Photosensitive Drug Carrier:Chemical Preparation, Surface Modification And Application

Cancer has greatly threatened human health in recent years. Photodynamic therapy was emerging for cancer treatment as fewer side-effects for human based on photochemical reaction. Photosensitive drugs, light and oxygen were the three essential elements of photodynamic therapy, and light has great influence on therapeutic effect.Lanthanide ion-doped upconversion (UC) nanoparticles could emit short wavelength fluorescence under exciting by near-infrared light. Especially, UC core-shell nanoparticles can not only be tailored to greatly promote their UC fluorescence intensity or efficiency, but also provided to well control the excitation or emission, or multifunctionalities. However, most of the current protocols for synthesizing the UC core-shell nanoparticles generally involve a complex process including precipitation, pretreatment, and redispersion of the seed crystals. It is still a challenging task to develop a facile and user-friendly method for synthesizing the UC core-shell nanostructures.In this dissertation, we developed a facile sequential growth process to prepare lanthanide ion-doped NaYF4 core-shell nanoparticles. This protocol involved two steps. At first, core nanocrystals were formed in a high boiling-point hot solvent containing excessive NH4F and NaOH via a modified synthetic process. Subsequently, the RE ions oleate precursor solution was injected into the previous solution containing presynthesized core nanocrystals and grow a thin layer of NaREF4 epitaxially to form core-shell nanocrystals. This present protocol can also be extended to synthesize NaYF4:Yb/Er/Nd@NaYF4:Nd, NaYF4:Yb/Tm@NaYF4, NaYF4:Yb/Tm@NaGdF4, NaYF4:Yb/Er@NaYF4:Yb@NaNdF4:Yb core-shell nanoparticles. In addition, a seed-mediated sequential growth process has been developed to synthesize unique dumbbell-shaped NaYF4:Yb/Tm@NaYF4:Yb/Er@NaYF4:Yb@NaNdF4:Yb core-shell nanoparticles for the first time.The surface modification was also studied by coating amphiphilic mPEG2k-b-PEBEP6k copolymers (denoted as PPE) in order to transfer those hydrophobic UCNPs into the aqueous phase. TEM and fluorescence spectrum were chosed to research influence on nanoparticles by different surface modification.Upconconversion nanoparticles that excited using 808 or 980 nm near infrared light have been fabricated and modified using PPE with loading photosensitive drugs to develop the photodynamic therapy system. In vitro photodynamic therapy of cancer cells showed that the as-prepared photosensitive drugs carriers achieved ideal therapeutic effect under exciting by near-infrared light.