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Modulation Of MWCNTs' Perturbation To The Metabolic Activity Of CYP3A4 In The Liver And ZrO2NPs To Cytotoxicity Of Pollutants In MOECP

Posted on:2019-03-31Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y B WangFull Text:PDF
GTID:1360330572456694Subject:Analytical Chemistry
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With the rapid development of nanotechnology,nanonaterials have been applied to every field of life.Nearly 2,000 nanomaterials consumer products have been marketed and widely used in daily life.Nanomaterials are divided into zero-dimensional,one-dimensional and two-dimensional materials.CNTs are one-dimensional quantum materials with special structure,while ZrO,nanoparticles(ZrO2NPs)belong to the zero-dimensional materials.Nanomaterials are widely used not only in electronic devices,functional coatings,sewage treatment,but also in biological medicine such as drug delivery,imaging and tissue engineering.This increases the chances that the body will come into contact with these nanomaterials.Whether through unintentional pathways such as breathing and skin contact,or through oral and intravenous injection,nanoparticles enter the body and can be absorbed into the body's circulatory system,which are then mainly accumulated in organs of the reticuloendothelial system,such as liver.At present,the study and application of nanomaterials have changed the physical and chemical properties of nanomaterials,while the uptake,transport and fate of nanomaterials in cells are mainly influenced by their own physical and chemical properties.Understanding the safety issues of nanomaterials requires further understanding of how nanoparticles interact with biological systems and what their biological consequences are,which often lack systematic research.High specific surface area of nanometer particles indicates the surface chemical modification can be used to adjust its interact with biological systems,so we advocate for the systematic modification of physical and chemical properties of nanomaterials,and a comprehensive evaluation,leading to a QSAR model proved to be effective.In this thesis,effect of 84 kinds of MWCNTs with different surface modifications on the metabolism of hepatic drug enzyme CYP3A4 was first studied,and the QSAR model was constructed to predict the structure-activity relationship between them.It has been reported that regardless of the administration route,the accumulated organs of MWCNTs in the body are mainly the liver,which is often metabolized for months or years.The liver is an important detoxifying organ in the human body.The accumulation of carbon nanotubes in the liver raises concerns about whether nanoparticles will interfere with the metabolic function of liver CYP450 enzyme.Vivo studies have shown that there were indications that nano-particles interfere with the activity of CYP450,but it is not clear whether MWCNTs also have a certain interference effect and whether the surface properties of MWCNTs can regulate their effects on the activity of CYP450.Because CYP3A4 is not only the most abundant(30-60%)cytochrome protein in human,but also the subfamily of cytochrome with the largest number of metabolic drugs.In this work,we investigated the interaction between surface functionalized MWCNTs and hepatic drug enzyme CYP3A4.We found that:1)MWCNTs not only entered liver kupffer cells,but also into liver parenchyma cells after intravenous injection.Since CYP450 is mainly present in hepatocytes,it provides a necessary prerequisite for studying the interaction between MWCNTs and various CYP450.2)MWCNTs bind to a variety of CYP 450 enzymes,including CYP3A4,but MWCN-Ts with different surface modifications bind to the CYP 450 isoforms slightly differently,and have different binding forces with CYP3A4.This combination changes the secondary structure of CYP3A4 and the ability to metabolize drugs.3)Various chemical modifications were performed on the surface of MWCNTs to regulate their effects on the metabolic activity of CYP3A4.Among them,14 MWCNTs could enhance the metabolic activity of CYP3A4,34 MWCNTs could not change the metabolic activity of CYP3A4 and 32 MWCNTs could inhibit the metabolic activity of CYP3A4.In addition,in order to quantify the nature of MWCNTs without changing CYP3A4 activity,we studied the structure-activity relationship(QSAR)of MWCNTs surface ligands and determined the chemical characteristics of surface ligands that should be avoided.Through QSAR analysis of structure-activity relationships,it was determined that drug molecules with long and complex hydrophobic or aromatic side chains on the surface of the nanotubes were responsible for inducing the inhibition of f-MWCNTs on the metabolic activity of CYP3A4,while drug molecules with less aromatic properties and less tertiary nitrogen were more likely to prodduce safe carbon nanotubes.The results of this study indicated that the surface chemical properties of MWCNTs provided a feasible way to regulate the perturbation of its intrahepatic enzymes.Moreover,we can obtain sufficient experimental data based on systematic modification to establish a quantitative prediction model of structure-activity relationship,which is of great guiding significance for the development of the properties of nanomaterials with applicability.In addition to the combined library of MWCNTs,this paper also studies systematic studies on different toxic effects of ZrO2 nanomaterials commonly used in water treatment when exposed to the environment and co-exposed to different pollutants.ZrO2NPs are often used to synthesize ZrO2 composites to treat contaminants in water,such as As(?),PO43-,F-,Pb(?),Cd(?)and Cr(?),because they are metal,oxides with both acidic and alkaline levels on the surface and are resistant to acid and alkali and relatively safer than other nanomaterials.However,ZrO2 composites release ZrO2 nanoparticles during water treatment,so ZrO2 nanoparticles enter the organism through oral exposure.The nanoparticles are first absorbed through the gastrointestinal tract into the bloodstream,then distributed to the liver and kidneys,and eventually eliminated from the body.Therefore,we assessed the cytotoxicity of ZrO2NPs,contaminants(As,F,Pb,Cd and Cr)and ZrO2NP/pollutant complexes using a cell combination model that simulates human oral exposure,including GES-1,FHC,HepG2 and HEK293.We found:1)different pollutants are selective for different organ cells.The toxicity intensity of ZrO2NPs on cell lines from different organ sources was successively:GES-1>FHC>HEK293>HepG2;The main toxic target organs of Pb2+ and Cd2+ are liver(HepG2)and kidney(HEK293).F" showed obvious toxic effect on the other three cell lines except HepG2.The toxicity of As(?)to the four cell lines was the same;Cr(?)was significantly toxic to cell lines other than GES-1.This strongly suggests that it is necessary to model human cell combinations that mimic oral exposure.2)When exposed together with ZrO2NPs,Pb(?),Cd(?),Cr(?),As(?)and F-,the cytotoxicity induced by the complex is quite complex,including synergistic,antagonistic or additive effects.For example,ZrO2NPS and Pb(?)have synergistic effects to enhance Pb(?)toxicity in ges-1 cells,while those in HepG2 and HEK293 have antagonistic effects to mitigate Pb(?)cytotoxicity.Our results also indicated that ZrO2NPs exposure was considered safe even when the concentration of pollutants under state stipulated conditions was lower than 17?g/mL.It is more reasonable to use a cell assembly model to evaluate the damage of these nanomaterials than to use only one or two cell lines,and we should not evaluate their safety solely on the basis of a single chemical toxicity test.The study of the health effects of nanomaterials and other environmental pollutants by combining the cell combination model with the systematic evaluation method lays a foundation for the establishment of a safe zone for leakage of nanomaterials and the further study of the molecular mechanism of toxicity caused by NPs and its pollutant complexes.In addition,we can build a computational model with good predictability or explanation based on the big data of toxicity of ZrO2NPs,pollutants and their combined exposure in human cells.
Keywords/Search Tags:cytochrome CYP450, QSAR, synergistic effect, antagonistic effect, oral exposure
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