Sun Conroy, Sze Raymond, Zhang Miqin
Department of Materials Science and Engineering, University of Washington, Seattle, 98195, USA.
J Biomed Mater Res A. 2006 Sep 1;78(3):550-7. doi: 10.1002/jbm.a.30781.
We report the development and in vitro study of a nanoconjugate serving as a targeted magnetic resonance imaging (MRI) contrast enhancement agent for detection of cancer cells overexpressing the folate receptor. The nanoconjugate was synthesized by coating superparamagnetic iron oxide nanoparticles with covalently bound bifunctional poly(ethylene glycol) (PEG), followed by conjugation with folic acid (FA). The specificity of the nanoconjugate targeting cancerous cells was demonstrated by comparative intracellular uptake of the nanoconjugate and PEG-/dextran-coated nanoparticles by human adenocarcinoma HeLa cells. Preferential targeting to cancerous cells was studied by comparing the uptake of the nanoconjugate by HeLa cells and by non-FR expressing osteosarcoma MG-63 cells. Uptake of the nanoconjugate by HeLa cells after 4 h incubation was found to be a 12-fold higher than that of PEG- or dextran-coated nanoparticles as quantified by inductively coupled plasma spectroscopy. A significant negative contrast enhancement was observed with magnetic resonance (MR) phantom imaging for HeLa cells over MG-63 cells, when both were cultured with the nanoconjugate. Specificity of the nanoconjugate for folate receptors was also verified with a competitive inhibition assay, in which HeLa cells were incubated with both NP-PEG-FA and free FA. The bifunctional PEG used has amide linkages within the PEG chains that can form interchain hydrogen bonding, leading to improved stability of the PEG coating. Self-assembled PEG can be controlled at the molecular level and are suitable for nanoscale coatings.
我们报告了一种纳米缀合物的研发及其体外研究，该纳米缀合物作为一种靶向磁共振成像（MRI）造影剂，用于检测过度表达叶酸受体的癌细胞。该纳米缀合物的合成方法是，先用共价结合的双功能聚乙二醇（PEG）包覆超顺磁性氧化铁纳米颗粒，然后与叶酸（FA）进行缀合。通过人腺癌HeLa细胞对该纳米缀合物以及PEG-或葡聚糖包覆的纳米颗粒的细胞内摄取比较，证明了该纳米缀合物对癌细胞的靶向特异性。通过比较HeLa细胞和不表达叶酸受体的骨肉瘤MG-63细胞对该纳米缀合物的摄取，研究了其对癌细胞的优先靶向作用。经电感耦合等离子体光谱定量分析，HeLa细胞在孵育4小时后对该纳米缀合物的摄取量比PEG-或葡聚糖包覆的纳米颗粒高12倍。当HeLa细胞和MG-63细胞都与该纳米缀合物一起培养时，磁共振（MR）体模成像显示HeLa细胞相对于MG-63细胞有显著的负性造影增强。还用竞争性抑制试验验证了该纳米缀合物对叶酸受体的特异性，即HeLa细胞同时与NP-PEG-FA和游离FA一起孵育。所使用的双功能PEG在PEG链内具有酰胺键，可形成链间氢键，从而提高PEG涂层的稳定性。自组装PEG可以在分子水平上进行控制，适用于纳米级涂层。
