A laser prepares to texture the surface of copper, enhancing its antimicrobial properties. Photo: Purdue University photo/Kayla Wiles.
A laser prepares to texture the surface of copper, enhancing its antimicrobial properties. Photo: Purdue University photo/Kayla Wiles.

Bacterial pathogens can live on surfaces for days. But what if frequently touched surfaces such as doorknobs could instantly kill them off? Engineers at Purdue University have now created a laser treatment technique that could potentially turn any metal surface into a rapid bacteria killer – just by giving the metal's surface a different texture.

In a paper in Advanced Materials Interfaces, the researchers demonstrate that their technique allows the surface of copper to immediately kill off superbugs such as MRSA.

"Copper has been used as an antimicrobial material for centuries. But it typically takes hours for native copper surfaces to kill off bacteria," said Rahim Rahimi, an assistant professor of materials engineering at Purdue University. "We developed a one-step laser-texturing technique that effectively enhances the bacteria-killing properties of copper's surface."

The technique is not yet tailored to kill viruses such as the one responsible for the COVID-19 pandemic, which are much smaller than bacteria. Since publishing its work, however, Rahimi's team has begun testing this technology on the surfaces of other metals and polymers that are used to reduce the risk of bacterial growth and biofilm formation on devices such as orthopedic implants or wearable patches for chronic wounds.

Giving implants an antimicrobial surface would help prevent the spread of infection and antibiotic resistance, Rahimi said, because there wouldn't be a need for antibiotics to kill off bacteria from an implant's surface. The technique might also apply to metallic alloys that are known to have antimicrobial properties.

Metals such as copper normally have a really smooth surface, which makes it difficult for the metal to kill bacteria by contact. The technique developed by Rahimi's team uses a laser to create nanoscale patterns on the metal's surface. These patterns produce a rugged texture that increases the surface area, giving more opportunity for bacteria to hit the surface and rupture on the spot.

Researchers in the past have used various nanomaterial coatings to enhance the antimicrobial properties of metal surfaces, but these coatings are prone to leaching off and can be toxic to the environment. "We've created a robust process that selectively generates micron and nanoscale patterns directly onto the targeted surface without altering the bulk of the copper material," said Rahimi, whose lab develops innovative materials and biomedical devices to address healthcare challenges.

The laser-texturing has a dual effect: it not only improves direct contact, but also makes the surface more hydrophilic. For orthopedic implants, such a surface can allow bone cells to attach more strongly, improving how well the implant integrates with bone. Rahimi's team observed this effect with fibroblast cells.

Due to the simplicity and scalability of the technique, the researchers believe that it could easily be translated into existing medical device manufacturing processes.

This story is adapted from material from Purdue University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.