Preparation of SiO2-Protecting Metallic Fe Nanoparticle/SiO2 Composite Spheres for Biomedical Application

Pin-Wei Hsieh,Ching-Li Tseng,Dong-Hau

doi:10.3390/ma8115416

Pin-Wei Hsieh, Ching-Li Tseng + Show 1 more

Open Access

https://doi.org/10.3390/ma8115416

Copy DOI

Abstract

Functionalized Fe nanoparticles (NPs) have played an important role in biomedical applications. In this study, metallic Fe NPs were deposited on SiO2 spheres to form a Fe/SiO2 composite. To protect the Fe from oxidation, a thin SiO2 layer was coated on the Fe/SiO2 spheres thereafter. The size and morphology of the SiO2@Fe/SiO2 composite spheres were examined by transmission electron microscopy (TEM). The iron form and its content and magnetic properties were examined by X-ray diffraction (XRD), inductively-coupled plasma mass spectrometry (ICP-MS) and a superconducting quantum interference device (SQUID). The biocompatibility of the SiO2@Fe/SiO2 composite spheres was examined by Cell Counting Kit-8 (CCK-8) and lactate dehydrogenase (LDH) tests. The intracellular distribution of the SiO2@Fe/SiO2 composite spheres was observed using TEM. XRD analysis revealed the formation of metallic iron on the surface of the SiO2 spheres. According to the ICP-MS and SQUID results, using 0.375 M FeCl3·6H2O for Fe NPs synthesis resulted in the highest iron content and magnetization of the SiO2@Fe/SiO2 spheres. Using a dye loading experiment, a slow release of a fluorescence dye from SiO2@Fe/SiO2 composite spheres was confirmed. The SiO2@Fe/SiO2 composite spheres co-cultured with L929 cells exhibit biocompatibility at concentrations <16.25 µg/mL. The TEM images show that the SiO2@Fe/SiO2 composite spheres were uptaken into the cytoplasm and retained in the endosome. The above results demonstrate that the SiO2@Fe/SiO2 composite spheres could be used as a multi-functional agent, such as a magnetic resonance imaging (MRI) contrast agent or drug carriers in biomedical applications.

Highlights

Magnetic nanoparticles (MNPs) exhibit superparamagnetic behavior, as they contain a single dipole in a single domain due to the size effect, which can be aligned under an applied external magnetic field [1]
Mass spectroscopy with an inductively-coupled plasma mass spectrometer (ICP-MS, X Series II, Thermo Scientific, Waltham, MA, USA) was used to quantitatively analyze the Fe content on the Fe/SiO2 composite spheres after they were digested in nitric acid solution
The SiO2@Fe/SiO2 composite spheres were synthesized as a carrier for magnetic drug targeting by using the sol-gel route and a chemical reduction method

Summary

Introduction

Magnetic nanoparticles (MNPs) exhibit superparamagnetic behavior, as they contain a single dipole in a single domain due to the size effect, which can be aligned under an applied external magnetic field [1]. Iron chloride hexahydrate (FeCl3 ̈ 6H2O, Sigma-Aldrich) solution of three different concentrations (0.1 M, 0.375 M and 0.51 M) was prepared by dissolving the appropriate amount (0.234g, 0.912 g and 1.285 g, respectively) in a mixture of SiO2 sphere (1.5 g) solution of 7.2 mL of anhydrous ethanol and 1.8 mL of de-ionized water. Characterization and Measurements of SiO2@Fe/SiO2 Composite Spheres

Results

Conclusion