"We were interested in developing a system for targeted delivery – intracellular uptake – and controlled release of an active chemotherapy drug over an extended period of time directly inside the cancer cells," Omid Farokhzad told nanotechweb.org. "To achieve this combination of effects, we developed nanoparticles (∼150 nm) using the polylactic-co-glycolic acid (PLGA) controlled release polymer system and encapsulated decetaxel within the particles."

Farokhzad and colleagues also attached RNA molecules called aptamers to the surface of the nanoparticles. "Aptamers can bind to the surface of prostate cancer cells," he explained. "The result is that the particles attach to prostate cancer cells but not normal cells, are brought into the cell by receptor-mediated endocytosis and release the active drug over an extended period of time."

Aptamer-decorated nanoparticles were more toxic to cancer cells in in vitro tests than drug-containing nanoparticles without aptamers.

"We observed a remarkable efficacy after a single injection of our particles in the tumours of mice," said Farokhzad. "Normally, there may be a need for re-dosing but our nanoparticles were efficacious after a single injection."

Now, the team plans to test the technique further before potentially beginning trials in humans.

"The utility of this technology in cancer therapy is obvious but we believe that similar systems can be designed for treatment of virtually any diseases as long as you can modify the surface of the nanoparticles to attach to the disease cells specifically," said Farokhzad.

The researchers reported their work in PNAS.