等离子体放电活化生理盐水杀菌应用研究

Bacteria sterilization application by using plasma activated physiological saline

等离子体中含有多种活性物种可实现高效安全杀菌,活性物种与生物体相互作用多在水环境下进行.因此等离子体与水的相互作用过程研究掀起了等离子体生物杀菌的新浪潮.本文采用水中阵列放电产生等离子体活化生理盐水,利用所产生的活化生理盐水对大肠杆菌开展了杀菌消毒研究,当等离子体放电时间达到120 s时产生的活化生理盐水与大肠杆菌混合后可使大肠杆菌的存活效率降至0.001%.通过紫外-可见吸收光谱测量及化学氧化还原沉降滴定表明放电电荷及激发态氧化性活性物种与水溶液相互作用,转化为活化生理盐水中长寿命相对稳定存在的H_2O_2和O_3等氧化性物种,与大肠杆菌作用并主导主要杀菌效果.

The plasma activated water has great application prospects in the fields of environmental protection, biomedicine, food safety, et al., due to its unique chemical activity. In this work, the plasma activated physiological saline is successfully generated by using hollow fiber-based cold microplasma jet array running in physiological saline solution. This design can lead to an obvious increase in the contact area between microplasmas and treated physiological saline solution, thus improving the chemical reaction e-ciency of short-lived species. The influences of working gases such as He, N2, O2 and air on the sterilization e-ciency of E. coli by using this plasma activated physiological saline are investigated as a function of discharge time. As the discharge time increases from 10 to 180 s, the sterilization e-ciency of the plasma activated physiological saline significantly increases. It is found that the bactericidal e-ciency of the air discharge activated physiological saline is highest. For a discharge time of 120 s, the sterilization e-ciency of E. coli in this plasma activated physiological saline can reach as high as 99.999%. The pH value of this air discharge activated physiological saline is achieved by using acidity meter and as the discharge time increases from 10 to 60 s, the pH value decreases from 7.3 to 3.1 and the physiological solution becomes acidic. This may be due to the NOX produced in the plasma reacting with water and producing nitric and nitrate acids. The reactive oxygen species generated in the plasma activated physiological saline are supposed to be O3 and H2O2. The concentrations of O3 and H2O2 are identified by using UV-visible absorption spectra and chemical deposition methods. The strong absorption peak of O3 in UV-visible absorption spectrum is at a wavelength of 253.7 nm. The concentration of O3 is calculated by using Beer-Lambert Law. As the discharge time increases, the concentration of O3 in the plasma activated physiological saline obviously increases. For a discharge time of 60 s, the concentration of O3 is 43.12 × 10-3 mol/L and nearly saturated. The concentration of H2O2 is obtained by the total amount of reactive oxygen species, which is calculated by using the chemical deposition method, deducting the O3 content. As the discharge time increases from 10 to 180 s, the concentration of H2O2 increases from 1.5× 10-3 to 4.7 × 10-3 mol/L. The analyses of experimental data from various methods indicate that air discharge activated physiological saline containing a variety of long-lived reactive oxygen species, such as H2O2 and O3, is very effective in killing E. coli cells in the acidic saline solution. The air discharge activated physiological saline can provide a means to store the advanced oxidation species induced by the discharge for sterilization applications.