The Application Research Of Fluorescent Carbon Dots For Metal Ions Detection,Imaging And Solid Luminescence

As a new style of zero-dimensional carbon-based nanomaterial.fluorescent CDs have been widely used in the field of biological and chemical sensing,bioimaging,drug delivery and photocatalysts,due to their superior optical properties,low cytotoxicity,excellent solubility and good biocompatibility.Recent studies showed that heteroatom doping is an effective method to adjust the structure and composition of CDs and thus changes their optical properties.Therefore,based on the screening of raw materials,heteroatom-doped CDs with different properties were successfully synthesized by hydrothermal or solvothermal method.The luminescence properties,formation mechanism,morphology characteristics and stability of CDs were investigated by some characterization methods,and their application in metal ion detection,cell imaging,zebrafish imaging and light-emitting diodes were investigated.The main content of the thesis is summarized as the following three parts:?1?Synthesis of nitrogen-doped carbon dots with dual-wavelength fluorescence emission for Hg²⁺detection and cell imagingHigh photoluminescent?PL?nitrogen-doped carbon dots?N-CDs?had been synthesized using ferric ammonium citrate and urea as raw materials by simple one-pot solvothermal process.The N-CDs possess bright blue fluorescence?centred at 450 nm;36.2%quantum yield?and green fluorescence?centred at 530nm;47.6%quantum yield?only by adjusting the excitation wavelength from 310 nm to 510 nm.The unique dual emission properties of N-CDs are ascribed to the synergistic effect between rich hydrophilic groups on the surfaces of the N-rich CDs.The N-CDs exhibited high N content of 32.81 wt.%,low cytotoxicity,and good PL stability at different pH values,ion strengths and temperature,respectively.Furthermore,the N-CDs could be used as sensitive and selective fluorescent probe for detection of Hg²⁺.As-prepared N-CDs were used for cell imaging.?2?Synthesis of carbon dots with red emission for sensing of noble metal ions of Pt²⁺,Au³⁺and Pd²⁺and their applications in cell and in zebrafishRed emissive carbon dots?R-CDs?have drawn more and more attention due to their good organ penetration depth and small biological tissues photodamage.Herein,the fluorescent carbon dots with red emission were synthesized by facile one-pot hydrothermal treatment of citric acid and neutral red,and they show red fluorescence both in aqueous solution and solid state.The solution of R-CDs exhibits the fluorescent quantum yield of 12.1%,good stability against photobleaching,and low cytotoxicity.As-prepared R-CDs can be used as fluorescent probe for peculiar detection of Pt²⁺,Au³⁺and Pd²⁺.Furthermore,the R-CDs show excellent biocompatibility,which were successfully used as hopeful bioimaging and biosensing of noble metal ions in PC12 cells and zebrafish.?3?One-pot synthesis of hydrophilic and organophilic carbon dots and their applications in biosensing of Au³⁺and white light-emitting devicesHydrophilic and organophilic carbon dots?HCDs,OCDs?had been synthesized using methylene blue and sulfuric acid as raw materials,ethyl alcohol as solvent by simple one-pot solvothermal process.Synthesized HCDs and OCDs can be dissolved in distilled water and ethanol,which exhibit bright white and blue fluorescence under an UV illumination of 365 nm,and they show the fluorescent QY of 16.5%and 21.1%,respectively.The different functional groups on the surface are responsible for the distinction in fluorescence and solubility of these two carbon dots.HCDs could be used as high selective fluorescent probe for detection of Au³⁺.Meanwhile,the HCDs possess great biocompatibility,which were successfully used for bioimaging and biosensing of Au³⁺in PC12 cells.Because of the unique emitting properties of HCDs,they can also be used to prepare white-light-emitting diodes.