New MRI contrast agents based on silicon nanotubes loaded with superparamagnetic iron oxide nanoparticles

This article describes the preparation and fundamental properties of a new possible material as a MRI contrast agent based on the incorporation of preformed iron oxide nanocrystals into hollow silicon nanotubes. Specifically, superparamagnetic iron oxide nanoparticles Fe3O4 of two different average sizes (5 nm and 8 nm) were loaded into silicon nanotubes of two different shell thicknesses (40 nm and 70 nm). To achieve proper aqueous solubility, the nanotubes were functionalized with an outer polyethylene glycol (PEG)-diacid (600) moiety via an aminopropyl linkage. Relaxometry parameters r1 and r2 were measured, with the corresponding r2/r1 ratios in PBS confirming the expected negative contrast agent behaviour for these materials. For a given nanocrystal size, the observed r2 values are found to be inversely proportional to nanotube wall thickness, thereby demonstrating the role of nanostructured silicon template on associated relaxometry properties.

本文报道了一种潜在新型磁共振成像（Magnetic Resonance Imaging，MRI）对比剂材料的制备方法与基本性能，该材料通过将预制氧化铁纳米晶负载至中空硅纳米管中制备而成。具体而言，本研究将两种平均尺寸分别为5 nm与8 nm的超顺磁性四氧化三铁（Fe3O4）纳米颗粒，负载至两种壳层厚度分别为40 nm与70 nm的硅纳米管中。为赋予材料良好的水溶性，研究团队通过氨丙基连接臂，在硅纳米管外表面接枝了聚乙二醇（Polyethylene Glycol，PEG）二酸（600）基团。研究测定了弛豫测定（Relaxometry）参数r1与r2，在磷酸盐缓冲液（Phosphate Buffered Saline，PBS）中测得的对应r2/r1比值，证实了该类材料具备预期的阴性对比剂性能。在纳米晶尺寸固定的条件下，测得的r2值与纳米管壁厚度呈反比关系，由此证明了纳米结构化硅模板对相关弛豫测定性能的调控作用。