High-resolution ICP-MS approach for characterization of magnetic nanoparticles for biomedical applications.

The potential of iron oxide-based nanoparticles (IONs) as theranostic agents is believed to be in a great part due to non-invasive diagnosis and therapeutic applications. However, there is still a lack of well-recognized methodology to assess bioresistance, hypotoxicity, reactivity toward pertinent biomolecules, as well as an eventual dose of IONs as prerequisites for their clinical use. In this study, we demonstrate how application of high-resolution ICP-MS in combination with conventional ultrafiltration can address these important issues in a simple and high-throughput way. Based upon interference-free and sensitive measurements of iron and sulfur isotopes ensured by sector-field ICP-MS mode, the comparative testing of a series of novel IONs modified by PEG or PEG and an ionic liquid, was performed. Satisfactory stability (less than 1 % of soluble Fe), minor toxicity (by virtue of releasing a free iron) and transit into bioconjugates in human serum, different in speed, proved the prospective of the tested IONs for in-depth preclinical development.