( ters or billionths of a meter in diam...)Nanoparticles, nanoshells, nanotubes: How tiny specks may provide powerful tools against cancer

Two new studies advance the use of this technology. One, reported by bioengineering graduate student Andre Gobin, is the first to demonstrate how nanoshells and imaging can be used together to treat tumors in animal models. Gobin and a team of Rice researchers injected nanoshells into the blood stream of mice implanted with colon cancer knowing, based on previous experiments, that the nanoshells would preferentially accumulate in the tumors. This occurs because blood vessels that develop in fast-growing solid tumors are ill-formed and permeable, and nanoshells traveling through blood end up spilling out of these leaky vessels into tumor tissue. Once there, the tumor only slowly excretes them as waste. The nanoshells are also hidden from the immune system because they are "shielded" by a protective polymer coating, poly-(ethylene glycol) or PEG. This does not change the properties of the nanoshells but renders them "invisible" to the body's natural defense mechanism.

Twenty hours after the nanoshells were injected, the researchers imaged their presence in the tumor by using a small hand-held optical coherence tomography (OCT) probe similar to that which dermatologists can use to find skin cancers. According to Gobin, the researchers hope that these probes, already commercially available, can be adapted to both image nanoshells in tumors with higher resolution, and then therapeutically heat them up with a secondary laser coupled to the probe, making nanoshell-assisted therapy user friendly.

In this study, however, a different laser source was used to irradiate the tumors in the experimental group of mice. At the end of the study, 82 percent of the mice survived in the experimental group, but

all mice in the control group that
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Source:American Association for Cancer Research