Nanotech News

November 28, 2005

Nanoparticles Enable Bio-Barcodes to Detect Small Molecules

The nanoparticle-enabled bio-barcode assay system developed at Northwestern University has become a powerful tool for detecting trace levels of proteins and nucleic acids in biological samples. Now, researchers at the University of California, Berkeley and the Lawrence Berkeley National Laboratory have shown that this same assay system can be used to detect low levels of small molecules in biological samples.

Writing in the journal Analytical Chemistry, Jay Groves, Ph.D., and his colleagues describe how they adapted the bio-barcode assay system to detect cytokines, small signaling molecules that the body’s immune system cells release when fighting disease. Using this system, the researchers were able to improve the sensitivity with which they could detect a specific cytokine, known as interleukin-2, by 1000-fold compared to the most sensitive system now in use to quantify these molecules. At this level of sensitivity, the researchers note, bio-barcode assays for cytokines could prove useful for earlier and more accurate diagnosis and treatments of a variety of cancers.

Bio-barcode assays rely on the fact that gold nanoparticles will clump together under the appropriate conditions and undergo a readily observed color change. Through the suitable design of the gold nanoparticles, as well as two other microparticles, this clumping only occurs when a specific molecule is present in a biological sample. The investigators comment in their paper that the simplicity of the method, and the fact that it does not require complex instrumentation or multiple purification steps, should make it suitable for bedside diagnostic testing.

This work is detailed in a paper titled, “Colorimetric bio-barcode amplification assay for cytokines.” An abstract is available through PubMed.
View abstract.