Our floating films are made of oils and glycoproteins, which break down into micelles (shown above) and capture certain waterborne pathogens.

Monitoring water quality in U.S. rivers and lakes has always been a challenge and is even more so with increased threats of terrorism. "There's a need to monitor the introduction and spread of waterborne infectious disease agents and biotoxins in rivers, lakes, and reservoirs," says Elaine Mullen, a biological researcher at MITRE's Center for Integrated Intelligence Systems. Mullen is working on a MITRE-sponsored research project to develop floating films that collect and concentrate pathogens at the water surface.

It's hoped that the films can be used as a low-cost method to rapidly survey surface waters for pathogens. The films could facilitate the collection of water samples for analysis and provide early warning of harmful biological contamination. When they are developed beyond the research stage, the films could be used by the Department of Homeland Security and the military to detect unsafe water supplies.

Even though low concentrations of harmful microbes and toxins are difficult to detect in large bodies of water, Mullen thinks that MITRE-patented "designer films" can do the trick. The films are made from oils and glycoproteins found in plant and animal tissue. Wave action breaks the film into tiny globules or micelles. The outer surface of the micelle contains glycoproteins that contact waterborne pathogens.

Mullen explains that, on a molecular level, the glycoprotein is a protein with an attached carbohydrate that resembles a tree branch composed of branching sugar units. "These sugars are the key," says Mullen, "because they act like biological Velcro when a pathogen contacts a certain sequence of sugar molecules. Specific sugar chains can grab onto pathogens and biotoxins like a burr sticks to your clothes. Pathogens adhere to people the same way. To infect you, a pathogen must stick to a tissue surface."

For almost three decades, Mullen has been studying how glycoproteins and oil react in water. Through a literature search, Mullen said she has recently found proof of her concept. For example, in one case, a film with a human blood-type sugar group captured certain E. coli strains from biological fluids. In another case, proteins in the whites of pigeon eggs were shown to have sugars that capture several serious pathogens, including E. coli strains that cause infections.

Before Mullen creates new films, she conducts research involving two bioinformatics databases. The first is a commercial database called GlycoSuite that lists sugars attached to proteins. The second is the new SugarBindDB™ database, which was developed by MITRE (see sidebar). SugarBindDB is a compilation of literature about sugars that attach to various bacteria and viruses. It lists human and domestic animal pathogens that bind to certain specific sugar configurations that are on the cells of tissue that is infected by that pathogen. Thus, Mullen works to create specific films to detect specific pathogens. Multiple glycoproteins can be put into a film so that one film can detect a variety of pathogens.

MITRE is working with the Johns Hopkins University Applied Physics Laboratory (APL) to investigate ways of enhancing biocapture films by varying glycoprotein components. A new atomic force microscope at APL will be used to look at film surfaces on a nanometer scale (one billionth of a meter). Another company, Versar/GEOMET, is working with MITRE and APL to do scale-up studies to test the ability of films to capture bacteria in different environments.

—by David Van Cleave

Related Information

Websites

• SugarBindDB: Pathogen Sugar-Binding Database

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