight of 360 000 g/mol, the PVP MNs were obtained within 1 h, which is relatively short time compared to the conventional methods like casting in conjunction with vacuum or centrifugation. Moreover, the MNs as fabricated possessed the similar mechanical strength compared to those by conventional methods and were able to penetrate the rat ear skin with a high insertion ratio. The proposed technique provides an attractive alternative to fabricate dissolvable and flexible, polymer MNs with a simple setup and easy procedures.