Targeted Biofilm Treatment Using Magnetic Microcapsule Collectives

Objectives: Oral biofilm infections in hard-to-reach sites remain an unresolved challenge requiring new antibiofilm approaches to enhance on-site drug delivery and killing efficacy. Microrobots offer a promising solution with their unique navigational and precision targeting abilities. However, they face constraints in mobility, payload and controlled drug release in complex biological environments. In this study, we report on a new robotic platform using magnetic microcapsules loaded with different drugs for precise targeted treatment by leveraging the coordinated behavior of these microcapsules.
Methods: Robotic microcapsules are fabricated through water-in-oil-in-water double emulsions using droplet microfluidics and iron oxide nanoparticles dispersed in the oil phase to create microcapsules with a liquid core surrounded by a nanoparticle shell. The mobility and dynamics of these magnetic microcapsules are studied using a three-axis Helmholtz coil control system, generating multi-unit microcapsule collectives with varying motion dynamics governed by directed magnetic fields.
Results: Our findings show that therapeutics-loaded robotic microcapsules display controllable and complex motion dynamics including rolling, climbing and rotation through external magnetic field modulation. Unexpectedly, these microcapsules create well defined clusters through local magnetic dipole–dipole interactions. The balance between these interactions can be adjusted based on the applied magnetic field, enabling microcapsules to form organized collectives, which improves their speed, directionality, and surface group-mobility to navigate obstacles. These microcapsules can efficiently overcome physical barriers like climbing walls and translocate over complex tissue topographies to reach biofilm infection sites.
Conclusions: We developed a novel therapeutic microrobotic system using microcapsules to enhance loading capacity and cargo protection and form dynamic collectives to navigate through physical and biological barriers to target biofilms. Our design integrates programmable assembly, propulsion, and microcapsule swarm behaviors via magnetic interactions to achieve ordered, synchronized robotic assemblies for environmental exploration and navigation to perform antibiofilm operations in situ.