A revolutionary technology employing gold nanorods heated by near-infrared light, developed at Chalmers University of Technology, promises to effectively sterilize medical implants and combat antibiotic resistance.
In a monumental step towards combating antibiotic-resistant infections, researchers at Chalmers University of Technology have introduced an innovative method to sterilize medical implants using gold nanorods and near-infrared (NIR) light. This groundbreaking technique could drastically reduce the incidence of infections related to surgical implants, such as hip and knee replacements.
Infections related to surgical procedures involving implants pose a significant health risk, often requiring high doses of antibiotics for prolonged periods, which can contribute to the global issue of antibiotic resistance. Recognizing this challenge, the team at Chalmers University devised a method where tiny gold rods attached to the implant surface are heated using NIR light, thereby eliminating bacteria without affecting the surrounding tissues.
“The gold rods absorb the light, the electrons in the gold are set in motion, and finally the nanorods emit heat. You could say that the gold nanorods work like small frying pans that fry the bacteria to death,” lead author Maja Uusitalo, a doctoral student at Chalmers, said in a news release.
The innovative use of NIR light is key to this method’s success. NIR light can penetrate human tissue, enabling the heating of gold nanorods embedded in implants beneath the skin surface. This controlled heating is both precise and localized, ensuring that only the bacteria on the implant are targeted, minimizing potential harm to human cells.
“The trick is to tailor the size of the rods. If you make them a little smaller or a little bigger, they absorb light of the wrong wavelengths. We want the light that is absorbed to penetrate skin and tissue well. Because once the implant is inside the body, the light must be able to reach the surface of the prosthesis,” corresponding author Martin Andersson, a professor of applied chemistry and research leader at Chalmers, said in the news release.
To understand how the gold nanorods’ temperature can be measured and regulated, the researchers utilized X-rays to observe the movement of gold atoms. The precision of this measurement is vital to ensure the rods do not exceed 120 degrees Celsius, beyond which they lose shape and efficacy.
“The temperature must not exceed 120 degrees Celsius, as higher temperatures cause the nanorods to lose their shape and transform into spheres. As a result, they lose their optical properties and can no longer absorb NIR light effectively, which prevents the rods from heating up,” added Uusitalo, while emphasizing the importance of localized heating to avoid damaging nearby tissues.
Importantly, this technology is highly adaptable and could potentially be applied to various implant materials, including titanium and specific plastics. The gold nanorods remain inactive until illuminated with NIR light, at which point they become hot and exhibit antibacterial properties. This control allows for an antibacterial effect post-surgery, with minimal impact on the healing process.
“We primarily believe in using NIR light for heating shortly after the implant is placed and the wound is sutured. By heating up the gold nanorods, we can eliminate any bacteria that may have settled on the prosthesis during surgery,” Andersson added.
The study is published in Nano Letters.
The application of this technology in health care could mark a significant shift in the management and prevention of postoperative infections, potentially reducing dependence on antibiotics and mitigating the rise of antibiotic-resistant bacteria.
While ordinary cells can also be damaged during treatment, Andersson emphasized the body’s rapid regeneration capabilities to mitigate this effect.
The research underscores a significant advancement in medical technology, paving the way for safer and more efficient surgical interventions.