Preparation And Activity Evaluation Of Upconversion Nanoparticles/Semiconductor Composite Photosensitizer

Rare-earth ion-doped upconversion nanoparticles(UCNPs)could convert near infrared(NIR)light to ultraviolet-visble-near infrared(UV-Vis-NIR)light,which have been used as nanotransducers for wide applications,including bioimaging,cancer treatment,and solar cells because of their physical and chemistry stability,relatively low toxicity,and narrow emission band,etc.Semiconductor materials,with the capability of generating photo-generated electron-hole pairs,haven been constantly recognized as one kind of prospective materials for applications in driving redox reaction or killing tumor cells.However,most semiconductor materials,including TiO2,CdS,and ZnO,were driven by visible light,which was an obstacle in its biological and catalytic applications.It has been a challenging task to improve the spectral response range of semiconductor and improve its utilization of NIR light.By preparing the composite materials of upconversion nanoparticles and semiconductors,it can effectively improve the absorption range of traditional semiconductors and its applications in biology and energy.In this dissertation,the effective assembly of UCNPs and semiconductor have been realized by various techniques.We demonstrated a facile electrospinning process to fabricate(?-NaYF4:Yb/Tm@NaYF4)/TiO2,and(?-NaYF4:Yb/Tm@NaYF4)/CdS/TiO2 nanofibers on a large scale by the electrostatic spinning technique.In addition,we developed a facile colloid solution approach for the synthesis of(?-NaYF4:Yb/Tm@NaYF4)@ZnO core-shell nanoparticles successfully.The energy transfer mechanism of various composites and the production performance of reactive oxygen species such as hydroxy radicals were studied in detail.The experimental results show that the as-prepared composites could effectively utilize near infrared light to produce a lot of reactive oxygen species.