From Bistate Molecular Switches to Self-Directed Track-Walking Nanomotors

Abstract

Track-walking nanomotors and larger systems integrating these motors are important for wide real-world applications of nanotechnology. However, inventing these nanomotors remains difficult, a sharp contrast to the widespread success of simpler switch-like nanodevices, even though the latter already encompasses basic elements of the former such as engine-like bistate contraction/extension or leg-like controllable binding. This conspicuous gap reflects an impeding bottleneck for the nanomotor development, namely, lack of a modularized construction by which spatially and functionally separable "engines" and "legs" are flexibly assembled into a self-directed motor. Indeed, all track-walking nanomotors reported to date combine the engine and leg functions in the same molecular part, which largely underpins the device-motor gap. Here we propose a general design principle allowing the modularized nanomotor construction from disentangled engine-like and leg-like motifs, and provide an experimental proof of concept by implementing a bipedal DNA nanomotor up to a best working regime of this versatile design principle. The motor uses a light-powered contraction-extension switch to drive a coordinated hand-over-hand directional walking on a DNA track. Systematic fluorescence experiments confirm the motor's directional motion and suggest that the motor possesses two directional biases, one for rear leg dissociation and one for forward leg binding. This study opens a viable route to develop track-walking nanomotors from numerous molecular switches and binding motifs available from nanodevice research and biology.

Self‐Propelled Micro/Nanomotors for Sensing and Environmental Remediation

“…Light also is an interesting stimulus for motion of micro/nanomotors, due to the wireless control and remote propagation, precise adjusted energy input, and reversible ON/OFF radiation state . Various types of light‐driven micro/nanomotors were developed such as molecular motors, liquid droplets, solid materials, and DNA‐based motors . These micro/nanomotors can be used for reactions in liquid, air and liquid/solid interfaces .…”

“…[41] Various types of lightdriven micro/nanomotors were developed such as molecular motors, [42,43] liquid droplets, [44,45] solid materials, [46,47] and DNAbased motors. [48][49][50] These micro/nanomotors can be used for reactions in liquid, [51] air [52] and liquid/solid interfaces. [46] Heat also can be used to regulate the motion of micro/nanomotors.…”

A Force to Be Reckoned With: A Review of Synthetic Microswimmers Powered by Ultrasound

“…Thus far, environmental cues such as chemical gradients and chemical reactions, magnetic, electric, light, sound, and temperature gradients have been successfully used to power synthetic nano‐ and microswimmers. However, very few of them meet the requirements of the ideal energy source for powering nano‐/microscale machines, especially for biomedical applications which are most heatedly anticipated for these devices.…”

Motor properties from persistence: a linear molecular walker lacking spatial and temporal asymmetry

“…While the majority of work on molecular motors consists of studying natural motors and their variants, a synthetic biology approach espouses the design and construction of artificial motors [21][22][23][24][25][26]. Using this approach in combination with modeling, it is possible to focus on one principle at a time and address possible physical mechanisms.…”

“…In essentially all known biological motors, directionality is established by a combination of track asymmetry (actin filaments, microtubules, single DNA strands) and structural changes in the motor protein (myosin, kinesin, helicases). Similarly, molecular motors in the nascent synthetic field generally have directionality imposed through asymmetric track design [21,22,24,25,27]. Alternatively, symmetric tracks and motors have been demonstrated to give rise to persistent directed motion following an initially random choice of translocation direction; these motors modify their tracks to establish and maintain local asymmetry as part of the motility mechanism [28][29][30][31].…”