Shared liposomes

Encapsulating arsenic- and platinum-based drugs together in the same liposome carrier has increased their efficiency for targeted cancer treatment and stability.

Credit: © 2009 Wiley

Arsenic and platinum complexes are promising anticancer drugs but face several challenges: they rapidly deactivate, are too toxic at high doses, and are difficult to transport to the tumour. Liposomes are generally good drug carriers, but only small amounts of platinum complexes can be encapsulated, and arsenic species diffuse through the liposome membrane. An approach to overcoming this unwanted release is to incorporate metal ions into the lipid shell, triggering the aggregation of arsenic species into nanoparticles.

Inspired by this, Thomas O'Halloran and co-workers at Northwestern University, along with colleagues from the University of Michigan, have now encapsulated both arsenic and platinum anticancer drugs into a liposome carrier by incorporating the platinum complex into the liposome membrane before loading the arsenic¹. The co-encapsulation was driven by the formation of arsenic–platinum complexes during the aggregation of nanoparticles of the two drugs, resulting in their stabilization. The drug-loaded liposome showed good stability in serum and lower cellular toxicity than the free arsenic and platinum species. Altering the composition of the liposome also enabled the drugs' release to be tuned.

This drug-delivery agent was also functionalized with a targeting ligand. When a folic acid derivative — known to target particular tumour cells — was inserted on the surface of the loaded liposome, the researchers observed a higher anticancer efficacy than with the non-functionalized version.