Synthesis And Properties Of Upconversion/Side Chain Azobenzene Nanoparticles

Light Stimulation Response Drug Delivery System has the characteristics of remote controllability,the material can be controlled flexibly by wavelength and irradiation time.Azobenzene is an excellent photosensitive group.The main chain or side chain structure of azobenzene can be used in drug carriers to successfully synthetise stimulation-responsive polymers.The drugs can be encapsulated and released by changing the light irradiation condition.Photosensitive groups need ultraviolet light irradiation ordinarily,but ultraviolet light will cause damage to the tissue of the organism,and ultraviolet light penetration ability in the organism is weak.In order to solve this problem,this paper combined the upconversion material with azophenyl group to synthetise the photoresponsive composite drug packaging material.The process of drug release and drug cellular uptake were studied.The specific content is as follows:In the first time,Yb,Tm double-doped upconversion particles were synthesized by solvothermal method,and the homogeneous structure of NaYF₄ was coated by the same method.The upconversion material was modified with silica to facilitate the coating of photosensitive groups by inverting microemulsion method.The experiment found that distillation precipitation polymerization can effectively solve the polymers dispersion and steric hindrance effect,the synthesized UCNPs@SiO₂@PAzo/MAA particles have good dispersion,and the particles was etched silica to get the material with UCNPs@PAzo/MAA hollow structure.The results of ultraviolet spectrum show that the photoisomerization responses of the particles to near-infrared light and ultraviolet light are different.It was found that the particles response to weak acidic environment can be effectively applied to the treatment of tumor cells.Microporous for subsequent drug release molecular"stirred"device provides the space was found in the surface of UCNPs@PAzo/MAA particles in nitrogen adsorption and desorption experiments.When the dynamic equilibrium is reached,more trans components in azobenzene are converted to cis,and the hydrophilicity of the particles increases,the polymer layer swells,and the particle size changes.Under the condition of ultraviolet light irradiation,the drug loading in vitro will not cause harm to the human body.The side chain azobenzene is equivalent to the light control switch on,and the drug loading amount reaches 17.50%.Under weak acid and near-infrared light irradiation,the side chain azobenzene is equivalent to a"molecular impeller"stirred.The cumulative release rate of the doxorubicin(DOX)reaches67.88%.The above particles were applied to the intracellular environment,the cytotoxicity was studied.The drug was almost not released without near infrared light,and there was no killing power to the cells.When the DOX concentration on the loaded particles was10?g/m L,the cell survival rate was 21.82%.The process of cellular uptake was observed by fluorescence microscope.Cells ingest particles into the cytoplasm by endocytosis,and the slow release of drugs was controlled by 980 nm near infrared light in the cytoplasm,which made the drugs act on the nucleus.Cells are effectively killed.