Materials
or partially ionised gas, that produces chemical reactions to change the properties at the material surface. Nikiforov and his colleagues have developed three different ways to manipulate the make-up of materials to either prevent bacteria from sticking to them (antifouling), or kill it instantly on contact (bactericidal). Anti-fouling materials prevent microorganisms from accumulating on surfaces to form biofilms and other dangerous microbial environments. “A typical example would be coatings based on fluorine-containing functional groups, similar to Teflon, that mean liquids cannot stick to the material,” Nikiforov explains.
Plasma technology uses the direct interaction between microorganisms and surfaces to kill bacteria immediately or prevent it from sticking.
increase in antimicrobial resistance and hospital- acquired infections. More than 2.8 million antibiotic- resistant infections occur in the US each year and more than 35,000 people die as a result. Meanwhile a 2021 study by researchers with the Centres for Disease Control and Prevention (CDC) showed that, after years of decline, US hospitals saw significant increases in healthcare-associated infections (HAIs) in 2020, driven largely by the Covid-19 pandemic.
The technology being developed by Nikiforov and his colleagues at the University of Ghent, in collaboration with research groups in the Czech Republic, Italy, Slovenia and Romania, differs from existing methods used to create biocidal materials in two important ways. “In general, these types of materials are produced by mixing a number of chemicals with your solvents, so you are using really heavy chemistry. Typically, it’s not a very green process, and it’s slow and expensive,” Nikiforov explains. “In addition, those techniques are typically substrate-dependent, so you can make them for one polymer but not for another.” Plasma technology, on the other hand, uses a limited number of chemicals in extremely small quantities and can be used for many different types of materials. “With the same technology we use to make coating on polymers, we can move to fibres, metals, glass, any kind of substrates. This is very interesting for the healthcare industry. They can start with one process and easily scale it up or modify it to be applied to another.”
How does it work?
The technology behind plasma-based surface engineering relies on nonequilibrium plasma,
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The bactericidal system on the other hand destroys microorganisms on contact by puncturing them with microscopic spikes. “Bacteria are basically killed by touching the material,” Nikiforov says. “You make some very tiny nano-scale needles on the surface and when bacteria stick to them, they penetrate the membrane and kill it.” The last technology, and Nikiforov’s favourite, combines anti-fouling with drug release. “Typically, we use different nanoparticles of copper or silver. When bacteria touches the surface, small quantities are released from the surface and can penetrate and kill bacteria. We are trying to develop this for different materials, including instruments and masks, which are often used in hospitals.”
Performance and toxicity In the lab at Ghent University, Nikiforov and his colleagues haven’t reached a level of industrial application for their technologies yet, but they are treating up to a few metres squared worth of materials. The next step is to bring in engineers with ideas on how to scale them up. “It is very demanding, not only to understand the physics, but to know how to control it. If you move to industrial level, you need to run it every single day,” Nikiforov explains. In addition to controlling the performance of the factory line, the team need more help from safety and bioengineering experts. “You can combine single nanoparticles and integrate them in a coating and it will be antibacterial. But that antibacterial coating could also be very toxic,” Nikiforov says. “The point for us is to find not only engineering skills and engineering partners to make machines bigger but also to find people who are very knowledgeable in the interaction of materials with bacteria and cells to be sure that our antibacterial coatings are purely antibacterial and not toxic.”
Even to reach the point the researchers are currently at has required a massive team effort. “You need chemists, people who are working in physics like me, people working on the engineering side, people working on the biological side. For such
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