doi:10.1038/nindia.2010.141 Published online 13 October 2010
Researchers have designed a new carbon-nanotube-based biosensor that detects superoxide anion radicals and nitrite ions, high levels of which are indicators of various diseases, including cancers.
Existing techniques for monitoring these radicals are very poor, both in terms of their sensitivity and selectivity. To devise an efficient alternative, the researchers first dissolved carbon nanotubes (CNTs) in nafion and polypyrrole (PPy), and then laid this nanocomposite on a platinum electrode. Then they immobilized the enzyme superoxide dismutase 1 (SOD1) on the modified SOD1–CNT–PPy–Pt electrode.
The SOD1–CNT–PPy–Pt electrode exhibited a twofold increase in current over other electrodes, including the SOD1-immobilized PPy–Pt electrode. This shows that the CNT–PPy nanocomposite facilitated the direct electron transfer between SOD1 and the base platinum electrode to help in the determination of the chemical species.
The biosensor was stable, showed constant current responses for at least 30 days and successfully detected superoxide radical and nitrite ion in breast cancer cells.
"The biosensor will have potential applications in understanding the mechanism of various diseases such as aging, nervous and heart diseases, and even cancer," says lead researcher Chandran Karunakaran.
The authors of this work are from: Biomedical Research Laboratory, Department of Chemistry, VHNSN College, Virudhunagar, Tamil Nadu; Center for Chemical Biology, Indian Institute of Chemical Technology, Hyderabad; Peptide and Proteomics Division, Defence Institute of Physiology and Allied Sciences (DIPAS), New Delhi, India.