In this article we present an overview of some of our research in the field of nanoscience. By combining two different scientific backgrounds (chemistry and biology), we investigate nanoparticle–cell interactions from different angles. This requires an interdisciplinary approach involving material synthesis and characterization, cell biology (biochemistry) and microscopy. In particular, we describe the synthesis and magnetic properties of superparamagnetic iron oxide nanoparticles as well as their behavior in cell culture, evaluate different visualization and detection methods, and investigate the interaction of such magnetic particles with immune cells.