# Translational and Rotational Dynamics of Colloidal Particles Interacting through Reacting Linkers

## TL;DR

This paper investigates how molecular linker details influence the movement and arrest of colloidal particles, revealing that particles can roll before becoming immobilized, which has implications for understanding biological interactions.

## Contribution

It introduces a simulation approach to study linker reaction kinetics and demonstrates how these affect colloid dynamics, including motion and arrest mechanisms.

## Key findings

- Particles can move via rolling before arrest.
- Reaction rates and linkage number control dynamics.
- Rolling motion detection can inform host-pathogen studies.

## Abstract

Much work has studied effective interactions between micron-sized particles carrying linkers forming reversible, inter-particle linkages. These studies allowed understanding the equilibrium properties of colloids interacting through ligand-receptor interactions. Nevertheless, understanding the kinetics of multivalent interactions remains an open problem. Here, we study how molecular details of the linkers, such as the reaction rates at which inter-particle linkages form/break, affect the relative dynamics of pairs of cross-linked colloids. Using a simulation method tracking single binding/unbinding events between complementary linkers, we rationalize recent experiments and prove that particles' interfaces can move across each other while being cross-linked. We clarify how, starting from diffusing colloids, the dynamics become arrested when increasing the number of inter-particle linkages or decreasing the reaction rates. Before getting arrested, particles diffuse through rolling motion. The ability to detect rolling motion will be useful to shed new light on host-pathogen interactions.