| Non-equilibrium atmospheric pressure plasma jet(N-APPJ)can generate a wide variety of reactive oxygen and nitrogen species(RONS)under normal pressure and normal temperature,so it has a bright future in many medical applications,such as anti-infections,cancer treatments and skin diseases treatments.Based on these two facts:1.RONS are the key species of plasma for its biological effects;2.Most of plasma medical applications must interact with biological tissues.Thus,study on the penetration of RONS across biological tissues is important for the plasma medicine,which can help us to understand the fundamental of plasma medicine deeply,and can provide some directions for the optimization of plasma parameters or even broaden the plasma medical applications.Focus on the theme“on the penetration of the RONS generated by the N-APPJ across biological tissues”,most of researchers use gels(agar gel or gelatin gel)to mimic real biological tissues as the research models,which cannot reflect the penetration of RONS fully and truly due to the differences with the real bio-tissues in the components and structures;besides,a gel model cannot mimic various bio-tissues.In order to study the penetration of RONS generated by N-APPJ fully and truly,real bio-tissues were used as research models to systematically study the penetration of the RONS across the muscle tissue,the skin tissue and the stratum corneum(SC).To understand the penetration behaviors of RONS across biological tissues further,molecular dynamics simulations were used to simulate and analyze the penetration of RONS across the SC lipid bilayer.The main contents and results of this thesis are summarized as follows:1.Muscle tissue distributes widely in human body,so the penetration of RONS(OH,O3,H2O2,NO2-,NO3-,total RONS)across the muscle tissue was investigated.By measuring the RONS penetrating across the muscle tissue in different thicknesses(0,500?m,750?m,1000?m,1250?m),the permeabilities of RONS across muscle tissue can be compared and the depth of RONS penetration into the muscle tissue can be investigated.Experimental results indicated OH and O3 could not penetrate into the muscle tissue due to their strong reactivities;the RONS(total RONS)could penetrate into 1.25 mm in muscle tissue when the treatment time was 15min.2.Most of plasma medical applications must interact with the skin tissue,so the penetration of RONS(OH,1O2,O3,H2O2,NO2-,NO3-,total RONS)across the mice skin tissue was investigated.By measuring the RONS penetrating across and stored in the skin with or without SC layer,the permeabilities of RONS across skin can be compared and the function of SC layer in RONS penetration barrier can be investigated.Experimental results indicated OH,1O2 and O3 could not penetrate into skin tissue due to their strong reactivities;the SC on the skin tissue affected the penetration strongly,a half of total RONS could be blocked by the SC;lots of RONS stored in the skin tissue after plasma treatment,which indicated the skin could be a receiving pool of RONS and the accumulation effect of plasma treatment could be induced,then the longer affecting time and potential safety hazard induced by the accumulation effect should be noticed.3.The SC layer is the outermost layer of the skin tissue and mainly contribute the barrier effects of the skin.In order to verify what role the SC layer play in the penetration of RONS,the penetration of long-lived RONS(H2O2,NO2-,NO3-)across the SC layer was investigated.By measuring the RONS penetrating and stored in the SC layer in dry and moist environment,the permeabilities of RONS across SC layer in dry and moist environment can be compared.Experimental results indicated H2O2 hardly penetrated through SC,while NO2-and NO3-could penetrate through SC;when the SC was moist,the penetration and storage of RONS were enhanced because more RONS were produced at moist environment and the permeability of the SC was also increased.4.In order to understand the penetration behaviors of RONS across the SC layer in the atom level,the penetration of RONS(H2O2,OH,HO2,O2,O3,NO,NO2,N2O4,HNO2,HNO3,NO2-,NO3-)across the SC lipid bilayer were simulated and analyzed by the molecular dynamics simulations.By calculating the transaction energy of RONS across SC lipid bilayer,the permeabilities of RONS across the SC layer can be compared in the molecular level.Results indicated,for the electrically-neutral species,the SC lipid bilayer has lower free energy barrier for hydrophobic RONS(H2O2,OH,HO2,HNO2,HNO3)than hydrophilic RONS(O2,O3,NO,NO2,N2O4),which indicates hydrophobic RONS penetrate through SC layer easier than hydrophilic RONS;the bilayer has a higher free energy barrier for the ions species(NO2-,NO3-);when the lipid molecules are oxidized,the order of lipid bilayer is destroyed,resulting in the lower free energy barrier,which enhances the penetration of RONS. |
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