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

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Schematic view of release-layer-mediated multilayer tattooing strategy using coated microneedles: (1) PLLA microneedles are coated with PNMP release-layer films through spray deposition; (2) ultraviolet irradiation imparts pH-sensitive aqueous solubility to the PNMP film, forming a uv-PNMP ‘release-layer’; (3) Overlying multilayer films containing nucleic acids are constructed using LbL deposition at pH 5.0. b, Mechanism of action for multilayer tattooing: (1) Microneedle application to skin and exposure to interstitial fluid gives rapid release-layer dissolution, mediating overlying film delamination and retention in skin following microneedle removal; (2) Implanted films provide sustained release of nucleic acids through hydrolytic PBAE degradation and release of in situ-formed PBAE/nucleic acid polyplexes; (3) released polyplexes mediate local transfection and immune modulation in the tissue.a, Representative whole-animal fluorescence images showing TMR-poly(I:C) retention at the application site and quantitative analysis of normalized total fluorescence R(t)relative to initial fluorescence Ro from groups of animals (n  =  3) over time following 15 min application of PLLA microneedles coated with (uv-PNMP)(PS/SPS) 20(PBAE/TMR-poly(I:C)) 35 multilayers containing poly-1 or poly-2 as the PBAE component. Data represent the mean±s.e.m. b, Representative whole-animal luminescent images and quantitative analysis of luminol signal from MPO-dependent oxidative burst in activated phagocytes at the treatment site over time following intradermal injection of 10 μg poly(I:C) or 15 min application of PLLA microneedles coated with (uv-PNMP)(PS/SPS) 20(poly-2/poly(I:C)) 35 multilayers. Data represent the mean±s.e.m., n  =  4. c, Representative whole-animal bioluminescence images of pLUC expression at the application site and mean bioluminescence intensity over time following 15 min application of microneedles coated with (uv-PNMP)(PS/SPS) 20(PBAE/pLUC) 35 multilayers containing poly-1 or poly-2 as the PBAE component. Data represent the mean±s.e.m., n  =  4. d, Mean bioluminescent intensity on day 2 following 15 min application of microneedles coated with (uv-PNMP)(PS/SPS) 20(Poly-1/pLUC) 35 multilayers stored dry at 25 °C for 0, 14 or 28 days. Data represent the mean±s.e.m., n  =  4.a, C57Bl/6 mice (n  =  4 mice per group) were immunized with 20 μg pGag and 10 μg poly(I:C) on days 0 and 28 intramuscularly (with or without electroporation (EP)) in the quadriceps, intradermally in the dorsal ear skin (with free pGag or pGag/poly-1 polyplexes, ID±Polyplex), or by 15 min application of (PNMP)(PS/SPS) 20(poly-1/poly(I:C)) 35(poly-1/pLUC) 35–coated microneedles with or without ultraviolet-priming of the PNMP release-layer (MN±UV) to the dorsal ear skin. b–d, Frequency of Gag-specific CD8+ T-cells in peripheral blood assessed by flow cytometry analysis of tetramer+CD8+ T-cells. Shown are mean±s.e.m. tetramer+ values from day 14 (b), representative cytometry plots from individual mice (c), and mean±s.e.m. tetramer+ values from day 42 (d). e,f, Analysis of T-cell effector/central memory phenotypes in peripheral blood by CD44/CD62L expression of tetramer+cells from peripheral blood. Shown are representative cytometry plots from individual mice at day 49 (e) and mean±s.e.m. percentages of tetramer+CD44+CD62L+ among CD8+ T-cells at day 98 (f). g, Mice immunized with microneedles were recalled on day 105 by IM injection of 50 μg pGag, and assessed for cytokine production on ex vivo restimulation with AL11 peptide on day 112. Shown is representative flow cytometry analysis of IFN- γ/TNFα-producing CD8+ T-cells. h, Enzyme-linked immunosorbent assay analysis of total Gag-specific IgG in sera at day 42. Data represent the mean±s.e.m., **P < 0.005, analysed by two-way ANOVA.
Professor Darrell Irvine
Department of Biological Engineering, MIT
External Link (irvine-lab.mit.edu)
Professor Paula Hammond
Department of Chemical Engineering
External Link (hammondlab.mit.edu)
Peter DeMuth
Department of Biological Engineering, MIT
Younjin Min
Department of Chemical Engineering, MIT
Managed By
Jon Gilbert
MIT Technology Licensing Officer
Patent Protection

Multilayer Compositions, Coated Devices And Use Thereof

US Patent Pending US 2015-0250739

Multilayer Compositions, Coated Devices And Use Thereof

US Patent Pending
Polymer multilayer tattooing for enhanced DNA vaccination
Nature Materials, Dec. 13, 2012 p. 367-376


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