Study On The Interaction Between Heavy Metal Ions And Lung Surfactant

Heavy metals in the atmospheric environment are one of the key components that cause air pollution.In the atmospheric environment,about 75%to 90%of heavy metals and their compounds will be concentrated on particulate matter and suspended in the air for a long time,in different valence states And form transfer and transformation with each other.Pulmonary surfactant?PS?spreads at the alveolar air-liquid interface to form a liquid membrane layer with special surface activity?such as reducing surface tension?,while keeping the alveolar cavity relatively stable and maintaining normal lung function.The lung is the only internal organ in the human body that directly communicates with the outside world.Therefore,the PS in the outermost layer of the alveolar fluid membrane will directly contact with the external pollutants that enter the lungs through respiration.If its adsorption and expansion,the film formation is stable the destruction of interfacial properties such as sex and surface tension reduction will cause abnormalities in PS structure or function,resulting in various respiratory diseases.The heavy metal ions present in the lungs may catalyze or participate in the generation and transformation of various reactive oxygen species,which will break the dynamic equilibrium state of the body's oxidative-antioxidant system,trigger oxidative damage to the lungs,and aggravate the inflammatory response of the lung.In this paper,the interface interaction between seven soluble heavy metals Cr³⁺,Cu²⁺,Hg²⁺,Pb²⁺,Cd²⁺,Ni²⁺,Fe³⁺and PS in atmospheric particles was studied by using the in vitro simulation method and the interface model of the respiratory model?-A isotherm.The effects of PS on surface tension,phase behavior,collapse pressure,?max,compressible modulus and other interface characteristic parameters were explored.Based on this,combined with infrared spectroscopy,the mechanism of interaction between heavy metal ions and PS head groups was further revealed.And confirmed by AFM surface morphology observation,and finally explored the relationship between the·OH induced by these heavy metal ions and PS and its individual active components?DPPC and BSA?.Through the analysis of the experimental content and data,the research conclusions drawn are:?1?Through the study of the?-A isotherm of the breathing model,it was found that among the 7 heavy metal ions,in addition to Fe³⁺induced PS monolayer condensation,0.01 mol/L Fe³⁺,Cr³⁺,Cu²⁺,Hg²⁺,Pb²⁺,Cd²⁺and Ni²⁺heavy metal subphases the PS monolayer on the solution was advanced to varying degrees in the gas-liquid expansion phase?G-LE?and liquid expansion-liquid condensed phase?LE-LC?phases,which was measured in the presence of 7 heavy metal ions the change of PS surface tension is consistent.?2?By examining the?-A isotherms of the six ionic strengths?0.01,0.05,0.1mol/L?of Cd²⁺,Cr³⁺,Cu²⁺,Ni²⁺,Hg²⁺,and Fe³⁺on the PS single-layer film,we know the five other heavy metal ions other than Fe³⁺all show different degrees of advancement relative to pure water during the G-LE phase transition.Cd²⁺,Cr³⁺,Ni²⁺,and Hg²⁺still expand outward in a concentration-dependent manner during the LE-LC phase transition,but at this stage,Cu²⁺exhibited a narrowing phase transition.Among them,Cu²⁺and Fe³⁺have the most obvious influence on?max,and the collapse pressure delay appears after the Fe³⁺concentration increases.Through compressive modulus analysis,it was found that the addition of Cd²⁺,Hg²⁺,Cr³⁺,and Ni²⁺reduced the compressibility of the single-layer PS,and the ordering was enhanced;however,the Cs^-1curves of Cu²⁺and Fe³⁺were less than pure water,which may be combined with PS Related.?3?Four representative heavy metal ions Cu²⁺,Fe³⁺,Cd²⁺,Hg²⁺were selected to explore the mechanism of their interaction with PS.The results of infrared spectrum analysis showed that Cu²⁺not only interacts with N-?CH₃?₃in the PS head group There is electrostatic interaction,and it also complexes with PO^2-to form a complex,which causes the phase change to narrow;Fe³⁺can combine phosphatidylcholine and glycerol groups in PS to dehydrate C=O;Hg²⁺can also be combined with N-?CH₃?₃complexes to form a stable complex and change the structure of the PS membrane;the effect of Cd²⁺is significantly weaker than the other three metal ions,and its role with PS is mainly based on the phosphate group of the PS head as the binding site of static electricity.And the above conclusions are confirmed by AFM image characterization.?4?The output of·OH is affected by conditions such as time,H₂O₂concentration,heavy metal ion activity and strength,etc.The four heavy metal ions produced by Cu²⁺,Fe³⁺,Cd²⁺and Hg²⁺·OH reaches equilibrium after 24 h;A variety of heavy metal ions induce Fenton reaction at different H₂O₂concentrations.The order of·OH is:Cu²⁺>Fe³⁺>Cd²⁺>Hg²⁺.The yield of·OH generally increases with the increase of the redox active transition metal,and the antioxidant?Ascorbic acid?can chelate Fe³⁺and Cu²⁺to act as an electron donor,which increases the production of·OH.?5?·OH will attack the disulfide bond of the protein and destroy the quaternary structure of the protein to reduce the·OH concentration in the system,and the oxygen free radicals produced by different metals can modify PS lipids and proteins differently.The way it interacts with the PS component forms a reactive difference.·OH induced by these heavy metal ions and PS and its individual active components?DPPC and BSA?.