Charge-Switchable Nanozymes for Bioorthogonal Imaging of Biofilm-Associated Infections.

Early detection of biofilms is crucial for limiting infection-based damage. Imaging these biofilms is challenging: conventional imaging agents are unable to penetrate the dense matrix of the biofilm, and many imaging agents are susceptible to false positive/negative responses due to phenotypical mutations of the constituent microbes. We report the creation of pH-responsive nanoparticles with embedded transition metal catalysts (nanozymes) that effectively target the acidic microenvironment of biofilms. These pH-switchable nanozymes generate imaging agents through bioorthogonal activation of profluorophores inside biofilms. The specificity of these nanozymes for imaging biofilms in complex biosystems was demonstrated using coculture experiments.