SemiSynBio-III: Precision assembly and electronic properties of protein nanowire circuits using DNA origami

Microelectronics fabrication critically relies on using silicon substrates and numerous masking/layering steps that bring serious drawbacks such as extreme entry costs, high energy consumption, and finite limits on scalability and device geometries that have nearly been reached, creating a gap in technologies able to effectively address these issues. New materials, sustainable fabrication processes, and novel circuit topologies are necessary to develop next-generation electronic devices.

This research will develop engineered protein nanowires using bacterial pili that conduct electricity by precisely designing and assembling structural scaffolds made of DNA, known as DNA origami. The interactions of the nanowires with each other and their environments can be read out using single molecule techniques and electronic methods developed for thin layer assembled structures to characterize conductivities at the molecular scale.

The combination of these interdisciplinary advances will ultimately enable the development of modular bioelectronic devices for next-generation computing applications. This research will provide interdisciplinary collaborative interactions and unique opportunities for cross-training students participating in this project and will further extend the reach by training undergraduates from each institution involved in the research to serve as ‘Ambassadors’ for outreach efforts.

The integrated graduate and undergraduate interactions will provide opportunities to host K-12 participation programs, including training for secondary school teachers. By working across schools and regions to share students, ideas, and best practices, this research program will generate ongoing student and public excitement around new discoveries in bionanoelectronics.

In nature, long-range (>10 nm) electron transport is often achieved in assembled proteins rich in aromatic residues or redox-active groups. From this view, conductive biological nanowires hold strong promise for a variety of technological applications in next-generation electronic devices. The bacterium Geobacter sulferreducens survives largely through the reduction of inorganic metal-oxides in its environment and efficiently transports electrons extracellularly via its type IV pili.

Pili conductivity has, in turn, been linked to a densely packed core of aromatic amino acids that effectively allows electron hopping between residues. This research will engineer the conductive pili of Geobacter using protein engineering and synthetic biology methods to create protein nanowires whose conductivity can be modulated through interactions with ligands and self-assembly.

The protein nanowires will, in turn, be assembled onto DNA origami at a nanoscale resolution to create precisely structured circuits with defined electrochemical junctions. Single-molecule electrochemical characterization will allow for a detailed understanding of the underlying circuitry, which will, in turn, lead to the development of basic design rules for bionanoelectronic assemblies.

Overall, this research will provide an improved understanding of structural design, assembly, and electron transport mechanisms in biological nanowires, including developing fundamental electronic parts, such as transistors, and building these elements into useful devices such as memory.

The project was jointly funded by the Division of Molecular and Cellular Biosciences (MCB) in the Directorate for Biological Sciences (BIO); Division of Computing and Communication Foundations (CCF) in the Directorate for Computer and Information Science and Engineering (CISE); Division of Electrical, Communications and Cyber Systems (ECCS) in the Directorate for Engineering (ENG) and the Division of Materials Research (DMR) in the Directorate for Mathematical and Physical Sciences (MPS).

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.