Magnetic nanoparticles have been used for biomedical purposes for several years. In recent years, nanotechnology has developed to a stage that makes it possible to engineer particles to provide opportunities for the site-specific delivery of drugs. To this end a variety of iron oxide particles have been synthesised. The size and surface of the particles are crucial factors in the application of the particles. This study therefore involves the use of magnetic nanoparticles synthesised and derivatised with either dextran or albumin, compared to identical underivatised plain particles. This influence in vitro was assessed using human dermal fibroblasts and various techniques to observe cell–particles interaction, including light and fluorescence microscopy, scanning and transmission electron microscopy. The results indicate that the derivatised particles induce alterations in cell behaviour and morphology distinct from the plain particles, suggesting that cell response can be directed via specifically engineered particle surfaces.