Researchers have developed microparticles that can penetrate stubborn bacterial matrices and release tiny oxygen bubbles to remove biofilms from surgical instruments and infected wounds.
They believe their innovation can clean surfaces and wounds more efficiently than hydrogen peroxide or other cleaning agents alone.
In two papers, the team demonstrated the effectiveness of the bubble-generating particles in removing tenacious biofilms from surgical instruments and, when embedded in bandages, in cleaning infected wounds and accelerating healing.
Chemical and biomolecular engineering professor Hyunjoon Kong, the research team’s leader at the University of Illinois Urbana-Champaign, said: ‘Biofilms are a dense matrix of bacterial cells and proteins. While sterilising agents can kill bacteria, the matrix protects them, making it much harder to treat or clean with chemicals.
For example, hydrogen peroxide has been used for centuries, but it only cleanses the surface and does not penetrate the film. We take a mechanical approach: Our particles infiltrate the biofilm first and then generate bubbles inside the matrix, disrupting it.’
Kong’s group developed tiny cylinders made of biosilica coated in manganese dioxide, a catalyst which releases tiny oxygen bubbles when exposed to a hydrogen peroxide solution.
The bubbles accumulate within the hollow cylinder, then are released, propelling the microparticles even deeper into the matrix where they continue to produce bubbles, said graduate student Joo Hun Lee, the first author of the first paper.
The researchers watched the bubbles form and rupture, the particles move, and the biofilm disperse using high-speed cameras.
In addition to describing the microparticles in the first paper, published in ACS Applied Materials and Interfaces, the researchers demonstrated their ability to remove stubborn biofilms from surgical instruments.
The Illinois team compared the biofilms remaining within the serrations of surgical instruments after the standard protocol with those remaining after treatment with microparticles. They found that the microparticles were at least as effective as the standard protocol. As an added benefit, microparticle cleaning can be combined with autoclaving, Kong said.
In the second paper, published in the journal Advanced Science, the researchers embedded microparticles in bandages to treat persistent wounds, another site where biofilms frequently form.
The researchers embedded the microparticles in the bandages beneath a mesh that steadily releases hydrogen peroxide, thereby activating the particles. They called the bandage assembly a ‘microblasting wound dressing’ because it localises microbubble generation at the wound site, continually blasting the wound surface with tiny scrubbing bubbles, said postdoctoral researcher Yujin Ahn, the first author of the paper.
As with the surgical instruments, the microparticles and the bubbles they produced dislodged complex biofilms from the wound surface.
The researchers now plan to evaluate their microparticle technology for cleaning surgical endoscopes, addressing the challenges of cleaning complex internal surfaces.
They have also obtained a patent for the bubble-generating microparticle technology and are collaborating with partners to explore manufacturing at larger scales.
