Facile Fabrication of Biodegradable Polymer Microneedle Arrays with Varying Aspect Ratio using Acupuncture Needle

Abstract

Microneedle have received much attention as a method for enhancing the drug delivery efficiency of transdermal route. Although drug delivery using transdermal delivery route has many advantages such as easy administration, convenience of patients and sustainable drug release, epidermis, especially stratum corneum, obstructs the movement of drug molecules into deep skin layer by their properties from corneocytes and intracellular lipid layer. Among the numerous method such as chemical enhancer, iontophoresis, ultrasound, electroporation, thermal ablation, microdermabrasion and microneedle for enhancing the drug delivery efficiency, microneedle therapy is simple, safe and effective method. I suggested facile method for the fabrication of a biodegradable polymer microneedle array in the respect of cost-effective, simple and safe microneedle array. Fabricated microneedle array based on the commercially available acupuncture needle that is used for the insertion into human skin. Using this acupuncture needle, a master template was prepared by fixing them onto a plastic substrate with selectively drilled holes. In this step, the design of microneedle array was determined by the location of drilled hole and the fixing depth of acupuncture needle, and it gave more freedom about the arrangement of microneedle and curvature of microneedle array. A polydimethylsiloxane (PDMS) mold was fabricated by partially immersed master template. Various height type of microneedle array could be determined by controlling the level height of PDMS mixture from one master template. A biodegradable polymer microneedle array was successfully fabricated by means of micromolding process with the PDMS flexible mold. In the view of microneedle material, polycaprolactone (PCL), well known biodegradable material, was not appropriate as a microneedle material due to low Young’s modulus. A PCL microneedle was not able to penetrate porcine cadaver skin, and the tip of microneedle bent before the insertion. A microneedle, made of polylactic acid (PLA) showed enough mechanical strength to penetrate porcine cadaver skin. PLA microneedle was tested in four ways to verify the applicability for microneedle therapy. The mechanical force and degradation behavior of the replicated PLA microneedle array were characterized with the help of a compression test and an accelerated degradation test, respectively. Finally, the transdermal drug delivery performance of the PLA microneedle array was successfully simulated by two different methods of penetration (poke and release) and staining (coat and poke) using the porcine cadaver skin. The results indicated that the proposed method can be effectively used for the fabrication of polymer microneedle arrays which can be used in various microneedle applications.