title: Chemical recognition and binding kinetics in a functionalized tunnel junction.
abstract: 4(5)-(2-mercaptoethyl)-1H-imidazole-2-carboxamide is a molecule that has multiple hydrogen bonding sites and a short flexible linker. When tethered to a pair of electrodes, it traps target molecules in a tunnel junction. Surprisingly large recognition-tunneling signals are generated for all naturally occurring DNA bases A, C, G, T and 5-methyl-cytosine. Tunnel current spikes are stochastic and broadly distributed, but characteristic enough so that individual bases can be identified as a tunneling probe is scanned over DNA oligomers. Each base yields a recognizable burst of signal, the duration of which is controlled entirely by the probe speed, down to speeds of 1 nm s -1, implying a maximum off-rate of 3 s -1 for the recognition complex. The same measurements yield a lower bound on the on-rate of 1 M -1 s -1. Despite the stochastic nature of the signals, an optimized multiparameter fit allows base calling from a single signal peak with an accuracy that can exceed 80% when a single type of nucleotide is present in the junction, meaning that recognition-tunneling is capable of true single-molecule analysis. The accuracy increases to 95% when multiple spikes in a signal cluster are analyzed.
authors.affiliation: Department of Physics, Arizona State University, Tempe, AZ 85287, USA. schang23@asu.edu
authors.forename: Shuai
authors.initials: S
authors.lastname: Chang
authors.forename: Shuo
authors.initials: S
authors.lastname: Huang
authors.forename: Hao
authors.initials: H
authors.lastname: Liu
authors.forename: Peiming
authors.initials: P
authors.lastname: Zhang
authors.forename: Feng
authors.initials: F
authors.lastname: Liang
authors.forename: Rena
authors.initials: R
authors.lastname: Akahori
authors.forename: Shengqin
authors.initials: S
authors.lastname: Li
authors.forename: Brett
authors.initials: B
authors.lastname: Gyarfas
authors.forename: John
authors.initials: J
authors.lastname: Shumway
authors.forename: Brian
authors.initials: B
authors.lastname: Ashcroft
authors.forename: Jin
authors.initials: J
authors.lastname: He
authors.forename: Stuart
authors.initials: S
authors.lastname: Lindsay
mesh_terms: D001665:Binding Sites; D003217:Conductometry / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007700:Kinetics; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D009711:Nucleotides / Q000032:analysis*; D020411:Oligonucleotide Array Sequence Analysis / Q000295:instrumentation*; D010316:Particle Size; D012666:Semiconductors
chemical_list: D009711:Nucleotides