nn8b01842_si_002.avi (9.12 MB)
Bacteria-Activated Janus Particles Driven by Chemotaxis
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posted on 2018-05-23, 00:00 authored by Zihan Huang, Pengyu Chen, Guolong Zhu, Ye Yang, Ziyang Xu, Li-Tang YanIn the development
of biocompatible nano-/micromotors for drug
and cargo delivery, motile bacteria represent an excellent energy
source for biomedical applications. Despite intense research of the
fabrication of bacteria-based motors, how to effectively utilize the
instinctive responses of bacteria to environmental stimuli in the
fabrication process, particularly, chemotaxis, remains an urgent and
critical issue. Here, by developing a molecular-dynamics model of
bacterial chemotaxis, we present an investigation of the transport
of a bacteria-activated Janus particle driven by chemotaxis. Upon
increasing the stimuli intensity, we find that the transport of the
Janus particle undergoes an intriguing second-order state transition:
from a composite random walk, combining power-law-distributed truncated
Lévy flights with Brownian jiggling, to an enhanced directional
transport with size-dependent reversal of locomotion. A state diagram
of Janus-particle transport depending on the stimuli intensity and
particle size is presented, which allows approaches to realize controllable
and predictable propulsion directions. The physical mechanism of these
transport behaviors is revealed by performing a theoretical modeling
based on the bacterial noise and Janus geometries. Our findings could
provide a fundamental insight into the physics underlying the transport
of anisotropic particles driven by microorganisms and highlight stimulus-response
techniques and asymmetrical design as a versatile strategy to possess
a wide array of potential applications for future biocompatible nano-/microdevices.