Preparation Of Fluorescent Carbon Quantum Dots For Biological Application

Nanomaterisls have been widely applied in many fields such as bio-sensing and bio-imaging.Carbon nanomaterials have become the forefront of scientific research because of their excellent properties,including low toxicity and good biocompatibility.Carbon nanomaterials,such as fullerene,carbon nanotube,graphene and fluorescence carbon quantum dots,are widely used in the current study.Fluorescent carbon quantum dot not only has low toxicity and good biocompatibility,but also has outstanding fluorescent properties.Therefore,carbon quantum dots have caught great focus since its discovery.Large amounts of carboxyl groups on the surface of carbon quantum dots and its large surface area make it very easy to integrate with different molecules.Thus,it provides an outstanding basis for constructing multi-functional fluorescence system.Functional carbon quantum dots play an important role in fluorescence imaging,in which,they are able to the real-time monitor physiological process in live cells and living creatures.Thereby,it will help people understand the biological behaviors of the body at cellular level.In this thesis,we reported a method for quick preparation of high fluorescent carbon quantum dots and systematically characterized the properties of the products.We further conducted surface functionalization of the carbon quantum dots and applied it for selectively targeting of tumor cells.We also designed the silver nanoparticles/carbon quantum dots assembly and studied explore the enhancement of the upconversion fluorescense of the carbon quantum dots.The details are as follows:Firstly,we prepared high fluorescence carbon quantum dots by microwave-assisted method and systematically characterized their physical and chemical properties.We also studied the fluorescence response of the carbon quantum dots to different metal ions and pH.We found that the carbon quantum dots exhibited selectivity and high sensitivity for Fe³⁺.Secondly,we demonstrated that the carbon quantum dots can be used as fluorescent probes for living cell labeling,and to detect the concentration of Fe³⁺within living cells.We functionalized the carbon quantum dots with cyclo?Arg-Gly-Asp-D-Phe-Cys??RGD?for fluorescent targeting of the tumor cells.We also studied the carbon quantum dots in vivo fluorescence imaging.Thirdly,we found that the carbon quantum dots show upconversion fluorescence properties.Based on this finding,we designed AgNPs/SiO₂/3-Aminopropyltrimethoxysilane?APTMS?/CQDs and AgNPs/PEG/CQDs assembly and studied the enhancement of upconversion fluorescence of carbon quantum dots with the metal surface plasma effect.In this thesis,a new train of thought for the design,preparation and application of new biological fluorescent probes was provided.