Long‐Term Stability and Reproducibility of Magnetic Colloids Are Key Issues for Steady Values of Specific Power Absorption over Time. Issue 27 (2nd June 2015)

• Record Type: Journal Article
• Authors: Sanz, Beatriz; Calatayud, M. Pilar; Cassinelli, Nicolás; Ibarra, M. Ricardo; Goya, Gerardo F.
• Other Names: Trindade Tito sponsoringEditor.; Wong Wing‐Tak sponsoringEditor.
• Is Part Of: European journal of inorganic chemistry. Issue 27(2015)
• Page Start: 4524
• Page End: 4531
• Publication Date: 2015-06-02
• Subjects: Magnetic properties -- Nanoparticles -- Hyperthermia -- Colloids -- Surface modification; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201500303
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: Virtually all clinical applications of magnetic nanoparticles (MNPs) require the formulation of biocompatible, water‐based magnetic colloids. For magnetic hyperthermia, the requirements also include a high colloidal stability against precipitation and agglomeration of the constituent MNPs to maintain the heating efficiency of the ferrofluid in the long term. Agglomeration can change the heating efficiency by forming MNP clusters that modify the magnetic dipolar interactions between particles. Additionally, precipitation of the MNPs (i.e., the heating sources within the liquid) can change the measured heating rates of a colloid by altering the heat flow dynamics as the particles plunge to the precipitate. The specific power absorption (SPA) of single‐domain MNPs depends critically on the average particle size and size distribution width and therefore first‐rate reproducibility of different batches with respect to these parameters is also needed. We have studied the evolution of the SPA of highly reproducible and stable water‐based colloids composed of polymer‐coated Fe3 O4 magnetic nanoparticles. By measuring the specific power absorption (SPA) values for 1 year as a function of field amplitude and frequency ( H ≤ 24 kA/m; 260 ≤ f ≤ 830 kHz), we have demonstrated that the SPA values of these samples can be reproduced in successive synthetic batches and stable for several months due to the in situ polymer coating that provides colloidal stability and keeps dipolar interactions negligible. Abstract : The poly(ethyleneimine)‐coated magnetic nanoparticles (PEI‐MNPs) prepared in this work by oxidative hydrolysis show good reproducibility of size and size distribution. In addition, these PEI‐MNPs show only a moderate decrease in the specific power absorption when they aggregate over time. These results render these particles suitable for applications in magnetic hyperthermia.