A lipase-based electrochemical biosensor for target DNA.

A lipase-based electrochemical biosensor has been fabricated for the quantitative determination of target DNA. It is based on a stem-loop nucleic acid probe labeled with ferrocene containing a butanoate ester that is hydrolyzed by lipase. The other end of the probe DNA is linked, via carboxy groups, to magnetic nanoparticles. The binding of target DNA transforms the hairpin structure of the probe DNA and causes the exposure of ester bonds. This results in the release of electro-active ferrocene after hydrolysis of the ester bonds, and in an observable electrochemical response. The quantity of target DNA in the concentration range between 1 × 10 mol·L and 1 × 10 mol·L can be determined by measuring the electrochemical current. The method can detect target DNA with rapid response (30 min) and low interference. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]