Polymer Base-layer for Rapid Delamination of Multi-layer Films from Microneedles


A microneedle delivery platform that can be used to safely and painlessly inject a combination of drugs, such as plasmid DNA-encoding antigens and adjuvants, can be used in a variety of therapeutic settings.

Problem Addressed

Microneedle arrays have been employed as an alternative approach to traditional needles because they are safer, more convenient, and pain-free. Upon contact with the skin, they rapidly dissolve and release the encapsulated drug. However, sustained or kinetically controlled drug release, which is especially important for certain applications such as DNA vaccine delivery, is difficult to achieve through this method. A new microneedle platform that can deliver drugs for controlled release will improve upon the current microneedle arrays in use.


This invention comprises an approach for encapsulation and controlled release of a combination of drugs via microneedle injection. The microneedles are base-coated in the UV-treated poly(o-nitro benzyl methacrylate-co-poly(ethylene glycol) methacrylate polymer (PNMP), which is unstable when exposed to biological fluids. Polyelectrolyte multilayer films (PEM films) embedded with drugs are added layer by layer to the base coat of PNMP. Upon injection, the base coat of PNMP dissolves and the coats of PEM are shedded into the body, where they slowly degrade and release their contents. This system has been shown to successfully deliver a DNA vaccine consisting of a combination of adjuvants, transfection agents, and plasmid DNA in vivo in mice. The application of microneedles to the skin for 15 minutes deposits the multi-layer films to the epidermis. The films initially show a burst release of 35% of drug content and subsequently slow to a linear release for 10 days. Compared to mice injected using traditional intradermal and intramuscular methods, mice that were injected using this invention showed significantly greater immunoglobulin G titers in sera, as well as a significantly greater frequency of antigen-specific and central memory T cells two weeks following treatment. These results indicate that the invention improves upon current methods to deliver exogenous material such as DNA vaccines in a therapeutic setting. 


  • Fast and painless delivery of drugs
  • Modular, tunable, and flexible assembly of microneedle arrays
  • Controlled drug release over a span of days
  • Optimized for the delivery of DNA therapeutics for transfection
  • Significantly greater immunity compared to traditional vaccine injection methods