Researchers from Stanford University, the Massachusetts Institute of Technology (MIT) and the University of Duisburg-Essen are studying targeted carbon nanotubes as delivery agents for a plantinum IV complex.

Low molecular weight platinum anticancer drugs are known for having short blood circulation times and thus reduced tumour uptake and intracellular DNA binding. The current research is an attempt to overcome these limitations.

A platinum IV complex containing a folate derivative at an axial position was attached to a PEGylated single-walled carbon nanotube through multiple amide linkages. The drug is capable of targeting tumour cells that highly overexpress the folate receptor on their surface. Thanks to this capability, the modified nanotubes rapidly enter the target cell. Once inside the cell platinum IV is reduced and converted into cisplatin, a far more toxic anticancer drug. This chemical reduction has the effect of releasing cisplatin from the nanotube and enabling it to travel to the cell nucleus where it reacts with its target nuclear DNA.

According to the researchers, this nanotube formulation of platinum is more than 8 times more potent than the approved formulation of cisplatin. Additionally, it would be the first time in which both the targeting and the moieties are incorporated into the same molecule.

Nevertheless, the uncertain toxicity of carbon nanotubes requires further investigation before they can be an alternative to nanoparticles in drug delivery.

Source: Dhar S, Liu Z, Thomale J, Dai H, Lippard SJ. Targeted single-wall carbon nanotube-mediated Pt(IV) prodrug delivery using folate as a homing device. J Am Chem Soc 2008;130(34):11467-76.