The Design of Polymer-based Nanocarriers for Effective Transdermal Delivery

This study reports a facile and practical means to non‐invasively deliver biologically active ingredients through the skin using polymer‐based nanocarriers. For this, polymer nanocapsules were fabricated with different surface charges as well as glass transition temperatures and we observed their ability to deliver the encapsulated active ingredient, coenzyme Q10, through the skin layer. Direct imaging of a probe molecule, Nile Red, and a matrix polymer labeled with fluorescence moiety, Lucifer Yellow, allowed us to demonstrate that the probe molecule readily permeates into the deep skin, while the matrix polymer stays in the stratum corneum layer due to electrostatic interactions. Quantitative characterization of the penetrating amount of coenzyme Q10 using the Frantz cell method proved that, to achieve improved delivery efficiency, the nanocapsule should have a low glass transition temperature as well as positive surface charges. This study introduces a facile fabrication method of polymer nanocapsules that are truly effective for non‐invasive transdermal delivery. The key to our approach is to give the nanocapsules the ability to electrostatically interact with the intercellular lipid lamellae of the stratum corneum. Also, we show that control over the phase property of the polymer nanocapsules is indeed important and plays a role in improving delivery efficiency.