  Recently, great attention has been paid to the possibility of implementing
hybrid electronic devices exploiting the self-assembling properties of single
molecules. Impressive progress has been done in this field by using organic
molecules and macromolecules. However, the use of biomolecules is of great
interest because of their larger size (few nanometers) and of their intrinsic
functional properties. Here, we show that electron-transfer proteins, such as
the blue copper protein azurin (Az), can be used to fabricate biomolecular
electronic devices exploiting their intrinsic redox properties, self assembly
capability and surface charge distribution. The device implementation follows a
bottom-up approach in which the self assembled protein layer interconnects
nanoscale electrodes fabricated by electron beam lithography, and leads to
efficient rectifying behavior at room temperature.
