Atmospheric-Pressure Plasma Essay Example | Topics and Well Written Essays - 1500 words

Atmospheric-Pressure Plasma - Essay Example However, the mechanism of regeneration of tissues through the short-time plasma exposure has not been explicitly revealed as yet in spite of its increased practical application. In order to improve the situation, it may be important to clarify the mechanism from multilateral standpoints including plasma science and engineering, molecular biology, and biochemistry. Therefore, we conducted a basic experiment on the direct irradiation of cells by using micro-spot atmospheric-pressure plasma source, which is hardly harmful to the living bodies both thermally and electromagnetically. In this experiment, murine fibroblast cell line (NIH3T3), which is usually used for cell experiments, was used and effect of plasma on the culture cells was considered. As a result of the experiment, it was revealed that cell multiplication is activated by plasma exposure. In response to the result, we considered factors related to the multiplication. Although there are many factors involved in the cell multi plication, we particularly focused on neoangiogenesis and NO production, and considered vascular endothelial growth factor (VEGF) and acidic fibroblast growth factor (bFGF). Schematic diagram of the experimental apparatus is shown in Fig 1. The apparatus comprised a coaxial structure with tungsten electrodes employed in a glass capillary (internal diameter of plasma genesis region: 8 mm, internal diameter of the tip: 1 mm) with cylindrical electrodes on the exterior. High voltage for plasma generation was generated by externally-controlled high-voltage power supply device. Plasma generation conditions were: applied voltage: 5-9 kV; frequency: 1-3 kHz; helium (He) gas flow rate: 1 L/min; and plasma exposure time: 1-100 sec. It was found in the earlier studies that NO gas is not generated by this apparatus. In the experiment, a culture containing 1 x 105 murine fibroblast cell lines (NIH3T3) was set in a 12-hole culture vessel. It was cultured for 24 hours in a CO2 incubator (culture conditions: temperature: 37 deg. C and CO2 gas concentration: 5%). The medium was replaced with serum-free medium. The unprocessed specimens (control), those processed with He gas flow and others exposed to plasma were compared. Processing time for each specimen group was 1, 10 and 100 sec, respectively. They were cultured for 24 hours in CO2 incubator after plasma exposure and then cell forms were observed with optical microscope. Afterwards, only live cells of NIH3T3 cell line attached to the bottom face of the culture vessel were peeled off by trypsin treatment and the number of cells under each condition was counted, followed by consideration of multiplication rate changes among the conditions. In addition to that, they were continuously cultured for 7 days in NIH3T3 cell line. Differences in the cell multiplication curves of specimens exposed to plasma for 90 sec per day and those processed with He gas flow were also considered. With this experiment, we considered the effects o f plasma exposure on cell multiplication based on both the trends of exposure time-dependent cell multiplication and the effects of plasma exposure on cell multiplication. Fig 2 shows cells exposed to the plasma. Culture medium thickness was 6 mm. Plasma was radiated from capillary of 1 mm diameter to cells adhering to 6 cm2 base area at a flow rate of 1 L/min.