Complex Assemblies of Colloidal Microparticles with Compliant DNA Linkers and Magnetic Actuation

Abstract

Active colloids are modular assemblies of distinct micro- and nanoscale components that can perform complex robotic tasks. While recent advances in templated assembly methods enable high-throughput fabrication of multi-material active colloids, their limitations reduce the ability to construct flexibly linked colloidal systems, restricting their complexity, agility, and functionality. Here, templated assembly by selective removal (TASR) is leveraged to construct multicomponent colloidal microstructures that are connected with compliant DNA nanotube linkages. Polycarbonate heat (PCH) molding is employed to create high-surface-energy templates for improved polystyrene microsphere assembly via TASR. This increase in template surface energy improves microsphere assembly by more than 100-fold for two-sphere microstructures. An inverse relationship between microstructure complexity (i.e., the number of microspheres) and assembly yields is observed. PCH-assisted TASR is leveraged to construct larger colloidal structures containing up to 26 microspheres, multi-sphere microrotors, and structurally homogeneous populations of flexibly linked, two-sphere microswimmers that locomote in fluid environments. Real-time modification of a microswimmer is also demonstrated through nuclease-mediated degradation of the DNA linkages, highlighting the DNA-enabled reconfiguration and responsiveness capabilities of these microswimmers. These results establish PCH-assisted TASR as a versatile method for constructing flexibly linked, modular microrobots with controlled geometry, enhanced agility, and dynamic response.