Naposome: Peptide supramolecular aggregates as target specific nanocarriers.

In the last years, oncology research was focused to develop carriers for contrast agents and chemotherapeutics to obtain well esolved images and to improve the drug efficiency. Long circulation micelles and liposomes are capable to release drug, thus reducing severe side effects. A crucial facet is to target the cancer tissues in order to hit only the pathological cells. Naposomes are peptide labeled aggregates able to recognize membrane receptors overexpressed by cancer cells. The features of these aggregates are the contemporary presence of a bioactive peptide and a chelating agent able to coordinate a metal ion as contrast agents for nuclear medicine techniques or magnetic resonance imaging (MRI). Both moieties are linked to a lipophilic tail through an ethoxilic spacer able to increase the hydrophilicity of the aminoacidic sequences and increase the blood circulation time. These amphiphilic molecules auto-assemble in micelles and vesicles. The driving force of aggregation process is the presence of negative charges on chelating agent. These new aggregates have been designed to target the bombesin receptor family, the somatostatin or the cholecystokinin receptors. They are able to encapsulate the doxorubicin cytotoxic drug or the PtCl2 cis-platinum fragment. Therefore these supramolecular compounds combine together imaging and therapeutics capabilities. All aggregates have been structurally characterized by dynamic light scattering (DLS) and small angle neutron scattering (SANS). Results concerning cellular binding and in vivo biodistribution studies by nuclear medicine techniques, and therapeutic efficacy of the encapsulated drug will be reported.