Assembly of Sequence-Defined Peptoids into Crystalline Nanomaterials as Carbonic Anhydrase Mimics for Promoted Hydration and Sequestration of CO₂

Carbonic anhydrase (CA) mimics have received significant attention due to their promising applications in the enhanced hydration and sequestration of CO₂. Despite advances made in designing CA mimics using sequence-defined macromolecules, this area is underexplored with limited success. Herein, we report the assembly of sequence-defined peptoids into crystalline nanomaterials with controlled microenvironment of active sites as CA mimics for promoted hydration and sequestration of CO₂. By incorporating specific ligands into self-assembling peptoids and coordinating these ligands with metal cations, we synthesized a variety of crystalline nanosheets and nanotubes and demonstrated their high efficiency as CA mimics for catalytic hydrolysis of p-nitrophenyl acetate (p-NPA). We demonstrated that tuning of morphology, crystallinity, and surface and ligand chemistries of these CA mimics is crucial for their catalytic activities. Among them, Zn²⁺-containing crystalline nanotubes with three imidazolyl side chain groups exhibited the highest catalytic efficiency comparable to natural bovine CA. Molecular dynamics simulations revealed the critical roles of peptoid-Zn²⁺ binding energy and the active stie local microenvironment on the catalytic performance of these CA mimics. CO₂ precipitation results showed that these CA mimics remarkably promote the hydration and sequestration of CO₂ while remaining high thermal and chemical stability. Nuclear magnetic resonance (NMR) results further confirmed the catalytic feature of these CA mimics and demonstrated their promoted CO₂ hydration and deprotonation of HCO₃^- into CO₃^2- accompanied by the change of CaCO₃ formation pathways, thus accelerating the mineralization of CO₂ into stable calcite solids. This study offers essential guidance for the future design of high-performance CA-mimics suitable for applications in CO₂ capture and sequestration.