First developed as sensors to explore and monitor cellular processes, PEBBLEs now hold promise for diagnosing and treating cancer, said Raoul Kopelman, who is the Kasimir Fajans Collegiate Professor of Chemistry, Physics and Applied Physics at U-M. At the 229th national meeting of the American Chemical Society in San Diego, Calif., March 17, Kopelman will describe the research that he and his collaborators have been doing over the past seven years, including encouraging preliminary results using PEBBLEs to treat a virulent form of brain cancer in rats.
PEBBLEs are polymer spheres, typically 20 to 200 nanometers in diameter—about the size of a virus. The spheres carry an assortment of molecules on their surfaces, some to guide the PEBBLEs to their targets inside the body, some to enhance their visibility on MRI images, and others to deliver a deadly cargo to cancer cells when triggered by exposure to light.
Unlike chemotherapy drugs that attack tumors by invading cancer cells and disrupting their DNA, PEBBLEs never enter the cells they target. Instead, they attach to the outside of the targeted cell and shoot reactive oxygen species into it, setting off "an avalanche of damage," said Kopelman. By staying outside the cell, PEBBLEs avoid a problem that thwarts many chemotherapy drugs.
"The really bad cancer cells get immune to chemotherapy drugs ?they pump the drugs back out," Kopelman said. Cancer cells can't do that to PEBBLEs, though, because PEBBLEs are already on the outside. Another advantage: the "killer oxygen" that PEBBLEs
Source:University Of Michigan