The objective of the present project is the demonstration of a biomolecular transistor consisting of self-assembled single blue copper proteins inserted in the gap between two metal electrodes. The ultimate resolution of the nanolithography tools available with the partners will be exploited to fabricate metallic gates with gaps below 10 nm, allowing the interconnection of virtually single molecules, opening the way to a bio-device exploiting just a few electrons. The synergy between nanotechnooogy and deliberately engineered redox blue copper proteins (azurin and plastocyanin) will be a unique tool to achieve a self-assembled biotransistor in which the current flowing through self-assembled (eventually single) redox proteins can be controlled via the application of a suitable gate potential. To achieve these results the project will pass through a series of steps which will involve both experimental and theoretical studies aimed at characterizing the self-assembly and the functional behaviour of the protein ensembles constituting the channel. The protein transistor is expected to operate at room temperature, to show power dissipation as low as some nW, to be characterized by a capacitance of the order of 10-19F and to have overall performances superior to those of single electron transistors made of semiconductor nanocrystals and carbon nanotubes. It is expected to show a relevant sensitivity to the surface chemisorption and to the chemical changes of the environment, so that a noticeable application as a bio-sensor can be envisaged for the proposed architecture.
DESCRIPTION OF WORK
The project is carried out by three partners P1= INFM-Italy, P2= Leiden University-Holland, P3=Oxford University UK. Electron beam lithography (EBL), self assembled metalloprotein layers of controlled density (down to the single molecule limit) will be used to interconnect two and three terminal metallic nanodevices to fabriate prototype bio-field effect transistors for electronics and biosensor applications. Type I copper proteins (azurin, plastocyanin and their suitably designed mutants) capable of self-assembling on to different solid or soft substrates will be arranged to form the channel of biomolecular transistors. The presence of a redox center inside these molecules will allow the control of the drain-source current through a channel made of an ordered protein monolayer or a single molecule by varying the gatevoltage in a range around the equilibrium potential of the redox center. This property will be exploited for both bio-FET and biosensor applications. The biomolecules chosen for the project are blue copper proteins physiologically involved in the bacterial respiratory phosphorylation and in some steps on the photosynthesis of green plants respectively. The resemblance of the hybrid metalloprotein/metal system with a gate potential into the channel of a field effect transistor or a single electron transistor is at the basis of our project, and will be exploited to fabricate a new class of prototype biomolecular devices such as field effect transistors operating with self assembled protein layers deposited across wide gates and few (single)-metalloprotein molecules across nanogates. Moreover, we will test the electrical properties of our hybrid devices in the presence of different chemical and biological environemnts to explore their potential application as bio-sensors.
The final demonstration of the project will consist two new hybrid devices, exploiting different architectures, namely:
1) A field effect transistor based on self assembled azurin ayers deposited on gold patterns, to be used either as electronic component or as a biosensor;
2) A few electron transistor operating at room temperature based on single (a few) molecule interconnecting a metallic gold nanogate with gap of the order of 10 nm or less.
The project will be developed along 5 workpackages (WP):
1) WP1: synthesis, basic biochemical characterization, structural and spectroscopic investigation of self assembling on metallic surfaces of metalloproteins;
2) WP2: Design, fabrication and characterization of two and three terminal hybrid devices for transport studies of self assembled layers and single molecules interconnecting gold nanostructures;
3) WP3: Investigation of FET and biosensor operation of the hybrid-devices;
4) WP4: Theoretical modelling of the basic physical processes controlling the biomolecular transport and devices;
5)WP5: Management and dissemination of result
Funding SchemeCSC - Cost-sharing contracts
OX1 2JD Oxford
2300 RA Leiden