Engineered antibodies (green/red) are covalently bound to carbon-nanotube transistors, which serve as the readout element for the binding of osteopontin (orange/blue). Osteopontin is a biomarker protein indicative of prostate cancer, as well as several other cancers. (Courtesy: University of Pennysylvania)

 

Nanotube transistors detect cancer biomarkers

Mar 1, 2013

Carbon-nanotube transistors could be used to detect minute quantities of disease biomarkers, such as the proteins implicated in prostate cancer, according to new experiments by researchers in the US. The technique could rival conventional methods when it comes to sensitivity, cost and speed.

Conventional techniques to detect proteins are typically based on some form of “immunoassay”, with the most famous of these being enzyme-linked immunosorbent assay (ELISA). This technique involves introducing an enzyme-modified antibody protein to an unknown amount of target molecule or protein, known as an antigen, and allowing them to bind together. Unreacted antibodies are washed away, leaving behind only antibody–antigen pairs.

The reaction can usually be detected by a colour change in the solution or by a fluorescent signal. The degree of colour change or fluorescence depends upon the number of enzyme-modified antibodies present, which in turn depends on the initial concentration of antigen in the sample.

Although such tests are routinely used in hospitals and clinics, they are quite long, taking several days or even weeks to complete. They are also costly, complicated to perform and can only detect single proteins at a time.

Read more: Nanotube transistors detect cancer biomarkers – physicsworld.com.

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