| Plasma medicine is an emerging interdisciplinary research field developed in the last twenty years,which aims to apply advanced plasma science and technology to clinical medical research.It shows great application prospects in biomedical field and provides new ideas for disease treatment.Plasma medicine is a relatively new field initiated by high voltage discharge technology and the frontier of biological electromagnetic research area.In addition to ultraviolet radiation and electric field,plasma also generates a variety of chemical species,among which ROS(Reactive Oxygen Species)and RNS(Reactive Nitrogen Species)are considered to be critical for plasma to exert biological effects.The effects of plasma treatment on biological tissue and even the human body have already been demonstrated by a multitude of experimental studies,but little is known about the internal mechanism of plasma medicine.Therefore,the reactive molecular dynamic simulation is performed in this paper to investigate the interaction mechanism of ROS produced in plasma with fatty acids in vegetable oil and peptide structures,with the goal of clarifying the mechanism of plasma with vegetable oil and proteins and deepening the understanding of plasma medicine.In recent years,plasma-activated liquids have been presented as a new tool for biomedical applications,where vegetable oils treated by plasma jets are found to play an important role in wound healing,but the underlying mechanism is still unclear.Therefore,a reactive molecular dynamic simulation is performed to investigate the interaction of ROS and fatty acids of vegetable oil,analyze the specific reaction processes between ROS and fatty acids,and determine the final products of fatty acids and newly generated active groups after plasma treatment.For example,unsaturated chemical bonds are formed on fatty acids due to the dehydrogenation reaction,and alcohols and aldehyde groups are added to fatty acids after addition reactions,or carboxylic acids and unsaturated aldehydes are generated during reaction processes.Furthermore,the dose effect of ROS is also investigated in the simulation,and it can be found that the dose of ROS is an important factor affecting the oxidation of fatty acids.Usually,the ratio of bond breaking and formation for fatty acids will increase by increasing the number of species.Proteins yield chemical modifications similar to post-translational protein modifications in organisms during plasma treatment,leading to changes in protein conformation that affect their functions.Proteins are compounds folded from polypeptide chains formed by dehydration condensation of amino acids.In order to reduce the computational burden,two peptides with a length of 10 amino acids are selected as the research object in this paper,and the interaction mechanism between ROS and peptide structures is investigated from the perspective of simulation.According to the simulation results,the oxidation targets of plasma are the amino acid side chains within the investigated peptides,and oxidative modifications such as dehydrogenation,sulfonation,hydroxylation,carbonylation,nitrosylation,ring cleavage and decarboxylation can be observed.These results show that both the type and dose of ROS are the necessary factors affecting the degree of oxidative modifications of peptides.When the peptide reacts with 100 O atoms,the phenomenon of peptide chain fragmentation occurs,which may induce the denaturation or inactivation of the protein.In this study,the reactive molecular dynamic simulation is used to explore the interaction mechanism of ROS produced in plasma with fatty acids in vegetable oil and peptide structures,as well as to provide the specific reaction processes and detailed reaction pathways between plasma and biomolecules on the molecular level.This research will contribute to a better understanding of the interactions of plasma reactive species and macromolecular structures,which further promotes the development of plasma medicine and plasma pharmacy. |
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