Tumor necrosis factor-alpha (TNF-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 [profile] have now created a simple and inexpensive electrochemical method that detects TNF-alpha 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-alpha protein. The researchers attached a second antibody, one that binds to a different part of the TNF-alpha protein, to a carbon electrode, which functions as the electrochemical sensor.