Magnetic Force Microscopy Characterization of Superparamagnetic Iron Oxide Nanoparticles (SPIONs)

摘要

Superparamagnetic iron oxide nanoparticles (SPIONs), due to theircontrollable sizes, relatively long in vivo half-life and limitedagglomeration, are ideal for biomedical applications such as magnetic labeling,hyperthermia cancer treatment, targeted drug delivery and for magneticresonance imaging (MRI) as contrast enhancement agents. In order to understandhow SPIONs interact with cells and cellular membranes it would be of interestto characterize individual SPIONs at the nanoscale in physiologically relevantconditions without labeling them. We demonstrate that Magnetic Force Microscopy(MFM) can be used to image SPIONs in air as well as in liquid. The magneticproperties of bare and SiO2 coated SPIONs are compared using MFM. We reportthat surface modification using (3-mercaptopropyl)-trimethoxysilanesignificantly improves adsorption and distribution of SPIONs on gold surfaces.To obtain proof of principle that SPIONS can be imaged with MFM inside the cellwe imaged SPIONs buried in thin polymer films (polystyrene (PS) and polymethyl-methacrylate (PMMA)). This opens the possibility of visualizing SPIONsinside the cell without any labeling or modifications and present MFM as apotential magnetic analogue for fluorescence microscopy. The results of thesestudies may have a valuable impact for characterization and further developmentof biomedical applications of SPIONs and other magnetic nanoparticles.