Penetration and distribution of PLGA nanoparticles in the human skin treated with microneedles.

This study was designed to investigate the penetration and the distribution of poly(d,l-lactic-co-glycolic acid) (PLGA) nanoparticles in the human skin treated with microneedles. Fluorescent nanoparticles were prepared to indicate the transdermal transport process of the nanoparticles. Permeation study was performed on Franz-type diffusion cells in vitro. The distribution of nanoparticles was visualized by confocal laser scanning microscopy (CLSM) and quantified by high performance liquid chromatography (HPLC). CLSM images showed that nanoparticles were delivered into the microconduits created by microneedles and permeated into the epidermis and the dermis. The quantitative determination showed that (i) the permeation of nanoparticles into the skin was enhanced by microneedles, but no nanoparticle reached the receptor solution; (ii) much more nanoparticles deposited in the epidermis than those in the dermis; (iii) the permeation was in a particle size-dependent manner; and (iv) the permeation increased with the nanoparticle concentration increasing until a limit value was reached. These results suggested that microneedles could enhance the intradermal delivery of PLGA nanoparticles. The biodegradable nanoparticles would sustain drug release in the skin and supply the skin with drug over a prolonged period. This strategy would prove to be useful for topical drug administration.