Antimicrobial coatings: Billion Dollar Bugs

What most people can not see might make them sick, and often even kill them. And it seems there is no safe place when it comes to bacteria and other germs growing on surfaces.

 

About 10% of hospital patients get sicker during their stay after coming into contact with germ-laden equipment and surfaces, resulting in about 100,000 deaths each year in the U.S., and more than $20 billion in added healthcare costs.

 

Doctors and hospitals across the globe have talked for years about making medical equipment “cleaner” to reduce unwanted illnesses. The Center for Disease Control even impaneled a “Healthcare Infection Control Practices Advisory Committee” last year to examine the issue.

 

At the same time, the U.S. Food and Drug Administration and several leading paint and powder coating companies have strengthened efforts to fine-tune antimicrobial coatings used to finish medical equipment and supplies to prevent bacteria growth.

 

But now it appears the antimicrobial coatings are starting to make an even bigger entry into U.S. homes. More consumer goods manufacturers are offering “germ resistant” surfaces on many household items such as refrigerators, dishwashers, stoves and other appliances and fixtures.

 

A report by Global Industry Analysts Inc. says the U.S. antimicrobial coatings market alone is expected to reach $1 billion by 2015.

 

Why? Consider that the CDC says most household surfaces such as appliances, computers and other items humans use and touch every day often are laden with as much as 60 times the microbial matter found on a toilet seat.

 

Major manufacturers like Bosch and Siemens are applying antimicrobial powder coatings to the interior of refrigerators and other appliances. Honeywell is using powder coatings to coat portable, air-blown humidifiers where wicks soak up water, often a breeding ground for germs.

 

Paint and powder coating suppliers have also increased their research and production of antimicrobial products in the last few years. DuPont, for example, has aggressively marketed Alesta AM, a powder coating formulated with antimicrobial additives that are allowed in food preparation areas by the FDA. PPG and The Sherwin-Williams Company also have lines of germ-fighting coatings.

 

“The long-term performance of the coating will depend to some extent on the cleaning methods, materials and frequency employed in service,” says Tom Jeffers, New Technology Group Leader, DuPont Industrial CoatingSolutions’ Powder Coatings Group

 

“The antimicrobial efficacy has been maximized by the uniform distribution of the inorganic silver through the coated film,” he says.

 

Sherwin-Williams Chemical Coatings now offers seven new coating products infused with antimicrobial protection, including select Polane, Powdura and Kem Aqua. BASF Corporation introduced Irgaguard as an inorganic silver glass/zeolite based antimicrobial coating that can be processed at temperatures >500°C.

 

The Global Industry Analysts report says antimicrobial products were one of the fastest growing segments of the coating industry in a slumping economy.

 

“The medical devices segment is all set to witness an impressive growth over the years. Factors such as increasing number of hospital acquired infection cases and Centers for Medicare and Medicaid adjusting their coverage policies are encouraging greater use of antimicrobial coated medical devices,” the report says.

 

The U.S. antimicrobial coatings market was not affected by the worldwide economic recession and continued to display strong, double-digit growth even during the turbulent period of 2008-09, GIA reports. It also helped that media coverage of the deadly H1N1 flu outbreak and other such infections played a major role in sustaining demand for antimicrobial-coated products.

 

“Over the near term, the market for antimicrobial coatings is poised for a bright future,” the GIA report says. “Major end-use markets such as medical, household care and food processing are all growing at a robust pace, mainly driven by the need for enhanced sanitary facilities.”

 

That’s good news to OEMs and to paint and powder coatings suppliers who could see a big jump in their product lines.

 

“These new finishes are an important tool in preventing the growth of microbes in or on commercial and consumer products such as HVAC systems, food service equipment, refrigerators and humidifiers, for use in hospitals, commercial buildings and homes,” says Paul Ford, CEO of Sciessent, maker of Agion branded antimicrobial technology, one of the leading manufacturers of antimicrobial coatings additives and a partner with many large coating companies.

 

Neither the FDA nor the EPA has signaled impending requirements for antimicrobial coatings, but the trend is almost there, say some researchers.

 

“While it is not a good idea to coat our entire world with antimicrobial substances, we are looking for any help we can get in eliminating microbes,” says Marjorie Kelly Cowan, Ph.D., a professor of microbiology at Miami University in Ohio who has done extensive research in antimicrobial coatings.

 

Sciessent’s Agion antimicrobial technology has been used extensively in healthcare related products. The active ingredient is silver, which is recognized for its broad spectrum efficacy, has a long history of success in medical devices, and its inorganic carrier material that provides stability and versatility when incorporated into materials and manufacturing processes.

 

The company’s partners include Akno Nobel, BASF, DuPont, PPG and Sherwin-Williams, as well as consumer goods giants such as adidas, Office Depot, Dell, Motorola and dozens of others.

 

Ford says it is constantly working with partners on new applications, especially coated products that go in homes.

 

“Agion’s advanced features allowed one of the largest door hardware manufacturers to incorporate the technology into several of their major brand lines of door security hardware,” Ford says.

 

The company says its antimicrobial solution is an inorganic compound of elemental silver, ionically bound to a bio-inert silver-based zeolite. The delivery system ensures the regulated slow release of silver ions, thereby ensuring long-term protection against bacteria build-up on the surface. The release of silver ions is immediate upon contact with fluid and, unlike silver salts, does not depend on chemical reaction, Ford says.

 

Silver ions attack multiple targets in the microbe to prevent it from growing to a destructive population. This tri-modal action fights cell growth in three ways: prevents respiration by inhibiting transport functions in the cell wall; inhibits cell division (reproduction); and disrupts cell metabolism.

 

To create an antimicrobial protected surface for the door handles, Sciessent incorporated its technology into the specific coatings, in

 

this case a powder coat. The coating was developed to provide long lasting protection, with high efficacy. In some instances, their technology is integrated directly into polymers, but that is largely driven by the end customer’s requirements, Ford says.

 

Once coated, the surface of the door hardware is protected from bacterial colonization by an array of particles at the surface of the part. The silver ion release mechanism is activated in the event of bacterial activity on the device. Ford says this generally occurs via some fluid coming in contact with the device, such as sweat or blood through hand contact, or a cough or sneeze droplet landing on the device’s surface. As the coating wears through the years, new particles are exposed and remain ready to be released.

 

“The process works by harnessing the natural antimicrobial properties of silver,” Ford says. “While there are several types of silver-based antimicrobials, all work by releasing silver ions. Therefore, the technical challenge is to modulate the release kinetics to fit the environment and the performance requirements.”

 

Agion accomplishes this by using a controlled-release technology that limits the delivery of silver unless the environment for bacterial growth—moisture and nutrients—exist. Therefore no loss of the activity exists when the product is in storage or is not in contact with blood or other bodily fluids that often carry contaminants.

 

“Even when silver is being released, a very low concentration in parts per billion is reached, which is precisely the concentration range at which bacterial growth begins to be inhibited,” Ford says.

 

Bacteria are affected by silver through various mechanisms. Silver interacts with enzymes that are fundamental to the cell’s metabolisms and renders them inactive, which effectively starves or suffocates the cell. In addition, silver can impact transport of nutrients across the cell wall and interrupt cell division.

 

Ford says these mechanisms—and the low concentration required—make silver the most effective antimicrobial compound that can be incorporated into plastics and coatings.

 

“Consumers have never been more ready to embrace antimicrobial products,” he says.