Propulsion and controlled steering of magnetic nanohelices
Propulsion and controlled steering of magnetic nanohelices
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DOI：
10.1039/c8sm00037a
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发表时间：
2019-02-21
期刊：
影响因子：
3.4
通讯作者：
Ala-Nissila, Tapio
中科院分区：
文献类型：
--
作者：
Alcanzare, Maria Michiko;Karttunen, Mikko;Ala-Nissila, Tapio
微纳米马达在流体环境中的外部控制运动构成了生物传感、靶向递送和环境修复中有前途的工具。特别是，最近的实验表明，通过在磁性螺旋形结构上施加外部磁场，可以实现无燃料推进。螺旋和旋转场之间的磁相互作用通过耦合的旋转-平移运动引起旋转和推进它们的扭矩。最近的工作表明，存在某些螺旋形状的推进的最佳几何形状。然而，实验表明，由于布朗运动会干扰确定性运动并使其难以实现受控转向，因此受控运动在纳米尺度上仍然是一个挑战。在目前的工作中，我们采用定量准确的模拟方法来设计一个设置，其中磁性纳米螺旋的半径为30 nm，长度为180 nm（对应于先前确定的最佳长度与半径比为6），有和没有货物，可以准确地推进和操纵的存在下的热波动。特别是，我们展示了这种纳米马达的快速运输，并设计了在生物相关温度下操纵外部磁场以实现定向控制转向的协议。
Externally controlled motion of micro and nanomotors in a fluid environment constitutes a promising tool in biosensing, targeted delivery and environmental remediation. In particular, recent experiments have demonstrated that fuel-free propulsion can be achieved through the application of external magnetic fields on magnetic helically shaped structures. The magnetic interaction between helices and the rotating field induces a torque that rotates and propels them via the coupled rotational-translational motion. Recent works have shown that there exist certain optimal geometries of helical shapes for propulsion. However, experiments show that controlled motion remains a challenge at the nanoscale due to Brownian motion that interferes with the deterministic motion and makes it difficult to achieve controlled steering. In the present work we employ quantitatively accurate simulation methodology to design a setup for which magnetic nanohelices of 30 nm in radius and 180 nm in length (corresponding to previously determined optimal length to radius ratio of 6), with and without cargo, can be accurately propelled and steered in the presence of thermal fluctuations. In particular, we demonstrate fast transport of such nanomotors and devise protocols in manipulating external fields to achieve directionally controlled steering at biologically relevant temperatures.