IP: 94.231.219.213 On: Wed, 17 Jul 2019 06:55:33 Copyright: American Scientific Publishers Delivered by Ingenta Materials Express Article Copyright © 2019 by American Scientific Publishers All rights reserved. Printed in the United States of America 2158-5849/2019/9/328/009 doi:10.1166/mex.2019.1505 www.aspbs.com/mex Role of interface quality in iron oxide core/shell nanoparticles on heating efficiency and transverse relaxivity Venkatesha Narayanaswamy 1 , Ihab M. Obaidat 1, * , Sachin Latiyan 2 , Shilpee Jain 2 , Chiranjib Nayek 1 , Sumana Goankar 3 , M-Ali AL-Akhras 4 , and Imaddin A. Al-Omari 5 1 Department of Physics, United Arab Emirates University, Al-Ain 15551, United Arab Emirates 2 Center for Biosystems Science and Engineering, Indian Institute of Science, Bangalore 560012, India 3 NMR Research Centre, Indian Institute of Science, Bangalore 560012, India 4 Physics Department, Jordan University of Science and Technology, Irbid 22110, Jordan 5 Department of Physics, Sultan Qaboos University, PC 123, Muscat, Sultanate of Oman ABSTRACT Core/shell Fe 3 O 4 / -Fe 2 O 3 nanoparticles have been designed as a promising agent for magnetic hyperthermia and contrast agents for MRI imaging applications, because of their high magnetic moment and biocompatibility. Three sets of core/shell nanoparticles with the same core diameter of 8 nm and shell thicknesses of 1, 3 and 5 nm were synthesized by chemical coprecipitation. The nanoparticles were coated with PEG and the specific absorption rate for the nanoparticles was determined by applying 3.6 kA/m alternating magnetic field with 236 kHz frequency. The biocompatibility of the nanoparticles was confirmed by MTT assay. Three sets of nanoparticles presented in the study have shown the ability to kill 80–85% HeLa cells upon exposure to alternating magnetic field for 10 minutes in the presence of the nanoparticles. The transverse relaxivity of water protons for the three sets of the nanoparticles were obtained using 400 MHz Bruker NMR. The core/shell interface structure is found to be of poor quality because of interface defects which results in interface spin glass structures. The existence of the spin glass clusters suppresses the interface exchange coupling which leads to weak interface magnetic anisotropy. The insignificant role of core/shell structure on the heating efficiency is attributed to the insignificant contribution of the interface structure towards the effective anisotropy. Keywords: Interface, Nanoparticles, Core/Shell, Hyperthermia, MRI. 1. INTRODUCTION Designing the nanoparticles with the improved prop- erties for biomedical applications has always been an interesting and challenging subject. 12 Biomedical appli- cations of magnetic nanoparticles include drug deliv- ery, magnetic resonance imaging (MRI) and magnetic hyperthermia. 34 Great amount of research has been ∗ Author to whom correspondence should be addressed. Email: iobaidat@uaeu.ac.ae dedicated and numerous studies have been reported on the use of magnetic nanoparticles in biomedical applications for cancer treatment. 56 Magnetic nanoparticles when subjected to alternating magnetic field (AMF) produce local heating due to various magnetic relaxations which are particle-size-dependent processes. This local heating can be used for the killing of cancer cells as they are more sen- sitive to temperature raise compared to the normal cells. Thermotherapy for cancer treatment includes hyperthermia and thermoablation. 7 Hyperthermia involves elevating the 328 Mater. Express, Vol. 9, No. 4, 2019