Dendrimer nanoparticles, made of spherical, highly branched polymers, have shown promise as drug delivery vehicles capable of targeting tumors with large doses of anticancer drugs.
Dendrimer nanoparticles have also been used to entrap metal nanoparticles, a combination that could serve as a potent imaging and thermal therapy agent for tumors if it were not for associated toxicity issues that researchers have had a difficult time overcoming.
To eliminate the toxicity associated with dendrimer-metal nanoparticle combinations, a team led by James Baker, Jr., M.D., principal investigator of a National Cancer Institute Cancer Nanotechnology Platform Partnership at the University of Michigan, has developed methods for modifying the surface of dendrimers laden with gold nanoparticles. This chemical treatment greatly reduces the toxicity of the hybrid nanoparticle without changing its size. Baker and his collaborators published the results of this work in the journal Small.
Of equal importance, the investigators also found that the chemical modification they developed makes it possible to add targeting molecules to the surface of the dendrimer. In the current work, the researchers added between four and five folic acid molecules to the surface of the dendrimer. Folic acid binds to a high-affinity receptor found on many types of tumor cells. Previous work by Baker's group and other teams has shown that nanoparticles coated with folic acid do target tumors and preferentially deliver their drug or imaging payloads to cancer cells.