Direct ultrasensitive electrical detection of DNA and DNA sequence variations using nanowire nanosensors

The development of electrically addressable, label-free detectors for DNA and other biological macromolecules has the potential to impact basic biological research as well as screening in medical and bioterrorism applications. Here we report two-terminal silicon nanowire electronic devices that function as ultrasensitive and selective detectors of DNA. The surfaces of the silicon nanowire devices were modified with peptide nucleic acid receptors designed to recognize wild type versus the DeltaF508 mutation site in the cystic fibrosis transmembrane receptor gene. Conductance measurements made while sequentially introducing wild type or mutant DNA samples exhibit a time-dependent conductance increase consistent with the PNA-DNA hybridization and enabled identification of fully complementary versus mismatched DNA samples. Concentration-dependent measurements show that detection can be carried out to at least the tens of femtomolar range. This nanowire-based approach represents a step forward for direct, label-free DNA detection with extreme sensitivity and good selectivity, and could provide a pathway to integrated, high-throughput, multiplexed DNA detection for genetic screening and biothreat detection.