Graphene Thought to Create Biological Microsensor

Graphene, a recently invented material that can have a thickness of as little as one atom, is beginning to see potential use in biosciences. Because of the material’s physical structure, when traversing the surface of graphene, its electrons can travel at almost the speed of light at room temperature. Thus any contaminants on the surface can slow down electron speed, a characteristic that can be used to sense the presence of particular DNA strands or other biomolecules. Vikas Berry, a research scientist at Kansas State University, has been studying graphene’s properties.

One of Berry’s developments is a graphene-based DNA sensor. When electrons flow on the graphene, they change speed if they encounter DNA. The researchers notice this change by measuring the electrical conductivity. The work was published in Nano-Letters.
“Most DNA sensors are optical, but this one is electrical,” Berry said. “We are currently collaborating with researchers from Harvard Medical School to sense cancer cells in blood.”
Another area he is exploring is loading graphene with antibodies and flowing bacteria across the surface.
“Most researchers focus on pristine graphene, but we’re making it dirty,” he said.
Berry and Nihar Mohanty, a graduate student in chemical engineering, used a type of bacteria commonly found in rice and interfaced it with graphene. They found that the graphene with tethered antibodies will wrap itself around an individual bacterium, which remains alive for 12 hours.
Berry said that possible applications include a high-efficiency bacteria-operated battery, where by using geobater, a type of bacteria known to produce electrons, can be wrapped with graphene to produce electricity. The research was presented at the annual American Physical Society conference in Pittsburgh and the American Institute for Chemical Engineers conference in Philadelphia.
“Materials science is an incredible field with several exploitable quantum effects occurring at molecular scale, and biology is a remarkable field with a variety of specific biochemical mechanisms,” Berry said. “But for the most part the two fields are isolated. If you join these two fields, the possibilities are going to be immense. For example, one can think of a bacterium as a machine with molecular scale components and one can exploit the functioning of those components in a material device.”
For his doctoral research, Berry used bacteria to make a humidity sensor.
“That was only possible through combining materials science with biological science,” he said.
Another area of his current research is compressing and stretching molecular-junctions between nanoparticles. Berry said that his group has developed a molecular-spring device where they can compress and stretch molecules, which then act like springs, allowing researchers to study how they relax back. He said that this technology could be used to create molecular-timers in which the spring action from a decompressed molecule on a chip could trigger a circuit, for instance.
Berry said for stretching the molecules, Kabeer Jasuja, a doctoral student in chemical engineering, came up with the idea to place the device on a centrifuge to stretch the molecules with centrifugal force.

Press release: CONNECTING MATERIALS SCIENCE WITH BIOLOGY, K-STATE ENGINEERS CREATE DNA SENSORS THAT COULD IDENTIFY CANCER USING MATERIAL ONLY ONE ATOM THICK…
Abstract in Nano Letters: Graphene-Based Single-Bacterium Resolution Biodevice and DNA Transistor: Interfacing Graphene Derivatives with Nanoscale and Microscale Biocomponents…