Preparation And Antitumor Research Of Functional Gallic Acid Carbon Dots

Carbon dots are carbon nanoparticles with a diameter of less than 10 nm and excellent photoluminescence properties.Carbon dots have attracted the attention of researchers for their high-water solubility,low toxicity,good biocompatibility and flexibility of surface modification.At present,carbon dots have been widely used in the fields of fluorescence sensing,ion detection,photocatalysis and optoelectronic devices due to the unique photoelectric properties.Additionally,carbon dots have been increasingly used in the fields of biological imaging and drug delivery because of their better biocompatibility and lower toxicity than semiconductor quantum dots and fluorescent dyes.However,research of carbon dots with both fluorescence imaging and antitumor activity are rarely reported in the existing researches.In this thesis,gallic acid with antitumor activity but low water solubility was chosen to be the functional carbon source,carbon dots were synthesized by microwave-assisted method.Functional carbon dots based on gallic acid not only can be used for cell imaging,but also have good tumor inhibition effect.In addition,tumor recognition and targeting functions are also introduced into the reaction system to enhance the diagnosis and treatment effect of carbon dots.The specific research is as follows:(1)Gallic acid was chosen as the functional carbon source,carbon dots GACDs with cell imaging effect and antitumor activity were synthesized by simple microwave-assisted method.GACDs were characterized by transmission electron microscope,fourier transform infrared spectrometer and X-ray photoelectron spectrometer.Excitation and emission spectra were scaned by fluorescence spectrophotometer.In order to proved the fluorescence stability of GACDs,fluorescence intensity corresponding to different irradiation time,pH values and concentrations of KCl were measured.GACDs were successfully applied in cell imaging.In addition,antitumor activity of GACDs was demonstrated by in vitro and in vivo antitumor experiments.According to the results,functional carbon dots GACDs with a particle size of 2-4 nm were successfully prepared.The carbon dots have great photoluminescence properties and can be used in cell imaging.At the same time,results of in vitro and in vivo antitumor experiments suggesting that GACDs inherit the antitumor effect of gallic acid and realized the antitumor functional design of carbon dots.(2)Folic acid was added into the reactant system to introduce tumor recognition and targeting functions into carbon dots.Targeted carbon dots GFCDs were synthesized via one-step microwave reaction.TEM images of GFCDs indicating that the diameter is about 3 nm and it has obvious lattice structure.The characteristic peaks of ester bonds can be clearly observed in FTIR and XPS spectra of GFCDs,indicating that the reactants are polymerized by ester bonds.According to fluorescence spectra,raw material ratio of reaction system is continuously optimized to obtain GFCDs with high solubility,strong fluorescence and targeted folic acid.The emission wavelength of GFCDs is 455 nm when the optimal excitation wavelength is 360 nm.In addition,the influence of ultraviolet irradiation time,pH value and ionic strength on the fluorescence of GFCDs were studied.MTT assay proved that GFCDs have better antitumor effect than pure GA on account of the introduction of targeting folic acid.(3)In addition,HeLa cell membrane was used to disguise gallic acid-based carbon dots GGCDs prepared by microwave reaction and biomimetic carbon dot particles(CM-GGCDs)with homotypic adhesion abilities were successfully synthesized.Fluorescence spectra of samples are scanned by fluorescence spectrophotometer,raw material ratio of reaction system is optimized to obtain GGCDs with higher solubility and stronger fluorescence according to the emission spectra.The effects of ultraviolet radiation time,solution pH and ionic strength on the fluorescence of GGCDs were also studied.Elemental composition and functional group structure of GGCDs are analyzed by FTIR and XPS spectra,the morphology and structure of GGCDs and CM-GGCCDs were observed by transmission electron microscopy.According to the results,the particle size of GGCDs is about 5 nm and the particle size of CM-GGCDs is 100-150 nm.Finally,in vivo and in vitro antitumor experiments confirmed that the antitumor effect of CM-GGCDs with homologous adhesion abilities is better than that of pure gallic acid and GGCDs.