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)(3)(3+) 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 RITE infections. Direct adsorptive stripping potentiometric measurements of ultratrace levels of MTB DNA are also reported.