Effect of negative charged particles on the recovery of skin barrier function after EP treatment

Electropomtion (EP) may irreversibly damage the barrier function of skin, although it can he used to increase the skin permeation of drugs and cosmetic ingredients. The recovery effect on the skin barrier was evaluated using several nanomaterials. Polystyrene microspheres with surface sulfate groups (PSMS), sodium polystyrene sullonate particles (KXL) and several titanium dioxide (TiO2) nanoparticles were applied to the skin after EP treatment. Negatively charged materials, PSMS and hydrous silicate-coated TiO2 nanoparticles accelerated the recovery of skin impedance. The highest effect was observed with highly negative-charged PSMS. Skin impedance was also recovered by aluminum-coated TiO2 nanoparticles, whereas recovery of the skin barrier function was delayed by non-coated TiO2 nanoparticles. The skin permeation of drugs was suppressed after EP treatment, followed by PSMS application, compared with that without PSMS application. The suppressed skin permeation was almost the same as that without EP treatment. In addition, no skin damage was observed by PSMS and other nanomaterials. These results strongly support the fact that some particles can be utilized as additives in topical drug formulations and cosmetics, making EP safer.