Stabilized and Immobilized Carbonic Anhydrase on Electrospun Nanofibers for Enzymatic CO₂ Conversion and Utilization in Expedited Microalgal Growth

Abstract

Carbonic anhydrases convert CO2 to bicarbonate at a high turnover rate up to 106 s–1, but their actual applications in CO2 conversion processes are hampered by their poor stability. This study reports highly loaded and stabilized bovine carbonic anhydrase (bCA) upon being immobilized onto electrospun polymer nanofibers in the form of enzyme precipitate coating (EPC). The EPC protocol, consisting of enzyme covalent attachment, precipitation, and cross-linking, maintained 65.3% of initial activity even after being incubated in aqueous solution at room temperature under shaking at 200 rpm for 868 days. EPC also showed strong resistance to the treatment of the metal chelation agent, ethylenediaminetetraacetic acid, and molecular dynamic simulation was carried out to elucidate the prevention of metal leaching from the active site of bCA upon being cross-linked in the form of EPC. Highly stable EPC with high bCA loading was employed for the conversion of bubbling CO2 to bicarbonate, and the bicarbonate solution was utilized as a carbon source for expedited microalgae growth in a separate bioreactor. The addition of EPC in the bubbling CO2 reactor resulted in 134 and 231% accelerated microalgae growths compared to the controls with and without 25 mM sodium bicarbonate, respectively. EPC with high enzyme loading and unprecedentedly successful stabilization of enzyme stability has a great potential to be used for the development of various enzyme-mediated CO2 conversion and utilization technologies.

Post Processing Strategies for the Enhancement of Mechanical Properties of ENMs (Electrospun Nanofibrous Membranes): A Review

“…This range can be termed as the processing window or optimum range beyond which electrospinning is not possible. Many applications of electrospun fibers and membranes include biomedical (tissue engineering [12][13][14], drug delivery [15][16][17], immobilization of enzymes [18][19][20], wound dressing [21][22][23] and antibacterial membranes [24][25][26]), textiles [27][28][29], separation membranes (Li ion battery separators [30][31][32], distillation [33][34][35] and filtration membranes [36][37][38]), sensors [39][40][41], and high performance composite materials (reinforcing agents [42][43][44] or vascular networks of healing agents [45][46][47]), etc.…”

Current Status and Future Perspectives of Supports and Protocols for Enzyme Immobilization

“…High voltage is applied to a polymer solution and the sample collector to produce electric field jets supporting the formation of fibers through solvent evaporation during the process [222,223]. The use of the technique focuses on the main discussions intrinsically connected with the area; it is interpreted as an innovative, effective technique with low cost and versatility that can be applied in several industrial fields [220,[224][225][226]. The electrified nanofibers have attracted the attention of enzyme engineering and biocatalysis, being considered a potential tool because of their numerous advantages: high surface area, multiple fixation points to the support, high porosity, interconnectivity, high thermal resistance, pH stability, and several solvents [216,220,222,223,227].…”

Tunable Polymeric Scaffolds for Enzyme Immobilization

“…Thus, this method significantly increases the enzyme loads in comparison with conventional supports. On the last two decades, this technique has been employed to immobilize diverse (bio)molecules, including enzymes, in applications such as biosensors ( Teepoo et al, 2017 ), pollution control ( Jun et al, 2020 ), or bioreactors ( Sakai et al, 2008 ) ( Figure 8D ). So far, two methodologies are followed for the fabrication of the enzyme-nanofiber hybrids: entrapment ( in situ immobilization) and surface attachment (adsorption or covalent binding).…”