Fabrication of carbon nanotube—polyimide composite hollow microneedles for transdermal drug delivery
We introduce a novel method for fabricating hollow microneedles for transdermal drug delivery using a composite of vertically-aligned carbon nanotubes and polyimide. Patterned bundles of carbon nanotubes are used as a porous scaffold for defining the microneedle geometry. Polyimide resin is wicked through the carbon nanotube scaffold to reinforce the structure and provide the prerequisite strength for achieving skin penetration. The high aspect ratio and bottom-up assembly of carbon nanotubes allow the structure of the microneedles to be created in a single step of nanotube fabrication, providing a simple, scalable method for producing hollow microneedles. To demonstrate the utility of these microneedles, liquid delivery experiments are performed. Successful delivery of aqueous methylene blue dye into both hydrogel and swine skin in vitro is demonstrated. Electron microscopy images of the microneedles taken after delivery confirm that the microneedles do not sustain any structural damage during the delivery process.
© 2014 Springer Science+Business Media New York. Published online: 07 August 2014. This work was supported by ZCube s.r.l. The authors acknowledge the support and infrastructure provided by the Charyk Laboratory for Bio-Inspired Design, Kavli Nanoscience Institute, and the Geology and Planetary Sciences Analytical Facility of the California Institute of Technology. The authors also acknowledge Melissa Cronin, Neeru Ravi, and Sreenivas Appasani, for their assistance in fabricating carbon nanotubes and skin patches.