Technical applications of plasma treatments: current state and perspectives.

Rapidly evolving cold atmospheric pressure plasma (CAPP)-based technology has been actively used not only in bioresearch but also in biotechnology, food safety and processing, agriculture, and medicine. High variability in plasma device configurations and electrode layouts has accelerated non-thermal plasma applications in treatment of various biomaterials and surfaces of all sizes. Mode of cold plasma action is likely associated with synergistic effect of biologically active plasma components, such as UV radiation or reactive species. CAPP has been employed in inactivation of viruses, to combat resistant microorganisms (antibiotic resistant bacteria, spores, biofilms, fungi) and tumors, to degrade toxins, to modify surfaces and their properties, to increase microbial production of compounds, and to facilitate wound healing, blood coagulation, and teeth whitening. The mini-review provides a brief overview of non-thermal plasma sources and recent achievements in biological sciences. We have also included pros and cons of CAPP technologies as well as future directions in biosciences and their respective industrial fields.

Cold plasma treatment triggers antioxidative defense system and induces changes in hyphal surface and subcellular structures of Aspergillus flavus.

The cold atmospheric-pressure plasma (CAPP) has become one of the recent effective decontamination technologies, but CAPP interactions with biological material remain the subject of many studies. The CAPP generates numerous types of particles and radiations that synergistically affect cells and tissues differently depending on their structure. In this study, we investigated the effect of CAPP generated by diffuse coplanar surface barrier discharge on hyphae of Aspergillus flavus. Hyphae underwent massive structural changes after plasma treatment. Scanning electron microscopy showed drying hyphae that were forming creases on the hyphal surface. ATR-FTIR analysis demonstrated an increase of signal intensity for C=O and C-O stretching vibrations indicating chemical changes in molecular structures located on hyphal surface. The increase in membrane permeability was detected by the fluorescent dye, propidium iodide. Biomass dry weight determination and increase in permeability indicated leakage of cell content and subsequent death. Disintegration of nuclei and DNA degradation confirmed cell death after plasma treatment. Damage of plasma membrane was related to lipoperoxidation that was determined by higher levels of thiobarbituric acid reactive species after plasma treatment. The CAPP treatment led to rise of intracellular ROS levels detected by fluorescent microscopy using 2',7'-dichlorodihydrofluorescein diacetate. At the same time, antioxidant enzyme activities increased, and level of reduced glutathione decreased. The results in this study indicated that the CAPP treatment in A. flavus targeted both cell surface structures, cell wall, and plasma membrane, inflicting injury on hyphal cells which led to subsequent oxidative stress and finally cell death at higher CAPP doses.