Nanotechnology takes on the fight against antibiotic-resistant bacteria

Professor Ken Welch and doctoral student Oscar Jansson illuminate titanium surfaces with UV light at the Ångström Laboratory.

With every implant operation we run the risk of contracting an infection. Bacteria we normally live in symbiosis with can suddenly pose a threat to our health. In order to tackle the problems with infections and antibiotic-resistant bacteria, newly appointed professor Ken Welch uses nanotechnology and functional materials.

In Sweden tens of thousands of people undergo implant surgery every year. For the most part, the implants work well. But in 1 per cent of hip or knee implants and up to 10 per cent of dental implants, complications arise. The cause is bacteria – including those that are resistant to antibiotics. These numbers may not sound so dramatic, but the problem is growing due to the increasing number of implants, says Ken Welch at the Department of Engineering Sciences. He heads a research group focused on developing new effective strategies to combat implant-related infections.

“New implants are constantly being produced, including new varieties of everything from knee and hip replacements to lens and dental implants, catheters and pacemakers. But more implants can also lead to more infections. Not only do infections cause great suffering for the individual but they also result in very high costs to society,” explains Ken Welch.

In addition, some bacterial infections can only be treated with one or two types of antibiotics. Doctors avoid using these antibiotics unless absolutely necessary: if bacteria develop resistance to these forms of antibiotics, there are no other alternatives left. Perhaps the biggest challenge is to find technologies that can combat these antibiotic-resistant bacteria. We also need to develop new antibiotics and smarter ways to administer them, adds Ken Welch.

Antibiotics at the implant surface

One of these smart ways for combatting infections that Ken Welch is focusing on in his research is developing coatings for implants that can be loaded with antibiotics. When antibiotics are applied directly at the implant surface, significantly smaller amounts of antibiotics are required. Another benefit is the increased concentration of antibiotics where it is most needed. The downside is that the effect only lasts for a limited time - when the antibiotics are released from the surface, no more antibiotics can be added, he explains.

 “Also, there’s a large risk of bacterial contamination at the time of implant surgery. It's very difficult to make the area sterile enough to be completely free of all bacteria. In and around our body alone, we have ten times as many bacteria as we have cells in our body. With most of them, we live in symbiosis. But if the bacteria end up in places where they ought not to be, such as on implants in our body, then we’ve got a problem.”

Another one of his research focuses is a technique where silver is added to the surface of an implant. This results in the release of silver ions, known for their antibacterial properties. Silver is, for example, found in some adhesive bandages for wounds and even sold as health supplements in the form of colloidal silver. But because of the health risks associated with the use of silver, more studies of the metal's toxic properties will be required before this technology can be used on patients, according to Ken Welch.

Photocatalysis knocks out bacteria

When the titanium dioxide coating is illumunated,
a chemical reaction is triggered.

His research group is also working on a third technique for combatting implant-related infections in which the implant is coated with a photocatalytic surface. A material often used for implants is titanium, which bone can easily bind to. Ken Welch and his colleagues have developed a titanium dioxide coating with a crystalline structure. When the coating is illuminated, a chemical reaction is triggered.

“At this point, small reactive oxygen compounds are formed that oxidize adherent organic material, which effectively means that they burn off clusters of bacteria from the implant surface,” says Ken Welch. “This photocatalytic technique can be used to treat infections on implant surfaces that we can directly illuminate, for example on skin-penetrating implants.”

At the Department of Nanotechnology and Functional Materials, as well as the rest of the Ångström Laboratory, the research team has access to the instruments and tools needed to produce their materials. But despite several collaborations across campus, he would like to create even wider contact networks.

“When you’re dealing with the body, it’s incredibly important as a materials scientist to understand the problem from the clinical perspective,” says Ken Welch. He adds:

“My next goal is to take a big step closer to the clinical use of these antibacterial techniques related to implants. I intend to do so by making even more contacts and start collaborations with, for example, specialists in infectious diseases at the Uppsala University Hospital. They understand the need and can help us develop the right type of techniques.”


Find out more:

Contact information Ken Welch

Link to Ken Welch’s installation lecture

Read more about Uppsala University's research in nanotechnology and functional materials


6 February 2017