Abstract

The surface–chemically modified superparamagnetic iron oxide nanoparticles are broadly investigated as magnetic resonance imaging contrast agents based on their unique characteristics such as high magnetization values, diameter from 4 to 100 nm, and narrow distribution of particle size. However, naked nanoparticles might be easily oxidized by the air leading to loss of dispersibility and magnetization. Therefore, suitable surface coating strategies were developed to increase the stability of magnetic iron oxide contrast agents in the physiological conditions. In addition, the polymer-coated agents possess an improved biocompatibility in comparison with conventional agents. This review discusses important aspects of newly developed magnetic contrast agents such as chemical synthesis strategies, physical parameters, relaxivity parameters, the effect of various coatings, and emerging applications. Disadvantages associated with commercially available gadolinium contrast agents are considered, and the advantages of potential applications of iron oxide alternatives to traditional agents are presented. Finally, perspectives of the future developments, applications, and concerns of the magnetic nanoparticles are also included. Graphical abstract: Figure not available: see fulltext.. © 2021, The Author(s), under exclusive licence to Springer Nature B.V. part of Springer Nature.