# An Endogenous Proton-Powered Adaptive Nanomotor for Treating Muscle Atrophy

## TL;DR

A proton-powered nanomotor was developed to treat muscle atrophy by converting proton gradients into ATP, showing promising results in restoring muscle health.

## Contribution

A novel proton-gradient-driven ATP transport motor (ATM) was developed using chloroplast-derived FoF1-ATPase and a biocompatible organic shell.

## Key findings

- The ATM nanomotor achieved high biocompatibility and pH-responsive motility in vitro.
- ATM treatment in mice with muscle atrophy restored muscle cell sizes to levels seen in healthy controls.
- The nanomotor demonstrated speeds up to 4.32 μm/s under physiological proton gradients.

## Abstract

Nanomotors driven by endogenous enzymes are favored in biology and pharmacy due to their spontaneous driving and efficient biocatalytic activity, and have potential applications in the treatment of clinical diseases that are highly dependent on targeted effects. For diseases such as muscle atrophy, using energy molecules such as ATP to improve cellular metabolism is a relatively efficient treatment method. However, traditional adenosine triphosphate (ATP) therapies for muscle atrophy face limitations due to instability under physiological conditions and poor targeting efficiency. To address these challenges, we developed an endogenous proton-gradient-driven ATP transport motor (ATM), a nanomotor integrating chloroplast-derived FoF1-ATPase with a biocompatible flask-shaped organic shell (FOS). The ATM is synthesized by vacuum-injecting phospholipid-embedded FoF1-ATPase nanothylakoids into ribose-based FOS, enabling autonomous propulsion in acidic microenvironments through proton-driven negative chemotaxis (directional movement away from regions of higher proton concentration). This nanomotor converts proton gradients into ATP synthesis, directly replenishing cellular energy deficits in atrophic tissues. In vitro studies demonstrated high biocompatibility (>90% cell viability at 150 μg/mL) and pH-responsive motility, achieving speeds up to 4.32 μm/s under physiological gradients (ΔpH = 3). In vivo experiments using dexamethasone-induced muscle atrophy mice revealed that ATM treatment accelerated weight recovery and restored normal muscle morphology, with treated mice exhibiting cell sizes comparable to healthy controls (30–40 μm vs. 15–25 μm in untreated). These results highlight the ATM’s potential as a precision therapeutic platform for metabolic disorders, leveraging the natural enzyme functionality and synthetic material design to enhance efficacy while minimizing systemic toxicity.