Canadian researchers are working to develop specially-treated but inexpensive paper that can combat SARS, listeriosis and other deadly pathogens.
Dubbed bioactive paper, products would be embedded with chemicals and agents that would recognize and kill specific pathogens, and alert humans about their presence.
“The man-on-the-moon vision is to have something like litmus paper in food packaging or air filters that changes color or otherwise reacts to tell humans there’s a pathogen problem,” says Dr. Robert Pelton, a professor of chemical engineering at McMaster University in Hamilton and scientific director of the Sentinel Bioactive Paper Network.
The consortium is comprised of researchers at 10 universities across Canada, government agencies and nine business partners that include pulp-and-paper companies. The concept was conceived by Pelton and three other scientists in the wake of the SARS epidemic that swept through Toronto in 2003.
Working with a five-year, $12-million grant from government and industry, the group hopes to develop models that can decrease the threat from communicable diseases, food-borne illnesses and water contamination, while also boosting Canada’s forest-products industry.
The vision is bioactive paper that works alone to detect and neutralize pathogens without extra equipment, processing or laboratories, says Pelton. “We haven’t achieved that yet but we’ve solved some parts of the problem.”
There are many killing agents that can be used in paper to kill germs. Kimberley-Clark, for example, produces anti-viral Kleenex that kills cold germs. The tissue is treated with citric acid and sodium lauryl sulphate – two common household ingredients – that are activated by the moisture of a runny nose to kill germs. This kills 99 per cent of the four most common cold viruses in 15 minutes, according to Kleenex’s website.
But Sentinel’s bioactive paper vision is far more complex, as there is no one chemical or agent that kills all bugs, nor does anti-viral Kleenex detect or alert people about the presence of specific viruses.
Cracking the code with llamas and tobacco
Finding ways to detect specific pathogens is a fundamental step in developing a viable product. “We have to selectively trap the target pathogen, which means finding the nasty ones amongst a sea of less nasty ones,” says Pelton.
However, there are ways to narrow the search for the needle in the haystack, he says. There are only a few really dangerous pathogens in any given geographic region or environments such as hospitals, so researchers only need to find ways to detect the top three or four, not thousands, to deal with most outbreaks.
Researchers are also working on finding ways to produce the large quantities of antibodies needed to treat paper, he says. Once found, inexpensive processes such as inkjet printing can be used to mass-produce bioactive paper.
Sentinel is using an inventive approach to cracking the detection problem by embedding antibodies that counteract specific pathogens in paper. To accomplish this, researchers are using llamas to produce the antibodies.
“One of the issues with putting antibodies on paper is that they must be stable and last a long time sitting in store shelves,” he says. “Llamas produce special antibodies that don’t decompose when they dry out or require refrigeration.”
The animals are injected with a target pathogen, which stimulates their immune systems to generate antibodies to combat it. “We isolate the DNA that generated the antibody from their blood, and then genetically engineer that DNA in tobacco plants.”
Why tobacco? Antibodies could be produced in huge fermentation vats, but they can also be grown in genetically-engineered crops, he explains. But there’s a danger in working with food crops such as corn if genetically altered plants escape into the wider environment and contaminate the food supply, he says. “The advantage of tobacco is that we don’t eat it, and there’s a dying tobacco industry in Ontario that wants to produce something that has higher value.”
Sentinel is getting very close to solving the detection problem, he says. “We have demos where we can detect some pathogens such as E. coli, but we can only detect relatively high levels of bacteria.”
But researchers are still working on the reporting problem, he says. “We still don’t have something that changes colors or otherwise alerts humans – we have to do something like treat and wash the paper with other chemicals,” he says. “It’s like traditional photo processing with various baths but what we want is an instant Polaroid.”
Bioactive paper that requires extra steps would still be useful in hospital settings, he adds. “They do have labs, so we could see a system where they swab an area and then drop in some chemicals to check for signs of contamination. We could see that in the near future.”
Creating bioactive paper is ultimately about assembling components from various existing technologies to develop a viable product, he says. “We’re not inventing these things. Our idea is just to take the low-hanging fruit and try to figure out how to put it on paper inexpensively.”
Sentinel’s industry partners are working on bioactive gas masks, filters and proprietary research into other products they plan to bring to market in the near future, he says. Early applications will likely be in agriculture, veterinary and hospital settings. Once the technology has developed a track record in these areas, bioactive paper may move into consumer settings, he adds.