title: Conductance titration of single-peptide molecules.
abstract: We have measured the conductance of single peptides covalently bonded to two Au electrodes via S-Au bonds by repeatedly forming a large number of molecular junctions. The conductance decreases exponentially with the peptide length, with a decay constant of beta = 0.9 +/- 0.1 A-1, suggesting that tunneling is the mechanism of electron transport in the peptides. The conductance of the peptides is sensitive to the solution pH, due to the protonation/deprotonation of the amine and carboxyl groups of the peptides, which provides titration measurements based on single-molecule conductance.
authors.affiliation: Center for Solid State Electronics, Arizona State University, Tempe, Arizona 85287, USA.
authors.forename: Xiaoyin
authors.initials: X
authors.lastname: Xiao
authors.forename: Bingqian
authors.initials: B
authors.lastname: Xu
authors.forename: Nongjian
authors.initials: N
authors.lastname: Tao
mesh_terms: D004553:Electric Conductivity; D004566:Electrodes; D006046:Gold / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D017186:Titrimetry
chemical_list: D010455:Peptides; D006046:Gold