Newly developed “smart” coatings for surgical orthopedic implants can monitor stress on the devices to provide early warning of implant failure while killing infection-causing bacteria, report researchers at the University of Illinois Urbana-Champaign. The coatings integrate flexible sensors with a nanostructured antibacterial surface inspired by the wings of dragonflies and cicadas.
In a new study in the journal Progress of sciencea multidisciplinary team of researchers found that the coatings prevented infection in live mice and mapped the stress on commercial implants applied to sheep’s spines to warn of multiple implants or failure to heal.
“This is a combination of bioinspired nanomaterial design with flexible electronics to combat a complicated long-term biomedical problem,” said study leader Qing Cao, a U. of I professor of materials science and engineering.
Both infection and device failure are major problems with orthopedic implants, each affecting up to 10% of patients, Cao said. Various approaches have been tried to fight infection, but all have serious limitations, he said: Biofilms can still form on surfaces that repel water, and coatings laden with chemical antibiotics or drugs wear out within months and have toxic effects. around. tissue with poor efficacy against drug-resistant strains of bacterial pathogens.
Taking inspiration from the naturally antibacterial wings of cicadas and dragonflies, the Illinois team created a thin sheet patterned with nanoscale pillars like those found on insect wings. When a bacterial cell attempts to attach itself to the lamina, the pillars pierce the cell wall, killing it.
“Using a mechanical approach to kill bacteria allowed us to avoid many of the problems with chemical approaches, while giving us the flexibility to apply the coating to implant surfaces,” said Professor of Pathobiology Gee Lau. , co-author of the study.
On the back of the nanostructured sheet, where it comes into contact with the implant device, the researchers integrated highly sensitive, flexible electronic sensor arrays to monitor tension. This could help doctors monitor the healing progress of individual patients, guide their rehabilitation to shorten recovery time and minimize risks, and repair or replace devices before they reach the point of failure, the researchers said.
The engineering group then partnered with Professor of Veterinary Clinical Medicine Annette McCoy to test their prototype devices. They implanted the sheets into live mice and monitored them for any signs of infection, even when bacteria were introduced. They also applied the coatings to commercially available spinal implants and monitored the stress of the implants in sheep spinal cords under normal load to diagnose device failure. The liners performed both functions well.
The prototype electronics required cables, but the researchers plan to develop wireless power and data communication interfaces for their coatings, a crucial step for clinical application, Cao said. They are also working to develop large-scale production of the nanopillar-textured bacteria-removing sheet.
“These types of antibacterial coatings have many potential applications, and since ours uses a mechanical mechanism, it has potential for locations where chemicals or heavy metal ions, as now used in commercial antimicrobial coatings, would be detrimental.” Cao said. saying.
The National Science Foundation and the US Congressionally Directed Medical Research Programs supported this work.
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