Mechanistic Study Of Plasma Interactions With DNA Molecules Based On Reaction Molecular

Plasma medicine is a new research field of plasma science and biomedicine.In recent years,the rapid progress of Cold Atmospheric Plasma(CAP)technology has greatly promoted the development of Plasma medicine.There are many active components in CAP,among which Reactive Oxygen Species(ROS)is considered as the key component for CAP to play a biomedical role.ROS can interact with biological molecules in tissues or cells to change their molecular structure.It may also affect the normal physiological processes of the cell as a signaling factor.Our research group has proved that krill oil activated by CAP has highly effective anti-cancer activity,which indicates that ROS leads to the change of krill oil composition.The specific change process and the mechanism of krill oil activity improvement cannot be determined by experiments,and further exploration is still needed.In addition,other studies have shown that plasma can effectively kill cancer cells,and there are fragmented DNA fragments in the inactivated cancer cells,which is believed to be caused by ROS.However,people's understanding of the microscopic mechanism of the specific reaction between ROS and DNA molecules is still not very clear,which also requires further in-depth research.Along with the development of computer technology,molecular simulation technology has become an important means to explore the microscopic reaction mechanism between material,it can break through the oneness and limitations of experiment testing means,is a powerful supplement of the experimental method and theory method.In recent years,more and more scholars have applied the molecular simulation technology to the research of plasma medicine,which has been widely recognized.The above phenomena were simulated by the method of reaction molecular dynamics and the plasma dose problem was also studied.The main contents of this paper mainly include the following aspects:1.The atmospheric pressure low-temperature plasma is briefly introduced,the application of CAP in biomedicine is summarized,and the feasibility of the application of molecular simulation in biomedicine is demonstrated.The simulation method of reaction molecular dynamics and ReaxFF field used in this paper are introduced,the principle of reaction molecular dynamics method is explained in detail,and the establishment of simulation model and pretreatment process are discussed.Then,taking the structure of capsid protein of HIV as an example,we analyzed the microscopic reaction process between plasma ROS and capsid protein,and discussed the effect of dose action,which proved the effectiveness of the reaction molecular dynamics method.2.The main components of krill oil were analyzed.Taking EPA,DHA and astaxanidin,three components with anti-cancer effects,as the research objects,I established the corresponding model,conducted the simulation of reaction molecular dynamics,and analyzed the reaction paths and related products of chemical reactions.It was found that the structure of astaxanthin was destroyed under the action of plasma,and astaxanthin could not maintain strong antioxidant,which also had a great impact on its anti-cancer effect.Due to the role of ROS,EPA and DHA have mainly changed in two aspects.On the one hand,the isolated double bonds on the two molecules are converted into more active conjugated polyene bonds.On the other hand,there is a chance that the terminal methyl group can be oxidized to an aldehyde group,which eventually produces unsaturated aldehydes,which are biotoxic and can cause damage to cancer cells.Therefore,EPA and DHA can be transformed into more biologically active structures after being treated by plasma,which may be the key to improving the anti-cancer effect of krill oil after being activated by plasma.3.In this paper,the reactions of the ground state oxygen atoms,hydroxyl groups and hydrogen peroxide molecules with the four basic deoxynucleotides that constitute DNA in the plasma were simulated by the method of reaction molecular dynamics.Through the simulation,it is found that oxygen atoms and hydroxyl groups can destroy the bases and deoxyribose of deoxynucleotides by taking away hydrogen,which may lead to the breaking of hydrogen bonds and phosphodiester bonds in DNA molecules,thus causing the separation of DNA double chains and even the breaking of DNA skeleton.The hydrogen peroxide molecule can both grab hydrogen from the base and add hydrogen to the base to affect the distribution of hydrogen,thus breaking the hydrogen bond between DNA molecules,but the hydrogen peroxide molecule has little effect on the part of the deoxyribose.Of the three ROS types,oxygen is the most effective at capturing hydrogen,followed by the hydroxyl group,the weakest is the hydrogen peroxide molecule,and cytosine and guanine are more susceptible to hydrogen capture than thymine and adenine.By comparing the reactions of oxygen atoms with different concentrations,it is found that as the oxygen atom concentration increases,the probability that the hydrogen atoms of the base are taken away increases,and the hydrogen loss on deoxyribose also shows a similar trend.However,the probability of chain scission and ribose ring opening did not continue to increase with the increase in the concentration of oxygen atoms,but remained relatively early at a level.This is mainly due to the occurrence of olefinic bonds on the ring of deoxyribose under the action of high concentration of oxygen atoms.