Carbonic Anhydrase@ZIF-8 Hydrogel Composite Membrane with Improved Recycling and Stability for Efficient CO₂ Capture

Abstract

In this study, carbonic anhydrase (CA, EC 4.2.1.1) molecules were embedded into metal–organic frameworks (MOFs) via co-precipitation (CA@ZIF-8), and then these CA@ZIF-8 nanocomposites were encapsulated in the poly­(vinyl alcohol) (PVA)–chitosan (CS) hydrogel networks to prepare CA@ZIF-8–PVA–CS composite hydrogels (PVA/CS/CA@ZIF-8) with high activity, stability, and reusability. The immobilization efficiency of CA was greater than 70%, suggesting the high immobilization efficiency. The prepared PVA/CS/CA@ZIF-8 composite membranes displayed excellent higher stability against a high temperature, denaturants, and acid than free CA and CA@ZIF-8. Furthermore, these membranes exhibited an excellent performance for CO2 capture. The amount of calcium carbonate obtained by PVA/CS/CA@ZIF-8 hydrogel membranes was 20- and 1.63-fold than free CA and CA@ZIF-8 composites, respectively. Furthermore, the hydrogel membranes exhibited superior reusability and mechanical strength. The hydrogel membrane maitained 50% of its original activity after 11 cycles. However, CA@ZIF-8 completely lost activity. These results indicated that the PVA/CS/CA@ZIF-8 membranes can be efficiently applied to capture CO2 sequestration.

Co-immobilization multienzyme nanoreactor with co-factor regeneration for conversion of CO2

“…The previous reports have demonstrated that enzymes could be encapsulated in situ by co-precipitation in the ZIF-8 [37,38]. The formed ZIF-8 protective shell around immobilized enzymes could prevent the leakage of enzyme molecules from ZIF-8 [39,40].…”

Combining Active Carbonic Anhydrase with Nanogels: Enzyme Protection and Zinc Sensing

“…Many attempts have been made to immobilize CA in various supports, including hydrogels, for the biocatalysis of the reversible conversion of CO 2 to bicarbonate. [35][36][37][38][39][40][41] Studies by Fierke and Thompson have demonstrated another unique application of CA, namely as a zinc biosensor, with advantages well-discussed in the literature. [25][26][27][28][29][30][31] Here we report, for the first time, a proof-of-concept study of combining active CA with nanogels.…”

“… 35 Immobilizing CA on various supports has been used to improve its stability and reusability for CO 2 capture, among which a few attempts have successfully immobilized CA in a hydrogel network. For example, CA-liposome conjugates 36 and metal-organic hybrid nanocomposites 37 , 38 have been reported to be embedded into hydrogel beads and membranes during the polymerization process. CA was also encapsulated in silk protein hydrogel via a dual crosslinking strategy, which employed a photoinduced dityrosine chemical crosslinking followed by a dehydration-mediated physical crosslinking.…”

Chitosan/ZIF‐8 Composite Beads Fabricated by In Situ Growth of MOFs Crystals on Chitosan Beads for CO2 Adsorption

“…[12] However, MOFs was crystalline powders with the high brittleness, poor stability in water, and difficult to be recycled, which greatly limited the application range of MOFs. [13,14] The combination of flexible polymers with MOFs was considered as one of the effective strategies to cover the shortage of MOFs. [15] Introduction of flexible polymers containing a large number of hydrophilic groups can not only make MOFs more stable in water, but also provide them flexibility.…”