Research On The Mechanisms Of Interactions Between Atmospheric Pressure Low Temperature Plasma And Pathogens

In recent years,atmospheric pressure low temperature plasma(APLTP)has attracted considerable interest in the field of biomedicine,especially with regard to disinfection.Low temperature plasma with non-toxic,hazard-free,non-polluting,high efficiency and reliable is favored.Particularly,there are many reactive species in plasma when reactant gases(N2,O2)are used.Numerous experimental studies have revealed that reactive species play crucial roles in biological disinfection.However,most investigations on the mechanisms of plasma sterilization are at the stage of experiment and the sterilization mechanisms are controversial.Namely,the microscopic mechanisms underlying the interactions between plasma-generated species and bio-organisms have not yet been elucidated clearly.Therefore,it is urgent to find a new way to clarify the microscopic mechanisms of plasma sterilization.To elucidate the mechanisms of plasma sterilization at the molecular level and from the angel of biochemical reaction,the present work carries out a series of works.The paper is organized as follows:First,two appropriate molecular simulation methods that can precisely describe the processes of plasma sterilization are analyzed in detail.Subsequently,proper bio-molecular models of pathogens are established.Finally,the biochemical reactions between reactive oxygen plasma species and bio-organisms are simulated and the deep inactivation mechanisms are investigated intensively.Several observations were made,which are given below:(1)Based on a variety of frequently-used molecular simulation methods,we analyze deeply the applicability of molecular dynamics and reactive molecular dynamics simulation methods in plasma medicine,which can lay a theoretical foundation for investigation of the microscopic mechanisms of plasma disinfection.(2)Based on ReaxFF molecular dynamics simulation method,we build the?-1,6-glucan(a skeleton model for the C.albicans cell wall).Then ReaxFF-MD is employed to investigate the mechanisms of interactions between reactive oxygen plasma species(O,OH,and O2)and ?-1,6-glucan.Our simulations show that O2 molecules exhibit only weak,non-bonded interactions with ?-1,6-glucan,while O and OH species can create biochemical reactions with ?-1,6-glucan,causing irreversible damage to the cell wall by breaking structurally important bonds(C-C and C-O bonds)and introducing new functional groups(C=O and C=C bonds).The latter two species are similar in damage mechanisms.The only difference is that O atom is more active.(3)Based on molecular dynamics simulation method,we build the POPC-SPC water membrane model.Then MD is employed to investigate the microscopic mechanisms of reactive oxygen plasma species(O2,OH,and H2O2)penetrating membrane.Our simulations show that the difficult degree of different kinds of species penetrating membrane is obvious due to the interactions between every kind species and POPC and the permeable barrier energy.The morphological characteristics of membrane are also changed in these processes,which causing the fluidity of membrane to change.The penetration behavior enhances the oxidative stress level in the cell and increasing the death rate of pathogens.In the present work,two molecular dynamics simulation methods are employed for the first time to investigate the mechanisms of interactions between plasma-generated species and bio-organisms,which can establish the relations between microstructure and macroscopic properties of plasma sterilization.We can make a more detailed and accurate assessment to plasma biomedicine.Furthermore,the simulation results can provide much support for the improvement of sterilization and related mechanisms using atmospheric pressure low temperature plasma,which will promote the development of plasma medicine.