| Carbon quantum dots(CQDs)are currently popular nano-scale fluorescent materials,with a size of about 1-10 nm,and the structural composition is a carbon core and related groups attached to the surface.It has excellent biocompatibility,low cellular toxicity and fluorescence stability.In this paper,two kinds of temperature-sensitive carbon quantum dots were prepared and synthesized by hydrothermal method and solvothermal method,respectively.The morphology and internal structure were characterized,and the optical properties and cellular applications were studied.The specific research contents are as follows:1.Preparation and characterization of blue light emitting carbon quantum dots.Nitrogen-doped blue-emitting carbon quantum dots(B-CDs)were prepared by a one-step hydrothermal method,and the structure and morphology were characterized.The results showed that the average particle size of B-CDs is 2.7±0.21 nm,and the carbon lattice spacing is 0.22 nm.It has good water solubility,stability and biocompatibility.The results of fluorescence performance test showed that the fluorescence emission wavelength of B-CDs solution changed with the change of excitation wavelength,and had fluorescence dependence,and the temperature and fluorescence intensity had a linear relationship.Adding RGB codes can estimate the temperature of the B-CDs solution.2.Preparation and characterization of red light-emitting carbon quantum dots.Nitrogen-doped red light-emitting carbon quantum dots(R-CDs)were prepared by solvothermal method,and the structure and morphology were characterized.The results showed that the average particle size of R-CDs is 5.0±0.22 nm,and the carbon lattice is0.21 nm.It has good dispersibility,water solubility and biocompatibility.The fluorescence performance test results showed that the emission spectrum of R-CDs was excitation-independent,the fluorescence emission wavelength did not change with the excitation wavelength,and the temperature was linearly related to the fluorescence intensity.Adding RGB coding can estimate the current temperature of the R-CDs solution.3.Application of carbon quantum dots in cells.The cytotoxicity of the above two carbon quantum dots was evaluated by MTT method.The results showed that the carbon quantum dot solution at the concentration of 1000 μg/m L did not damage the cells.B-CDs were co-cultured with Ha Cat cells for 24 h,and observed by fluorescence microscope.The results showed that after Ha Cat cells endocytosed B-CDs,the cells were not damaged obviously,and the fluorescence intensity of B-CDs changed with temperature.C2C12 cells were treated with 1000 μg/m L R-CDs for 24 h,and the cytoskeleton and nucleus were stained.The results of fluorescence microscopy showed that the cells had endocytosed R-CDs without obvious apoptosis.The cell morphology and mechanical properties(adhesion,Young’s modulus)were examined by atomic force microscopy(AFM).The results showed that after co-culturing B-CDs and R-CDs with Ha Cat cells and C2C12 cells for 24 h,carbon quantum dots with a concentration of less than 1000 μg/m L had little effect on cell morphology and mechanical properties.It shows that B-CDs and R-CDs have good biocompatibility.The above results demonstrate that the two carbon quantum dots have the potential to be used as nanoprobes to detect cell temperature. |
