Artificial cilia exhibit spontaneous beating
In a recent paper published in the journal Science, Associate Professor of Physics Zvonimir Dogic and colleagues present the first example of a simple microscopic system that self-organizes to produce cilia-like beating patterns. The findings also open a door for the development of one of the major goals of nanotechnology — to design an object that’s capable of swimming independently.
Cilia, tiny hair-like structures that perform feats such as clearing microscopic debris from the lungs and determining the correct location of organs during development, move in mysterious ways. Their beating motions are synchronized to produce metachronal waves, similar in appearance to “the wave” created in large arenas when audience members use their hands to produce a pattern of movement around the entire stadium.
Due to the importance of ciliary functions for health, there is great interest in understanding the mechanism that controls the cilias’ beating patterns. But learning exactly how cilia movement is coordinated has been challenging.
The mechanism that drives the regular beating of individual cilia and flagella, as well as dense ciliary fields, remains unclear. We describe a minimal model system, composed of microtubules and molecular motors, which self-assemble into active bundles exhibiting beating patterns reminiscent of those found in eukaryotic cilia and flagella. These observations suggest that hundreds of molecular motors, acting within an elastic microtubule bundle, spontaneously synchronize their activity to generate large-scale oscillations. Furthermore, we also demonstrate that densely packed, actively bending bundles spontaneously synchronize their beating patterns to produce collective behavior similar to metachronal waves observed in ciliary fields. The simple in vitro system described here could provide insights into beating of isolated eukaryotic cilia and flagella, as well as their synchronization in dense ciliary fields.