Impact of Colloidal Forces and Broken Symmetry on the Design of a Protein-Material Interface

The era of protein design ^1,2 has enabled the creation of hybrid protein-inorganic interfaces, leading to both surface-directed self-assembly of novel protein architectures ^2–4 and protein-directed formation of inorganic materials ⁵ . However, the resulting patterns of protein assembly are often unexpected ^2,4,6 implying that essential interactions are unaccounted 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 ^6,7 . 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 ⁸ ,emerges when crystal symmetry introduces a directional bias. The findings demonstrate the importance of incorporating colloidal forces and hydration structure inherent to interfacial systems when designing protein assemblies at liquid-crystal interface. Coupling physics-based simulations that can account for these factors to de novo protein design algorithms can lead to a new class of design platforms for bio-inspired, hybrid materials.