Influence of matrix on external mass transfer resistance in immobilized urease membranes

Developing Enzyme Immobilization with Fibrous Membranes: Longevity and Characterization Considerations

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.

A hierarchical assembly of flower-like hybrid Turkish black radish peroxidase-Cu2+ nanobiocatalyst and its effective use in dye decolorization

Effective dye decolorization in wastewater still shows a big challenge. Although the biological methods, especially using enzymes, offer alternative and effective process for dye degradation and overcome the limitations of chemical and physical methods such as the instability, lack of reusability and high cost of free enzymes strictly, which limit their use in many scientific and technical applications. Enzymes rapidly lose their activities in aqueous solutions and against environmental changes due to their very susceptibility and unfavorable conformations. Herein, we report preparation of the enzyme-inorganic hybrid nanostructures with flower-like shape consisting of Turkish black radish peroxidase and Cu²⁺ metal ions using an encouraging enzyme immobilization approach. The peroxidase-Cu²⁺ hybrid nanoflowers (NFs) exhibited enhanced stability and activity towards various pH values and provided excellent dye decolorization efficiency for Victoria blue (VB) dye with more than 90% within 1 h. The NFs were also repeatedly used in efficient and caused 77% VB decolorization efficiency even at tenth cycles. However, to the best of our knowledge, for the first time, we prepared peroxidase enzyme isolated from Turkish black radish incorporated NFs and used them for dye decolorization. We believe that the NFs can be promising materials for dye decolorization in real wastewater treatment.

Development of antibacterial polyacrylonitrile membrane modified with a covalently immobilized lysozyme

A novel antibacterial polyacrylonitrile (PAN) membrane covalently immobilized with lysozyme was prepared.

Synthesis of copper ion incorporated horseradish peroxidase-based hybrid nanoflowers for enhanced catalytic activity and stability

Hybrid nanoflowers (hNFs) consisting of horseradish peroxidase (HRP) enzyme and copper ions (Cu²⁺) with dramatically enhanced catalytic activity and stability.

Self-encapsulation of oxidases as a basic approach to tune the upper detection limit of amperometric biosensors

This study describes a new, basic procedure for the tuning of some analytical parameters of enzymatic biosensors that are based on hydrogen peroxide-producing oxido-reductases. An amperometric biosensor based on glucose oxidase (GOx) (EC 1.1.3.4) from Penicillum vitale, immobilized on a carbon rod electrode by cross-linking with glutaraldehyde, was exploited as a model system for demonstration of the approach described here. Such an important analytical parameter as the upper detection limit was dramatically changed by the formation of a polypyrrole conducting polymer layer by the GOx-induced polymerization of polypyrrole (Ppy). An increase in the upper detection limits for differently modified electrodes was estimated by calculation of the apparent Michaelis-Menten constant [K(M(app))]. A significant increase in the long-term stability of the GOx-based electrode modified by Ppy (GOx/Ppy) was detected compared with that of an unmodified one. Further application of this approach, based on the self-encapsulation of glucose oxidase and other oxidases, is predicted for such biosensors where extension of the detection rate as well as K(M(app)) are required.