Nanoparticles find tumors, form clumps

Newly designed nanoparticles could have dual benefits for fighting cancer. Not only do these tiny particles home in on tumors, but they also stick together once they enter tumors’ blood vessels. The particles could eventually be a means to choke off the blood vessels that deliver nutrients to tumors or to ferry cancer-killing drugs, researchers report.

In the past several years, scientists have designed several types of cancer-seeking nanoparticles by coating bits of iron with molecules that stick to proteins found only in tumors. Choosing an even tighter target, Erkki Ruoslahti of the Burnham Institute for Medical Research in Santa Barbara, Calif., and his colleagues covered iron nanoparticles with a peptide they designed to adhere to proteins found only in tumor blood vessels.

The researchers injected these nanoparticles into mice that had been implanted with human-breast tumors. After gathering inside tumors, the particles clumped and blocked about 20 percent of each tumor’s blood vessels. Adorned with the iron clumps, the tumors became easily visible in magnetic resonance images, Ruoslahti’s team reports in the Jan. 16 Proceedings of the National Academy of Sciences.

The team is currently working to improve the particles’ cancer-fighting abilities by increasing their potential to block blood vessels and by designing hollow nanoparticles that can also deliver chemotherapy drugs.

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