Recent advances in biotechnology, nanofabrication, and imaging have created a highly interdisciplinary research area: nano-bioelectronics. The goal of this research is to understand better some of the most complex molecules that can be made in the lab, and ultimately, to interface smoothly between the world of nanofabrication and the world of living cells and organisms. In this research, methods based on nanotechnology are used to study biological phenomena, and biomolecules are used to bring novel functions to nanoelectronic devices.
Some of the world’s most innovative research in this field is being conducted at the University of Notre Dame’s Center for Nano Science and Technology, where a multidisciplinary team of engineers, chemists and biologists is studying how biomaterials like DNA can serve as structural frameworks for nanoelectronic devices. These discoveries could improve the speed, capacity and performance of electronic circuits and simplify their fabrication.
"We are experimenting with different shapes of DNA origami to make self-assembling computer circuits," says Marya Lieberman, a professor in the department of chemistry and biochemistry. "A long strand of DNA is extracted from a virus, and we use short pieces of synthetic DNA to fold it into a specific shape. It’s like yarn that knows how to knit itself into a scarf. We can make different shapes by changing the sequences of the synthetic DNA strands. We study the shapes using atomic force microscopy. Our goal is to build highly functional nanoelectric circuitry on top of these DNA objects."
Another group, led by Paul Bohn in the department of chemical and biomolecular engineering, is exploring nanofluidics and atom-scale junctions for chemical sensing. Nanofluidics encompasses phenomena that occur when fluid flow and chemical reactions are constrained to occur in incredibly tiny volumes (measured in zeptoliters, or 0.000,000,000,000,000,000,001 liters). Atom-scale junction studies focus on the creation of metallic nanowires that consist of strings of single atoms (known as pearl necklaces) and their response to adsorption of molecular species from nanofluidic flows. These structures could allow detection of very small numbers of target molecules for lab-on-a-chip applications.
Nanotechnology provides novel tools that are just the right size for studying biological structures and phenomena at their natural scales. Some researchers in NDnano—such as Holly Goodson of the department of chemistry and biochemistry and Mark Alber of the department of applied mathematics—hope to understand biological behavior in order to replicate some of the capabilities of living organisms. For example, the cytoskeleton, which provides mechanical support for cells and acts as a railroad for distribution of intercellular components, is able to disassemble and reassemble dynamically, allowing cells to move, grow, and heal, and Goodson and Alber collaborate to understand and model the dynamic behavior of these structures.
Dynamic behavior is also critical for the molecules that make up cell membranes. The Schultz lab tries to understand how the organization of lipids and proteins in cellular membranes affects signal transduction.
"We utilize laser spectroscopy and nanoscale imaging techniques to identify the properties of molecules that are important in regulating signaling events," says Professor Zachary Schultz, of the department of chemistry and biochemistry.
While most biologists and biochemists must study large groups of cells or molecules, Professor Greg Timp of the department of electrical engineering and the department of biological sciences has made nanopores so tiny that only a single DNA molecule can fit through. The electrical currents that accompany DNA translocation provide a new way to sequence DNA, with potential applications in personal medicine, biology, and biochemistry. The Timp group has also used optical tweezers to assemble individual cells into artificial tissues.