The Preparation Of Graphene Quantum Dots And Their Application In Detecting Cell Apoptosis

In recent years,graphene quantum dots(GQDs)have attracted extensive interest because of their excellent optical properties and wide application prospects.At present,the synthesis and preparation methods of graphene quantum dots are diversified,but it is difficult to modify,which limits the application of graphene quantum dots in biological imaging and the pharmaceutical analysis.Based on the above problems,this dissertation starts from the controlable synthesis of the surface functional groups and luminescent properties of graphene quantum dots,to reach the purpose of monitoring the cell apoptosis.Therefore,the following researches were conducted:(1)The dynamic monitoring of the apoptosis induced by cobalt ion basred on thre fluorescence quenching mechanism of the graphene quantum dots.In this work,nitrogen-doped graphene quantum dots were prepared with PEI and lysine by microwave synthesis method.Due to the intermolecular bonding assembly on the surface of graphene quantum dots carbon nuclei and coordination with cobalt ions,graphene quantum dots aggragretes were formed.The morphology and structure change of graphene quantum dots was found after the introduction of cobalt ions,thus,the fluorescence quenching mechanism of graphene quantum dots were discusses,and other physical and chemical property changes of graphene quantum dots were fully investigated.More importantly,the graphene quantum dots can be used as probes to monitor the visual dynamic process of cell apoptosis induced by cobalt ion invasion cells.(2)The application of graphene quantum dots in the detection of cytochrome c.Mitochondria plays an important role in cell apoptosis,and the release of cytochrome c from mitochondria into cytoplasm is the important part of apoptosis program.Therefore,cell apoptosis can be indirectly monitored by detection of cytochrome c.In this work,graphene quantum dots were prepared through the hydrothermal method with para-phenylene diamine and ethylenediamine as carbon source and nitrogen source,which reached the property that the emission spectrum of graphene quantum dots matched the absorption spectrum of cytochrome c.Through the investigation of other properties of graphene quantum dots and cytochrome c,the fluorescence quenching mechanism of graphene quantum dots was investigated.The results show that the graphene quantum dots havd the characteristics of anti photobleaching,good stability,low toxicity and good biocompatibility.As a fluorescent probe with good luminescence properties,they can be applied in the analysis and detection of cytochrome c in cells.(3)The application of graphene quantum dots in the detection of glutathione.Glutathione plays an important role in the process of cell apoptosis.It is found that the depletion of glutathione will induce cell apoptosis.Based on this,graphene quantum dots were synthesized,which can interact with glutathione.Through a series of characterization,it is found that the surface of the graphene quantum dot is rich in the amino group and can be coordinated with copper ions with high selectivity,which causes aggregation and fluorescence quenching of graphene quantum dots when in the presencre of copper ions.Because of the strong coordination ability of copper ions and glutathione,the presence of glutathione drived copper ions far away from graphene quantum dots,leading to the fluorescence recovery of graphene quantum dots.This method is highly specific and selective,which lays the foundation for future fluorescent probes for cell apoptosis.In conclusion,the preparation and properties of graphene quantum dots were fully investigated in this thesis.The surface functional groups of graphene quantum dots were carefully designed to reach the purpose of apoptosis research,and the possible mechanism were fully discussed.At the same time,the graphene quantum dots are applied to cell imaging to lay a foundation for futher application in vivo.