Multi-functionalized micro-helical capsule robots with superior loading and releasing capabilities.

The functionalization of microrobots is essential for realizing their biomedical application in targeted cargo delivery, but the multifunctional integration of microrobots and controllable cargo delivery remains an enormous challenge at present. This work reports a kind of multi-functionalized micro-helical robot with superior loading capabilities for the controlled release of encapsulants. The magnetic microrobot, with a multilayer capsule helical structure, was developed via multifunctional strategies, including microfluidic synthesis, polyelectrolyte complexation, and surface coating with magnetic nanoparticles. The microrobot is constructed of a helical structure from a calcium alginate microfiber via a co-axial capillary microfluidic system. Then, it is coated with a polyelectrolyte complexation membrane and decorated with magnetic nanoparticles. After multi-step layer-by-layer (LbL) assembly with functionalized units, the structure is converted to a helical capsule possessing a soft and biocompatible polysaccharide alginate/chitosan/alginate shell with Fe