Carbon Quantum Dots Synthesized By Using Glucose As Carbon Source And Its Fluorescent Characteristics

Semiconductor Quantum Dots?QDs?have great potential applications in bioimaging,optoelectronic materials,energy conversion,etc.due to their excellent tunable photoluminescence properties.However,most QDs have poor solubility and high toxicity,making their use in the biological field limited.In this context,carbon quantum dots?Carbon Quantum Dots or CQD?,also known as carbon dots?Carbon Dots or CD?,have become a strong competitor for next-generation bio-imaging due to their excellent PL properties and biocompatibility.The rapid development of carbon dots for bioimaging,especially targeted imaging,has proven this in recent years.In fact,biocompatibility is one of the main advantages of carbon dots in applications.Although there are many different methods and raw materials for synthesizing CDs today,most of them focus on the improvement of quantum yield?QY?of carbon dots,and there are few studies focusing on increasing the production of carbon dots,so the development yield is high.Simple synthesis method with great research and application value.In this thesis,carbon quantum dots 1?CDs-1?were synthesized by using glucose as carbon source,urea as nitrogen source and dimethylformamide?DMF?as reducing agent.First,we optimized the synthesised conditions to obtain CDs-1 with relatively high brightness.Secondly,the structure,morphology and luminescence characterization of CDs-1,X-ray diffraction?XRD?and Fourier transform infrared spectroscopy?FT-IR?analysis showed that the synthesized CDs-1 has a typical graphite lattice.The structure and corresponding functional groups demonstrate that CDs-1 are carbon quantum dots.Using a fluorescence spectrophotometer,it was found that CDs-1 emits blue light?436 nm?with a maximum excitation wavelength of 350 nm.In order to apply CDs-1 to bioimaging,we carried out biotoxicity tests while conducting stability tests for carbon quantum dot luminescence in different extreme environments.The results showed that CDs-1 not only had good acid and alkali resistance and optical stability,but also its test on zebrafish embryos showed that CDs-1 had no biological toxicity,but Fe³⁺had obvious quenching effect on CDs-1.In view of the low brightness of CDs-1,we have found through a series of experiments that chloroform has a strong fluorescence enhancement effect on CDs-1.At the same time,for the problem of low yield of CDs-1,a higher brightness CDs-2 was prepared by changing the microwave method to hydrothermal method.The same method was used to test the structure,morphology,luminescence and various extreme environments of CDs-2.It proved that CDs-2,like CDs-1,is not only stable in fluorescence,but also non-toxic,and has high yield.The fluorescence intensity is larger,which is more suitable for biological imaging.In addition,most of the current bioimaging studies on CD focus on in vitro studies,while studies on in vivo bioimaging are rare and mostly use mice as models,and few studies on other animal models such as zebrafish.Zebrafish was selected as an imaging vector for its good optical clarity,relative to the short developmental cycle of mice,and low maintenance costs.Finally,it was verified that the synthesized CDs have a good imaging effect on zebrafish.