Cytotoxicity suppression and cellular uptake enhancement of surface modified magnetic nanoparticles.

The aim of this study was to modify the surfaces of superparamagnetic iron oxide nanoparticles (SPION) with pullulan in order to reduce the cytotoxicity and enhance the cellular uptake of the nanoparticles. In this study, we have prepared and characterised the pullulan coated superparamagnetic iron oxide nanoparticles (Pn-SPION) of size around 40-45 nm with magnetite inner core and hydrophilic outer shell of pullulan. We have investigated the effect of cellular uptake of uncoated and Pn-SPION on cell adhesion/viability, cytotoxicity, morphology and cytoskeleton organisation of human fibroblasts. Cell cytotoxicity/adhesion studies of SPIONs on human dermal fibroblasts showed that the particles are toxic and their internalisation resulted in disruption of cytoskeleton organisation of cells. On the other hand, Pn-SPIONs were found to be non-toxic and induced changes in cytoskeleton organisation different from that observed with SPION. Transmission electron microscopy results indicated that the SPION and Pn-SPION were internalised into cells via different mechanisms, thereby suggesting that the particle endocytosis behaviour is dependent on the surface characteristics of the nanoparticles.