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Plasma medicine is a relatively new field that investigates potential applications of cold atmospheric-pressure plasmas in bioengineering, such as for bacterial inactivation and degradation of organic molecules in water. In order to enunciate mechanisms of bacterial inactivation at molecular or atomic levels, we investigated the interaction of atmospheric-pressure air microplasmas with amino acids in aqueous solution by using high-resolution mass spectrometry (HRMS). Results show that the oxidation effect of plasma-induced species on the side chains of the amino acids can be categorized into four types, namely hydroxylation, nitration, dehydrogenation and dimerization. In addition, relative activities of amino acids resulting from plasma treatment come in descending order as follows: sulfur-containing carbon-chain amino acids > aromatic amino acids > five-membered ring amino acids > basic carbon-chain amino acids. Since amino acids are building blocks of proteins vital to the growth and reproduction of bacteria, these results provide an insight into the mechanism of bacterial inactivation by plasma. [ABSTRACT FROM AUTHOR]

A self-made microplasma jet array device is used to treat deoxyadenosine (dA) and adenosine (Ado) solutions to avoid the effect of air on genetic materials. Results show that Ado is easily converted into dA through deoxidation reaction. In addition, dA solution is treated with different microplasma arrays (i.e., atmospheric-pressure Ar, N2, air, and O2­) for comparative analysis. The dA molecule is relatively stable within the Ar plasma for 3 min treatment time. This molecule can be modified into different structures with N2, air, and O2 microplasma arrays. The results obtained in this study provide references for the application of plasma in biology and the effect of oxygen-containing free radicals in biological plasma. [ABSTRACT FROM AUTHOR]