AVS 52nd International Symposium
    Electronic Materials and Processing Thursday Sessions
       Session EM1-ThM

Paper EM1-ThM7
Conduction through Cytochrome c Molecules

Thursday, November 3, 2005, 10:20 am, Room 309

Session: Molecular Electronics
Presenter: T. Matsumoto, Osaka University, Japan
Authors: T. Matsumoto, Osaka University, Japan
M. Kataoka, Osaka University, Japan
T. Kawai, Osaka University, Japan
Correspondent: Click to Email
Cytochrome c, which mediates electron transfer in biological system, is a candidate molecule with the suitable structure for electronic elements that comprise insulating and active parts. Since this redox center is isolated from the surroundings by the insulating part, the structure of cytochrome c can be regarded as a double tunneling junction for single electron tunneling. However, thin film of cytochrome c shows low conductivity, whereas, in vivo, single or several molecules derive electrons with high efficiency. For this reason, the measurement of the electrical conduction through single or several cyt.c molecules in solid state is a challenge to a critical stage towards the realization of bioelectronic devices using electron transfer proteins. Here, we demonstrate that cytochrome c molecules are electrically active on electrode surface modified with self-assembled monolayer. We also found that the strong influence of the variation of self-assembled monolayer on the conduction through cytochrome c. The gap-edge voltages observed are 0.5V for 2,2â?T-PySSPy and 1.3V for 4,4â?T-PySSPy. To confirm the participation of heme in the conduction through cytochrome c, the comparative experimenht for Zn cytochrome c, whose heme ion of Fe is replaced to Zn, was performed. In case of Zn cytochrome c, any detectable current has not been observed. This implies that the current goes through the ion in the reaction center of cytochrome c molecules suggesting that the conduction mechanism might be single electron tunneling. The SAM modification is also useful for nanogap electrode. The current through the molecule increases with increasing temperature suggesting the presence of thermal excitation.