Developing Enzyme Immobilization with Fibrous Membranes: Longevity and Characterization Considerations

Abstract

Fibrous membranes offer broad opportunities to deploy immobilized enzymes in new reactor and application designs, including multiphase continuous flow-through reactions. Enzyme immobilization is a technology strategy that simplifies the separation of otherwise soluble catalytic proteins from liquid reaction media and imparts stabilization and performance enhancement. Flexible immobilization matrices made from fibers have versatile physical attributes, such as high surface area, light weight, and controllable porosity, which give them membrane-like characteristics, while simultaneously providing good mechanical properties for creating functional filters, sensors, scaffolds, and other interface-active biocatalytic materials. This review examines immobilization strategies for enzymes on fibrous membrane-like polymeric supports involving all three fundamental mechanisms of post-immobilization, incorporation, and coating. Post-immobilization offers an infinite selection of matrix materials, but may encounter loading and durability issues, while incorporation offers longevity but has more limited material options and may present mass transfer obstacles. Coating techniques on fibrous materials at different geometric scales are a growing trend in making membranes that integrate biocatalytic functionality with versatile physical supports. Biocatalytic performance parameters and characterization techniques for immobilized enzymes are described, including several emerging techniques of special relevance for fibrous immobilized enzymes. Diverse application examples from the literature, focusing on fibrous matrices, are summarized, and biocatalyst longevity is emphasized as a critical performance parameter that needs increased attention to advance concepts from lab scale to broader utilization. This consolidation of fabrication, performance measurement, and characterization techniques, with guiding examples highlighted, is intended to inspire future innovations in enzyme immobilization with fibrous membranes and expand their uses in novel reactors and processes.

Recent Advances in Bioactive Carbon Nanotubes Based on Polymer Composites for Biosensor Applications

“…These groups play a crucial role in reducing the van der Waals interactions between CNTs and allow additional modifications through covalent connections with various molecules such as long polymer molecules, alkyl chains, nucleic acids, dendrimers and enzymes. [100,101] Direct covalent functionalization has a greater influence on the chemical and physical properties of CNTs than the oxidation method and thus opens up more possibilities for the use of CNTs. [100] To facilitate the attachment (immobilization) of the biomolecule to the CNT surface, the functional groups on the CNTs can react with complementary functional groups in the structure of the biomolecule to form a covalent bond.…”

“…When EDC combines with carboxyl groups, an o-acylurea ester is formed as an intermediate. [101] This ester can easily be replaced by the main amine of the biomolecule. The result is that the main amine and the carboxyl group form an amide bond.…”

“…Each technique possesses its own strengths and limitations, necessitating researchers to carefully evaluate these factors in order to choose the most appropriate method for a specific application. [95,96,101]…”

Upstream and Downstream Bioprocessing in Enzyme Technology

“…Flexible immobilization matrices fabricated from fibers possess physical attributes such as a large surface area, light weight, and controllable porosity that grant them the mechanical properties required to create filters, sensors, scaffolds, and other functional interfaces. Coatings can also promote the longevity of biocatalytic membranes, which is why they have attracted interest and application in membrane bioreactors [ 84 ].…”

An Accessible Method to Improve the Stability and Reusability of Porcine Pancreatic α-Amylase via Immobilization in Gellan-Based Hydrogel Particles Obtained by Ionic Cross-Linking with Mg2+ Ions

“…These disadvantages can also be partially or totally eliminated by immobilizing the enzyme using different methods. These methods offer five key advantages: (a) the effective recovery and reusability of the enzyme; (b) the easy separation of the enzyme from the reaction mixture; (c) the uncomplicated design and performance control of bioreactors; (d) increased enzyme activity; (e) improved catalytic features, like stability and specificity (selectivity) [ 15 , 16 , 17 , 18 , 19 , 20 ].…”