Biodegradable Mg Electrodes for Iontophoretic Transdermal Drug Delivery

Abstract Biodegradable metals have received limited attention for application in transdermal drug delivery, although metallic microneedles (MNs) and iontophoresis have been thoroughly researched for this purpose. Here, we present Mg as a salient candidate for an MN electrode. Its metallic properties enable the application of voltage to enhance the diffusion of charged drug molecules, while hydrogen gas generated during Mg corrosion prevents its application to electrodes. The Mg MN electrode was fabricated using a nanosecond laser, and the amount of hydrogen gas were measured with applied potential during iontophoresis. Accordingly, an appropriate potential window for iontophoresis was established based on the combined effect of enhanced drug diffusion by applied electric potential and impediment from hydrogen generation. The dye permeation tests of the Mg MN on the porcine skin demonstrated the combined effect of the Mg MN and iontophoresis. The dye migration decreased at higher voltages due to excess hydrogen generation and the corrosion of needle tips, both making the diffusion of charged dye molecules along the Mg MN surface harder. These results demonstrate optimal potential range of Mg MN electrodes for transdermal drug delivery with an electric field and bubble generation during iontophoresis. Graphical Abstract