Analysis of Non-Thermal Plasma-Treated Water using Single Molecule Measurement of Large DNA Damage
S. Cunningham1, T. Nakajima2, H. Kurita2, H. Yasuda2, K. Takashima2, and A. Mizuno2
1Department of Electrical Engineering, University of Glasgow, Scotland, United Kingdom
2Department of Environmental and Life Sciences, Toyohashi University of Technology, Japan
Abstract— An investigation to evaluate water safety regarding residual radicals as a result of water exposure to non-thermal plasma (NTP) is reported. In this investigation the kinetic of strand breakages of large DNA molecules suspended in water exposed to an argon plasma jet was studied using single molecule measurements. The single molecule measurements were also conducted on pure water after post exposure to plasma. Results show that plasma (Argon jet) exposure caused a marked reduction in length of DNA molecules suspended in water. The value of constant k- (compare the average length of DNA) was estimated using a simple mathematical model. The estimated k-value was less than 1/20 of that of the direct exposure. Data analysis show that k-value decreased by increasing the post-exposure time to plasma. Evidence of fragmentation of DNA molecules lasted at least 1 hour after plasma exposure (the longest post exposure time measured in the experiment). This direct DNA fragments analysis allows the evaluation of safety of plasma treated water effectively. It also permits the comparison between the effects of different plasma treatments on DNA rate of fragmentation. It is not clear from the data if the increase in exposure time causes an increase in the number of radicals or another mechanism is taking place.
Keywords— Non-thermal atmospheric pressure plasma, plasma-treated water, DNA damage, single-molecule DNA