Plasma Jets Facilitate Transdermal Drug Delivery

A new study describes how atmospheric microplasma irradiation (AMI) can be used to decrease the barrier function of skin and adapt it for transdermal drug delivery.

Researchers at Shizuoka University (Japan) used a plasma jet and a microplasma discharge method in order to investigate the barrier function of the stratum corneum – the outermost skin layer – of Yucatan micropig skin, which was chosen because of its similarities to human skin. The physical changes following plasma jet administration in the pig skin were studied microscopically, with the researchers focusing specifically on changes in the outer skin layer using Attenuated Total Reflectance – Fourier Transform InfraRed (ATR-FTIR) spectroscopy.

The ATR-FTIR spectra provides precise information about water content, the lipid bilayer, and proteins in the stratum corneum, all related directly to the skin’s permeability. The researchers found that when using AMI, which conducts electricity, they could successfully decrease the skin’s barrier function for transdermal drug delivery. A tape-stripping test – an evaluation method for skin-barrier performance – was also conducted to compare with AMI, confirming the findings. The study was presented at the 63rd AVS International Symposium and Exhibition, held during November 2016 in Nashville (TN, USA).

“Our data suggested that dye pathways through skin samples could be related to the dynamic behavior of intercellular lipid bilayers, suggesting that AMI could enhance percutaneous absorption,” said lead author and study presenter electrical engineer Marius Blajan, MSc, of the Shizuoka University Innovation and Joint Research Center. “Placement of skin on the conductive material caused burned spots on the skin by the plasma jet, while treatment of the skin by microplasma showed little physical damage.”

Delivering drugs through needles presents risks of infection to patients, not to mention causing pain and discomfort. Oral delivery of drugs, on the other hand, can prove toxic and can be less effective than more direct methods, unless higher does are administered. Transdermal delivery, where the drug is absorbed into the blood stream through the skin, provides an ideal solution, but only a fraction of drugs currently on the market can be administered this way because skin, by its very nature, is difficult to permeate, a characteristic measured by its barrier function.

Plasma is one of the four fundamental states of matter, the others being solid, liquid, and gas. The plasma stream contains charged particles: positive ions and negative electrons or ions, accompanied by dissociation of molecular bonds.

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Shizuoka University