Synthesis And Application Of Rare Earth Upconversion Nanoparticles/Photoresponsive Multifunctional Particles

Cancer has always been a serious disease to human health.Clinical diagnosis and treatment are separated,so it is easy to miss the best treatment opportunity,treatment is difficult.Because light stimulation belongs to external stimuli,and it is easy to get,it is also flexible.Therefore,light-responsive materials have unparalleled advantages in biomedical applications.However,most photo-responsive materials need to be excited by short-wave high frequency ultraviolet light,which will be absorbed by biological tissues,which will not only lead to low penetration depth,but also lead to biological damage.It severely limits its application in biological clinic.Therefore,in order to solve these key problems,this paper mainly synthesizes double-response composite nanospheres with uniform particle size,and combines up-conversion nanoparticles with azobenzene and nitrogen isopropylacrylamide.The temperature and light responsiveness of the shell can be fully utilized to achieve controlled release of the drug,which can not only be applied to biological imaging but also can be used as a drug carrier for the treatment of tumors,thereby realizing an anti-cancer treatment integrating diagnosis and treatment.The specific content can be summarized as follows:In this dissertation,the solvothermal method was first used to prepare the NaYF₄:Yb³⁺,Tm³⁺/NaYF₄ rare earth upconversion nanoparticles with uniform size,controllable morphology and good crystallinity.In reverse microemulsion method,a layer of controllable silicon dioxide layer was coated on the surface of the rare earth up-conversion nanoparticle with a covalent bond.The prepared UCNPs@SiO₂ composite nanospheres had good hydrophilicity and could transfer the rare earth upconverting nanomaterials from the oil phase to the aqueous phase,so that they had good biocompatibility and laid a foundation for subsequent biological applications.Then,using 4,4?-dimethyl acrylamide azobenzene?BMAAB?as cross-linker,NIPAM as monomer,azobisisobutyronitrile?AIBN?as initiator,acetonitrile as a solvent,the surface of UCNPs@SiO₂ composite nanospheres were further coated with PAzo/PNIPAM by novel distillation precipitation method.The UCNPs@SiO₂@PAzo/PNIPAM composite nanospheres were successfully prepared with uniform particle size and no obvious viscosity.After the silicon dioxide layer was etched with hydrofluoric acid,the UCNPs@PAzo/PNIPAM composite nanospheres were obtained.Then,the temperature and photo-responsive behavior of UCNPs@SiO₂@PAzo/PNIPAM composite nanospheres were further investigated.The composite nanospheres were studied with a contact angle tester and an ultraviolet-visible spectrophotometer,and it was found that the composite nanospheres had a good dual response of temperature and light.The doxorubicin hydrochloride was loaded into the nanospheres by diffusion,and then the drug release behavior of the nanospheres under different temperature and near-infrared light conditions were investigated by UV spectrophotometer.The composite nanospheres which reached the release equilibrium at 25°C would further release the adriamycin hydrochloride molecules when the temperature rised.In the light-controlled release experiment,the amount of drug released under visible light was22%,and the amount of drug released under near-infrared light was 43%.Taking into account both temperature and light,the maximum drug release was 65%under the conditions of 47°C and near-infrared light.UCNPs@SiO₂@PAzo were synthesized by a novel distillation polymerization method with the ethylene glycol dimethacrylate?EGDMA?as a cross-linker,methacrylic acid-6-?4-methoxy-4-oxo-azobenzene?hexyl ester?AzoM?as a monomer,AIBN as an initiator,and acetonitrile as a solven.At the same time,the shell of multi-functional composite microspheres was azobenzene shell with light switch effect.This thesis supplies broad prospects for cancer therapy and provides new ideas and technical basis for the development of multi-functional composite nanoparticles.