Preparation of Magnetic Iron Oxide Nanoparticles (MIONs) with Improved Saturation Magnetization Using Multifunctional Polymer Ligand.

Bien Tan,Muhammad Majeed,Wei Yan,Jiaojiao Guo

doi:10.3390/polym8110392

Abstract

This paper describes the preparation of ultra-small magnetic iron oxide (Fe3O4) nanoparticles (MIONs) coated with water-soluble thioether end-functionalized polymer ligand pentaerythritol tetrakis 3-mercaptopropionate-polymethacrylic acid (PTMP-PMAA). The MIONs were prepared by co-precipitation of aqueous iron precursor solution at a high temperature. The polymer modified MIONs were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), and vibrating sample magnetometery (VSM). It was found that these MIONs were successfully modified by this water-soluble polymer ligand with a fairly uniform size and narrow size distribution. The dried powder of MIONs could be stored for a long time and re-dispersed well in water without any significant change. Additionally, the polymer concentration showed a significant effect on size and magnetic properties of the MIONs. The saturation magnetization was increased by optimizing the polymer concentration. Furthermore, the 3-(4,5-dimethylthiazol-2-yl)-2-5-diphenyltetrazolium bromide (MTT)-assay demonstrated that these MIONs were highly biocompatible and they could be successfully coupled with fluorescent dye Rhodamine due to the formation of amide bond between carboxylic acid groups of MIONs and amine groups of dye. The obtained results indicated that these multifunctional MIONs with rich surface chemistry exhibit admirable potential in biomedical applications.

Highlights

Magnetic nanoparticles (NPs) have gained much scientific interest for their unique magnetic properties such as superparamagnetism, high coercivity, low Curie temperature, and high magnetic susceptibility [1,2]
We have described the synthesis of magnetic iron oxide (Fe3O4) nanoparticles (MIONs) with a multifunctional water-soluble polymer ligand pentaerythritol tetrakis 3-mercaptopropionate-polymethacrylic acid (PTMP-PMAA), following our previous work [20]
We report the preparation of MIONs using PTMP-PMAA with improved saturation magnetization through our original high temperature single step co-precipitation method [20] but with few modifications in order to improve the magnetic properties of MIONs, such as lower polymer concentrations as compared to previous report, iron precursors were dissolved in concentrated hydrochloric acid (HCl) instead of 1 M HCl solution in order to prevent their hydrolysis and condensation before the addition of precipitating agents and the inert conditions were maintained, by nitrogen gas bubbling throughout the course of reaction, which protects MIONs from critical oxidation and keeps their size smaller [25]

Summary

Introduction

Magnetic nanoparticles (NPs) have gained much scientific interest for their unique magnetic properties such as superparamagnetism, high coercivity, low Curie temperature, and high magnetic susceptibility [1,2]. It is usually desired to develop a simple, one step, cost effective and environment friendly protocol for the preparation of water-soluble, uniform, multifunctional, superparamagnetic iron oxide NPs with a better control over their size, shape and magnetic properties. In aqueous co-precipitation process, polymer ligands can efficiently control the size and shape of the NPs due to the presence of abundant functional groups such as –COOH, –OH, –NH2 , etc These multifunctional polymers render magnetic NPs more stable, water-soluble and uniform in addition to providing them rich surface chemistry which opens up ways for easier post-synthesis modification and functionalization for bio-applications [5,18,19,20,21,22]

Methods

Results

Conclusion