Conjugation of homing peptide to magnetite nanoparticles and their specific intracellular uptake

In this study, a homing peptide denoted as AP was successfully conjugated to the surface of aminodextrancoated magnetite nanoparticles (ADNP) in order to use it as a targeting ligand for IL-4 receptors bearing tumor cells. Fluorescence isothiocyanate (FITC) was also immobilized on the AP-conjugated magnetite nanoparticles (PDNP) to visualize the nanoparticles in the cells. The PDNP were monodispersed and superparamagnetic in nature at room temperature. It was revealed, from cell culture experiments, that the PDNP are biocompatible. Again, microscopic fluorescence images showed that FITC-bound PDNP (FPDNP) were specifically internalized into HT1376 cells and emitted intense fluorescence images whereas FITC-bound DNP (FDNP) were slightly internalized into the cells. Furthermore, confocal images confirmed that the fluorescence signal originates from the cells interior. These phenomena indicate that AP-conjugated magnetite nanoparticles have a high affinity to IL-4 receptor-bearing tumor cells. Thus, AP-conjugated magnetite nanoparticles have the potential to be used for molecular imaging and other biomedical applications.