The American Vacuum Society (AVS) is holding its 58th International Symposium and Exhibition from Oct. 30 – Nov. 4, 2011 in Nashville, Tennessee. Presentations are not focused on vacuuming (hoovering) floors but rather on something called vacuum science and they span from a presentation on bacteria and coatings to another on photocopying DNA to more.
From the Oct. 31, 2011 news item on Nanowerk,
“Sea water is a very aggressive biological system,” says Gabriel Lopez, whose lab at Duke University studies the interface of marine bacterial films with submerged surfaces. While the teeming abundance of ocean life makes coral reefs and tide pools attractive tourist destinations, for ships whose hulls become covered with slime, all this life can, quite literally, be a big drag. On just one class of U.S. Navy destroyer, biological build-up is estimated to cost more than $50 million a year, mostly in extra fuel, according to a 2010 study performed by researchers from the U.S. Naval Academy and Naval Surface Warfare Center in Maryland. Marine biofouling can also disrupt the operation of ocean sensors, heat-exchangers that suck in water to cool mechanical systems, and other underwater equipment.
I think rather than describing sea water as ‘aggressive’ which suggests intent, I’d use ‘active’ as Lopez does later in another context (excerpted from the news item),
Lopez and his group focus on a class of materials called stimuli-responsive surfaces. As the name implies, the materials will alter their physical or chemical properties in response to a stimulus, such as a temperature change. The coatings being tested in Lopez’s lab wrinkle on the micro- or nano-scale, shaking off slimy colonies of marine bacteria in a manner similar to how a horse might twitch its skin to shoo away flies. The researchers also consider how a stimulus might alter the chemical properties of a surface in a way that could decrease a marine organism’s ability to stick.
At the AVS Symposium, held Oct. 30 – Nov. 4 in Nashville, Tenn., Lopez will present results from experiments on two different types of stimuli-responsive surfaces: one that changes its texture in response to temperature and the other in response to an applied voltage. The voltage-responsive surfaces are being developed in collaboration with the laboratory of Xuanhe Zhao, also a Duke researcher, who found that insulating cables can fail if they deform under voltages. “Surprisingly, the same failure mechanism can be made useful in deforming surfaces of coatings and detaching biofouling,” Zhao said.
“The idea of an active surface is inspired by nature,” adds Lopez, who remembers being intrigued by the question of how a sea anemone’s waving tentacles are able to clean themselves. [emphasis mine] Other biological surfaces, such as shark skin, have already been copied by engineers seeking to learn from nature’s own successful anti-fouling systems.
(I did profile some biomimicry work being done with shark skin in my comments on part 4 of the Making Stuff programmes broadcast as part of the Nova series on PBS (US Public Broadcasting Stations) in my Feb. 10, 2011 posting.)
This next presentation is in the area of synthetic biology. From the Oct. 31, 2011 news item (DNA origami from inkjet synthesis produced strands) on Nanowerk,
In the emerging field of synthetic biology, engineers use biological building blocks, such as snippets of DNA, to construct novel technologies. One of the key challenges in the field is finding a way to quickly and economically synthesize the desired DNA strands. Now scientists from Duke University have fabricated a reusable DNA chip that may help address this problem by acting as a template from which multiple batches of DNA building blocks can be photocopied. The researchers have used the device to create strands of DNA which they then folded into unique nanoscale structures.
“We found that we had an “immortal” DNA chip in our hands,” says Ishtiaq Saaem, a biomedical engineering researcher at Duke and member of the team. [emphasis mine] “Essentially, we were able to do the biological copying process to release material off the chip tens of times. [emphasis mine] The process seems to work even using a chip that we made, used, stored in -20C for a while, and brought out and used again.”
After releasing the DNA from the chip, the team “cooked” it together with a piece of long viral DNA. “In the cooking process, the viral DNA is stapled into a desired shape by the smaller chip-derived DNA,” explains Saaem. One of the team’s first examples of DNA origami was a rectangle shape with a triangle attached on one side, which the researchers dubbed a “nano-house.” The structure could be used to spatially orient organic and inorganic materials, serve as a scaffold for drug delivery, or act as a nanoscale ruler, Saaem says.
I’m not very comfortable with the notion of an “immortal DNA chip” but then I have many reservations about synthetic biology. Still, I think it’s important to pay attention and consider the possibility that my fears about synthetic biology might make as much sense as the fears many had about electricity in the 19th century.