大气压等离子体与细胞相互作用的理论研究

Plasma medicine or biomedical application is an emerging field in atmospheric plasma research. It is a relatively recent area of research compared to traditional areas of plasma processing, and has been growing very quickly in recent years. It is very much a multidisciplinary field on the intersection of medicine, biology, microbiology, chemistry, biochemistry and physics. Plasma medicine envisages to offer an improved alternative to existing technologies for e.g. inactivation of microorganisms, blood coagulation, cancer treatment, and dental surgery. For improving these applications, a good insight in the interaction of the plasma with the relevant biomolecules is indispensable, in order to control the processes occurring in the contact region of the plasma with the bio-organisms. However, this still remains a big challenge. Computer simulations usually could also be very valuable, and complementary to experiments, as they can study the interaction processes in detail, even on the atomic level, which is difficult to achieve by experiments. For studying the interaction processes between plasma species and biomolecules. Various simulation studies have been highlighted, including both atomic-scale methods, i.e. reactive molecular dynamics (MD) simulations, and macro scale methods (typically as part of hydrodynamic models, that are used to describe the plasma behavior). Macro scale methods typically make use of reaction–diffusion equations or a reactive penetration model for mass-transfer of plasma species across a gas-liquid boundary. Researchers developed a model to describe the non-plasma material by considering it as a dielectric material with certain conductivity and permittivity, to represent for instance the cell membrane. Typical results of such simulation studies include the fluxes and densities of radicals and ions towards the treated surface. This type of model can yield information about plasma–cell interaction in the millisecond time-scale and beyond, but due to the nature of these models, the resolution is limited to the supramolecular level. This allows, for instance, to obtain some insight in the propagation of electric fields through the cell, but it cannot provide information on the atomic-scale interaction of plasma species with biomolecules. Furthermore, this type of models makes use of input parameters, such as the conductivity and permittivity of a cell, which are not always well known, so this modeling approach is more approximate. In this study these atomic-scale simulations could be coupled to macro scale simulations, by using detailed atomistic MD results (e.g., chemical reaction probabilities) as input for macro scale simulations, to cover a much wider scale of the biomedical systems. The simulation results will deepen the understanding of plasma-cell interactions at atmospheric pressure.

等离子体医学是随着大气压气体放电技术的发展而兴起的交叉学科研究领域，实验研究已经表明等离子体在生物医学应用方面的有效性，然而从理论上对其内在机理却仍然缺乏深刻认识。本项目拟以介质阻挡放电与等离子体射流为等离子体源，以细菌与真核细胞为处理对象，借助于理论模型重点研究等离子体与细胞相互作用的电磁效应与生化效应。通过耦合等离子体流体模型与细胞多层介电模型，从整体上自洽的研究电场在细胞内的分布，电荷积累与能量密度传输对细胞的影响。借助于反应分子动力学模拟，研究等离子体中活性粒子与细胞中生物大分子的相互作用，讨论化学键断裂的种类与概率，特别是与流体模拟耦合，给出微观机理的宏观效应，进而直接与实验测量对比。使用该模型研究等离子体剂量对细胞的影响,重点分析对化学键断裂种类与概率的影响。本项目的研究将深化人们对等离子体与细胞相互作用机理的认识,并根据理论结果提出调控与优化等离子体医学应用的有效手段。

等离子体医学是随着大气压等离子体技术的发展而兴起的典型的交叉学科，涉及到物理、生物、电气、化学等多学科知识的交叉融合。等离子体在生物医学方面的应用已显示了其独特的优势，但其内在机理仍需要深入的理论研究。本研究结合等离子体流体模型与生物电磁模型，研究了等离子体作用于细胞上的电磁效应，分析了细胞内各层的电压分布及肿瘤细胞与正常细胞电压分布的比较。同时借助于反应分子动力学模拟，将流体模拟的结果作为输入参数，分析了活性粒子（主要包括O，OH，O3，H2O2等中性基态粒子）对构成蛋白质的主要氨基酸结构的作用效果，包括化学键断裂与合成的种类与具体过程，进而总结分析了活性粒子对较大蛋白质结构的可能影响；研究了活性粒子作用于四种DNA基本构成单元的过程，分析了活性基团的分解与合成，并与实验结果进行了比较。同时研究等离子体对橄榄油的影响，分析了活性粒子作用于油酸、亚油酸与软脂酸等的具体过程，并讨论了新活性基团的生成与演化，得到了与实验测量一致的结果。这些研究，系统发展了研究等离子体医学的理论方法与计算手段，深化了人们对等离子体医学内在机理的理解。