Strategies for tumor targeting by gold nanorods

Due to their tunable surface plasmon and functional photothermal effects, gold nanorods (GNRs) have proved to be promising in a wide range of biomedical applications such as imaging, hyperthermia therapy and drug delivery. All these applications can be controlled by the use of near infrared (NIR) light, which can penetrate deep into human tissues with minimal invasiveness. AuNRs thus hold the potential to combine both imaging diagnosis and therapeutic treatment into one single platform. Targeting of cancer cells by such devices can be carried out by three different strategies: 1) passive targeting based on the Enhanced Permeability and Retention (EPR) effect. Polyethylene glycol modified (PEGylated) GNRs tend to accumulate into tumors after intravenous injection much more than they do into normal tissue because of the leaky vasculature and the poor drainage of tumoral tissues; 2) active targeting which involves the immobilization of a selective ligand onto the surface of the GNRs; 3) the exploitation of cellular vehicles, i.e. cells that exhibit tropism to a lesion.