Stable aqueous dispersion of superparamagnetic iron oxide nanoparticles protected by charged chitosan derivatives

Agnieszka Szpak,Szczepan Zapotoczny,Tomasz Skórka,Gabriela Kania,Waldemar Tokarz,Maria Nowakowska

doi:10.1007/s11051-012-1372-9

Abstract

This article presents the synthesis and characterization of biocompatible superparamagnetic iron oxide nanoparticles (SPIONs) coated with ultrathin layer of anionic derivative of chitosan. The water-based fabrication involved a two-step procedure. In the first step, the nanoparticles were obtained by co-precipitation of ferrous and ferric aqueous salt solutions with ammonia in the presence of cationic derivative of chitosan. In the second step, such prepared materials were subjected to adsorption of oppositely charged chitosan derivative which resulted in the preparation of negatively charged SPIONs. They were found to develop highly stable dispersion in water. The core size of the nanocoated SPIONs, determined using transmission electron microscopy, was measured to be slightly above 10 nm. The coated nanoparticles form aggregates with majority of them having hydrodynamic diameter below 100 nm, as measured by dynamic light scattering. Their composition and properties were studied using FTIR and thermogravimetric analyses. They exhibit magnetic properties typical for superparamagnetic material with a high saturation magnetization value of 123 ± 12 emu g−1 Fe. Very high value of the measured r 2 relaxivity, 369 ± 3 mM−1 s−1, is conducive for the potential application of the obtained SPIONs as promising contrast agents in magnetic resonance imaging.Electronic supplementary materialThe online version of this article (doi:10.1007/s11051-012-1372-9) contains supplementary material, which is available to authorized users.

Highlights

Magnetic resonance imaging (MRI) is one of the noninvasive diagnostic techniques used in medicine to visualize internal structures that, needs injection of a contrast agent to enable efficient imaging of different tissues
The presence of the cationic polymer, cationic derivative of chitosan (CCh), during the co-precipitation leads to fabrication of stable aqueous dispersion of small aggregates of superparamagnetic iron oxide nanoparticles (SPIONs) required for biomedical applications
This can be explained considering the fact that SPIONs formed in a presence of CCh exhibited highly positive zeta potential—greater than 40 mV for both polymer concentrations used during the synthesis

Summary

Introduction

Magnetic resonance imaging (MRI) is one of the noninvasive diagnostic techniques used in medicine to visualize internal structures that, needs injection of a contrast agent to enable efficient imaging of different tissues. The development of an alternative material which could replace the contrast agents based on gadolinium is highly imperative Toward this purpose, superparamagnetic iron oxide nanoparticles (SPIONs) have become the central points of the interest within the research community, because they are non-toxic and biodegradable/bioresorbable (Yang et al 2008; Liu et al 2011; Bhattacharya et al 2012). Superparamagnetic iron oxide nanoparticles (SPIONs) have become the central points of the interest within the research community, because they are non-toxic and biodegradable/bioresorbable (Yang et al 2008; Liu et al 2011; Bhattacharya et al 2012) These SPIONs may exhibit better magnetic properties than gadolinium complexes implying the use of lower doses of these contrasts necessary to maintain good quality of MRI images. SPIONs predominantly shorten T2 relaxation time and provide negative contrast in T2-weighted images

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Conclusion