Protein-Based Enzyme Bionanoreactor for Efficient CO2 Mineralization under Benign Conditions

Mineralization is an emerging approach for carbon capture and sequestration (CCS), but current methods rely on high pH conditions to overcome the kinetic and thermodynamic barriers of CO2 reacting with metal cations to form carbonate minerals. This is often achieved through adding alkaline chemicals or using electrochemical catalysis, which are resource-intensive, environmentally disruptive, and require extensive pH adjustments. Inspired by natural biomineralization, this study presents a novel enzyme bionanoreactor approach based on self-assembling lumazine synthase AaLS-13 protein nanocages to facilitate efficient CO2 mineralization under mild conditions. The AaLS-13 nanocage actively encapsulates and concentrates metal cations within its cavity, with its assembled structure playing a critical role in enhancing the cation availability for subsequent reactions. By encapsulating carbonic anhydrase into the nanocages, the resultant bionanoreactors integrate CA catalysis with metal cation concentration, showing significantly improved catalytic performance. They efficiently convert dissolved CO2 into carbonate minerals as well as capture and mineralize atmospheric CO2 under benign, ambient conditions. This research lays the groundwork for developing AaLS-13 nanocage-based bionanoreactors for sustainable carbon mineralization, offering an eco-friendly CCS alternative. It also provides new insights into leveraging AaLS-13 nanocage-substrate interactions to modulate local microenvironments and optimize enzyme catalysis for diverse nanotechnological, biomedical, and environmental applications.