Harvard-MIT Division of Health Sciences and Technology
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In Silico Bioelectromagnetics
Electroporation Theory
Magnetic Field Effects
Weak Field Effects
Microconduit Creation
Skin Electroporation

Skin Electroporation

Localized Transport Regions in Human Skin, unconstrained (left) and constrained (right)

Rapid, controlled molecular transport across human skin is of great interest for transdermal drug delivery and non-invasive chemical sensing. The main barrier is the stratum corneum (SC), which can be described by a ``brick wall'' model in which the dead, hydrated corneocytes are the bricks, and the surrounding multilamellar lipid bilayer membranes are the mortar. Small lipid-soluble molecules can partition into the SC, and then diffuse across the lipid bilayer membranes, but water soluble molecules, particularly charged molecules, cannot penetrate significantly by this route.

Our general hypothesis is that high voltage (HV) pulsing (Uskin > 50V) creates aqueous pathways (``pores'') through stratum corneum (SC) lipid bilayer membranes, a more specific hypothesis is that short pathway segments are formed across 5--6 lipid bilayer membranes which connect adjacent corneocyte interiors forming transcellular straight-through pathways. Moderate voltage (MV) (Uskin = 5 to 50V) pulses appear to electroporate cell linings of the appendages. Our overall aim continues to be understanding of the mechanism of electrical creation of pathways, and the associated ionic and molecular transport.

Previous work shows that pulsing causes large and rapid increases in the flux of charged molecules across human skin. The basic idea is to permeabilize the SC (reversibly or irreversibly, under control), to provide major improvements in transdermal drug delivery and the possibility of better minimally-invasive sampling of subcutaneous fluid analytes (e.g. glucose).