| Carbon quantum dots（CQDs）are a type of carbon nanomaterials.The carboxylic acid group of carbon quantum dots makes it hydrophilic.It also has the characteristics of photoluminescence,non-toxicity and stability.Therefore,it is used in photoelectric materials,probes or Biological imaging and other fields have a particularly wide range of applications.However,due to the small size of CQDs,usually only a few nanometers,the surface energy is high,and aggregation is prone to occur,so there are many obstacles in application.If CQDs are loaded in a solid phase carrier,its practical application range will be greatly expanded.Because silica microspheres have high mechanical strength,good stability,good dispersibility,are conducive to surface modification,large specific surface area,relatively uniform and adjustable particle size,and optically transparent,they can be used as a solid for CQDs.Phase carrier.In this paper,silica and fluorescent carbon quantum dots are combined,and CQDs are coated with silica to prepare composite microspheres of carbon quantum dots and silica.The experimental conditions of this method are mild,the surface of CQDs does not need special modification,and the prepared composite material maintains good fluorescence performance and shows low cytotoxicity and excellent cell imaging ability.The main research contents and conclusions of this paper are as follows:1.Using microwave-assisted hydrothermal method,green,yellow and orange carbon quantum dots were directly synthesized with L-cystine and 1,2-o-phenylenediamine.The successful synthesis of carbon quantum dots was confirmed by transmission electron microscopy,Fourier transform infrared spectroscopy,Raman spectroscopy and X-ray diffraction spectroscopy,and the structural characteristics of the carbon quantum dots were studied.The optical properties of CQDs are characterized by fluorescence spectrometer.The results show that the three kinds of carbon quantum dots have relatively uniform size and bright fluorescence under ultraviolet light irradiation.2.Through the improved St（?）ber method.Utilizing the interaction between the carboxyl and amino groups on the surface of the carbon quantum dots and the intermediate product of ethyl orthosilicate hydrolysis,the CQDs were wrapped in situ during the formation of silica,and three types of fluorescent composite microspheres（CQDs@SiO2）were prepared.).The size control method of SiO2 microspheres was studied,and the fluorescence properties of CQDs doped SiO2 were studied,and it was found that CQDs@SiO2 continued good and stable fluorescence luminescence characteristics.3.Incubate Hela cells with three CQDs@SiO2 composite microspheres,and observe live cell imaging and endocytosis under a 405 nm laser using a confocal microscope.The results show that all three CQDs@SiO2 can penetrate through the cell membrane to enter cell.The standard MTT method of Hela cells was used to study the cytotoxicity of the three CQDs@SiO2.It was found that the cytotoxicity of the three CQDs@SiO2 composite microspheres was low,and the cell survival rate after 24 hours of incubation exceeded 90%. |
