Fabrication of DNA-coated microneedles for transdermal DNA delivery

Transdermal delivery has been widely recognized as a powerful method for drug delivery that can overcome shortcomings of oral administration. Injection with hypodermic needles, however, have problems including pain, bleeding, need of special training to use and high risk of infection. To overcome those limitations, microneedles are widely studied for the delivery of a variety of therapeutics into body. Here, we introduce DNA-coated microneedles that can be used as a tool for gene therapy. Therapeutic DNA is first amplified by rolling circle amplification from template circular DNA to deliver multiple copies of them. Microneedles with two monomers of poly(ethylene glycol) diacrylate and acrylamide that are known to be biocompatible are then coated with amplified DNA strands by electrostatic interactions. Our DNA-coated microneedles can highly localize the delivery site while minimizing pain. We expect that this approach will help turning biological potential into medical reality.