Abstract
Abstract In living systems, protein assemblies have essential functions, serving as structural supports, transport highways for molecular cargo, and containers of genetic material. The construction of protein assemblies, which involves control over space and time, remains a significant challenge in biotechnology. Here, we show that anionic boron clusters, 3,3′‐commo‐bis[closo‐1,2‐dicarba‐3‐cobaltadodecaborane] (COSAN − ), and halogenated closo‐dodecarboranes (B 12 X 12 2− , X=H, Cl, or I), described as super‐chaotropic nano‐ions, induce the formation of 2D assemblies of model proteins, myoglobin, carbonic anhydrase, and trypsin inhibitor. We found that the nano‐ion concentration reversibly controls the size of the protein assemblies. Furthermore, the secondary structures of the proteins are only slightly affected by assembly formation. For myoglobin, the formation of these assemblies even prevents temperature denaturation, highlighting a preservation effect of nano‐ions. Our study reveals that inorganic boron‐based nano‐ions act as a reversible molecular glue for proteins, providing a potential starting point for the further development of controlled protein assemblies.