RALEIGH, NC—A North Carolina State University (NCSU) engineer has spearheaded groundbreaking research considered a milestone achievement in fighting post-surgical infections.
Rohan Shirwaiker, PhD, an assistant professor and adjunct assistant professor of biomedical engineering for the NCSU Department of Industrial and Systems Engineering (ISE), led a research team to develop and test battery-activated nanotechnology built directly into orthopedic implants to stave off microscopic, infection-causing pathogens, including antibiotic-resistant bacteria such as MRSA.
“Silver has long been known for its anti-bacterial properties, but first it must ionize to be effective,” explained Shirwaiker, who has been engaged in research on the project since 2007, when it became his doctoral theme at Penn State University. “Understanding how this work could be effectively improved for medical devices, especially implants, hadn’t been explored much from an engineering standpoint. The breakthrough was in demonstrating that a little electric current to the silver on the implant releases the ion particles, which attach to bacteria cells and either kill them or prevent them from replicating.”
Here’s how it works: The power source, similar to a watch battery, is integrated into the joint implant design. A low-intensity electrical charge to a silver-titanium implant releases low-toxicity silver ions to kill or neutralize bacteria. The body’s own fluids serve as a conducting medium between battery and silver, enabling the low-level charge.
“It was very exciting when we showed how the electrical activation of silver significantly enhances the antimicrobial efficacy connected to the implant,” he said, “and when I say significantly, I mean quite significantly.”
Research showed a 99 percent decrease in bacteria growth on and around implants after 24 hours, and an infection-free environment after 48 hours.
The son of a retired pharmacist, and a native of Mumbai (Bombay), India, Shirwaiker completed his master’s degree in engineering at Penn State University, while concurrently interning with Harley Davidson making motorcycles. “A great experience,” he called the internship. “I really enjoyed it. But when I was searching for a research project for my PhD, I was fascinated by the biomedical world, and started collaborating with orthopedic surgeons.”
Shirwaiker, 31, named the American Academy of Orthopaedic Surgeons’ (AAOS) Best Young Investigator in 2014, is also exploring the development of a smartphone app to control the power source and the release of silver ions remotely, and track the biophysical activity around the implant area.
“It’s quite exciting work,” said Shirwaiker. “The possibilities to improve the patient experience are endless.”
With more than 1 million joint replacement surgeries performed annually in the United States, Shirwaiker’s innovation in silver microbial technology has the potential to save significant healthcare sums while allaying treatment costs for post-surgical infections (now topping $1.6 billion annually) and also boosting patient outcomes.
“A few years ago, a study predicted that by 2020, the number of knee replacements would increase six-fold,” he said. “Similarly, cases of infection could dramatically increase.”
Shirwaiker’s research extends to the development and characterization of 3D-bioprinting processes for knee joint tissues and the trachea. His work also includes similar projects with the University of North Carolina (UNC)-NCSU Joint Department of Biomedical Engineering.
“I’m heavily involved in some of the 3-D printing aspects of medical projects, especially tissues of the knee joint,” said Shirwaiker. “There will be a point when these types of implants, combined with live cells and silver microbial technology to fight infections, won’t even show up on x-rays a few years down the road because tissues will have formed around them and the body will have absorbed them.”
Shirwaiker, whose 9-member research team includes PhD candidates, graduate students and undergraduates, said groundbreaking research will translate to commercial success with total collaboration from invested parties.
“When you really have contributions from doctors, surgeons and biomedical engineers,” he said, “that’s truly when things are going to start working very well.”
LINKS:
- Journal of the American Academy of Orthopaedic Surgeons (Musculoskeletal Infections Supplement), “A clinical perspective on musculoskeletal infection treatment strategies and challenges”: http://www.jaaos.org/content/23/supplement/S44.full.pdf+html?sid=19993497-87e7-40d6-bb5f-2890f6fea0e2
- North Carolina State University ISE: www.ise.ncsu.edu