Magnetoresponsive Artificial Cilia Self-Assembled with Magnetic Micro/Nanoparticles

Abstract

Biological cilia have exquisitely organized dynamic ultrafine structures with submicron diameters and exceptional aspect ratios, which are self-assembled with ciliary proteins. However, the construction of artificial cilia with size and dynamic functions comparable to biological cilia remains highly challenging. Here, we propose a self-assembly technique that generates magnetoresponsive artificial cilia with a highly ordered 3D structural arrangement using vapor-phase magnetic particles of varying sizes and shapes. We demonstrate that both monodispersed Fe3O4 nanoparticles and Fe microparticles can be assembled layer-by-layer vertically in patterned magnetic fields, generating both “nanoscale” or “microscale” artificial cilia, respectively. The resulting cilia display several structural features, such as diameters of single particle resolution, controllable diameters and lengths spanning from nanometers to micrometers, and accurate positioning. We further demonstrate that both the magnetic nanocilia and microcilia can dynamically and immediately actuate in response to modulated magnetic fields while providing different stroke ranges and actuation torques. Our strategy provides new possibilities for constructing artificial nano- and microcilia with controlled 3D morphology and dynamic field responsiveness using magnetic particles of varied sizes and shapes.

Magnetically Stimulated Bio‐ and Electrochemical Systems: State‐of‐the‐Art, Applications, and Future Directions

“…Therefore, the future integration of magnetically triggered bioelectrocatalytic systems into surfaces with high‐density patterns is anticipated. This evolution is made possible by electrosynthesis approaches [200,201] and recent surface patterning technologies, such as microfabrication [202] and block‐copolymer nanolithography, [203] enabling the localized deposition/activation of magnetic materials [204] . It should also be noted that there is no theoretical obstacle to extending the concept to conventional batteries and/or supercapacitors.…”

Bioinspired magnetic cilia: from materials to applications

“…Alternatively, ferromagnetic or ferrimagnetic particles can be used for the irreversible formation of artificial cilia. In this case, the cilia can maintain their chain configuration through magnetic dipole‒dipole interactions 72 , 99 , 124 , even in the absence of an external field, regardless of the surface chemistry (Fig. 6e ).…”

“…Although this method is effective for assembling nanoparticles, the strong capillary forces between magnetic particles and between magnetic particles and the substrate make it challenging to precisely manipulate individual particles at the single-particle level and to assemble magnetic particles into a vertical 3D structure (Fig. 7a, b ) 124 , 125 . Furthermore, it is challenging to transport high-AR magnetic cilia that are synthesized in liquid to the air, as the capillary forces at the liquid‒gas interfaces cause the structures to stick together during the process of evaporation 99 , 100 , 124 – 129 .…”

“…7a, b ) 124 , 125 . Furthermore, it is challenging to transport high-AR magnetic cilia that are synthesized in liquid to the air, as the capillary forces at the liquid‒gas interfaces cause the structures to stick together during the process of evaporation 99 , 100 , 124 – 129 .…”

“…The limitations of traditional liquid-phase self-assembly of magnetic nanoparticles can be effectively addressed through the use of vapor-phase magnetic particles 99 , 100 , 124 , 126 . For instance, Kang et al utilized magnetic particles in the vapor state as building blocks for self-assembly (Fig.…”