Santa Barbara, Calif. -- Researchers at the University of California, Santa Barbara have discovered that attaching polymeric nanoparticles to the surface of red blood cells dramatically increases the in vivo lifetime of the nanoparticles. The research, published July 7 in Experimental Biology and Medicine, could offer applications for the delivery of drugs and circulating bioreactors.

Polymeric nanoparticles are excellent carriers for delivering drugs. They protect drugs from degradation until they reach their target and provide sustained release of drugs. Polymeric nanoparticles, however, suffer from one major limitation: they are quickly removed from the blood, sometimes in minutes, rendering them ineffective in delivering drugs.

The research team, led by Samir Mitragotri, a professor of chemical engineering, and Elizabeth Chambers, a recent doctoral graduate, found that nanoparticles can be forced to remain in circulation when attached to red blood cells. The particles eventually detach from the blood cells due to shear forces and cell-to-cell interactions, and are cleared from the system by the liver and spleen. Red blood cell circulation is not affected by attaching the nanoparticles.

Attachment of polymeric nanoparticles to red blood cells combines the advantages of the long circulating lifetime of the red blood cell, and their abundance, with the robustness of polymeric nanoparticles, said Mitragotri. Using red blood cells to extend the circulation time of the particles avoids the need to modify the surface chemistry of the entire particle, which offers the potential to attach chemicals to the exposed surface for targeting applications.

The researchers have learned that particles adhered to red blood cells can escape phagocytosis because red blood cells have a knack for evading macrophages. Nanoparticles arent the first to be piggybacking on red blood cells; the strategy has already been adopted by certain bacteria, s
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Contact: Barbara B. Gray
bbgray@engineering.ucsb.edu
818-889-5415
University of California - Santa Barbara
27-Jun-2007