Sequence-specific electrochemical biosensing of M. tuberculosis DNA

An electrochemical biosensor for the determination of short sequences from the Mycobacterium tuberculosis (MTB) DNA is described. The sensor relies on the modification of the carbon-paste transducer with 27- or 36-mer oligonucleotide probes and their hybridization to complementary strands from the MTB DNA direct repeat region. Chronopotentiometry is employed to transduce the hybridization event, in connection with a Co(phen)33+ indicator. Short (5–15 min) hybridization periods permit convenient quantitation of ng ml−1 levels of the MTB DNA target. Similar results are observed using microfabricated carbon-strip transducers. The new sensor holds great promise for rapid screening for MTB infections. Direct adsorptive stripping potentiometric measurements of ultratrace levels of MTB DNA are also reported.