Abstract
Magnetically driven catalytic antimicrobial robots eliminate biofilms precisely via a synergistic “kill-degrade-remove” mechanism.
Magnetically driven robots can perform complex functions in biological settings with minimal destruction. However, robots designed to damage deleterious biostructures may also be useful. Biofilms are intractable, firmly attached structures associated with drug-resistant infections and surface destruction. We designed catalytic antimicrobial robots (CARs) that precisely, efficiently, and controllably killed, degraded, and removed biofilms. CARs exploiting iron oxide nanoparticles (NPs) with dual catalytic-magnetic functionality (i) generated bactericidal free radicals, (ii) broke down the biofilm exopolysaccharide (EPS) matrix, and (iii) removed the fragmented biofilm debris via magnetic field–driven robotic assemblies. We developed two distinct CAR platforms. The biohybrid CAR platform was formed from NPs and biofilm degradation products. After catalytic bacterial killing and EPS disruption, magnetic field gradients assembled NPs and the biodegraded products into a plow-like superstructure. When driven with an external magnetic field, the biohybrid CAR completely removed biomass in a controlled manner, preventing biofilm regrowth. Biohybrid CARs could be swept over broad swathes of surface or moved over well-defined paths for localized removal with microscale precision. The 3D molded CAR platform is a polymeric soft robot with embedded catalytic-magnetic NPs, formed in a customized 3D-printed mold to perform specific tasks in enclosed domains. Vane-shaped CARs remove biofilms from curved walls of cylindrical tubes, and helicoid-shaped CARs drill through biofilm clogs while simultaneously killing bacteria. We demonstrate applications of CARs to target highly confined anatomical surfaces in the interior of human teeth. These “kill-degrade-and-remove” CARs systems may fight persistent biofilm infections and mitigate biofouling of medical devices and diverse surfaces.