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: Green tea as a therapeutic delivery system for anticancer drugs

Related Stories

US govt sued over sea turtles snared in shrimp nets

7 hours ago

Tens of thousands of endangered sea turtles die every year in the United States when they are inadvertently snared in shrimp nets, an environmental group alleges, filing a lawsuit Wednesday against the government.

EU alleges Google's abuses hurt consumers, innovation

7 hours ago

The European Union's escalating legal attack on Google is likely to ignite a debate about whether the Internet search leader makes life more convenient for consumers or abuses its power to squeeze out rivals ...

Space open for business, says Electron launch system CEO

7 hours ago

Space, like business, is all about time and money, said Peter Beck, CEO of Rocket Lab, a US company with a New Zealand subsidiary. The problem, he added, is that, in cost and time, space has remained an incredibly ...

EU action on Google marks divergence with Washington

7 hours ago

The EU antitrust complaint filed Wednesday against Google represents a sharp divergence with Washington, which dropped a similar investigation two years ago, citing a lack of evidence against the Internet ...

Recommended for you

United States, China team explore energy harvesting

Apr 18, 2015

Six authors have described their work in harvesting energy in a paper titled "Ultrathin, Rollable, Paper-Based Triboelectric Nanogenerator for Acoustic Energy Harvesting and Self-Powered Sound Recording." ...

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.