title: Label-free detection of DNA hybridization and single point mutations in a nano-gap biosensor.
abstract: We describe a conductance-based biosensor that exploits DNA-mediated long-range electron transport for the label-free and direct electrical detection of DNA hybridization. This biosensor platform comprises an array of vertical nano-gap biosensors made of gold and fabricated through standard photolithography combined with focused ion beam lithography. The nano-gap walls are covalently modified with short, anti-symmetric thiolated DNA probes, which are terminated by 19 bases complementary to both the ends of a target DNA strand. The nano-gaps are separated by a distance of 50 nm, which was adjusted to fit the length of the DNA target plus the DNA probes. The hybridization of the target DNA closes the gap circuit in a switch on/off fashion, in such a way that it is readily detected by an increase in the current after nano-gap closure. The nano-biosensor shows high specificity in the discrimination of base-pair mismatching and does not require signal indicators or enhancing molecules. The design of the biosensor platform is applicable for multiplexed detection in a straightforward manner. The platform is well-suited to mass production, point-of-care diagnostics, and wide-scale DNA analysis applications.
authors: Nanobioengineering Laboratory, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac, 10-12, Barcelona E-08028, Spain. Department of Electronics, Barcelona University (UB), Martí i Franques, 1, Barcelona 08028, Spain.
authors: R L
authors: RL
authors: Zaffino
authors: M
authors: M
authors: Mir
authors: J
authors: J
authors: Samitier
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004247:DNA / Q000235:genetics*; D015342:DNA Probes / Q000737:chemistry* / Q000235:genetics*; D004563:Electrochemistry / Q000295:instrumentation; D004867:Equipment Design; D006046:Gold; D049329:Nanostructures; D009693:Nucleic Acid Hybridization; D017354:Point Mutation
chemical_list: D015342:DNA Probes; D006046:Gold; D004247:DNA