Optimization of synthesis and peptization steps to obtain iron oxide nanoparticles with high energy dissipation rates Fernando Mérida a , Andreina Chiu-Lam b , Ana C. Bohórquez c , Lorena Maldonado-Camargo b , María-Eglée Pérez d , Luis Pericchi d , Madeline Torres-Lugo a , and Carlos Rinaldi b,c,* a Deparment of Chemical Engineering, University of Puerto Rico. Mayagüez, P.O. Box 9046, Mayagüez, PR 00680 b Department of Chemical Engineering, University of Florida, P.O. Box 116005, Gainesville, FL 32611-6005 c J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, P.O. Box 116131, Gainesville, FL 32611-6131 d Department of Mathematics, University of Puerto Rico, Río Piedras. P.O.Box 70377 San Juan, PR 00936-8377 Abstract Magnetic Fluid Hyperthermia (MFH) uses heat generated by magnetic nanoparticles exposed to alternating magnetic fields to cause a temperature increase in tumors to the hyperthermia range (43–47 °C), inducing apoptotic cancer cell death. As with all cancer nanomedicines, one of the most significant challenges with MFH is achieving high nanoparticle accumulation at the tumor site. This motivates development of synthesis strategies that maximize the rate of energy dissipation of iron oxide magnetic nanoparticles, preferable due to their intrinsic biocompatibility. This has led to development of synthesis strategies that, although attractive from the point of view of chemical elegance, may not be suitable for scale-up to quantities necessary for clinical use. On the other hand, to date the aqueous co-precipitation synthesis, which readily yields gram quantities of nanoparticles, has only been reported to yield sufficiently high specific absorption rates after laborious size selective fractionation. This work focuses on improvements to the aqueous co- precipitation of iron oxide nanoparticles to increase the specific absorption rate (SAR), by optimizing synthesis conditions and the subsequent peptization step. Heating efficiencies up to 1,048 W/g Fe (36.5 kA/m, 341 kHz; ILP = 2.3 nH·m 2 ·kg −1 ) were obtained, which represent one of the highest values reported for iron oxide particles synthesized by co-precipitation without size- selective fractionation. Furthermore, particles reached SAR values of up to 719 W/g Fe (36.5 kA/m, 341 kHz; ILP = 1.6 nH·m 2 ·kg −1 ) when in a solid matrix, demonstrating they were capable of significant rates of energy dissipation even when restricted from physical rotation. Reduction in * Corresponding author. Tel. +1 352 294 5588. carlos.rinaldi@bme.ufl.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Disclosure The authors report no conflicts of interest in this work. HHS Public Access Author manuscript J Magn Magn Mater. Author manuscript; available in PMC 2016 November 15. Published in final edited form as: J Magn Magn Mater. 2015 November 15; 394: 361–371. doi:10.1016/j.jmmm.2015.06.076. Author Manuscript Author Manuscript Author Manuscript Author Manuscript