Molecular electron transfer of protein junctions characterised by conducting atomic force microscopy.
The transport characteristics of the blue copper metalloprotein, azurin, have been characterised by conducting atomic force microscopy (C-AFM) at molecular level. Tunnel junctions have been constructed by sandwiching chemisorbed protein molecules between a conducting AFM tip and a planar conducting substrate. Asymmetric current curves with respect to the polarity of the bias (I-V) have been observed. The modulation of I-V behaviour with compressional force has been examined and is described by a modified Simmons model within which both tunnel distance (protein dimensions) and tunnel barrier are modulated. The modified Simmons formula, which considered unequal Fermi level shifts on two electrodes as being responsible for the asymmetric I-V curves, accurately describes the behaviour observed.
Zhao
Jianwei
J
Inorganic Chemistry Laboratory, Department of Chemistry, South Parks Road, Oxford OX1 3QR, UK.
Davis
Jason J
JJ
D001400:Azurin / Q000737:chemistry* / Q000378:metabolism*; D003553:Cystine / Q000378:metabolism; D006108:Graphite; D018625:Microscopy, Atomic Force / Q000379:methods*
D001400:Azurin; D003553:Cystine; D006108:Graphite