Bioeffect Of Metal Oxides Nanoparticles And Carbon-based Graphene Quantum Dots

In the 21st century,all walks of life are rejuvenating.The rapid development of information,biotechnology,energy,environment and national defense places new demands on materials.To achieve the goals of miniaturization,intelligence,and integration,more"tiny"materials are needed.So,nanotechnology came into being and developed rapidly.However,while nanotechnology is booming,people's exposure to nanomaterials is also increasing.While benefiting humanity,it also poses a threat to human health.Therefore,the safety of nanomaterials has received widespread attention.Three types of nanomaterials,ZnO NPs,Fe3O4 NPs and quantum dots were studied to discuss the safety and influencing factors of nanomaterials.This thesis is divided into the following three parts:The first part is the compound effect of ZnO NPs and phosphorus additives,and the biological effects of phosphorus additives on cytotoxicity and uptake of ZnO NPs.We purchased 6 commonly used ZnO NPs from the company.Through TEM and DLS characterization,we found that ZnO NPs interacted with the phosphorus additive to form a complex,and the particle size increased.And ZnO NPs dissolved and released more Zn²⁺because of the different p H of phosphorus additive in water,and further affects the biological effects of ZnO NPs.Therefore,we evaluated the biotoxicity of ZnO NPs through various biological test methods.As a result,it was found that 18 mg/L ZnO NPs were significantly toxic to both GES-1 cells and IEC-6,which was semi-lethal.We think the source of the toxicity is from the Zn²⁺,dissolved from ZnO NPs.The release of Zn²⁺destroys the cell homeostasis after entering the cell,leading to the changes in ROS,a decrease in mitochondrial membrane potential,an increase in intracellular calcium ion concentration,shrinkage of the cell nucleus,damage to the cell membrane,and caused apoptosis and necrosis.However,when interacting with phosphorus additives,it promotes the dissolution of ZnO NPs,and complexes with the dissolved Zn²⁺to promote the uptake of zinc by the cells,but the complex has no obvious effect on the physiological activities of the cells,including ROS,mitochondrial membrane potential,calcium levels,etc.Thereby inhibiting the toxicity of ZnO NPs to cells.At the same time,we also found that in the intestinal sac model,phosphorus additives also promote the uptake of zinc in the small intestine.The second part studies the influence of protein and magnetic field on the biological effects of Fe₃O₄ NPs.First,it was found that when Fe₃O₄ NPs incubated with protein,their particle size,potential and fluorescence spectrum changed,indicating that Fe₃O₄ NPs interacted with protein,resulting the change of protein microenvironment.Then we compared the cytotoxicity of Fe₃O₄ NPs in complete medium and serum-free medium and the effect of protein on the biotoxicity of Fe₃O₄ NPs was studied.The results showed that the interaction between protein and Fe₃O₄ NPs reduced the toxicity of Fe₃O₄ NPs.In addition,the effect of magnetic field on the toxicity of Fe₃O₄ NPs was studied by placing a steady magnetic field of 0.5 T,and it was found that the magnetic field increased the cytotoxicity of Fe₃O₄ NPs.In order to further study its mechanism,we studied the influence of protein and magnetic field on the cellular uptake capacity of Fe₃O₄ NPs.ICP quantitatively found that in serum-free medium,cells obviously took up more Fe₃O₄ NPs.Similarly,under the magnetic field,the cells also took up more Fe₃O₄ NPs.These results were positively correlated with their toxicity assessment.The more Fe₃O₄ NPs the cells took up,the higher toxicity.The third part is to explore the correlation between the biological effect of quantum dots and functional group modification as well as the stability of the material itself.Selecting three kinds of quantum dots synthesized in our laboratory by simple hydrothermal method,we found that the same synthesis method with different reducing agents obtained quantum dots with different functional group,they have great differences in biological effects such as toxicity and distribution.Through the CCK-8toxicity test,it was found that GTTN and S-GQDs carrying sulfonic acid groups were not significantly toxic to cells;the toxicity test in mice also showed no significant toxicity;while A-GQDs showed strong toxicity both in vitro and in vivo,indicating that the modification of functional groups of NPs has a greater impact on biological toxicity.Then we co-localized with quantum dots through cell membrane dyes and lysosomal dyes,and found that both S-GQDs and A-GQDs can enter cells and distribute in lysosomes.However,GTTN has difficulty entering cells.In order to further study its mechanism,we selected GTTN and S-GQDs with the same functional group and similar morphology and size as the research object.Through TEM characterization,ultraviolet spectroscopy and fluorescence spectroscopy,the stability difference between the two GQDs was studied.It was found that S-GQDs is unstable in solution,easy to agglomerate and precipitate,and it is easier to fall on the surface of cell and be taken up by the cell.When we injected S-GQDs into the mouse through tail vein,it mainly distributed in the liver and kidney.After being metabolized by urine,its infrared spectrum is changed,indicating that it reacts with proteins and other components in the mouse's body.This also reflected its instability on the side.GTTN maintains its own properties,whether it is in solution or circulating in the body.It doesn't interact with proteins and other components.It has excellent dispersibility in solution,lead to contact with cell and enter cells difficultly.So,we believe that the biological effects of these two GQDs may be related to its own stability.