Immobilization of carbonic anhydrase on polyvinylidene fluoride membranes

Abstract

In recent years, the application of carbonic anhydrase (CA) in CO removal has attracted great interest. However, obtaining high enzyme recovery activity is difficult in existing immobilization techniques. In this work, water plasma-treated poly(vinylidene fluoride) (PVDF) membranes were modified via 3-aminopropyl triethoxy silane (KH550) or γ-(2, 3-epoxypropoxy) propyl trimethoxy silane (KH560), and then CA was attached. The immobilization process was optimized, and the catalytic properties of PVDF-attached CA were characterized. The maximum activity recovery of PVDF-KH550-CA was 60%, whereas that of PVDF-KH560-CA was 33%. The K values of PVDF-KH550-CA, PVDF-KH560-CA, and free enzyme were 9.97 ± 0.37, 12.5 ± 0.2, and 6.18 ± 0.23 mM, respectively, and their K /K values were 206 ± 2, 117 ± 5, and 488 ± 4 M ·Sec . PVDF-attached CA shows excellent storage stability and reusability, and their half-life values were 82 and 78 days at 4 °C. At 25 °C, they were 50 and 37 days, respectively. PVDF-KH550-CA and PVDF-KH560-CA retained approximately 85% and 72% of the initial activity after undergoing 10 cycles. In the presence of them, the generation rates of CaCO were 76% and 65% of the free CA system, which were 1.6 and 1.3 times that of the blank system, respectively. Its role in accelerating CO sequestration holds great promise for its practical application.

Biocatalytic Membranes for Carbon Capture and Utilization

“…On pre-existing (often commercially available) membrane carriers, enzymes are immobilized through various mechanisms including adsorption, covalent bonding, and affinity binding [32]. Sun et al [35] used water plasma for treating a polyvinylidene fluoride (PVDF) flat sheet membrane, followed by silanization to introduce amine and epoxide groups on the membrane surface for subsequent covalent attachment of enzymes. Another versatile surface coating reagent, dopamine (DA), can impart amine functionalities on almost any type of material surface.…”

“…Additionally, membranes provide ample surface area for enzymes to be immobilized, and therefore, can provide high catalytic enhancement. Considering the membrane's separation function, when substrate is delivered as dissolved CO 2 -saturated water [35,36], the membrane structure creates a localized environment where the CO 2 conversion reaction can take place continuously in the liquid phase. Membranes can separate either dissolved or immobilized biocatalysts from products [38,39] (exemplified by two schematics under "Separation" in Figure 2).…”