CHEMICAL ENGINEERING

PRESERVING BACTERIA THROUGH A HEALTHY COLLABORATION

Chemical and Biological Engineering Professor Juan de Pablo (second from right) and graduate student Nancy Ekdawi-Sever (left) are working with Rhodia Staff Scientist Greg Leyer (right) and Process Engineer Fabrice Beretta (second from left) to create freeze-dried probiotics that have superior stability and a longer shelf life. (Photo by Bob Rashid) (33K JPG)

Professor Juan de Pablo is working to create freeze-dried probiotics that have superior stability, a longer shelf-life and the ability to survive in greater numbers at room temperature.

Probiotics are health-enhancing bacteria found predominantly in yogurt, fermented milks and dietary supplements. They are credited with numerous health benefits including warding-off intestinal tract infections, modulating the immune system, helping the body produce B vitamins and aiding in dairy product digestion. de Pablo's group developed patent-pending formulations optimized to suit each type of probiotic.

"We have a general class of chemicals and materials that can be used for cryopreservation, or freeze-drying, of biological systems," said de Pablo. "We have tested these products on enzymes and proteins, and more recently also on bacteria. We've demonstrated the efficacy of these methods on several classes of bacteria, and we have created optimized formulations that offer an economically attractive alternative to what is currently being done in industry."

NEW CLASS OF SENSORS FASHIONED FROM LEDs

Chemical Engineering Professor Tom Kuech (right), ECE Associate Professor Luke Mawst (left) and Chemistry Professor Art Ellis, pictured with a photoluminescence system, are developing LEDs as chemical sensors. (33K JPG)

This LED light fixture (left) replaces the normal incandescent light bulbs with an array of light-emitting diodes. The diodes have a high energy efficiency and light output. (27K JPG)

Already glowing away on thousands of consumer electronics products, the light-emitting diode (LED) is proving to be a remarkably versatile device. A group of UW-Madison scientists, including Professor Thomas Kuech, Electrical and Computer Engineering Associate Professor Luke Mawst and Chemistry Professor Art Ellis, have demonstrated the LEDs' usefulness as chemical sensors.

Chemical exposure can alter the surface structure of LED materials, causing the intensity of the light to fluctuate. That resulting light change can be put to use in simple, highly sensitive systems that sense chemicals in the air or water.

"There's a big movement to make sensors smaller, more versatile and to use the economy of scale you get from the semiconductor industry," said Kuech "What's nice about this effort is the prospect of making tiny optical emitters and detectors that are chemically sensitive to a wide range of substances you would care about in the environment."

FAST, CHEAP AND PORTABLE — A NEW PATHOGEN DETECTION TOOL

Professor Nicholas Abbott's advances in liquid crystals may help in the quest for early detection of pathogens like foot and mouth disease, West Nile virus, cryptosporidum or E. coli.

By using liquid crystals in combination with nanostructured surfaces, Abbott's credit card-sized plastic chips can offer rapid detection of bacteria or a virus. When exposed to a specific pathogen, the tendency to organize will make the presence of microscopic bugs visible to the naked eye.

The inventors first use techniques of nanofabrication to alter the surface of their device with ridges and bumps that match the size of contours of a species of virus or bacteria. The next step is to expose the surface to a field sample. A liquid crystal surface is laid over the sample. If the pathogen is in the sample, the liquid crystals will change color or brightness.

"We're seeing an increasing focus on food pathogens and emerging diseases," said Abbott. "We really don't have methods of detection in use now that are rapid, robust and inexpensive."