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3D-printed parts that kill dangerous bacteria could stop spread of MRSA

Professional Engineering

The 3D-printed parts were effective against Pseudomonas aeruginosa bacteria (in purple) (Credit: University of Sheffield)
The 3D-printed parts were effective against Pseudomonas aeruginosa bacteria (in purple) (Credit: University of Sheffield)

3D-printed parts have killed dangerous bacteria, leading to the possibility of printed items that protect the lives of vulnerable patients in hospitals and care homes.

Objects built using the technique could stop the spread of infections such as MRSA, said researchers from the University of Sheffield.

A team from the department of mechanical engineering and the school of clinical dentistry built the parts, which combined 3D printing with a silver-based antibacterial compound. Results showed the compound had no negative influence on material processing or part strength. Under the right conditions, the parts demonstrated anti-bacterial properties without being toxic to human cells.

The findings could be useful in a wide range of areas including medical devices, frequently-touched hospital parts, door handles, children’s toys, dentures and consumer products such as mobile phone cases. Further projects are planned in each of these areas, and the researchers hope to work with industry leaders to bring some products to market.

“Managing the spread of harmful bacteria, infection and the increasing resistance to antibiotics is a global concern. Introducing antibacterial protection to products and devices at the point of manufacture could be an essential tool in this fight,” said project leader Dr Candice Majewski from Sheffield’s Centre for Advanced Additive Manufacturing.

“Most current 3D-printed products don’t have additional functionality. Adding antibacterial properties at the manufacturing stage will provide a step-change in our utilisation of the processes’ capabilities.”

Medical devices are often already coated with antibacterial compounds and are subject to strict cleaning and sterilisation procedures. While this provides a certain level of protection, the process has limitations such as human error in cleaning or damage occurring to the coating.

Geometric parts such as cubes, spheres and 'dog bones' were printed with and without the antibacterial additive and then submerged in various bacterial solutions to test how many bacteria remained after 24 hours. The research announcement said parts containing the additive were “effective” against examples of the two main groups of bacteria, Gram positive (Staphylococcus aureus) and Gram negative (Pseudomonas aeruginosa), both of which can cause many different types of infection. MRSA is an antibiotic-resistant version of Staphylococcus aureus.

Dr Majewski told Professional Engineering: "We couldn't say our approach killed all the bacteria, but it's fair to say that we see a significant reduction in bacteria with our approach, when considering conditions representative of partially-hydrated surfaces we might find in a kitchen or bathroom environment, or in some clinical or semi-clinical settings."

The modified parts also reduced the number of bacteria stuck to the surfaces. Bacteria form ‘biofilms’ that are often difficult to remove but an anti-biofilm effect was observed due to bacteria dying before they could stick to the parts. Parts worked less well in liquid containing lots of nutrients, which interfered with the silver before it could do its job. This will help determine which environments the technology could be used in. Parts were also tested with human cells and found to have no toxicity.

“Our interactions with microbes are complex and contradictory – they’re essential to our survival and they can knock us dead. Technology like this will be key to informed and sustainable management of this crucial relationship with nature,” said Dr Bob Turner, from the Sheffield department of computer science.  

The research was funded by the Engineering and Physical Sciences Research Council.

The work was published in Scientific Reports.

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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.

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