Photothermal Conversion Properties And Biological Application Of GO/NaGdF₄:Yb,Er Composites

Photothermal therapy has shown great potential in the field of anti-tumor and has attracted the attention of many researchers.Graphene oxide(GO)has two-dimensional carbon-based material,which has a strong absorption capacity for near-infrared light,and a surface-rich oxygen-containing group makes it easy to be modified.The upconversion nanoparticles(UCNP)has a narrow emission band,strong photostability,long fluorescence lifetime,and is applied to bioluminescence imaging.In this paper,GO and rare UCNP were investigated.Hydrothermal synthesis of GO base on UCNP was carried out,and the application of composites in photothermal conversion was explored.The research results obtained are as follows:(1)The cubic phase GdF3:Yb,Er was synthesized by co-precipitation method and were annealed at different temperatures.The effect of the morphology,crystal structure and upconversion luminescence properties after being annealed was inverstigated.The results suggest that the translation temperature of NaGdF4:Yb,Er crystals from GdF3:Yb,Er crystals was 740.15℃.The UC luminescence intensity is enhanced firstly increased and then decreased as the rise of temperature due to the improvement of crystallization and a structure change of cubic GdF3:Yb,Er to NaGdF4:Yb,Er particles.(2)The synthesis of graphene oxide via the Hummers method show that the graphene oxide has good extensibility,oxyen-containning groups and the structure is monolayer.The GO/NaYF4:Yb,Er nanocomposite have been synthesized via hydrothermal systhesis,in which spherical cubic phase NaYF4:Yb,Er nanocrystals with uniformity are implanted onto the surface of GO,the effect of different rare earth doping amount on UC fluorescence intensity was discussed.(3)The experimental setup for measuring the photothermal conversion was upgraded,two photothermal conversion models,temperature balance method and initial balance method are proposed.The experimental results show that the temperature balance method is greatly affected by the ambient temperature,while the initial balance method avoids the influence of ambient temperature,the photothermal conversion phenomenon of GO/NaYF4:Yb,Er composites material is tested,and its photothermal conversion mechanism explore.(4)In vitro cell experiments were performed on GO/NaYF4:Yb,Er composites.The results show that the composites has good stability and bio-safety,and the composites pair can effectively kill the suppressing cells under 980 nm laser irradiation.And as the concentration of the composites is larger,the effect is more significant.