# Impact of solvent forces and broken symmetry on the assembly of designed proteins at a liquid-solid interface

## TL;DR

This paper shows how solvent forces and surface symmetry affect the assembly of designed proteins at liquid-solid interfaces.

## Contribution

The study reveals that solvent forces and hydration structures significantly influence protein assembly, which is often overlooked in design platforms.

## Key findings

- High-speed AFM and machine learning revealed protein nanorod assembly patterns influenced by mica surface symmetry.
- Monte Carlo simulations showed a smectic phase arises due to crystal symmetry-induced directional bias.
- Incorporating solvent forces and hydration structures can improve protein design for hybrid materials.

## Abstract

The era of protein design has enabled the creation of hybrid protein-inorganic interfaces, leading to both surface-directed self-assembly of de novo protein architectures and protein-directed formation of inorganic materials. However, the resulting patterns of protein assembly are often unexpected, implying that essential interactions are not accounted for in current design platforms. Here, we use high-speed atomic force microscopy (AFM) analyzed through machine learning to follow the assembly of protein nanorods in aqueous electrolytes on two types of mica exhibiting disparate symmetry elements, which are imprinted on the overlying hydration structure. Using Monte Carlo simulations, we reproduce the observed phases and show that an observed smectic phase, previously thought to be unstable for non-interacting rods in two dimensions, emerges when crystal symmetry introduces a directional bias. The findings demonstrate the importance of incorporating solvent forces as modulated by the hydration structure inherent to interfacial systems when designing protein assemblies at liquid-crystal interfaces. Coupling physics-based simulations that can account for these factors to de novo protein design algorithms can lead to improved design platforms for bio-inspired, hybrid materials.

Manipulating chemical interactions is crucial in protein assembly. Here, the authors highlight the importance of accounting for solvent forces mediated by interfacial hydration structures when designing protein assemblies at liquid-crystal interfaces.