title: Effect of Nanoclustering and Dipolar Interactions in Heat Generation for Magnetic Hyperthermia.
abstract: Biomedical magnetic colloids commonly used in magnetic hyperthermia experiments often display a bidisperse structure, i.e., are composed of stable nanoclusters coexisting with well-dispersed nanoparticles. However, the influence of nanoclusters in the optimization of colloids for heat dissipation is usually excluded. In this work, bidisperse colloids are used to analyze the effect of nanoclustering and long-range magnetic dipolar interaction on the magnetic hyperthermia efficiency. Two kinds of colloids, composed of magnetite cores with mean sizes of around 10 and 18 nm, coated with oleic acid and dispersed in hexane, and coated with meso-2,3-dimercaptosuccinic acid and dispersed in water, were analyzed. Small-angle X-ray scattering was applied to thoroughly characterize nanoparticle structuring. We proved that the magnetic hyperthermia performances of nanoclusters and single nanoparticles are distinctive. Nanoclustering acts to reduce the specific heating efficiency whereas a peak against concentration appears for the well-dispersed component. Our experiments show that the heating efficiency of a magnetic colloid can increase or decrease when dipolar interactions increase and that the colloid concentration, i.e., dipolar interaction, can be used to improve magnetic hyperthermia. We have proven that the power dissipated by an ensemble of dispersed magnetic nanoparticles becomes a nonextensive property as a direct consequence of the long-range nature of dipolar interactions. This knowledge is a key point in selecting the correct dose that has to be injected to achieve the desired outcome in intracellular magnetic hyperthermia therapy.
authors.affiliation: Physics Department, Physics Institute of La Plata (IFLP- CONICET), Faculty of Exact Sciences, National University of La Plata , c.c. 67, 1900 La Plata, Argentina.
authors.forename: Diego F
authors.initials: DF
authors.lastname: Coral
authors.affiliation: Physics Department, Physics Institute of La Plata (IFLP- CONICET), Faculty of Exact Sciences, National University of La Plata , c.c. 67, 1900 La Plata, Argentina.
authors.forename: Pedro Mendoza
authors.initials: PM
authors.lastname: Zélis
authors.affiliation: Department of Biomaterials and Bioinspired Materials, Materials Science Institute of Madrid (ICMM)/CSIC , Sor Juana Inés de la Cruz 3, Cantoblanco, 28049 Madrid, Spain.
authors.forename: Marzia
authors.initials: M
authors.lastname: Marciello
authors.affiliation: Department of Biomaterials and Bioinspired Materials, Materials Science Institute of Madrid (ICMM)/CSIC , Sor Juana Inés de la Cruz 3, Cantoblanco, 28049 Madrid, Spain.
authors.forename: María del Puerto
authors.initials: Mdel P
authors.lastname: Morales
authors.affiliation: Institute of Physics, University of Sao Paulo , C.P. 66318 Sao Paulo SP, Brazil.
authors.forename: Aldo
authors.initials: A
authors.lastname: Craievich
authors.affiliation: Physics Department, Physics Institute of La Plata (IFLP- CONICET), Faculty of Exact Sciences, National University of La Plata , c.c. 67, 1900 La Plata, Argentina.
authors.forename: Francisco H
authors.initials: FH
authors.lastname: Sánchez
authors.affiliation: Physics Department, Physics Institute of La Plata (IFLP- CONICET), Faculty of Exact Sciences, National University of La Plata , c.c. 67, 1900 La Plata, Argentina.
authors.forename: Marcela B Fernández
authors.initials: MB
authors.lastname: van Raap