Nanoconfined catalytic {\AA}ngstr\"om-size motors

TL;DR

This study investigates nanometer-scale chemically powered motors confined between walls, revealing structural ordering and anisotropic dynamics crucial for their potential biological and laboratory applications.

Contribution

It provides molecular dynamics insights into the behavior of Angstrom-sized synthetic motors in confined environments, highlighting structural and dynamical properties.

Findings

Strong structural ordering due to solvent depletion forces

Anisotropic motor velocities and relaxation times

Dependence of properties on confinement distance

Abstract

Self-propelled chemically powered synthetic micron and nano-scale motors are being intensively studied because of the wide range of potential applications that exploit their directed motion. This paper considers even smaller {\AA}ngstr\"om-size synthetic motors. Such very small motors in bulk solution display effects arising from their self-propulsion. Recent experiments have shown that small-molecule catalysts and single enzyme molecules exhibit properties that have been attributed to their chemical activity. Molecular dynamics is used to investigate the properties of very small {\AA}ngstr\"om-size synthetic chemically powered sphere-dimer motors in a simple atomic-like solvent confined between walls separated by distances of tens of nanometers. Evidence for strong structural ordering of the motors between the walls, which reflects the finite size of solvent molecules and depends on solvent depletion forces, is provided. Dynamical properties, such as average motor velocity, orientational relaxation, and mean square displacement, are anisotropic and depend on the distance from the walls. This research provides information needed for potential applications that use molecular-scale motors in the complex confined geometries encountered in biology and the laboratory.