This is a sterilization technique for those materials where the existing methods (Wet/Dry heat, Irradiation, Chemical gases etc) is not suitable / applicable. The material properties, such as molecular weight, volume, and morphology, of sensitive devices, including polymeric biomaterials, can be negatively altered. This can influence the physical and biological performance of the device. Cold atmospheric plasma (CAP) technology does not have these disadvantages.
The plasmas operate under atmospheric conditions below 40°C. CAP is a weakly ionized gas. Only a small fraction of gas atoms and molecules, which are the main carriers of heat, collide with electrically generated highly energetic electrons. This results in further excitation, ionization, and dissociation, while the plasma remains “cold.” CAP specifications permit the disinfection or sterilization of thermo sensitive materials and allow in vivo applications, opening a new and larger spectrum of possible applications.
The first devices developed have already proven their bactericidal properties in vitro, ex vivo, and in vivo.
A micro-hollow cathode based, direct-current, atmospheric pressure, He/O2He/O2 (2%) cold plasma microjet was used to inactive antifungal resistants Candida albicans, Candida krusei, and Candida glabrata in air and in water. Effective inactivation (>90%) was achieved in 10 min in air and 1 min in water.
Antifungal susceptibility tests showed drastic reduction of the minimum inhibitory concentration after plasma treatment. The inactivation was attributed to the reactive oxygen species generated in plasma or in water. Hydroxyl and singlet molecular oxygen radicals were detected in plasma-water system by electron spin resonance spectroscopy. This approach proposed a promising clinical dermatology therapy.
Fungal skin and nail infections pose significant therapeutic and economical problems. To test the plasma susceptibility of clinical strains of the most frequently encountered fungal species involved in dermatomycosis, clinical isolates of Trichophyton interdigitale, Trichophyton rubrum, Microsporum canis, and Candida albicans were irradiated by a cold atmospheric pressure plasma jet. Punctual plasma irradiation eradicated fungal growth of all species with the largest inactivation zones with most progress in the first 15 s of treatment, treating C. albicans and least progress in that of the lowest being M. canis. No isolate exhibited resistance to plasma treatment. Plasma treatment also completely eradicated reproductive fungal elements of T. interdigitale in dandruff of patients with Tinea pedis ex vivo and in the environment in contaminated shoes. Accordingly, cold plasma seems suited to antifungal in vivo treatment of fungal skin infections and decontamination of environmental infective material.
The technologies are evolving fast, there are a number of publication, infact the above one is cut and paste from published literature.