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Conductance Titration of Single-Peptide Molecules

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journal contribution
posted on 05.05.2004, 00:00 by Xiao, Xu, Tao
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 β = 0.9 ± 0.1 Å-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.