It Takes Two to Make a Thing Go Right: Boosting Current in Coupled Motors

TL;DR

This paper demonstrates that mechanically coupling synthetic molecular motors can increase their average current by enhancing activity levels, and that bias loss can be compensated by increasing fuel concentration, offering a new design strategy.

Contribution

It introduces a simulation-based approach showing that coupling synthetic motors boosts current and suggests a method to recover bias by adjusting fuel levels.

Findings

Coupling increases motor activity and current.

Boosts are achievable with single-digit amplification.

Bias loss can be mitigated by higher fuel concentration.

Abstract

Catalysis-driven synthetic molecular motors operate in a loose mechanochemical coupling regime, one in which a decomposition of a fuel molecule does not reliably produce a forward step. In that regime, stochastic backward steps can significantly degrade the motor's current, prompting us to ask whether mechanically coupling multiple such motors can boost their averaged current. By simulating rotaxane-based motors with two classes of models--particle-based nonequilibrium molecular dynamics and jump-diffusion models--we show that current boosts are physically achievable. Our observed boosts, which amplify current by single-digit factors, emerge when coupling between motors can increase the activity, speeding up the rate of both forward and backward steps. In doing so, the bias for preferring forward steps actually degrades, but the lost bias can be largely recovered by raising the fuel concentration, demonstrating a general design strategy: amplify activity through coupling and restore bias through stronger driving.