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The aim of the present study is to determine the deoxyribonucleic acid (DNA) damage by cells exposed to atmospheric pressure non-thermal plasma (APNTP). Mouse leukocytes embedded in agarose were exposed to the plasma at two different distances from a helium plasma needle outlet and during three different exposure periods. Damage was assessed by the single cell gel electrophoresis assay. The results indicate that, at 0.1 cm from the plasma needle, the exposure caused complete DNA fragmentation determined by the presence of so called "clouds". Samples exposed at 0.5 cm from the slide sample surface presented damage proportional to the exposure periods in terms of tail intensity, tail moment and "clouds" frequency. Studies performed with alkaline single cell gel electrophoresis assay to determine DNA breaks and alkali-labile sites, indicates that DNA damage produced by exposure to APNTP was caused mainly by oxidative radicals, rather than by UV light which causes cyclobutane pyrimidine dimers. These results allow us to conclude that plasma needle induced DNA breaks in mice leukocytes proportionally to exposure time.

Plasma immersion ion implantation (PIII) has proved to be a good method to implant ions into materials in order to modify their surface properties. In this article, we describe the design and construction of a small and low cost PIII device. The instrumentation consists of: (i) a simple plasma immersion experimental setup for ion implantation based on direct current glow discharges, (ii) a 25 kV pulse generator, (iii) an electrical probe system endowed with a guard to carry out diagnostics of the plasma parameters, and (iv) an automatic spectroscopy system for determining the plasma temperature. A study of the sheath expansion has been considered in order to fulfill the requirements of electron temperature, plasma density, high voltage bias, pulse frequency, and pulse duration for an adequate PIII process. [ABSTRACT FROM AUTHOR]