Skin Hydrophilization and Disinfection of T. mentagrophytes using Multi-Gas Stylus-Type Plasma Jet

Atmospheric low temperature plasma irradiation has been reported to promote healing in chronic wounds, selectively kill cancer cells. It is essential to selectively target the infected area without damaging the surrounding tissue. In this study, we developed a multi-gas stylus-type plasma jet for processing narrow areas, and hydrophilization effect on the skin surface by plasma irradiation, as well as disinfection effect against T. mentagrophytes which causative fungus of athlete’s foot was investigated.

The multi-gas stylus-type plasma jet has a diameter of the cylinder at the tip is 8 mm and the nozzle inner diameter of 0.8 mm. Plasma is generated using an AC voltage of 3.6 kV at a frequency of 16 kHz. This device can generate plasma using argon, nitrogen, oxygen, carbon dioxide, air, and mixtures of these gases. In the experiments, a fiber-optic thermometer was positioned 5 mm below the irradiation nozzle to monitor the plasma gas temperature. The irradiation distance was set to 5 mm, and the discharge voltage was controlled to keep the plasma temperature below 40 °C in order to prevent thermal denaturation of skin proteins.

Samples for the disinfection experiment were prepared by dropping 10 μL of a bacterial suspension of T. mentagrophytes onto glass plates and allowing them to dry. After the plasma irradiation, bacteria were recovered and made step wise dilution, the number of living bacteria were counted after incubation. In the presentation, the disinfection effect on T. mentagrophytes will be reported.