Color-Changing Turkey Wattles Inspire New Toxin and Germ Detector

[Buster's Uncle]

Color-Changing Turkey Wattles Inspire New Toxin and Germ Detector
By Rachel Barclay Tue, Jan 21, 2014



It turns out turkeys aren't only great with gravy and cranberry sauce. Scientists have long drawn inspiration from nature, and the humble turkey wattle is their next muse.

Turkeys can change the color of the skin on their heads from red to blue to white, depending on whether they are calm or excited. This characteristic is so distinctive that it’s earned turkeys the name “seven-faced bird” in Korean.

In a new study released today in Nature Communications, a research team at the University of California, Berkeley, led by Seung-Wuk Lee, explains how they have developed a synthetic toxin sensor based on the turkey’s color-changing technique.


Happy Turkey, Angry Turkey

A turkey’s head is normally bright red, a color caused by visible blood vessels lying directly under the skin of the wattle. The blood vessels are surrounded by long bands of a connective tissue called collagen, which is one of the basic building blocks of animal life. When the turkey gets flustered, the blood vessels contract, exposing more of the collagen bands.

This changes the way that incoming light scatters and reflects off of the turkey's skin, causing it to appear blue or white. It’s the same scattering effect that makes the sky appear blue but sunsets yellow or red. It’s also the reason that blood vessels appear blue beneath pale skin, even though the blood inside them is red.

“If we can build a similar structure and use the resulting structure to detect chemical or environmental information, it can be a great color sensor that we can easily use in our daily life,” said Lee, an associate professor in bioengineering at Berkeley, in an interview with Healthline.


A Viral Rainbow

To create their sensor, Lee’s team needed a building block of their own. They chose the M13 virus, which can stick to itself in a simple, repeating pattern that forms fibers. “The M13 virus has a physical shape like a natural building block and can easily produce identical copies,” explained Lee.

These fibers, it turns out, have properties similar to collagen. They can expand or contract to change color, shifting from blue to green to yellow to red. As luck would have it, the fibers are naturally responsive to a range of chemical vapors, including water and alcohol.

“The color change is so obvious for the high-vapor chemicals, we can easily detect color changes even with the naked eye,” said Lee.

Lee’s team developed a smartphone app called iColour Sensor, which uses a phone camera to read the color changes and detect just how much of the measured chemical is present in the air.

The sensor isn’t limited to just water and alcohol. To demonstrate the flexibility of their invention, Lee’s team bioengineered the M13 virus to contain a site that is sensitive to the chemical explosive TNT. When exposed to TNT fumes, the fibers expanded rapidly, turning from dark blue to yellow or red.

The test was also quite selective—the team tried their TNT-sensitive test on two related but non-explosive chemicals, DNT and MNT. The iColour Sensor was able to easily tell the difference between the dangerous chemical and the harmless ones.

Although the test isn't quite sensitive enough to be useful for detecting TNT in the military field, Lee is confident that it is a good proof-of-concept test. He says the viral fibers could potentially be bioengineered to contain sites that are sensitive to any number of toxins and microbes.


Making a Better Detector

Color-coded chemical detectors are easier and faster to read than sensors that just display a numerical readout. Most chemical detectors are also expensive to manufacture and are only sensitive to a small number of chemicals. Lee’s technology is cheap, fast-acting, and could be customized to nearly any chemical.

And we have turkeys to thank.

“Nature provides a rich source of inspiration,” said Lee. “All the natural products that we see are an example of [winning adaptations for] their given environments. Only a fraction of them are discovered and utilized for scientific and engineering subjects. There are a lot of remarkable structures and phenomena that are still waiting to be discovered.”


http://health.yahoo.net/articles/healthcare/color-changing-turkey-wattles-inspire-new-toxin-and-germ-detector

[Buster's Uncle]

Turkey-Inspired Sensors Could Detect Toxins
LiveScience.com
By Sarah Yang, University of California, Berkeley  40 minutes ago



The material properties and coloring of turkey waddles inspired Berkeley engineers to design a new type of chemical sensor.



Sarah Yang is a public information officer at the University of California, Berkeley. This article was adapted from a piece on the Berkeley website. She contributed this article to LiveScience's Expert Voices: Op-Ed & Insights.

Some may think of turkeys as good for just lunch meat and holiday meals, but bioengineers at the University of California, Berkeley (UC Berkeley) saw inspiration in the birds for a new type of biosensor that changes color when exposed to chemical vapors. This feature makes the sensors valuable detectors of toxins or airborne pathogens.

Turkey skin, it turns out, can shift from red to blue to white, thanks to bundles of collagen that are interspersed with a dense array of blood vessels. It is this color-shifting characteristic that gives turkeys the name "seven-faced birds" in Korean and Japanese.

The researchers said that the spacing between the collagen fibers changes when the blood vessels swell or contract, depending on whether the bird is excited or angry. The amount of swelling changes the way light waves are scattered and, in turn, alters the colors people see on the bird's head.

Seung-Wuk Lee, UC Berkeley associate professor of bioengineering, led a research team in mimicking this color-changing ability to create biosensors that can detect volatile chemicals.

"In our lab, we study how light is generated and changes in nature, and then we use what we learn to engineer novel devices," said Lee, who is also a faculty scientist at the Lawrence Berkeley National Laboratory.



Berkeley engineers developed bio-inspired sensors made from bacteriophages (bacteria-targeting viruses) that mimic the collagen fibers in turkey skin. When exposed to target chemicals, the collagen-like bundles expand or contract


The researchers created a mobile app, the iColour Analyser, to show that a smartphone photo of the sensor's color bands could be used to help identify chemicals of interest, such as vapor of the explosive TNT. They described their experiments in a study published today (Jan. 21) in the journal Nature Communications.

Sensors that give off color readings are easier to use and read than conventional biosensors. However, the major color-based sensors in development elsewhere can only detect a limited range of chemicals and, the researchers said, can be very difficult to manufacture.

"Our system is convenient, and it is cheap to make," Lee said. "We also showed that this technology can be adapted so that smartphones can help analyze the color fingerprint of the target chemical. In the future, we could potentially use this same technology to create a breath test to detect cancer and other diseases."

In copying this turkey-skin design, Lee and his team employed a technique to mimic nanostructures like collagen fibers. The researchers found a way to get M13 bacteriophages, benign viruses with a shape that closely resembles collagen fibers, to self-assemble into patterns that could be easily fine-tuned.

The researchers found that, like collagen fibers, these phage-bundled nanostructures expanded and contracted, resulting in color changes. The exact mechanism behind the shrinking or expanding phage bundles is still unclear, but it's possible that the small amount of water in the phage is reacting to the chemical vapors, the researchers said.

The turkey-inspired biosensors were exposed to a range of volatile organic compounds, including hexane, isopropyl alcohol and methanol, as well as TNT, at concentrations of 300 parts per billion. The researchers found that the viruses swelled rapidly, resulting in specific color patterns that served as "fingerprints" to distinguish the different chemicals tested.

The researchers showed that they could coax the biosensor to better detect TNT by genetically engineering the DNA in the M13 bacteriophage to bind with sites specific to TNT. The researchers then exposed the biosensor to two additional chemicals, DNT and MNT, which have similar molecular structures to that of TNT. The engineered biosensor successfully distinguished TNT from the other chemicals with distinct color bands.

The biosensors were also able to signal changes in relative humidity, ranging from 20 percent to 90 percent, becoming redder with moister air and bluer with drier air.

The study lead author is Jin-Woo Oh, a former postdoctoral researcher in Lee's lab and now an assistant professor in the Department of Nanomaterial Engineeringat Pusan National University in South Korea.

The National Science Foundation; the Defense Acquisition Program Administration and Agency for Defense Development in South Korea; Korea's Ministry of Education, Science and Technology; and Samsung helped support this work.


http://news.yahoo.com/turkey-inspired-sensors-could-detect-toxins-193427781.html