Silica Functionalized Magnesium Ferrite Nanocomposites for Potential Biomedical Applications: Preparation, Characterization and Enhanced Colloidal Stability Studies Ehi-Eromosele C.O. 1,a* , Ita B.I. 1 & 2,b , Iweala E.EJ. 3,c , Ogunniran K.O. 1,d , Adekoya J.A. 1,e , Siyanbola T.O. 1,f 1 Department of Chemistry, Covenant University, PMB 1023, Ota, Nigeria. 2 Department of Pure and Applied Chemistry, University of Calabar, Calabar, Nigeria. 3 Department of Biological Sciences, Covenant University, PMB 1023, Ota, Nigeria. a cyril.ehi-eromosele@covenantuniversity.edu.ng, b iserom2001@yahoo.com, c emeka.iweala@covenantuniversity.edu.ng, d kehinde.ogunniran@covenantuniversity.edu.ng, e joseph.adekoya@covenantuniversity.edu.ng, f tolutope.siyanbola@covenantuniversity.edu.ng Keywords: Silica; biomedical applications; colloidal stability; combustion synthesis; magnetic nanoparticles. Abstract. Magnetic nanocomposite material composed of silica coated MgFe 2 O 4 for potential biomedical applications were synthesized by a two-step chemical method including solution combustion synthesis, followed by silica coatings of the ferrite nanoparticles. The effects of silica coatings on the structural, morphological and magnetic properties were comprehensively investigated using powder X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), energy dispersive absorption x-ray (EDAX), Fourier Transform Infrared spectroscopy (FTIR), thermogravimetric analysis and differential thermal analysis (TG–DTA) and vibrating sample magnetometer (VSM). The colloidal behaviour of coated MNPs in physiological saline medium like water or phosphate buffer saline (PBS) was also studied by zeta potential measurements. The XRD patterns indicate that the crystalline structure is single cubic spinel phase and the spinel structure is retained after silica coating. Also, after silica coating, the crystallite size (from Scherrer formula) decreases from 53 to 47 nm. The magnetic results show that MgFe 2 O 4 MNPs (bare and silica coated) is ferrimagnetic at room temperature. Zeta potential studies revealed that there is enhanced colloidal stability of MgFe 2 O 4 MNPs after silica coating in aqueous media which is an applicable potential in biomedical applications. 1.0 Introduction In the last two decades, a number of nanoparticle-based therapeutic and diagnostic agents have been developed for the treatment of cancer, diabetes, pain, asthma, allergy, infections, and so on [1,2] (Brannon-Peppas and Blanchette, 2004; Kawasaki and Player, 2005). Magnetic nanoparticles (MNPs) have attracted great interest in a number of biomedical applications due to their inherent magnetic properties and biocompatibility [3]. The functional properties of these MNPs can be tailored for specific biological functions, such as drug delivery [4,5], hyperthermia or magnetic targeting [6,7], magnetic resonance imaging (MRI) [8,9], cell labeling and sorting [10,11], and immunoassays [12]. The spinel ferrite ferromagnetic or superparamagnetic nanomaterials with general formula MFe 2 O 4 (M = Mn, Fe, Ni, Co, Zn, Mg) are currently under extensive development in advanced therapeutics and diagnosis of a wide range of diseases. Typically, they have been used as heating foci in hyperthermia, contrast agents in MRI and magnetic field-guided drug delivery [5,13-15]. The structural and magnetic properties of spinel ferrites strongly depend on magnetic moment, particle size and distribution, shape and crystallinity which are highly sensitive to method of preparation [16,17]. Various methods of synthesis such as ball milling, co-precipitation, sol-gel, reverse micelle, hydrothermal and combustion methods have been used for the synthesis of MgFe 2 O 4 nanoparticles [18-22]. Most of the wet chemical methods like chemical co-precipitation and hydrothermal require careful control of pH of the solution, temperature, time and concentration Journal of Nano Research Submitted: 2015-11-03 ISSN: 1661-9897, Vol. 40, pp 146-157 Revised: 2016-01-21 doi:10.4028/www.scientific.net/JNanoR.40.146 Accepted: 2016-01-27 © 2016 Trans Tech Publications, Switzerland All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, www.ttp.net. (ID: 197.210.200.118-04/02/16,15:45:23)