# Tuning the Transdermal Transport by Application of External Continuous Electric Field: A Molecular Dynamics Coarse-Grained Study

## TL;DR

This study uses coarse-grained molecular dynamics to explore how external electric fields influence water vesicle formation in the skin's outer layer, revealing controllable phase transitions that could enhance transdermal drug delivery.

## Contribution

It provides the first molecular-level insight into electric field effects on skin's stratum corneum, demonstrating controllable vesicle formation and phase transitions via electric field tuning.

## Key findings

- Electric fields induce water-rich vesicle formation in skin model
- Phase diagram shows phenomena controllable by electric field strength
- Electric shielding effects follow Arrhenius-like time dependence

## Abstract

Since a long time the application of small electric potentials on biological membranes (iontophoresis) proved enabling control and improvement of transdermal delivery of substances across this barrier. In spite of a large experimental data, the detailed molecular mechanism of iontophoresis is absent. In the present work the interaction among the external continuous electric field with the outermost layer of the skin (\textit{stratum corneum}) was studied by coarse-grained molecular dynamics. Our results pointed out the occurrence of water-rich vesicles formation depending on the field strength. The corresponding phase diagram indicated that the large set of phenomena (vesicle formation, reversibility, phase transition, disruption) could be completely controlled by tuning external continuous electric fields. Interestingly, electric field shielding effects are in the origin of observed effects and followed a general Arrhenius-like time dependence. Direct current (DC) electric field usage would also have booster diffusion effects due to vesicles creation and reincorporation which would have direct beneficial absorption effects on water-soluble topical agents (vitamins) or dermal jet-injection of drugs by fine needles.