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

Roberto Gonzalez-Rodriguez,Jeffery L. Coffer,Klemens Rumpf,Petra Granitzer

doi:10.1098/rsos.180697

Roberto Gonzalez-Rodriguez, Jeffery L. Coffer + Show 2 more

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https://doi.org/10.1098/rsos.180697

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Abstract

This article describes the preparation and fundamental properties of a new possible material as a magnetic resonance imaging contrast agent based on the incorporation of preformed iron oxide (Fe3O4) nanocrystals into hollow silicon nanotubes (Si NTs). Specifically, superparamagnetic Fe3O4 nanoparticles of two different average sizes (5 nm and 8 nm) were loaded into Si NTs of two different shell thicknesses (40 nm and 70 nm). To achieve proper aqueous solubility, the NTs were functionalized with an outer polyethylene glycol-diacid (600) moiety via an aminopropyl linkage. Relaxometry parameters r1 and r2 were measured, with the corresponding r2/r1 ratios in phosphate buffered saline 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 NT wall thickness, thereby demonstrating the role of nanostructured silicon template on associated relaxometry properties.

Highlights

Superparamagnetic iron oxide nanoparticles (Fe3O4 NPs) are the focus of extensive attention in areas such as catalysis [1], as well as biomedical applications such as cell labelling [2], biosensing [3], drug delivery [4], hyperthermia [5] and magnetic resonance imaging (MRI) [6]
Transmission electron microscopy (TEM) analysis (JEOL JEM-2100) confirms that the Fe3O4 NPs used in these experiments are uniformly spherical and have narrow size distributions of 5.10 ± 0.98 nm and 8.15 ± 1.76 nm
TEM confirms the successful loading of Fe3O4 NPS into the silicon nanotubes (Si NTs)

Summary

Introduction

Superparamagnetic iron oxide nanoparticles (Fe3O4 NPs) are the focus of extensive attention in areas such as catalysis [1], as well as biomedical applications such as cell labelling [2], biosensing [3], drug delivery [4], hyperthermia [5] and magnetic resonance imaging (MRI) [6]. In addition to their size-selective synthesis and useful fundamental magnetic properties, Fe3O4 NPs have a very low toxicity and are biocompatible [7,8]. The NT length, along with the outer and inner diameter of the Si NTs, is in principle broadly tunable, with a wall thickness-dependent aqueous dissolution behaviour [16]

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