# Long-Range Interactions Between Neighboring Nanoparticles Tuned by Confining Membranes

## TL;DR

This paper explores how nanoparticles interact in soft biological membranes, revealing that their movement is influenced by confinement deformation and distance.

## Contribution

The study introduces a new understanding of nanoparticle interactions in soft confinement using simulations and mechanics analysis.

## Key findings

- Nanoparticle interactions are controlled by confinement deformation and centroid distance.
- Directional movement of nanoparticles is governed by asymmetric deformation in soft confinement.
- Nanoparticles remain still in rigid confinement but move in soft confinement environments.

## Abstract

Membrane tubes, a class of soft biological confinement for ubiquitous transport intermediates, are essential for cell trafficking and intercellular communication. However, the confinement interaction and directional migration of diffusive nanoparticles (NPs) are widely dismissed as improbable due to the surrounding environment compressive force. Here, combined with the mechanics analysis of nanoparticles (such as extracellular vesicles, EVs) to study their interaction in confinement, we perform dissipative particle dynamics (DPD) simulations to construct a model that is as large as possible to clarify the submissive behavior of NPs. Both molecular simulations and mechanical analysis revealed that the interactions between NPs are controlled by confinement deformation and the centroid distance of the NPs. When the centroid distance exceeds a threshold value, the degree of crowding variation becomes invalid for NPs motion. The above conclusions are further supported by the observed dynamics of multiple NPs under confinement. These findings provide new insights into the physical mechanism, revealing that the confinement squeeze generated by asymmetric deformation serves as the key factor governing the directional movement of the NPs. Therefore, the constraints acting on NPs differ between rigid confinement and soft confinement environments, with NPs maintaining relative stillness in rigid confinement.