Chemical Engineering

Bandage Solution

A Canadian company is using its unique expertise in silver chemistry to create a new line of wound care products.

By Tyler Irving

In medicine — a field rife with snake oil salesmen — it is rare and refreshing to find a substance whose folkloric reputation for healing is actually borne out by science. Silver is one of those substances. Its ability to kill a wide range of infectious bacteria and fungi is well-documented, and over the last 20 years has seen increasing application in products from medical-grade dressings to sport socks. But not all silver is created equal, and nobody knows this better than chemical engineer turned CEO Rod Precht, founder of Exciton Technologies, Inc. The Edmonton-based company has leveraged an advanced understanding of metal chemistry to develop a new kind of coating for bandages that is both more effective and less expensive than those of their competitors. All that remains is to convince their potential customers.

Silver’s reputation as a healing metal dates back to Hippocrates, the ancient Greek “father of medicine,” who recommended its use in treating skin lesions. Throughout history, royals ate from silverware not only to show their wealth, but to reduce their chances of food poisoning. Well into the 20th century, silver coins were placed in bottles of milk to keep them from spoiling, and fruit juices were filtered through special silver-containing apparatuses in order to destroy bacteria. By 1937 James Gibbard, a bacteriologist working for the Canadian government, decided to get to the bottom of silver’s mysterious effects. In a paper published in the American Journal of Public Health he showed that pure silver metal melted and cooled in a hydrogen atmosphere had no effect on bacteria. However, when he placed silver formed in air into a bacteria-filled petri dish, a thin ‘kill zone’ developed around the sample. He concluded that the coating of silver oxide on the surface of the metal was giving off ions — Ag1+, Ag2+ and Ag3+ — and that it was these ions, not the native metal, that were responsible for the antibacterial effect.

All of this would have been news to Rod Precht as he completed his degree in chemical engineering at the University of Alberta in the early 1990s. Like most students in his year, Precht assumed he would get a job in Alberta’s burgeoning oil industry. But halfway through his program, a presentation by David Suzuki inspired him to look into the more human side of the discipline. He began taking technical electives in biochemistry and microbiology and learning more about how his engineering skills could be applied to biological problems.

As it happened, such skills were in demand just up the road in Fort Saskatchewan, Alta. There, the mining company Sherritt Inc. had partnered with the federal and provincial governments to create the Westaim (Western Advanced Industrial Materials) Initiative. This was a research centre that aimed, among other things, to develop new commercial applications for metals, and silver’s medicinal properties were tantalizing. “They wanted engineering students that had some biology background, and I was one of the lucky few who had actually taken those courses,” says Precht. A summer job eventually led to full-time work on some of the first commercial wound care products to contain silver.

A scanning electron micrograph shows particles of the oxysalt bound to the polyetheylene/ polyester fibres of Exciton’s finished bandage.

Precht’s task was to coat polyethylene mesh with silver salts or nanocrystals of silver metal, which would corrode on contact with the body’s fluids and release the ions that kill microbes. There were lots of challenges. “We worked on trying to get the silver to be more active, to stay active, to get a reasonable shelf-life for the product in a package, and to make commercial manufacturing viable,” he says. The product Precht helped develop was named Acticoat, and it was a commercial success. In 2001, Westaim sold Acticoat to Smith & Nephew, a U.K.-based medical technology company which has distributed it ever since. Westaim then changed its name to Nucryst and its focus from medical technology to pharmaceuticals, applying its nanocrystalline silver product to creams, gels and tablets.

The new direction didn’t resonate with Precht, who preferred medical technology to the slow-moving world of pharmaceuticals. “When you start developing drugs, it takes millions of dollars and years of clinical studies before you can bring a product to market,” he says. “As an engineer, I wanted to keep moving forward on products that can be quickly commercialized.” He also believed that the wound coatings had not yet reached their full potential. One drawback was that the corrosion of silver not only released the ions, but also altered the pH of bodily fluids near the wound, leading to pain for the patient. Another issue was the rising price of silver, which today trades at more than five times what it cost in the 1990s. Finding a more active form of silver would allow for a product that required less of the precious metal, reducing both cost and the potential for irritation. In 2001, Precht gathered together some ‘love money’ from family and friends and founded Exciton Technologies, Inc.

The silver oxysalt Ag7O8NO3 degrades to provide Ag2+ and Ag3+ ions, which are more active against microbes than the Ag1+ used in many silver-based coatings.

To develop the new technology, Precht recruited Stojan Djokić, an expert in electrochemistry he’d met while working at Westaim. Now an adjunct professor of chemical and materials engineering at the University of Alberta, Djokić is an independent-minded scientist with a passion for getting his hands dirty in the lab. “Without experiments, you cannot really find new concepts. I do all my own experimental work,” says Djokić. This suited Precht just fine, as he didn’t have the resources to hire students or technicians. Still, without the backing of a university or private research institution, even finding a suitable space to set up shop was a challenge. “It was a pretty difficult time, going from one lab to another lab,” recalls Djokić. Much of the early work was done in rented facilities in the basement of Edmonton General Hospital.

Djokić’s preliminary experiments showed that higher valence state ions of silver had the strongest antimicrobial activity. So he pursued a strategy of taking Ag1+ ions from a solution of silver nitrate (AgNO3) and reacting them with strong oxidizing agents such as ammonium persulfate ((NH4)2S2O8) or potassium persulfate (K2S2O8) in the hope of converting them to Ag2+ or Ag3+. The compound he ended up creating — Ag7O8NO3, known as a ‘silver oxysalt’ — had an unusual history. In 1804, a German chemist named J.W. Ritter had created it on a platinum electrode using an electrochemical process, but noted it merely as an interesting byproduct. Two centuries later, Djokić was the first to recognize its practical value: it could provide a source of the higher valence Ag2+ or Ag3+ ions to the wound, and release them at a controlled rate. The more active form of silver allowed for a decrease in concentration, resulting in a less expensive product and less pain for the patient. And unlike Ritter, Djokić worked out a process to precipitate the compound out of solution directly onto the high density polyethylene (HDPE) mesh used in wound care products, without the need for external electrical circuits or expensive electrochemical equipment.

In 2007, the basic concept — dubbed exSALT — was patented, but it took another two years to get approval by the United States Food and Drug Administration to market the devices. “It always takes more money than you think, and it always takes longer than you think,” says Precht, citing one of the major lessons he’s learned in the transition from engineer to entrepreneur. The delay led to a new challenge: in the decade since he founded Exciton, the market in silvercoated wound care products had changed significantly. “It’s gone from two approvals in the late 1990s to more than 50 approvals now; so there’s quite a bit of competition,” says Precht. While Exciton’s silver chemistry is certainly unique, there is a tendency for customers to paint all silver-based wound dressings with the same brush. This is troubling for Precht, especially considering that many of them have more in common with the silver coins of old than with Djokic’s patented oxysalts.

“Several products on the market have demonstrated minimal or non-effective antimicrobial activity, but are still used,” says Daniel Lozano, a physician and the Medical Director of the LeHigh Valley Regional Burn Center in Allentown, Pennsylvania. Each year, Lozano’s team sees over 800 patients, ranging from injured firefighters to children scalded by hot liquids from the kitchen stove. In almost 20 years of practice, Lozano has seen his fair share of silver-based treatments, and he knows their shortcomings well. “Most of them don’t work, the few that do work are relatively expensive,” he says. According to Lozano, the ideal dressing is one that releases ions at levels that are high enough to kill microbes, but low enough not to be toxic to regular tissue or cause the pH spikes that lead to pain. Since many commercial dressings rely on corrosion of silver to release their ions, their delivery rates can be unpredictable.

Exciton's silver oxysalts can be deposited onto bandage fabric by simple chemical precipitation, eliminating the need for expensive electrochemical equipment. Rolling machineslike this one currently produce between 10,000 and 20,000 units per year at Exciton's manufacturing facility in Edmonton, Alta.

Lozano was first made aware of Exciton’s technology a little more than a year ago through the company’s sales representative. Although initially skeptical, he was intrigued by Exciton’s unique knowledge of silver chemistry, as well as their ability to compete on price. “You get salespeople saying: I have a new, better product, but it costs more. This is the first time in my career that I’ve heard of a new, better product that costs less,” he says. Lozano decided to compare exSALT to another silver-containing product. “With the previous silver dressing we still got bacterial infections. We switched, and within a day, that infection was gone.” The slow, steady release of active ions also led to less pain for patients. After repeating the results numerous times, Lozano was convinced and decided to switch his entire centre over to exSALT’s technology. “What we’re looking at is something that is equivalent or better, but with a 30 to 40 per cent cost differential compared to other products.”

Building relationships with professionals like Lozano will be crucial as Exciton looks to expand its nascent sales force. Currently, Exciton manufactures about 10,000 to 20,000 units per year from its facility in Edmonton, selling them directly to hospitals across North America. Precht estimates the total value of this market at $250 million, with the potential to triple over the next five years. However, Exciton is also looking to expand overseas, and in the last year exSALT has been approved for use in New Zealand, Korea and India. The company is in discussions with established medical supply companies who will be able to market and sell the product in these jurisdictions.

Today, Precht spends most of his time thinking about how to grow his company at the right pace. Until now, Exciton has been financed by angel investors, and although Precht plans to maintain Exciton as a private company for the foreseeable future, he will likely require venture capital to move things to the next level. That brings its own set of risks, of which Precht is all too aware. “Faster is not always better, particularly in life sciences,” he says. “We’ve been very careful not to over-finance the company, which can lead to dilution and losing control.” Current manufacturing facilities will max out once sales hit $100 million dollars. While Precht says he’s pleased with the pace of growth so far, there is still some distance to go before this threshold is reached.

In the future, Precht hopes to apply Exciton’s unique silver technology to other medical products such as catheters. For now, though, he’s focusing on the core message about the difference his products can make for burn victims. “I’ve spent 20 years investigating the benefits of silver, and people still debate about whether it is even effective,” he says. “When you meet with key opinion leaders and they confirm that yes, your technology does add some benefit for people who are suffering, that’s what keeps you going.”

Photo Credits: Exciton Technologies, Inc.

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