Researchers at the University of Pennsylvania have developed nanorobots that can travel to the site of a fungal infection under the influence of an external magnetic field, bind to the fungal cells, and then release reactive oxygen species to completely destroy the fungus. The tiny particles are an example of catalytic nanoparticles, which the researchers have dubbed ‘nanozymes’. Made using iron oxide, they are maneuverable under the influence of magnet fields, allowing the researchers to localize them in a specific part of the body. In tests so far, the nanorobots have been shown to destroy fungal biofilms, which are particularly difficult to treat using conventional anti-fungal drugs.
Fungal infections can be a major challenge, particularly if the infective fungus forms a thick biofilm which conventional anti-fungal drugs can struggle to penetrate. “Candidae forms tenacious biofilm infections that are particularly hard to treat,” said Hyun Koo, a researcher involved in the study. “Current antifungal therapies lack the potency and specificity required to quickly and effectively eliminate these pathogens, so this collaboration draws from our clinical knowledge and combines Ed’s team [Edward Steager of Penn’s School of Engineering and Applied Science] and their robotic expertise to offer a new approach.”
The picture above shows a before (left) and after (right) fluorescence image of fungal biofilms being precisely targeted by nanozyme microrobots without bonding to or disturbing the tissue sample. (Image: Min Jun Oh and Seokyoung Yoon)
The tiny structures consist of iron oxide nanoparticles that can be tightly controlled using external magnetic fields. “The methods we use to control the nanoparticles in this study are magnetic, which allows us to direct them to the exact infection location,” said Steager. “We use iron oxide nanoparticles, which have another important property, namely that they’re catalytic.”
These catalytic properties are reminiscent of the enzyme peroxidase, which has a role in helping to break down hydrogen peroxide into water and oxygen. However, this also results in the creation of large amounts of reactive oxygen species, which can rapidly damage and destroy living cells in their vicinity. This is the mechanism of action through which the nanorobots can destroy fungal biofilms.
However, the nanorobots also possess another unexpected property which greatly assists them in their quest to destroy these biofilms. They appear to be highly attracted to fungal cells and will bind tightly within such biofilms, and show less affinity for human cells, greatly enhancing their specificity and safety profile.
“Our nanozyme assemblies show an incredible attraction to fungal cells, particularly when compared to human cells,” said Steager. “This specific binding interaction paves the way for a potent and concentrated antifungal effect without affecting other uninfected areas.”
Study in Advanced Materials: Nanozyme‐based robotics approach for targeting fungal infection