AFMによるリゾチーム単一分子の電気伝導計測

抄録

Although the protein attracts as a candidate molecular electronic material, its conduction mechanism in dry condition is not clear in detail. Electrical conductance through a single molecule of lysozyme, which is composed of only peptide chain without metal, was observed by conductive atomic force microscopy using a gold substrate and gold-coated tip modified with a self-assembled monolayer of 2-pyridine sulfide. A significant current (∼10⁻⁹ A) is observed to flow under a bias voltage, and the current-voltage (I-V) characteristics show non-linear I-V characteristics with clear thresholds about 2.5 V. Observed I-V characteristics can be well reproduced by the single barrier tunneling model based on the narrower barrier width with the bias voltage. These results suggest that the electrical conduction of lysozyme is governed by the tunneling mechanism via the peptide chain of protein.