纳米光敏剂NaYF4:Yb,Tm@NaGdF4:Yb@SiO2@TiO2-Au的制备和碘标记性能

Preparation and iodine labeling properties of nanophotosensitizer NaYF4:Yb,Tm@NaGdF4:Yb@SiO2@TiO2-Au

上转换纳米颗粒为发展深组织下肿瘤的成像和光动力治疗(PDT)提供契机.良好的活性氧物种(ROS)产生能力和显像灵敏度是光敏剂应用于肿瘤诊疗的前提.本研究采用吸附法将Au纳米粒(AuNPs)与聚乙烯亚胺修饰的NaYF4:Yb,Tm@NaGdF4:Yb@SiO2@TiO2纳米粒子(UST)复合,制备近红外光驱动的纳米光敏剂UST-Au,并借助Au-I?亲和作用标记放射性核素131I?.研究了AuNPs用量对产物的形貌特征和应用性质的影响,以及光敏剂在碘标记前后的分散稳定性和ROS产生性能,分析了^131I?标记的光敏剂作为单光子发射计算机断层扫描(SPECT)成像探针的可行性.结果表明AuNPs的负载使UST-Au的ROS产生能力明显优于UST.当AuNPs用量为3 wt%(重量百分比)时,光敏剂的尺寸分布较窄、zeta电位较高且ROS产生性能最佳.UST-Au对I?的结合量随Au含量的增加而增大,对131I?的标记率超过95%,且I?标记后光敏剂的分散稳定性和ROS产生性能无明显减弱.这些独特性能使UST-Au有望应用于SPECT影像引导的肿瘤光动力治疗.

Photodynamic therapy(PDT)is a promising therapeutic method for cancer due to many advantages including noninvasion,highly localized tissue region,low toxicity,and insignificant side effects.However,the poor tissue penetration of visible light for activating the traditional photosensitizer confines the utilization of PDT in the treatment of tumors embedded in thick biotissues.Upconversion nanoparticles(UCNPs)can be used to fabricate near-infrared light-triggered nanophotosensitizers by loading organic dyes or coating with inorganic semiconductor nanocrystals such as TiO2 and ZnO for deep-tissue PDT.In addition,some UCNPs-based nanophotosensitizers exhibit remarkable imaging properties for tumor detection.Improvement in reactive oxygen species(ROS)production and imaging sensitivity is the prerequisite for the application of UCNPs-based nanophotosensitizers in cancer diagnosis and therapy.Here,a near-infrared light-driven nanophotosensitizer UST-Au was prepared by assembling Au nanoparticles(AuNPs)on the surface of polyethyleneiminemodified NaYF4:Yb,Tm@NaGdF4:Yb@SiO2@TiO2 nanocomposites(UST),and then labeled with radioactive iodine ions(131I^?)by virtue of Au-I^?affinity interaction.The effects of AuNPs dosage on the morphology,diameter,zeta potential,optical properties,ROS generating ability and iodine labeling performance of the product were studied.And the feasibility of 131I^?-labeled UST-Au as a single photon emission computed tomography(SPECT)imaging probe was analyzed.The results showed that tunable amounts of AuNPs were immobilized on the surface of polyethyleneimine-coated UST and the obtained UST-Au produced more ROS than UST as exposed to 980 nm near-infrared light.As AuNPs was added to be 3 wt%of the mass of UST,the obtained nanophotosensitizer had a mean hydrodynamic diameter(258 nm),relatively high zeta potential(+22.4 mV),good colloidal stability and the optimal ROS generation ability.Unexceptionally,iodine ions were expeditiously labeled on UST-Au suspended in aqueous solution,and the amount of the bound iodine ions enhanced with the increase of the mass percent of Au in UST-Au.The radiolabeling yield of UST-Au-131I^?was more than 95%.Furthermore,the iodine labeling reaction had negligibly negative effect on the colloidal stability and ROS production of the nanophotosensitizer.In general,all these unique properties of the nanophotosensitizer facilitate the potential application in SPECT imaging-guided photodynamic therapy against tumor.