Enhanced transdermal delivery by using electrostatically interactive chitosan nanocapsules

This paper describes a useful means of noninva-sively enhancing transdermal delivery efficiency. For this, chitosan nanocapsules with positive surface charges were fabricated by using the in situ precipitation method. These nanocapsules cannot only have an ability to encapsulate the drug molecule (this study used riboflavin 5′-monophos-phate), but also electrotatically interact with the stratum corneum layer. To demonstrate this, fluorescence-labeled polymer nanoparticles with different particle sizes as well as surface charges were topically applied onto the skin and their distribution was directly imaged. This demonstration experiment allowed us to figure out that once the nano-capsules were provided with positive surface charges, they readily deposited into the stratum corneum layer due to the electrostatic interaction. Further quantitative characterization of the penetrating amount of riboflavin 5′-monophos-phate by using the Frantz diffusion cell method showed that our chitosan nanocapsule system effectively improved transdermal delivery efficiency.