Thermomagnetic determination of Fe sub(3O) sub(4) magnetic nanoparticle diameters for biomedical applications

• Published in: Journal of magnetism and magnetic materials 2011-09, Vol.323 (17), p.2310-2317
• Main Authors: Plouffe, Brian D, Nagesha, Dattatri K, DiPietro, Robert S, Sridhar, Srinvas, Heiman, Don, Murthy, Shashi K, Lewis, Lewis H
• Format: Article
• Language: English
• Subjects: Electron microscopy; Magnetization; Mathematical models; Nanocomposites; Nanomaterials; Nanoparticles; Nanostructure; Particle size distribution
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2011.04.013

The utility and promise of magnetic nanoparticles (MagNPs) for biomedicine rely heavily on accurate determination of the particle diameter attributes. While the average functional size and size distribution of the magnetic nanoparticles directly impact the implementation and optimization of nanobiotechnology applications in which they are employed, the determination of these attributes using electron microscopy techniques can be time-consuming and misrepresentative of the full nanoparticle population. In this work the average particle diameter and distribution of an ensemble of Fe sub(3O) sub(4) ferrimagnetic nanoparticles are determined solely from temperature-dependent magnetization measurements; the results compare favorably to those obtained from extensive electron microscopy observations. The attributes of a population of biocompatible Fe sub(3O) sub(4) nanoparticles synthesized by a thermal decomposition method are obtained from quantitative evaluation of a model that incorporates the distribution of superparamagnetic blocking temperatures represented through thermomagnetization data. The average size and size distributions are determined from magnetization data via temperature-dependent zero-field-cooled magnetization. The current work is unique from existing approaches based on magnetic measurement for the characterization of a nanoparticle ensemble as it provides both the average particle size as well as the particle size distribution. Size distribution of nanoparticles determined via thermomagnetic response. Calculated distribution exhibited reasonable agreement with electron microscopy. Effective anisotropy constant determined is by scaling of distribution function. Minimizes need for particle sizing using electron microscopy. Facile alternative to conventional size determination techniques.