Simple detection of nucleic acids with a single-walled carbon-nanotube-based electrochemical biosensor.

Institute of Biomedical Engineering and Health Technology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China.
Biosensors & bioelectronics (Impact Factor: 5.43). 07/2011; 28(1):257-62. DOI: 10.1016/j.bios.2011.07.028
Source: PubMed

ABSTRACT We report for the first time a simple approach to fabricate an electrochemical DNA (E-DNA) biosensor by introducing the single-walled carbon nanotubes (SWNTs). The SWNTs combine with the electrochemical label (methyl blue, MB)-modified single-stranded DNA (ssDNA) probes to generate a nanomaterial-biomolecule composite, which functions as a signal amplification platform to facilitate the electron-transfer between the electrochemical label and the electrode. This SWNT-based E-DNA biosensor produces a high square wave voltammetry (SWV) signal in the absence of target DNA. In the presence of target DNA, the MB-labeled ssDNA probes are removed from the SWNT-modified electrode due to the formation of a double-stranded DNA (dsDNA), generating a relatively low SWV signal. This signal-off SWNT-based E-DNA biosensor exhibits improved sensitivity and large linear dynamic range with low detection limit; it can even distinguish 1-base mismatched target DNA. Further experiments demonstrate that the SWNT-based E-DNA biosensor is superior to the multi-walled carbon nanotube (MWNT)-based one for DNA detection. Moreover, the introduction of aptamer into the SWNT-based biosensor might be further extended to detect small biomolecules such as adenosine.