[Lani]

besides nanospheres(nanoshells) there are also gold nanotubes, nanorods and nanocages--

Here is just a bit of info:

Immunonanoshells for Selective Photothermal Therapy (Abstract 3198) and Nanoshells for Combined Cancer Therapy and Imaging in vivo (Abstract 2711)

Researchers at Rice University are working on a novel and systematic approach to cancer treatment that involves the use of advanced technologies that are by themselves harmless − but appear to offer potent cancer-killing properties when used together.

This tactic focuses on two main ingredients: structures called "nanoshells," which are microscopic balls consisting of a silica core coated with a thin layer of gold and, secondly, near infrared light (NIR). Used alone, nanoshells are non-toxic and can be excreted with no ill effect because gold is biologically compatible. Near-infrared light delivered by a laser has minimal interaction with components found in tissue, and so also does not harm the body.

But when nanoshells are injected into an experimental animal with cancer, they accumulate in the tumor; the addition of NIR laser light heats up their gold shell, causing the particles to destroy tumor cells. Furthermore, because of their size − a few nanometers, or billionths of a meter, in diameter − these nanoshells interact with light in specific ways, and can be "tuned" to discrete destructive wavelengths by varying the size of the core and the shell.

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 did not receive nanoshells and laser therapy had to be sacrificed because of their large tumors.

The second Rice University study aims to improve the method of delivery of nanoshells to a tumor. Although the leaky blood vessel strategy can passively dump nanoshells into tumors, it cannot "find" tiny cancers that have metastasized and have not yet "recruited" a substantial system of blood vessels to feed them. To counteract that, researchers have fused a nanoshell to an antibody; the idea behind such "immunonanoshells" is to have a targeted nanoshell that can find a specific type of cancer wherever it may hide, says study author, bioengineering graduate student Amanda Lowery

In the study that Lowery reports, the researchers hooked "Y"-shaped anti-HER2 antibodies to nanoshells, and the antibody bound to HER2 over-expressing breast cancers. They then applied these immunonanoshells to the top of laboratory breast cancer cells, and used laser light to heat the agent. Researchers then stained the cells to see which lived and found that only HER2-expressing cells which had bound nanoshells and were exposed to the near infrared laser, died. Cells that were not exposed to laser light also survived, suggesting that the antibody-nanoshell treatment effectively destroyed HER2 over-expressing cancer cells. The research team is now planning to test this strategy in animal models.

According to Gobin, Lowery, and the Rice University faculty they work with, nanotechnology to treat cancer takes advantage of much of the biology already known about the disease, and marries it to a suite of techniques based on next era technology.