One Step Synthesis Of Four N-doped Fluorescent Carbon Nanodots And Their Multi-functional Applications

In contrast with traditional semiconductor quantum dots,novel carbon nanodots(CDs)have attracted great interest in recent years owing to their high resistance to photo bleaching,low toxicity and good biocompatibility.CDs are valuable in numerous exciting applications.Up to now,extensive efforts have been devoted to the synthesis of CDs,including “top-down” and“bottom-up” methods.Bare CDs obtained from the traditional synthesis method suffer a drawback of low quantum yield,so their applications are limited.Modification during or after synthesis,could enhances the quantum yield,improves the fluorescent properties,broadens the scope of applications of CDs in the domains of bioimaging,probes,photocatalyst,drug and gene delivery,and photoelectric material,et al.Chapter 1: We reviewed the theoretical and application studies of CDs on the bases of recent literatures.It was mainly focus on the there modified methods: the formation of the complexes of CDs/metal nanoparticle,doping of heteroatoms and surface engineering.Chapter 2: Two kinds of carbon dots(CDs)with different solubility,aqueous soluble CDs(ACDs)and organic soluble CDs(OCDs),were produced at the same time by one step hydrothermal synthesis method using sorbic acid and proline as carbon precursor and nitrogen dopant,respectively.The synthesized CDs were characterized by means of UV,fluorescence,TEM,elemental analysis,IR and XPS,et al.Based on Internal filtration effect(IFE)mechanism in the quenching process,the fluorescence of CDs could be effectively quenched by Cr(VI).Linear response for Cr(VI)was observed in the range of 0.5~100 ?mol/L,and the calculated detection limit was 34nmol/L.The method has been applied to detect Cr(VI)ions in water samples.Then,the ACDs were further applied for cell imaging in B16F10 Cells.Furthermore,OCDs were well dispersed into PMMA and fabricated OCDs/PMMA composites as fluorescent films.Chapter 3: In this work,we showed a green strategy for the synthesis of CDs with blue fluorescence by one step hydrothermal synthesis method using mandelic acid and proline.Based on fluorescence resonance energy transfer(FRET)mechanism between the donor CDs and acceptor Mn(VII),the fluorescence of CDs could be effectively quenched by Mn(VII).A linear range extend from 1 to 100 ?mol/L with a correlation coefficient(R2)of0.9986.A limit of detection of 0.04 ?mol/L was obtained,and the sensitivity and selective were perfect.The Hep G2 cells emitted blue fluorescence after incubated with CDs,and intracellular fluorescence intensities were roughly linear with the Mn(VII)concentration,which enabled the potential applications of CDs in Mn(VII)biosensing.Chapter 4: In this work,we showed a convenient and green strategy for the synthesis of CDs with blue fluorescence by one step hydrothermal synthesis method using mandelic acid and threonine.Based on fluorescence resonance energy transfer(FRET)mechanism from the donors CDs to acceptors PA,the fluorescence of CDs could be effectively quenched by PA.The linear quenching effect was in the concentration range of 0.5~40.0?mol/L with a correlation coefficient(R2)of 0.9981,and a limit of detection of 0.2 ?mol/L.The Hep G2 cells incubated with CDs emitted multicolor fluorescence at different excitation wavelengths.Amazingly,the synthesized CDs under solid state(CDs)overcame the typical aggregation-induced fluorescence quenching,and emitted bright blue fluorescence under UV light.Then,SCDs were dispersed uniformly into PMMA and fabricated SCDs/PMMA composite.The four kinds of CDs in this paper were obtained by simple synthesis methods with excellent luminescence performance.They have been successfully used in the detection of mental ions or small molecule,bioimaging and fluorescent film preparation,and have certain theoretical and applied research value.