Detecting Cancer with Silica Nanoparticles

Sep 18, 2006

Tumor necrosis factor-alpha is a widely accepted biomarker for cancer, but the minute amounts of this protein circulating in blood makes detecting the molecule and measuring its concentration accurately a technological challenge.

Using silica nanoparticles labeled with the molecule guanine, researchers at the Pacific Northwest National Laboratory have now created a simple and inexpensive electrochemical method that detects tumor necrosis factor-alpha (TNF-æ) at clinically useful levels. Moreover, this assay is amenable to miniaturization, suggesting that it could be easily incorporated into a microfluidics-based assay system.

Reporting its work in the journal Analytical Chemistry, a research team headed by Yuehe Lin, Ph.D., loaded guanine molecules onto the surface of silica nanobeads that also contained a chemical anchor known as avidin. They also attached biotin, which binds with extraordinary strength to avidin, to an antibody that binds to the TNF-æ protein. The researchers attached a second antibody, one that binds to a different part of the TNF-æ protein, to a carbon electrode, which functions as the electrochemical sensor.

When TNF-æ is present in a solution added to the antibody-labeled electrode, it binds to the antibody. Adding the second antibody produces a sandwich around the TNF-æ molecule. At this point, the researchers then added their labeled silica nanoparticle, which binds to the antibody-TNF-æ sandwich. In a final step, the investigators added a molecule that reacts with the guanines on the nanoparticle, creating an electrical current that the electrode senses. The current flowing into the electrode is proportional to the amount of TNF-æ bound to the first antibody. Experiments with this system showed that the limit of detection for the device is approximately 2 picomolar, well within the range needed to detect physiological levels of TNF-æ.

This work is detailed in a paper titled, “Sensitive immunoassay of a biomarker tumor necrosis factor-æ based on poly(guanine)-functionalized silica nanoparticle label.” This paper was published online in advance of print publication. An abstract of this paper is available at the journal’s website.

Source: National Cancer Institute

Explore further: Gold nanorods target cancer cells

add to favorites email to friend print save as pdf

Related Stories

US seeks China's help after cyberattack

4 hours ago

The United States is asking China for help as it weighs potential responses to a cyberattack against Sony Pictures Entertainment that the U.S. has blamed on North Korea.

Why the Sony hack isn't big news in Japan

21 hours ago

Japan's biggest newspaper, Yomiuri Shimbun, featured a story about Sony Corp. on its website Friday. It wasn't about hacking. It was about the company's struggling tablet business.

Hopes, fears, doubts surround Cuba's oil future

22 hours ago

One of the most prolific oil and gas basins on the planet sits just off Cuba's northwest coast, and the thaw in relations with the United States is giving rise to hopes that Cuba can now get in on the action.

Ancient clay seals may shed light on biblical era

22 hours ago

Impressions from ancient clay seals found at a small site in Israel east of Gaza are signs of government in an area thought to be entirely rural during the 10th century B.C., says Mississippi State University archaeologist ...

Recommended for you

Gold nanorods target cancer cells

Dec 18, 2014

Using tiny gold nanorods, researchers at Swinburne University of Technology have demonstrated a potential breakthrough in cancer therapy.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.