Dynamic Constitutional Gold Nanoparticles Frameworks for Carbonic Anhydrase Activation

Dynamic constitutional materials are constructed from reversibly connecting components adaptively self-assembling under the pressure of internal or external factors. Functional macromonomeric poly(ethylene glycol) segments and 3D connecting cores can be used to conceive biomimetic dynamic constitutional frameworks (DCFs) for selective/adaptive biomolecular encapsulation of proteins, enzymes, etc. Gold nanoparticles (AuNps) can be involved as core connectors to expand the networks of DCFs at the nanoscale, thereby increasing the biomolecular encapsulation and activity. Efficient encapsulation of bovine carbonic anhydrase (bCA) in host matrixes is of tremendous importance for maintaining its stability, catalytic activity, and durability. In this paper, we demonstrate that AuNps-DCFs-bCA bioconjugates, synthesized via reversible imine/amino-carbonyl as sulfide-AuNps chemistries, assemble into nanometric aggregates of around 200 nm with high stability for bCA encapsulation. This system showed an impressive improved catalytic activity, more than 30 times higher than that of bCA alone. The Km values were two to three times lower compared to free bCA indicating a stronger affinity for bCA under encapsulation, while Vmax was higher. This performance is very promising for current state-of-the-art carbon dioxide capture systems with equivalent amounts of enzyme, even after heating for a prolonged period at 100 °C, translating into a direct perspective for enhancing flue gas capture and conversion performances.