It is not always easy for oncologists to diagnose cancer, as cancer cells have the same biomarkers on their surface as healthy cells, but in different concentrations. Unfortunately, that difference can be so miniscule, it can make the cells very difficult to detect. As cancer specialist Joseph Jerry notes, "You often don't get a big signal for the presence of cancer. It's a subtle thing."

Now Jerry, along with chemist Vincent Rotello and their colleagues from the University of Massachusetts, Amherst, have used a "chemical nose" array of nanoparticles and polymers to create a sensor that can distinguish between healthy, cancerous and metastatic cells. The researchers believe this new tool will revolutionize cancer detection and treatment. "Our new method uses an array of sensors to recognize not only known cancer types, but it signals that abnormal cells are present," explains Rotello. "That is, the chemical nose can simply tell us something isn't right, like a check engine light, though it may never have encountered that type before." He adds that the chemical nose can be designed to alert doctors to those types of invasive cancer types for which early treatment is critical.

The new detection system was created by combining three gold nanoparticles that have a special affinity for the surface of chemically abnormal cells, along with a polymer called PPE, which glows when displaced from the nanoparticle surface. The researchers added this combination to human cells on a culture plate, inducing a response called competitive binding. When cell surfaces bind the nanoparticles, the PPE is displaced from the surface, turning its fluorescent switch on. "The chemical nose approach is so named because it works like a human nose, which is arrayed with hundreds of very selective chemical receptors," explains Rotello.

The researchers conducted several experiments using cervical, liver, testis and breast cancer cell lines, as well as three metastatic breast cell lines and normal cells, to test the effectiveness of the technique. The chemical nose accurately "sniffed out" the presence of the cancer cells, and successfully identified primary cancer from metastatic disease. Concerned that the tool had simply detected individual differences in cells from different donors, the scientists conducted the same experiments on skin cells from three groups of mice: healthy animals, those with primary cancer and those with metastatic disease. They were able to duplicate the results. "This result is key," says Rotello. "It shows that we can differentiate between the three cell types in a single individual using the chemical nose approach." Additional studies will be undertaken in animal models to determine if the chemical nose approach can identify cell status in real tissue and to figure out a way to train the chemical nose's sensors so that it can provide more precise information to oncologists.

News Release: Chemical nose may sniff out cancer earlier  www.sciencedaily.com   June 24, 2009