Study: Nanorods could improve cancer diagnosis and treatment
Gold nanoparticles are capable of identifying marker proteins on breast cancer cells, according to findings published in Analytical Chemistry.

Purdue University researchers created the nanoparticles that are a potential tool to better diagnose and treat cancer, according to an article released by the Purdue University News Service.

The gold nanoparticles, or nanorods, are tiny rod-shaped gold particles that are even smaller than viruses, which are equipped with antibodies designed to bind to a specific marker on cell surfaces. Researchers analyze these surface markers, proteins on a cell's exterior, because they can contain valuable information about what type of cell they belong to or what state that cell may be in.

Joseph Irudayaraj, an associate professor of agricultural and biological engineering at Purdue, showed in another recent study that the nanorods, when combined with a special imaging technique, were capable of recognizing cancer stem cells by binding to known markers on their exterior. Cancer stem cells are important to detect because they are particularly invasive and more likely than other types of cancer cells to spread, or metastasize, to other organs. These and other types of cells the technology utilizes are obtained from blood tests as opposed to biopsies.

The nanoparticles, or "gold nanorod molecular probes," are fabricated so that their size is unique to their target marker. That way, when nanorods bind to their marker, they "scatter," or disrupt light in a characteristic manner that researchers can then pair to the nanorod's dimensions, its antibody and the target cancer marker, which must be present for binding to occur.

Irudayaraj said using gold nanorods for cancer detection will be about one-third the cost of the current analogous technology, called flow cytometry. In this method, fluorescent probes are attached to cancer cells. The nanorod technology is based on sensing plasmons, or sub-atomic particles present in the gold nanoparticles.  

The nanorods also require only a few cells, whereas flow cytometry requires hundreds to thousands of cells. This could be advantageous when dealing with scarce sample sizes, Irudayaraj said.

Irudayaraj and his team demonstrated that the nanorods bind to three different markers. Two were used to calculate the invasiveness of the cancer cell and the other, which is present equally among the different cancer types, was used to calculate the degree to which the other markers were expressed. Irudayaraj said his gold nanorods may be able to detect as many as 15 different markers in the future, possibly opening the door for even more comprehensive tests. He hopes the nanorods will be commercially available in about four years.