Magnetic Nanoparticles: Surface Effects and Properties Related to Biomedicine Applications

TLDR

Magnetic nanoparticles exhibit size‑dependent magnetic properties due to high surface‑to‑volume ratios and altered crystal structures, and their controllable synthesis allows comparison across biological scales, making them attractive for diverse biomedical applications. This review examines how surface effects and ferrite composition of magnetic nanoparticles influence their biomedical use, particularly as MRI contrast agents. The authors analyze the magnetic properties of ferrite nanoparticles, emphasizing surface phenomena and their role in MRI contrast agent performance.

Abstract

Due to finite size effects, such as the high surface-to-volume ratio and different crystal structures, magnetic nanoparticles are found to exhibit interesting and considerably different magnetic properties than those found in their corresponding bulk materials. These nanoparticles can be synthesized in several ways (e.g., chemical and physical) with controllable sizes enabling their comparison to biological organisms from cells (10-100 μm), viruses, genes, down to proteins (3-50 nm). The optimization of the nanoparticles' size, size distribution, agglomeration, coating, and shapes along with their unique magnetic properties prompted the application of nanoparticles of this type in diverse fields. Biomedicine is one of these fields where intensive research is currently being conducted. In this review, we will discuss the magnetic properties of nanoparticles which are directly related to their applications in biomedicine. We will focus mainly on surface effects and ferrite nanoparticles, and on one diagnostic application of magnetic nanoparticles as magnetic resonance imaging contrast agents.