Electronic nanodevices based on self-assembled metalloproteins

A key challenge of the current research in nanoelectronics is the realization of biomolecular devices. The use of electron-transfer proteins, such as the blue copper protein azurin (Az), is particularly attractive because of their natural redox properties and self assembly capability. We present in this work our results about the fabrication, characterization and modeling of devices based on such redox protein. The prototypes of biomolecular devices operate in the solid state and in air . The charge transfer process in protein devices can be engineered by using proteins with different redox centers (metal atoms) and by controlling their orientation in the solid state through different immobilization methods. A biomolecular electron rectifier has been demonstrated by interconnecting two gold nanoelectrodes with an azurin monolayer immobilized on SiO2. The device exhibits a clear rectifying behavior with discrete current steps in the positive wing of the current–voltage curve, which are ascribed to resonant tunnelling through the redox active center. On the basis of these results we have designed an azurin-based transistor. The three terminal device exhibits an ambipolar behavior as a function of the gate bias, thus opening the way to the implementation of a new generation of logic architecture, such as fully integrated biomolecular logic gate.