| CPC A61M 37/0015 (2013.01) [A61K 9/0021 (2013.01); A61M 2037/0023 (2013.01); A61M 2037/0061 (2013.01)] | 32 Claims |

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1. A method of delivering a bioactive agent to a subject, the method comprising:
penetrating a stratum corneum of the subject with a microneedle having a channel in fluid communication with the bioactive agent, a plurality of nanostructures and a plurality of microstructures formed on an external surface of the microneedle, wherein at least a portion of the microstructures have a cross-sectional dimension of greater than about 500 nanometers and less than about 10 micrometers and a height of from about 20 nanometers to about 1 micrometer, wherein at least a portion of the microstructures have a cross-sectional dimension greater than a height of the microstructures, the plurality of nanostructures having a fractal and/or a fractal-like geometry;
transporting the bioactive agent through the channel of the microneedle; and
delivering the bioactive agent to the subject with a comparative bioavailability as compared to subcutaneous delivery of greater than about 20%;
wherein the stratum corneum comprises tight junctions between cells, the nanostructures rearranging tight junctions between the cells, thereby increasing porosity; and
wherein the rearrangement of the tight junctions leads to an increase in the porosity of a second tissue type that is not in direct contact with the microneedle.
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