Researchers in the U.S. and China have developed a carbon nanotube technology they suggest could form the basis of a rapid and highly sensitive new diagnostic platform. They claim tests have shown that the molecular imprinted polymer (MIP) nanotube biosensor can recognize proteins with subpicogram per litre sensitivity in real time and even discriminate between Ca2+-induced conformational changes in protein structure.
Their studies are reported in Nature Nanotechnology in a paper titled “A Molecular-Imprint Nanosensor for Ultrasensitive Detection of Proteins.” The research was carried out by Dong Cai, Ph.D., an associate research professor in biology at Boston College together with a multidisciplinary team at Boston College and the Institute of Nanoscience and Nanotechnology at Central China Normal University.
Dr. Cai and colleagues generated arrays of nanotubes and coated the tips with a nonconducting polymer imprinted with the protein molecules of interest. They found that the protein-shaped dents left in the polymer layer effectively resulted in the sensor displaying markedly reduced electrical impedance due to electrical leakage through the thinner imprinted areas of the surface. When the target protein was present in a sample and dropped into its corresponding shape in the polymer, the nanotubes registered a corresponding increase in impedance.
The U.S.-Chinese research team focused their tests on MIP arrays specific for human ferritin and human papillomavirus-derived E7 protein. They showed that such sensors could even discriminate between calcium ion-induced conformational changes in calmodulin.
“This ultrasensitive, label-free electrochemical detection of proteins offers an alternative to biosensors based on biomolecule recognition,” the authors write. “The nanosensor design should also prove highly useful in the detection of other pathogens and toxins, in diagnosing human diseases through the detection of disease biomarkers, and in a host of proteomic applications.”