Studies On Eco-friendly Preparation,Characterization And Application Of Novel Fluorescence Carbon Nanodots

Carbon nanodots(CDs),as a new kind of zero dimensional nano materials,have attracted much attention since their discovery in 2004.CDs are composed of an amorphous or crystalline core with predominant sp2 carbon and an oxidized carbon surface with oxygen-containing groups.By virtue of their small size,good water solubility,the excitation wavelength dependence,resistance to photobleaching,low toxicity and good biocompatibility,CDs have been applied to many fields,such as fluorescent probes,bioimaging,fluorescent ink,and fluorescent dyes.The main research contents are as follows:Chapter 1:This chapter reviews the preparation,properties,and applications of CDs.Based on the summary of previous work,we present our research in this thesis.Chapter 2:This chapter introduces the experimental characterizations of CDs in this paper.Chapter 3:An eco-friendly and one-pot hydrothermal method for synthesizing CDs using petals as carbon source is reported.The as-prepared CDs demonstrate small size distribution and high aqueous solubility.Moreover,they exhibit high tolerance to various external conditions,such as pH values,external cations,and continuous excitation.Due to minimum toxicity as well as good photoluminescence properties,these CDs can be applied to in vitro and in vivo imaging,patterning,and staining.According to confocal fluorescent imaging of human uterine cervical squamous cell carcinoma(A 193)cells,CDs penetrate into the cell and enter cytoplasm and nucleus.More strikingly,carp is directly fed with CDs for in vivo imaging and shows bright green fluorescence under 470 nm excitation.Additionally,the obtained CDs are applied as fluorescent inks for drawing luminescent patterns useful in anti-counterfeit and optoelectronic applications.Finally,we also apply the CDs as fluorescent dye.Interestingly,absorbent filter paper with staining emits dramatic fluorescence under 470 nm excitation.Chapter 4:We report a controllable strategy for fabrication of green and blue fluorescent CDs,and demonstrate their applications for pH and Cu2+sensing in living cells.Green and blue fluorescent CDs have been synthesized by hydrothermal method and pyrolysis of leeks,respectively,providing an easy way for the production of CDs without the request of tedious synthetic methodology or the use of toxic/expensive solvents and starting materials.Green fluorescent CDs(G-CDs)exhibit high tolerance to pH values and external cations.Blue fluorescent CDs(B-CDs)can be applied to pH and Cu2+ sensing.The linear range of Cu2+ detection is 0.01-10.00?M and the detection limit is 0.05?M.For pH detection,there is a good linearity in the pH range of 3.5-10.0.Confocal fluorescent imaging of human cervical carcinoma cells indicates that B-CDs could visualize Cu2+ and pH fluctuations in living cells with negligible autofluorescence.Chapter 5:We summarize the research results and the future possible work.