Preparation Of Small Organic Molecule-carbon Quantum Dots And Its Application In The Detection Of Fe³⁺ And Cell Imaging

Carbon quantum dots（CDs）are novel carbon-based fluorescent nanomaterials with particle size less than 10 nm.CDs have attracted much attention because of their excellent physical and chemical properties,low biological toxicity and good water solubility.Some studies have shown that CDs have broad application prospects in catalysis,analytical chemistry detection,biological imaging and so on.However,there are still many problems to be solved in the research of CDs.For example,the carbon dots obtained by some synthetic methods are complex in composition,different in structure and uneven in particle size,which leads to the low fluorescence quantum yield.Therefore,the preparation of CDs with high fluorescence quantum yield is still one of the research hotspots in the field of Nano-luminescent materials.In this paper,we used small organic molecules to modify the surface of CDs and obtained their conjugates,which were applied in the detection of metal ion and cell imaging further.The specific work is as follows:1.CDs with blue fluorescence were synthesized by hydrothermal method by using disodium ethylenediaminetetraacetate as carbon source and ethanolamine as passivator.The prepared CDs were characterized by transmission electron microscopy,infrared spectroscopy,ultraviolet spectroscopy,fluorescence spectroscopy and X-ray diffraction.The possible structure of CDs was preliminarily speculated.2.A novel HQS-ECH-CDs conjugates with green fluorescence had been prepared by using epichlorohydrin（ECH）to combine CDs and 8-hydroxyquinoline-5 sulfonic acid（HQS）.The formation conditions of the conjugates were further optimized.The absorption properties,fluorescence lifetime and fluorescence quantum yield of the conjugates were investigated.3.In the detection and identification of metal ions,it was found that Fe³⁺could quench the fluorescence signal of HQS-ECH-CDs conjugate effectively.The quantitative detection conditions of HQS-ECH-CDs conjugate for Fe³⁺were further discussed.In addition,the imaging and biological toxicity of HQS-ECH-CDs conjugates in Hela cells were also investigated.