Construction Of Light-controlled Rare Earth Upconversion Nanosystems And Their Application In Biomedicine

Ultraviolet light and visible light have great applications prospect in biomedical field,but they have weak tissue penetrating ability,severe biological damage,which severely limit their applications in vivo.Upconversion nanocrystals can capture near-infrared(NIR)light with high tissue penetration and high biosecurity,and then convert them into localized ultraviolet and visible light to achieve the application of short wavelength light in cells and in vivo.In this paper,the upconversion nanocrystals with various morphologies were prepared successfully by high temperature oil phase method,hydrothermal method and high temperature calcination method.And we also explored the following aspects of the application:(1)Light control cell labeling.The result shows that the nano-dye release system with upconversion nanocrystals as the core and mesoporous silica as the shell was successfully prepared.The azobenzene molecules in mesopores play a role of molecular plasma to control the release of organic dye in the mesoporous and cells labling after exciting by UV and visible light from the upconversion after irridaition by 980 nm NIR.The folic acid on the surface of the silicon layer can improve the cell uptake efficiency of the dye delivery system.(2)Light control gene expression.The result shows that the prepared upconversion rod-like crystals can convert the near-infrared light into ultraviolet light,and promote the photocleavage activity of the o-nitrobenzyl group between the gene nanocarrier and the upconversion rod,and then the green fluorescent protein gene released form the NIR-triggered gene nanocarrier release system and expressed in Hela cells.The system can better achieve the near-infrared light selective excitation the gene expression.(3)Complex nanocrystals fluorescence imaging.The result shows that the prepared long-lasting afterglow nanocrystals have excellent dual-mode imaging performance.Long afterglow luminescence can be detected very strong fluorescence signals after 40 minutes of removal the excitation light source,and then upconversion fluorescence can play its role effectively by 980 nm NIR light after afterglow luminescence decay.It has the ideal heating property with the help of the agent of indocyanine green(ICG)and 808 nm near infrared light irradiation.At the same time,980 nm near-infrared light excited upconversion long afterglow nanocrystals were prepared successfully,which can produce excellent long afterglow imaging after 980 nm NIR light irradiation.And then they were phagocytosised by macrophages after loading ICG and can effectively improve the tumor targeting region and heating property after 808 nm near infrared light irradiation.In this paper,a variety of upconversion nanocrystals based on blue-violet light have been prepared.They have developed new applications in controlling cell staining,triggered gene expression and enhancing fluorescence imaging performance.Our works is a new reference significance for expanding the applications of upconversion nanocrystals in biomedical field.