Development of impedimetric DNA biosensor for selective detection and discrimination of oligonucleotide sequences of the rpoB gene of Mycobacterium tuberculosis

摘要

Impedimetric DNA biosensor for the detection of oligonucleotide sequences of the rpoB gene of Mycobacterium tuberculosis, mutations of which cause resistance to anti-tuberculosis drug rifampicin, is developed. A bioselective element of the biosensor was formed on the gold electrode surface by immobilization of thiolated single-stranded DNA probes P2, which reproduce a corresponding fragment of the rpoB gene, and by passivation of the electrode surface (to reduce the non-specific adsorption) using 6-mercapto-1-hexanol. High selectivity of this biosensor has been shown: at injection of 1 nM complementary oligonucleotides T2, the charge transfer resistance (R_t) was significantly higher than that of 50 nM non-complementary oligonucleotides TC (632 Ω and 121Ω, respectively). Moreover, a high level of discrimination between complementary oligonucleotides T2 and TN with single-base mismatch was achieved by the increasing hybridization stringency (reducing the ionic strength of the hybridization buffer solution).