Orthopedic implant infections and device failure pose significant challenges, affecting up to 10% of patients. Existing approaches to combat infections have significant drawbacks, as biofilms can form on water-repellent surfaces and antibiotic-laden coatings have toxic effects on surrounding tissue with limited efficacy against drug-resistant bacteria. Now, newly-developed "smart" coatings for orthopedic implants can provide early warnings of device failure while eliminating infection-causing bacteria.

A multidisciplinary team of researchers at the University of Illinois Urbana-Champaign (Champaign, IL, USA) has created coatings that integrate flexible sensors with a nanostructured antibacterial surface, inspired by the wings of dragonflies and cicadas. These smart coatings feature bacteria-destroying nanopillars on one side and strain-mapping flexible electronics on the other, which could help physicians monitor patient rehabilitation and address device issues before failure occurs. The team's study showed successful infection prevention in live mice and the ability to provide early warnings of implant or healing failures in sheep spine experiments.

The team developed a thin foil, patterned with nanoscale pillars resembling those on cicada and dragonfly wings, which effectively puncture and kill bacterial cells attempting to bind to the foil. Flexible electronic sensors were integrated on the back side of the foil to monitor strain, helping physicians to track patient healing, optimize rehabilitation, and identify device issues before failure occurs.

To evaluate their prototypes, the researchers implanted the foils in live mice and observed no signs of infection even when bacteria were introduced. Additionally, they applied the coatings to commercial spinal implants in sheep spines and successfully monitored strain for device failure diagnosis. The current prototypes rely on wired electronics; however, the researchers plan to develop wireless power and data communication interfaces for clinical use. They are also working on scaling up production of the bacteria-killing nanopillar-textured foil.

“This is a combination of bio-inspired nanomaterial design with flexible electronics to battle a complicated, long-term biomedical problem,” said study leader Qing Cao, a U. of I. professor of materials science and engineering. “These types of antibacterial coatings have a lot of potential applications, and since ours uses a mechanical mechanism, it has potential for places where chemicals or heavy metal ions – as are used in commercial antimicrobial coatings now – would be detrimental.”

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