Preparation Of Carbon Dots-Based Nanocomposites And Its Application In Cell Imaging,Tumor Therapy And Catalysis

Carbon dots?CDs?,a new class of carbon nanomaterials,which are widely used in bioimaging,cancer therapy,photoelectric sensing and catalysis due to their special physicochemical properties,excellent optical properties and good biocompatibility.CDs-based nanocomposites can bring a variety of different functions and the preparation of different types of CDs nanocomposites to improve their application ability has also become a research hotspot in recent years.Therefore,it is very meaningful to explore a simpler and more energy-efficient method for preparing novel CDs nanocomposites and expanding their applications.In this paper,three different CDs nanocomposites were prepared by ultrasonic method,hydrothermal method and solvothermal method,and applied to intracellular imaging,anticancer drug delivery and catalytic reduction of organic pollutants.The main research contents are as follows:?1?We proposd a novel ultrasound-mediated synthesis method for preparing folic acid carbon dots?CDs?modified hydroxyapatite?HAp?nanocomposites?HAp-CDs?.In this system,folic acid not only act as carbon source to form fluorescent CDs but also as targeting molecules to specifically recognize human cervical cancer?HeLa?cells.Furthermore,HAp-CDs nanocomposite was successfully grafted with hyperbranched polyglycerol?PG?through surface-initiated ring-opening polymerization of glycidol.The grafted PG layer not only tremendously enhanced the aqueous dispersibility and stability of HAp-CDs,but also effectively inhibited non-specific cellular uptake of HAp-CDs-PG.So the PG layer can enhance the selectivity uptake of HAp-CDs to HeLa cells.The HAp-CDs-PG was used to load anticancer drug doxorubicin?Dox?and efficiently delivered into targeted cells by folate receptor-mediated endocytosis,leading to an enhanced therapeutic efficacy of Dox.Thus,the HAp-CDs-PG nanocomposite could potentially be used for cancer-targeted drug delivery and self-targeting cell imaging.?2?Nitrogen-doped CDs were successfully prepared in halloysite nanotube?HNTs?to obtain HNTs-CDs nanocomposites by one-pot hydrothermal method,which using citric acid as carbon source and urea as nitrogen source.HNTs-CDs not only has the fluorescence properties of carbon dots,but also has a strong load capacity which is derived from inner cavity and large specific surface of HNTs.In addition,HNTs-CDs were detected to be low-toxic by the CCK-8 kit.Therefore,HNTs-CDs can be used for intracellular imaging and drug delivery.The anti-tumor drug Dox was successfully loaded into HNTs-CDs to synthesize HNTs-CDs-Dox.It can release drugs under acidic conditions which is beneficial for the treatment of tumors,and has a sustained release effect for up to 58 hours in pH 5.2.Due to the advantages of simple synthesis methods and cheap raw materials,HNTs-CDs have great potential for application in biological field.?3?A simple one-pot solvothermal method was used to synthesis citric acid CDs coated copper ferrite?CuFe₂O₄?to obtain core-shell CuFe₂O₄-CDs nanocomposites.The morphology,structure and magnetic properties of the nanocomposites were characterized.Due to the protection of the CDs layer,CuFe₂O₄-CDs has excellent catalytic activity and stability.It is satisfactory in catalytic reduction of 4-nitrophenol?4-NP?,methylene blue?MB?and rhodamine B?RhB?organic pollutants,which is far superior to similar materials.The experimental result indicated that CuFe₂O₄-CDs nanocomposites can be used as an effective and reusable catalyst for water environment treatment.