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The Bioactive Paper Chase


January 1, 2008
By Pulp & Paper Canada

Imagine being able to dip a paper strip into a pail of third-world water to find out if it is contaminated with Salmonella, E-coli or some other disease-causing pathogen. Then, if the test is positive…

Imagine being able to dip a paper strip into a pail of third-world water to find out if it is contaminated with Salmonella, E-coli or some other disease-causing pathogen. Then, if the test is positive, pouring the water through a paper filter that captures or kills the pathogen, yielding safe drinking water. Or how about food packaging that changes colour if food becomes contaminated with bacteria and is no longer safe to eat? Or face masks that capture and possibly kill airborne pathogens?

These are examples of the goals set by the Sentinel Bioactive Paper Network, a research group formed in 2005 by McMaster University and nine other universities, nine companies and the Federal and Ontario provincial governments to develop paper that can detect, capture and possibly kill pathogens.

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Sentinel is working on a $2.2 million a year budget, 75% of which comes from the Natural Sciences and Engineering Research Council of Canada and 25% of which comes from an industrial consortium and the Ontario government.

The need and the market for paper products that could easily detect and deactivate pathogens is reflected in the plight of the 1.1 billion people worldwide who lacked access to safe water in 2007. In the US alone there are 76 million cases of food borne illnesses each year.

FPinnovations-Paprican is part of this research effort, providing funding, access to equipment, pulp and paper materials and manufacturing expertise to Sentinel. “We have a lot of different tools at our disposal,” says Franois Drolet, a scientist with FPinnovations-Paprican. “In addition to various equipment for producing paper in the lab, we have access to all the tools and techniques, such as microscopy, required to characterize paper structures. We also have a lot of expertise on the fibre side and can produce and supply different kinds of pulps to researchers in the network.”

For his part, Drolet is developing modeling tools to predict the filtration efficiency of fibre networks such as paper at the microscopic scale, in collaboration with, among others, the department of physics at McGill University.

As the research advances, FPinnovations-Paprican will be providing more services and staff resources to develop and scale up bioactive paper manufacturing methods.

Researchers have set their sights on three desirable properties of bioactive paper: the ability to detect and identify pathogens; capture them in the paper’s structure; and deactivate, or kill them. There are already products that advertise the ability to do the killing part; for example the KLEENEX anti-viral tissue with a middle layer that kills colds and flu viruses, made by Kimberly-Clark. Last January, Domtar launched a silver compound-treated anti-microbial office paper, which it says is, “…designed to protect paper against the growth of bacteria, odours, fungus, mold and mildew …” Domtar also reports that the paper kills 99% of Methicillin-resistant Staphylococcus aureus, responsible for problems ranging from skin infections to pneumonia, and Klebsiella pneumoniae, responsible for hospital-acquired illnesses, among other ailments.

For Sentinel, however, detection is the main focus of research at present, according to Drolet.

Achieving all three properties in paper is still several years away, although several patents have been filed over the past year. Which bioactive agents will be used, where on the paper they will be located and what the detection method will be are all still under development.

Sentinel researchers are studying a number of ways to attach bioactive agents such as enzymes or antibodies, to paper. They could be grafted onto paper fibres, inserted in paper layers, or they could be coated on the paper, post-production.

The challenges are numerous, says Drolet. “Say we go for the grafting approach. The challenge here is the temperature in the dryer section of the paper-making process, which is high enough to kill the bioactive agent. If we want to insert the agents on the wet end, we may lose a lot of these very expensive enzymes. It may be desirable for many applications to apply the bioagents by printing or coating on paper.”

Another issue to be considered is that most bioactive agents need moisture to remain active. Is paper with 10% moisture content moist enough? “This is not yet clear,” Drolet confirms.

Pathogen capture might be done classically with the fibre, or some other way. “There are a lot of hurdles and challenges that need to be overcome. For example, you have 10-micron gaps in the paper, but there are pathogens that are only 0.2 microns in size. How do you capture something that small in paper with such large gaps?” asks Drolet.

Many researchers at Sentinel are working on colour-based detection methods, although another possibility is signalling detection with a small current. Although removal of the pathogen is the ideal scenario, signalling is just fine for many applications — for example, it would be sufficient for food packaging to warn that its contents are spoiled, amd for this application, deactivating of the pathogen would be unnecessary.

While several types of pathogens that could be identifiable by bioactive papers are being considered, no paper mill has yet to make any bioactive paper that can detect pathogens. However, Sentinel researchers are working on several demonstration projects aimed at producing functioning bioactive paper in the lab by the next meeting of the Sentinel researchers, scheduled for May 2008.

At these meetings, held every six months, researchers from the biological, surfaces and materials sciences, which include biology, food science, chemistry, biochemistry, paper science and engineering, meet, mingle and discuss their progress. They also bring their industry partners up to date on their activities. The partners also get the opportunity to steer researchers in specific directions. “We make sure we stick to Sentinel’s basic [goal], which is to develop applied techniques,” Drolet notes.

FPinnovations-Paprican has a lot of equipment to place at the disposal of the Sentinel researchers. Trials of techniques to produce paper that contains biologically-active chemicals, for example, can be done on a hand-sheet machine or one of FPinnovations-Paprican’ dynamic sheet formers, which can create sheets of paper using centrifugal force. A lab coater and various printing equipment can also be used to surface-treat paper with bioactive agents. FPinnovations-Paprican additionally has a pilot paper machine which can be used for larger-scale trials.

Full-scale paper mill trials are still years away, but the day may come when a paper mill could produce high value-added bioactive paper as a competitive alternative to closing operations. “The focus is very much on developing techniques that will lead to products,” Drolet explains. “It is still a pretty young field, especially considering the range of the scope of the projects. Commercial products are a ways off, but we are making progress.”

FPinnovations-Paprican

After more than 80 years of providing research to the pulp and paper industry, Paprican became a division of FPinnovations in April 2007.

Paprican joined the Montreal-based R&D company’s three other divisions — Feric, Forintec and the Canadian Wood Fibre Centre — to tackle issues ranging from genome to marketing, with the depth of expertise offered by FPInnovation’s combined staff of over 600.

“Our members represent more than 75% of the tonnage produced by the industry. We have a united voice with which to discuss priorities with all the stakeholders and the government. We can determine with the industry a unified list of priorities,” says Martin Champoux, FPinnovations-Paprican’s director of membership relations and communications. “This is now an organization that is a lot more integrated to deliver value to the pulp and paper industry.”

FPinnovations’ research program is benefiting from a $125.7 million investment by the Federal government to address the
long-term competitiveness of the forest industry. This includes $55 million targeted for promoting forest sector innovation and investment in emerging and breakthrough technologies.

These monies are funding four programs at FPinnovations: value chain optimization, biorefining, nanotechnologies and next-generation papers. “An overall goal is how to obtain the maximum value out of fibres available,” says Jean Hamel, director of research with FPinnovations-Paprican.

For example, FPinnovations-Paprican just recently learned how to produce nanocrystalline cellulose (NCC) in large quantities. NCC is stronger than steel and could, for example, be used to increase the strength of lumber. The research collaborative is exploring different applications of NCC to take the industry beyond its traditional range of products.

“The most important change in the last few months is understanding that to jump ahead of the competition we need to embrace a new way of thinking; for example, grow from a commodities mindset to [manufacturing] niche and innovative products,” says Champoux.

One area of research for next-generation paper is developing technologies to help mills increase the filler content of their paper to reduce overall cost, while maintaining or even increasing sheet quality. “We want to provide the industry with different papers that have properties other countries cannot provide,” says Champoux.

FPinnovations-Paprican is also developing ways for mills to be more cost-competitive. For example, it has developed and implemented a new bleaching technology which has lead to significant reductions in cost per tonne. Another technology has reduced the power consumption in the thermomechanical pulp plant by about 5% and, in some cases, increased the quality of the pulp. A way has also been found to modify the chemistry at the wet end to increase the filler content, and this process has been successfully implemented in mills.

These are challenging times for the pulp and paper industry, as evidenced by closures that even include some well-run mills. However, says Hamel, “We have very good support from the Federal government to develop new technologies.” Champoux adds, “We are very pleased so far with the support and commitment the Federal and Provincial governments have provided.”


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