Up-Conversion Cell Imaging and pH-Induced Thermally Controlled Drug Release from NaYF4:Yb3+/Er3+@Hydrogel Core–Shell Hybrid Microspheres

作者：Yunlu Dai, Ping’an Ma, Ziyong Cheng, Xiaojiao Kang, Xiao Zhang, Zhiyao Hou, Chunxia Li, Dongmei Yang, Xuefeng Zhai, Jun Lin · 发表于：ACS Nano · 年份：2012 · DOI：10.1021/nn300303q · 被引用次数：321 · 研究领域：Luminescence Properties of Advanced Materials、Lanthanide and Transition Metal Complexes、Luminescence and Fluorescent Materials

In this study, we report a new controlled release system based on up-conversion luminescent microspheres of NaYF(4):Yb(3+)/Er(3+) coated with the smart hydrogel poly[(N-isopropylacrylamide)-co-(methacrylic acid)] (P(NIPAM-co-MAA)) (prepared using 5 mol % of MAA) shell. The hybrid microspheres show bright up-conversion fluorescence under 980 nm laser excitation, and turbidity measurements show that the low critical solution temperature of the polymer shell is thermo- and pH-dependent. We have exploited the hybrid microspheres as carriers for Doxorubicin hydrochloride (DOX) due to its stimuli-responsive property as well as good biocompatibility via MTT assay. It is found that the drug release behavior is pH-triggered thermally sensitive. Changing the pH to mildly acidic condition at physiological temperature deforms the structure of the shell, causing the release of a large number of DOX from the microspheres. The drug-loaded microspheres exhibit an obvious cytotoxic effect on SKOV3 ovarian cancer cells. The endocytosis process of drug-loaded microspheres is observed using confocal laser scanning microscopy and up-conversion luminescence microscopy. Meanwhile, the as-prepared NaYF(4):Yb(3+)/Er(3+)@SiO(2)@P(NIPAM-co-MAA) microspheres can be used as a luminescent probe for cell imaging. In addition, the extent of drug release can be monitored by the change of up-conversion emission intensity. These pH-induced thermally controlled drug release systems have potential to be used for...