Ultrasensitive Biosensor Detects Minute Amounts of Proteins

A biosensor made up of a cluster of carbon nanotubes coated with a thin layer of protein-recognizing polymer uses electrochemical signals to detect minute amounts of proteins.

The nanotube biosensor can detect human ferritin, the primary iron-storing protein of cells, and E7 oncoprotein derived from human papillomavirus (HPV). Further tests using calmodulin showed that the sensor could discriminate between varieties of the protein that take different shapes.

A multidisciplinary team of biologists, chemists, and physicists from Boston College (BC; Chestnut Hill, MA, USA) and from the Institute of Nanoscience and Nanotechnology at Central China Normal University (Wuhan, China) reported their findings in the online July 27, 2010 edition of the journal Nature Nanotechnology. The new biosensor could provide a crucial new diagnostic tool for the detection of a range of illnesses.

The BC team used arrays of wire-like nanotubes--approximately one 300th the size of a human hair--coated with a nonconducting polymer coating capable of recognizing proteins with subpicogram per liter sensitivity.

The detection can be read in real time, instead of after days or weeks of laboratory analysis, meaning the nanotube molecular imprinting technique could pave the way for biosensors capable of detecting human papillomavirus or other viruses weeks sooner than available diagnostic techniques currently allow.

"In the case of some diseases, no one can be sure why someone is ill,” said associate research professor of biology at Boston College Dong Cai. "All that may be known is that it might be a virus. At that time, the patient may not have detectable serum antibodies. So at a time when it is critical to obtain a diagnosis, there may not be any traces of the virus. You've basically lost your chance. Now we can detect surface proteins of the virus itself through molecular imprinting and do the analysis.”

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