Nano-Treatment for Brain Tumors

As reported everywhere today, Sen. Ted Kennedy died Tuesday night after a year-plus fight with malignant glioma, a type of brain cancer. The condition, in which tumor cells arise from glia cells of the brain, is known to be especially deadly and hard to treat – only about 16 percent of patients diagnosed with the condition survive five years. Treatment involves radiation, surgery and chemotherapy, but long-term survival is a challenge.

In this case, the nanoparticle being tested as a potential cancer treatment is titanium dioxide, an unusual compound currently used for everything from treating wastewater to self-cleaning windows to movie snow. The special thing about titanium dioxide (or TiO2 in chemistry shorthand) is that it’s a photocatalyst – expose it to light and it generates free radicals, unstable atoms, that can destroy dirt on a window or, potentially, kill off a cell.

The problem for the latter use is how to get TiO2 into the cells you want to kill, the ones in the tumor, without taking out a lot of innocent bystanders along the way. Argonne researchers solved this issue by attaching titanium dioxide to an antibody for the interleukin receptor, a molecule expressed on the cell surface of tumor cells. Essentially, the antibody in this case is a key that only works in certain locks (the interleukin receptor), and when it finds the right cell, it is brought inside along with its TiO2 party guest.

At first, that TiO2 doesn’t cause any trouble – it’s kind of a sleeper agent inside the tumor cell. But when the cell is exposed to UV light, it begins producing free radicals, which wreak havoc with the cell’s internal organs and cause it to self-destruct.

Experiments conducted by the research team at Argonne proved that this set-up could work, at least in the artificial environment of the laboratory. The modified TiO2 trojan horses successfully attached themselves to cancer cells that were grown in the lab, and even to the “invadopodia” of those cells – tendrils used by cancer cells to attack neighboring cells. When these cells were exposed to UV light for 6 hours, 80% of the tumor cells died off.

“When exposed to light, these nanoparticles actually cause the death of cancer cells,” Lesniak said. “There are many scenarios where this could work. For example, during surgery while resecting a tumor, you could inject these nanoparticles, target the tumor and expose it to a source of light.”

However, about 15% of normal cells were also bound by TiO2 particles and died after UV light, collateral damage that Lesniak said would be a potential concern, though it’s comparable to side effects of existing treatments.

“You have to offset against the certainty of death when you’re dealing with this kind of aggressive cancer,” he said.



Golden nanotubes as imaging agents to detect cancer cells

(Nanowerk News) Biomedical researchers at the University of Arkansas and University of Arkansas for Medical Sciences in Little Rock have developed a special contrast-imaging agent that is capable of molecular mapping of lymphatic endothelial cells and detecting cancer metastasis in sentinel lymph nodes. The new material could be used as a more efficient and less toxic alternative to nanoparticles and fluorescent labels used in the non-invasive, targeted molecular detection of normal cells, such as immune-related cells, and abnormal cells, such as cancer cells and bacteria. Findings were published Sunday in Nature Nanotechnology.

Developed by Zharov, photoacoustic and photothermal methods deliver energy, via laser pulses, into biological tissue. When some of the energy is absorbed and converted into heat, it expands and emits sound waves. However, the carbon nanotubes had not been fully developed as an imaging agent because of concerns about toxicity.

Kim’s research team addressed this problem by depositing a thin layer of gold around the carbon nanotubes. The gold layer enhanced absorption of laser radiation and reduced toxicity. In vitro tests showed only minimal toxicity associated with the golden nanotubes. Compared to existing nanoparticles, the golden nanotubes also exhibited high laser absorption at a miniscule diameter. The golden nanotubes required extremely low laser-energy levels for detection, and low concentrations were required for effective diagnostic and therapeutic applications.