Nanomaterials as Matrices for Enzyme Immobilization

Nitrilotriacetic Acid Functionalized Microgels for Efficient Immobilization of Hyaluronan Synthase

Enzymes play a vital role in synthesizing complex biological molecules like hyaluronic acid (HA). Immobilizing enzymes on support materials is essential for their efficient use and reuse in multiple cycles. Microgels, composed of cross-linked, highly swollen polymer networks, are ideal for enzyme uptake owing to their high porosity. This study demonstrates the immobilization of His6-tagged hyaluronan synthase from Pasteurella multocida (PmHAS) onto nitrilotriacetic acid functionalized microgels using different bivalent ions (Ni2+, Co2+, Mn2+, Mg2+, and Fe2+) via metal affinity binding. The results indicate that using Ni2+ yields the microgels with the highest enzyme uptake and HA formation. The immobilized PmHAS enables repetitive enzymatic production, producing high molecular weight HAs with decreasing dispersities in each step. Furthermore, the highest reported yield of HA with high molecular weight for immobilized PmHAS is achieved. This system establishes a foundation for continuous HA formation, with future works potentially enhancing PmHAS stability through protein engineering.

Green nanobiocatalysts: enhancing enzyme immobilization for industrial and biomedical applications

Nanobiocatalysts (NBCs), which merge enzymes with nanomaterials, provide a potent method for improving enzyme durability, efficiency, and recyclability. This review highlights the use of eco-friendly synthesis methods to create sustainable nanomaterials for enzyme transport. We investigate different methods of immobilization, such as adsorption, ionic and covalent bonding, entrapment, and cross-linking, examining their pros and cons. The decreased environmental impact of green-synthesized nanomaterials from plants, bacteria, and fungi is emphasized. The review exhibits the various uses of NBCs in food industry, biofuel production, and bioremediation, showing how they can enhance effectiveness and eco-friendliness. Furthermore, we explore the potential impact of NBCs in biomedicine. In general, green nanobiocatalysts are a notable progression in enzyme technology, leading to environmentally-friendly and effective biocatalytic methods that have important impacts on industrial and biomedical fields.

Nanodiamonds and natural deep eutectic solvents as potential carriers for lipase

This study investigates the use of nanodiamonds (ND) as a promising carrier for enzyme immobilization and compares the effectiveness of immobilized and native enzymes. Three different enzyme types were tested, of which Rhizopus niveus lipase (RNL) exhibited the highest relative activity, up to 350 %. Under optimized conditions (1 h, pH 7.0, 40 °C), the immobilized ND-RNL showed a maximum specific activity of 0.765 U mg-1, significantly higher than native RNL (0.505 U mg-1). This study highlights a notable enhancement in immobilized lipase; furthermore, the enzyme can be recycled in the presence of a natural deep eutectic solvent (NADES), retaining 76 % of its initial activity. This aids in preserving the native conformation of the protein throughout the reusability process. A test on brine shrimp revealed that even at low concentrations, ND-RNL had minimal toxicity, indicating its low cytotoxicity. The in silico molecular dynamics simulations performed in this study offer valuable insights into the mechanism of interactions between RNL and ND, demonstrating that RNL immobilization onto NDs enhances its efficiency and stability. All told, these findings highlight the immense potential of ND-immobilized RNL as an excellent candidate for biological applications and showcase the promise of further research in this field.

Advancements in enzyme immobilization on magnetic nanomaterials: toward sustainable industrial applications

Enzymes are widely used in biofuels, food, and pharmaceuticals. The immobilization of enzymes on solid supports, particularly magnetic nanomaterials, enhances their stability and catalytic activity. Magnetic nanomaterials are chosen for their versatility, large surface area, and superparamagnetic properties, which allow for easy separation and reuse in industrial processes. Researchers focus on the synthesis of appropriate nanomaterials tailored for specific purposes. Immobilization protocols are predefined and adapted to both enzymes and support requirements for optimal efficiency. This review provides a detailed exploration of the application of magnetic nanomaterials in enzyme immobilization protocols. It covers methods, challenges, advantages, and future perspectives, starting with general aspects of magnetic nanomaterials, their synthesis, and applications as matrices for solid enzyme stabilization. The discussion then delves into existing enzymatic immobilization methods on magnetic nanomaterials, highlighting advantages, challenges, and potential applications. Further sections explore the industrial use of various enzymes immobilized on these materials, the development of enzyme-based bioreactors, and prospects for these biocatalysts. In summary, this review provides a concise comparison of the use of magnetic nanomaterials for enzyme stabilization, highlighting potential industrial applications and contributing to manufacturing optimization.

Deciphering the immobilization of lipases on hydrophobic wrinkled silica nanoparticles

In this work, the adsorption of Candida antarctica B (CALB) and Rhizomucor miehei (RML) lipases into hydrophobic wrinkled silica nanoparticles (WSNs) is investigated. WSNs are hydrophobized by chemical vapor deposition. Both proteins are homogeneously distributed inside the pores of the nanoparticles, as confirmed by Transmission Electron Microscopy and Energy Dispersive X-ray measurements. The maximum enzyme load of CALB is twice that obtained for RML. Fourier Transform Infrared Spectroscopy confirms the preservation of the enzyme secondary structure after immobilization for both enzymes. Adsorption isotherms fit to a Langmuir model, resulting in a binding constant (KL) for RML 4.5-fold higher than that for CALB, indicating stronger binding for the former. Kinetic analysis reveals a positive correlation between enzyme load and RML activity unlike CALB where activity decreases along the enzyme load increases. Immobilization allows for enhancing the thermal stability of both lipases. Finally, CALB outperforms RML in the hydrolysis of ethyl-3-hydroxybutyrate. However, immobilized CALB yielded 20 % less 3-HBA than free lipase, while immobilized RML increases 3-fold the 3-HBA yield when compared with the free enzyme. The improved performance of immobilized RML can be explained due to the interfacial hyperactivation undergone by this lipase when immobilized on the superhydrophobic surface of WSNs.

Direct binding and characterization of laccase onto iron oxide nanoparticles

Iron oxide nanoparticles (IONPs) exhibit unique magnetic properties and possess a high surface-to-volume ratio, making them ideal candidates for the conjugation of substances, including enzymes. Laccase (EC 1.10.3.2), an oxidative enzyme with diverse applications, presents an opportunity for enhancing stability and reusability through innovative immobilization techniques, thus reducing overall process costs. In this study, we employed a direct binding procedure via carbodiimide activation to conjugate laccase onto IONPs synthesized using thermal chemical coprecipitation. Stabilization of the nanoparticles was achieved using thioglycerol and polyvinyl alcohol (PVA) as capping agents. Characterization of the synthesized nanoparticles was conducted using UV-spectroscopy, Fourier transform infrared spectroscopy (FTIR), x-ray diffraction, scanning electron microscopy, and energy dispersive x-ray spectroscopy. FTIR spectroscopy analysis confirmed successful laccase binding to magnetic nanoparticles, with binding efficiencies of 90.65% and 73.02% observed for thioglycerol and PVA capped IONPs, respectively. Furthermore, the conjugated enzyme exhibited remarkable stability, retaining nearly 50% of its initial activity after 20 reuse cycles. This research demonstrates that immobilizing laccase onto IONPs enhances its activity, stability, and reusability, with the potential for significant cost savings and expanded applications in various fields.

Antibiotic-enzyme-inorganic nanoflowers based immunoassay for the ultrasensitive detection of Staphylococcus aureus

In this work, we constructed a moderate and convenient approach for the determination of staphylococcus aureus (S. aureus) by using organic-inorganic flower-like hybrid nanoflowers and Pig IgG together in an enzyme-linked immunosorbent assay (ELISA) system. To ensure efficient capture, the hybrid nanoflowers were prepared by encapsulating horseradish peroxidase (HRP) and vancomycin (VAN) in the inorganic nanocrystal composites (calcium ion solution), just like the mimic biomineralization process. Owing to the self-assembly technique, the synthesized VAN-HRP-CaHPO₄ nanoflowers (NFs) can not only retain the ability to particularly capture the gram-positive bacteria but also enhance the stability and enzymatic activity to achieve the signal output amplification. Then, taking advantage of the integration of signal amplification elements (HRP) and biorecognition unit (VAN), the VAN-HRP-CaHPO₄ NFs were utilized as a new kind of capture & signal regent in the procedure of S. aureus detection. Based on this ELISA system, S. aureus could be clearly detected within the concentration ranging from 1.0 × 10² to 1.0 × 10⁷ CFU mL^-1. The detection limit was defined as 4.3 CFU mL^-1, which performance is superior to some commercial ELISA kits. Additionally, this system detected the S. aureus in food samples and showed an acceptable recovery. As a cost-effective and sensitive platform, this proposed assay was enable to fulfill the requirement of a quick and effective detection of S. aureus.

Sustainable enzymatic treatment of organic waste in a framework of circular economy

Enzymatic treatment of food and vegetable waste (FVW) is an eco-friendly approach for producing industrially relevant value-added products. This review describes the sources, activities and potential applications of crucial enzymes in FVW valorization. The specific roles of amylase, cellulase, xylanase, ligninase, protease, pectinase, tannase, lipase and zymase enzymes were explained. The exhaustive list of value-added products that could be produced from FVW is presented. FVW valorization through enzymatic and whole-cell enzymatic valorization was compared. The note on global firms specialized in enzyme production reiterates the economic importance of enzymatic treatment. This review provides information on choosing an efficient enzymatic FVW treatment strategy, such as nanoenzyme and cross-linked based enzyme immobilization, to make the process viable, sustainable and cheaper. Finally, the importance of life cycle assessment of enzymatic valorization of FVW was impressed to prove this approach is a better option to shift from a linear to a circular economy.

Nano-biocatalysts for food applications; immobilized enzymes within different nanostructures

The rapid progress in modern technologies and paying more attention to food safety has prompted new green technologies superior than chemical methods in the food industry. In this regard, enzymes can decrease the usage of chemical reactions but they are sensitive to environmental effects (pH and temperature). In addition, enzymes are scarcely possible to be reused. Consequently, their application as natural catalysts is restricted. Using nanotechnology and the possibility of enzyme immobilization on nanomaterials has led to nanobiocatalysts, resulting from the integration of nanotechnology and biotechnology. Nanocarriers have individual features like nanoscale size, excellent surface/volume ratio, and diversity in construction to improve the activity, efficiency, stability, and storage stability of enzymes. Nanobiocatolysts have a wide range of applications in purification, extraction, clarification, production, and packaging of various products in the food industry. Furthermore, the application of nanobiocatalysts to identify specific components of food contaminants such as microorganisms or their metabolites, heavy metals, antibiotics, and residual pesticides has been successful due to the high accuracy of detection. This review investigates the integration of nanotechnology and food enzymes, the nanomaterials used to create nanobiocatalysts and their application, along with the possible risks and legal aspects of nanomaterials in food bioprocesses.

Designing Sites in Heterogeneous Catalysis: Are We Reaching Selectivities Competitive With Those of Homogeneous Catalysts?

A critical review of different prominent nanotechnologies adapted to catalysis is provided, with focus on how they contribute to the improvement of selectivity in heterogeneous catalysis. Ways to modify catalytic sites range from the use of the reversible or irreversible adsorption of molecular modifiers to the immobilization or tethering of homogeneous catalysts and the development of well-defined catalytic sites on solid surfaces. The latter covers methods for the dispersion of single-atom sites within solid supports as well as the use of complex nanostructures, and it includes the post-modification of materials via processes such as silylation and atomic layer deposition. All these methodologies exhibit both advantages and limitations, but all offer new avenues for the design of catalysts for specific applications. Because of the high cost of most nanotechnologies and the fact that the resulting materials may exhibit limited thermal or chemical stability, they may be best aimed at improving the selective synthesis of high value-added chemicals, to be incorporated in organic synthesis schemes, but other applications are being explored as well to address problems in energy production, for instance, and to design greener chemical processes. The details of each of these approaches are discussed, and representative examples are provided. We conclude with some general remarks on the future of this field.

Cross-Linked Enzyme-Adhered Nanoparticles (CLEANs) for Continuous-Flow Bioproduction

Nanostructured but micro-sized biocatalysts were created by bottom-up technology using multi-functionalized silica nanoparticles (NPs) as nano-sized building blocks to form cross-linked enzyme-adhered nanoparticles (CLEANs) as robust micro-sized particles with beneficial internal structure and good mechanical properties. Systematic surface modification of NPs with a grafting mixture consisting of organosilanes with reactive (aminopropyl) and inert (e. g., vinyl, propyl, phenyl, or octyl) functions resulted in functional NPs enabling cross-linking agents, such as glutardialdehyde or bisepoxides (glycerol diglycidyl ether, neopentylglycol diglycidyl ether, and poly(propylene glycol) diglycidyl ether), to bind and cross-link enzymes covalently and to form macroporous microparticles. These CLEANs were able to diminish several weaknesses of traditional cross-linked enzyme aggregates as biocatalysts, such as poor mechanical resistance, difficult recovery, and storage, strengthening their use for packed-bed enzyme reactors. Lipase B from Candida antarctica (CaLB) was selected as model enzyme for development of robust CLEANs, which were successfully tested for various industrially relevant applications including a kinetic resolution of a racemic alcohol and the production of various natural fragrance compounds under continuous-flow conditions.

A Bi-enzymatic Immobilized Nanobiocatalyst for the Biotransformation of Oleuropein to Hydroxytyrosol

Multi-enzymatic assemblies offer the opportunity of bringing in proximity several enzymes that are enabled to work together for the catalysis of multi-step reactions. Especially, the development of robust nanobiocatalytic systems comprising of several enzymes has gained considerable attention over the last few years for the catalysis of complex reactions and the production of high added-value products. In the present chapter, we describe the methodology for the development of a bi-enzymatic nanobiocatalyst consisting of the enzymes β-glucosidase from Thermotoga maritima and lipase A from Candida antarctica (CalA) co-immobilized on chitosan-coated magnetic nanoparticles. This nanobiocatalyst can be efficiently applied for the biotransformation of oleuropein to hydroxytyrosol, a reaction of increased biotechnological interest. Several techniques, as well as methodologies that are required for the characterization of the structure and the activity of such systems are also comprehensively described.

Laccases as green and versatile biocatalysts: from lab to enzyme market-an overview

Laccases are multi-copper oxidase enzymes that catalyze the oxidation of different compounds (phenolics and non-phenolics). The scientific literature on laccases is quite extensive, including many basic and applied research about the structure, functions, mechanism of action and a variety of biotechnological applications of these versatile enzymes. Laccases can be used in various industries/sectors, from the environmental field to the cosmetics industry, including food processing and the textile industry (dyes biodegradation and synthesis). Known as eco-friendly or green enzymes, the application of laccases in biocatalytic processes represents a promising sustainable alternative to conventional methods. Due to the advantages granted by enzyme immobilization, publications on immobilized laccases increased substantially in recent years. Many patents related to the use of laccases are available, however, the real industrial or environmental use of laccases is still challenged by cost-benefit, especially concerning the feasibility of producing this enzyme on a large scale. Although this is a compelling point and the enzyme market is heated, articles on the production and application of laccases usually neglect the economic assessment of the processes. In this review, we present a description of laccases structure and mechanisms of action including the different sources (fungi, bacteria, and plants) for laccases production and tools for laccases evolution and prediction of potential substrates. In addition, we both compare approaches for scaling-up processes with an emphasis on cost reduction and productivity and critically review several immobilization methods for laccases. Following the critical view on production and immobilization, we provide a set of applications for free and immobilized laccases based on articles published within the last five years and patents which may guide future strategies for laccase use and commercialization.

Carbon nanomaterial properties help to enhance xylanase production from recombinant Kluyveromyces lactis through a cell immobilization method

Carbon nanomaterials, due to their catalytic activity and high surface area, have potential as cell immobilization supports to increase the production of xylanase. Recombinant Kluyveromyces lactis used for xylanase production was integrated into a polymeric gel network with carbon nanomaterials. Carbon nanomaterials were pretreated before cell immobilization with hydrochloric acid (HCl) treatment and glutaraldehyde (GA) crosslinking, which contributes to cell immobilization performance. Carbon nanotubes (CNTs) and graphene oxide (GO) were further screened using a Plackett-Burman experimental design. Cell loading and agar concentration were the most important factors in xylanase production with low cell leakage. Under optimized conditions, xylanase production was increased by more than 400% compared to free cells. Immobilized cell material containing such high cell densities may exhibit new and unexplored beneficial properties because the cells comprise a large fraction of the component. The use of carbon nanomaterials as a cell immobilization support along with the entrapment method successfully enhances the production of xylanase, providing a new route to improved bioprocessing, particularly for the production of enzymes. KEY POINTS: • Carbon nanomaterials (CNTs, GO) have potential as cell immobilization supports. • Entrapment in a polymeric gel network provides space for xylanase production. • Plackett-Burman design screen for the most important factor for cell immobilization.

Entrapment of Phenylalanine Ammonia-Lyase in Nanofibrous Polylactic Acid Matrices by Emulsion Electrospinning

Immobilization of the recombinant, plant-derived Petroselinum crispum phenylalanine ammonia lyase (PcPAL) in electrospun matrices have the potential to create promising, easy-to-use biocatalysts. Polylactic acid (PLA) a biologically inert, commercial biopolymer, was chosen as the material of the carrier system. PLA could be electrospun properly only from water-immiscible organic solvents, which limits its application as a carrier of sensitive biological objects. The emulsion electrospinning is a proper solution to overcome this issue using non-ionic emulsifiers with different hydrophilic-lipophilic balance (HLB) values. The stabilized emulsion could protect the sensitive PcPAL dissolved in the aqueous buffer phase and improve fiber formation, plus help to keep the biocatalytic activity of enzymes. In this study, the first approach is described to produce PLA nanofibers containing PcPAL enzymes by emulsion electrospinning and to use the resulted biocatalyst in the ammonia elimination reaction from l-phenylalanine.

Amylases from thermophilic bacteria: structure and function relationship

Amylases hydrolyze starch to diverse products including dextrins and progressively smaller polymers of glucose units. Thermally stable amylases account for nearly 25% of the enzyme market. This review highlights the structural attributes of the α-amylases from thermophilic bacteria. Heterologous expression of amylases in suitable hosts is discussed in detail. Further, specific value maximization approaches, such as protein engineering and immobilization of the amylases are discussed in order to improve its suitability for varied applications on a commercial scale. The review also takes into account of the immobilization of the amylases on nanomaterials to increase the stability and reusability of the enzymes. The function-based metagenomics would provide opportunities for searching amylases with novel characteristics. The review is expected to explore novel amylases for future potential applications.

Ionic Liquids for Development of Heterogeneous Catalysts Based on Nanomaterials for Biocatalysis

The development of effective methods of enzyme stabilization is key for the evolution of biocatalytic processes. An interesting approach combines the stabilization process of proteins in ionic liquids and the immobilization of the active phase on the solid support. As a result, stable, active and heterogeneous biocatalysts are obtained. There are several benefits associated with heterogeneous processes, as easy separation of the biocatalyst from the reaction mixture and the possibility of recycling. Accordingly, this work focused on the supported ionic liquid phases as the efficient enzyme stabilization carriers, and their application in both continuous flow and batch biocatalytic processes.

Engineered tyrosinases with broadened bio-catalysis scope: immobilization using nanocarriers and applications

Enzyme immobilization is a widely used technology for creating more stable, active, and reusable biocatalysts. The immobilization process also improves the enzyme's operating efficiency in industrial applications. Various support matrices have been designed and developed to enhance the biocatalytic efficiency of immobilized enzymes. Given their unique physicochemical attributes, including substantial surface area, rigidity, semi-conductivity, high enzyme loading, hyper catalytic activity, and size-assisted optical properties, nanomaterials have emerged as fascinating matrices for enzyme immobilization. Tyrosinase is a copper-containing monooxygenase that catalyzes the o-hydroxylation of monophenols to catechols and o-quinones. This enzyme possesses a wide range of uses in the medical, biotechnological, and food sectors. This article summarizes an array of nanostructured materials as carrier matrices for tyrosinase immobilization. Following a detailed background overview, various nanomaterials, as immobilization support matrices, including carbon nanotubes (CNTs), carbon dots (CDs), carbon black (CB), nanofibers, Graphene nanocomposite, platinum nanoparticles, nano-sized magnetic particles, lignin nanoparticles, layered double hydroxide (LDH) nanomaterials, gold nanoparticles (AuNPs), and zinc oxide nanoparticles have been discussed. Next, applied perspectives have been spotlights with particular reference to environmental pollutant sensing, phenolic compounds detection, pharmaceutical, and food industry (e.g., cereal processing, dairy processing, and meat processing), along with other miscellaneous applications.

Chitosan-based nanofibers for enzyme immobilization

The widespread application of soluble enzymes in industrial processes is considered restrict due to instability of enzymes outside optimum operating conditions. For instance, enzyme immobilization can overcome this issue. In fact, chitosan-based nanofibers have outstanding properties, which can improve the efficiency in enzyme immobilization and the stability of enzymes over a wide range of operating conditions. These properties include biodegradability, antimicrobial activity, non-toxicity, presence of functional groups (amino and hydroxyl), large surface area to volume ratio, enhanced porosity and mechanical properties, easy separations and reusability. Therefore, the present review explores the advantages and drawbacks concerning the different methods of enzyme immobilization, including adsorption, cross-linking and entrapment. All these strategies have questions that still need to be addressed, such as elucidation of adsorption mechanism (physisorption or chemisorption); effect of cross-linking reaction on intramolecular and intermolecular interactions and the effect of internal and external diffusional limitations on entrapment of enzymes. Moreover, the current review discusses the challenges and prospects regarding the application of chitosan-based nanofibers in enzyme immobilization, towards maximizing catalytic activity and lifetime.

Enzyme-Loaded Flower-Shaped Nanomaterials: A Versatile Platform with Biosensing, Biocatalytic, and Environmental Promise

As a result of their unique structural and multifunctional characteristics, organic-inorganic hybrid nanoflowers (hNFs), a newly developed class of flower-like, well-structured and well-oriented materials has gained significant attention. The structural attributes along with the surface-engineered functional entities of hNFs, e.g., their size, shape, surface orientation, structural integrity, stability under reactive environments, enzyme stabilizing capability, and organic-inorganic ratio, all significantly contribute to and determine their applications. Although hNFs are still in their infancy and in the early stage of robust development, the recent hike in biotechnology at large and nanotechnology in particular is making hNFs a versatile platform for constructing enzyme-loaded/immobilized structures for different applications. For instance, detection- and sensing-based applications, environmental- and sustainability-based applications, and biocatalytic and biotransformation applications are of supreme interest. Considering the above points, herein we reviewed current advances in multifunctional hNFs, with particular emphasis on (1) critical factors, (2) different metal/non-metal-based synthesizing processes (i.e., (i) copper-based hNFs, (ii) calcium-based hNFs, (iii) manganese-based hNFs, (iv) zinc-based hNFs, (v) cobalt-based hNFs, (vi) iron-based hNFs, (vii) multi-metal-based hNFs, and (viii) non-metal-based hNFs), and (3) their applications. Moreover, the interfacial mechanism involved in hNF development is also discussed considering the following three critical points: (1) the combination of metal ions and organic matter, (2) petal formation, and (3) the generation of hNFs. In summary, the literature given herein could be used to engineer hNFs for multipurpose applications in the biosensing, biocatalysis, and other environmental sectors.

Trends in the development of innovative nanobiocatalysts and their application in biocatalytic transformations

The ever-growing demand for cost-effective and innocuous biocatalytic transformations has prompted the rational design and development of robust biocatalytic tools. Enzyme immobilization technology lies in the formation of cooperative interactions between the tailored surface of the support and the enzyme of choice, which result in the fabrication of tremendous biocatalytic tools with desirable properties, complying with the current demands even on an industrial level. Different nanoscale materials (organic, inorganic, and green) have attracted great attention as immobilization matrices for single or multi-enzymatic systems. Aiming to unveil the potentialities of nanobiocatalytic systems, we present distinct immobilization strategies and give a thorough insight into the effect of nanosupports specific properties on the biocatalysts' structure and catalytic performance. We also highlight the development of nanobiocatalysts for their incorporation in cascade enzymatic processes and various types of batch and continuous-flow reactor systems. Remarkable emphasis is given on the application of such nanobiocatalytic tools in several biocatalytic transformations including bioremediation processes, biofuel production, and synthesis of bioactive compounds and fine chemicals for the food and pharmaceutical industry.

PTFE-Carbon Nanotubes and Lipase B from Candida antarctica-Long-Lasting Marriage for Ultra-Fast and Fully Selective Synthesis of Levulinate Esters

An effective method for levulinic acid esters synthesis by the enzymatic Fischer esterification of levulinic acid using a lipase B from Candida antarctica (CALB) immobilized on the advanced material consisting of multi-wall carbon nanotubes (MWCNTs) and a hydrophobic polymer—polytetrafluoroethylene (Teflon, PTFE)—as a heterogeneous biocatalyst, was developed. An active phase of the biocatalyst was obtained by immobilization via interfacial activation on the surface of the hybrid material MWCNTs/PTFE (immobilization yield: 6%, activity of CALB: 5000 U∙L∙kg⁻¹, enzyme loading: 22.5 wt.%). The catalytic activity of the obtained biocatalyst and the effects of the selected reaction parameters, including the agitation speed, the amount of PTFE in the CALB/MWCNT-PTFE biocatalyst, the amount of CALB/MWCNT-PTFE, the type of organic solvent, n-butanol excess, were tested in the esterification of levulinic acid by n-butanol. The results showed that the use of a two-fold excess of levulinic acid to n-butanol, 22.5 wt.% of CALB on MWCNT-PTFE (0.10 wt.%) and cyclohexane as a solvent at 20 °C allowed one to obtain n-butyl levulinate with a high yield (99%) and selectivity (>99%) after 45 min. The catalyst retained its activity and stability after three cycles, and then started to lose activity until dropping to a 69% yield of ester in the sixth reaction run. The presented method has opened the new possibilities for environmentally friendly synthesis of levulinate esters.

Green Synthesized Magnetic Nanoparticles as Effective Nanosupport for the Immobilization of Lipase: Application for the Synthesis of Lipophenols

In this work, hybrid zinc oxide-iron oxide (ZnOFe) magnetic nanoparticles were synthesized employing Olea europaea leaf aqueous extract as a reducing/chelating and capping medium. The resulting magnetic nanoparticles were characterized by basic spectroscopic and microscopic techniques, namely, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fourier-transform infrared (FTIR) and atomic force microscopy (AFM), exhibiting a spherical shape, average size of 15-17 nm, and a functionalized surface. Lipase from Thermomyces lanuginosus (TLL) was efficiently immobilized on the surface of ZnOFe nanoparticles through physical absorption. The activity of immobilized lipase was found to directly depend on the enzyme to support the mass ratio, and also demonstrated improved pH and temperature activity range compared to free lipase. Furthermore, the novel magnetic nanobiocatalyst (ZnOFe-TLL) was applied to the preparation of hydroxytyrosyl fatty acid esters, including derivatives with omega-3 fatty acids, in non-aqueous media. Conversion yields up to 90% were observed in non-polar solvents, including hydrophobic ionic liquids. Different factors affecting the biocatalyst performance were studied. ZnOFe-TLL was reutilized for eight subsequent cycles, exhibiting 90% remaining esterification activity (720 h of total operation at 50 °C). The green synthesized magnetic nanoparticles, reported here for the first time, are excellent candidates as nanosupports for the immobilization of enzymes with industrial interest, giving rise to nanobiocatalysts with elevated features.

Production and use of immobilized lipases in/on nanomaterials: A review from the waste to biodiesel production

As a highly efficient and environmentally friendly biocatalyst, immobilized lipase has received incredible interest among the biotechnology community for the production of biodiesel. Nanomaterials possess high enzyme loading, low mass transfer limitation, and good dispersibility, making them suitable biocatalytic supports for biodiesel production. In addition to traditional nanomaterials such as nano‑silicon, magnetic nanoparticles and nano metal particles, novel nanostructured forms such as nanoflowers, carbon nanotubes, nanofibers and metal-organic frameworks (MOFs) have also been studied for biodiesel production in the recent years. However, some problems still exist that need to be overcome in achieving large-scale biodiesel production using immobilized lipase on/in nanomaterials. This article mainly presents an overview of the current and state-of-the-art research on biodiesel production by immobilized lipases in/on nanomaterials. Various immobilization strategies of lipase on various advanced nanomaterial supports and its applications in biodiesel production are highlighted. Influential factors such as source of lipase, immobilization methods, feedstocks, and production process are also critically discussed. Finally, the current challenges and future directions in developing immobilized lipase-based biocatalytic systems for high-level production of biodiesel from waste resources are also recommended.

Development and characterization of a novel l-asparaginase/MWCNT nanobioconjugate

The enzyme l-asparaginase (ASNase) presents effective antineoplastic properties used for acute lymphoblastic leukemia treatment besides their potential use in the food sector to decrease the acrylamide formation. Considering their applications, the improvement of this enzyme's properties by efficient immobilization techniques is in high demand. Carbon nanotubes are promising enzyme immobilization supports, since these materials have increased surface area and effective capacity for enzyme loading. Accordingly, in this study, multi-walled carbon nanotubes (MWCNTs) were explored as novel supports for ASNase immobilization by a simple adsorption method. The effect of pH and contact time of immobilization, as well as the ASNase to nanoparticles mass ratio, were optimized according to the enzyme immobilization yield and relative recovered activity. The enzyme–MWCNTs bioconjugation was confirmed by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Raman and transmission electron microscopy (TEM) studies. MWCNTs have a high ASNase loading capacity, with a maximum immobilization yield of 90%. The adsorbed ASNase retains 90% of the initial enzyme activity at the optimized conditions (pH 8.0, 60 min, and 1.5 × 10⁻³ g mL⁻¹ of ASNase). According to these results, ASNase immobilized onto MWCNTs can find improved applications in several areas, namely biosensors, medicine and food industry.

l-Asparaginase immobilization by adsorption over MWCNTs for potential application in pharmaceutical and food industries.

Oxidation of Flame Retardant Tetrabromobisphenol A by a Biocatalytic Nanofiber of Chloroperoxidase

Background: Tetrabromobisphenol (TBBPA), a flame retardant compound, is considered a ubiquitous pollutant, with potential impact on the environment and human health. Several technologies have been applied to accelerate its degradation and minimize environmental impacts. Due to its aromaticity character, peroxidase enzymes may be employed to carry out its transformation in mild conditions. Therefore, the purpose of this work was to determine the capacity of the enzyme chloroperoxidase (CPO) to oxidize TBBPA in several water samples. Methods: The oxidation capacity of CPO was evaluated in catalytic conditions using water samples from surface and groundwater, as well as effluents from wastewater treatment plants. The biocatalytic performance of CPO was improved due to its immobilization on nanofibers composed of polyvinyl alcohol and chitosan (PVA/chitosan). Results: Free and immobilized CPO were able to transform more than 80% in short reaction times (60 min); producing more biodegradable and less toxic products. Particularly, the immobilized enzyme was catalytically active in a wider range of pH than the free enzyme with the possibility of reusing it up to five times. Conclusions: The biocatalytic oxidation of TBBPA under environmental conditions is highly efficient, even in complex media such as treated effluents of wastewater treatment plants.

Impact of immobilization technology in industrial and pharmaceutical applications

The current demands of the world's biotechnological industries are enhancement in enzyme productivity and development of novel techniques for increasing their shelf life. Compared to free enzymes in solution, immobilized enzymes are more robust and more resistant to environmental changes. More importantly, the heterogeneity of the immobilized enzyme systems allows an easy recovery of both enzymes and products, multiple reuse of enzymes, continuous operation of enzymatic processes, rapid termination of reactions, and greater variety of bioreactor designs. This review summarizes immobilization definition, different immobilization methods, advantages and disadvantages of each method. In addition, it covers some food industries, protein purification, human nutrition, biodiesel production, and textile industry. In these industries, the use of enzymes has become an inevitable processing strategy when a perfect end product is desired. It also can be used in many other important industries including health care and pharmaceuticals applications. One of the best uses of enzymes in the modern life is their application in diagnose and treatment of many disease especially when used in drug delivery system or when used in nanoform.

Development of a Four-Enzyme Magnetic Nanobiocatalyst for Multi-Step Cascade Reactions

We report the preparation, characterization and application of a novel magnetic four-enzyme nanobiocatalyst prepared by the simultaneous covalent co-immobilization of cellulase (CelDZ1), β-glucosidase (bgl), glucose oxidase (GOx) and horseradish peroxidase (HRP) onto the surface of amino-functionalized magnetic nanoparticles (MNPs). This nanobiocatalyst was characterized by various spectroscopic techniques. The co-immobilization process yielded maximum recovered enzymatic activity (CelDZ1: 42%, bgl: 66%, GOx: 94% and HRP: 78%) at a 10% v/v cross-linker concentration, after 2 h incubation time and at 1:1 mass ratio of MNPs to total enzyme content. The immobilization process leads to an increase of Km and a decrease of Vmax values of co-immobilized enzymes. The thermal stability studies of the co-immobilized enzymes indicated up to 2-fold increase in half-life time constants and up to 1.5-fold increase in their deactivation energies compared to the native enzymes. The enhanced thermodynamic parameters of the four-enzyme co-immobilized MNPs also suggested increment in their thermal stability. Furthermore, the co-immobilized enzymes retained a significant part of their activity (up to 50%) after 5 reaction cycles at 50 °C and remained active even after 24 d of incubation at 5 °C. The nanobiocatalyst was successfully applied in a four-step cascade reaction involving the hydrolysis of cellulose.

Enzyme Immobilization on Metal-Organic Framework (MOF): Effects on Thermostability and Function

MOFs are porous materials with adjustable porosity ensuing a tenable surface area and stability. MOFs consist of metal containing joint where organic ligands are linked with coordination bonding rendering a unique architecture favouring the diverse applications in attachment of enzymes, Chemical catalysis, Gases storage and separation, biomedicals. In the past few years immobilization of soluble enzymes on/in MOF has been the topic of interest for scientists working in diverse field. The activity of enzyme, reusability, storage, chemical and thermal stability, affinity with substrate can be greatly improved by immobilizing of enzyme on MOFs. Along with improvement in enzymes properties, the high loading of enzyme is also observed while using MOFs as immobilization support. In this review a detail study of immobilization on/in Metalorganic Frameworks (MOFs) have been described. Furthermore, strategies for the enzyme immobilization on MOFs and resulting in improved catalytic performance of immobilized enzymes have been reported.

LSPR-based cholesterol biosensor using a tapered optical fiber structure

Accurate cholesterol level measurement plays an important role in the diagnosis of severe diseases such as cardiovascular diseases, hypertension, anemia, myxedemia, hyperthyroidism, coronary artery illness. Traditionally, electrochemical sensors have been employed to detect the cholesterol level. However, these sensors have limitations in terms of sensitivity and selectivity. In this paper, a localized surface plasmon resonance (LSPR) -based biosensor is demonstrated that accurately detects and measures the concentration of cholesterol. In the present study, a tapered optical fiber-based sensor probe is developed using gold nanoparticles (AuNPs) and cholesterol oxidase (ChOx) to increase the sensitivity and selectivity of the sensor. Synthesized AuNPs were characterized by UV-visible spectrophotometer, transmission electron microscope (TEM), and energy dispersive X-ray spectroscopy (EDS). Further, coating of AuNPs over fiber was confirmed by scanning electron microscope (SEM). The developed sensor demonstrates for a clinically important cholesterol range of 0 to 10 mM, and the limit of detection is found to be 53.1 nM.

LSPR-based cholesterol biosensor using a tapered optical fiber structure

Accurate cholesterol level measurement plays an important role in the diagnosis of severe diseases such as cardiovascular diseases, hypertension, anemia, myxedemia, hyperthyroidism, coronary artery illness. Traditionally, electrochemical sensors have been employed to detect the cholesterol level. However, these sensors have limitations in terms of sensitivity and selectivity. In this paper, a localized surface plasmon resonance (LSPR) -based biosensor is demonstrated that accurately detects and measures the concentration of cholesterol. In the present study, a tapered optical fiber-based sensor probe is developed using gold nanoparticles (AuNPs) and cholesterol oxidase (ChOx) to increase the sensitivity and selectivity of the sensor. Synthesized AuNPs were characterized by UV-visible spectrophotometer, transmission electron microscope (TEM), and energy dispersive X-ray spectroscopy (EDS). Further, coating of AuNPs over fiber was confirmed by scanning electron microscope (SEM). The developed sensor demonstrates for a clinically important cholesterol range of 0 to 10 mM, and the limit of detection is found to be 53.1 nM.

Laccase-Catalyzed Reduction of Oxygen at Electrodes Modified by Carbon Nanotubes with Adsorbed Promazine or Acetosyringone

One of the problems with the use of enzymes as catalysts in biofuel cells is to achieve good contact between the enzyme and the electrode surface. One solution to this problem is the use of various nanostructures such as carbon nanotubes, fullerenes, graphene derivatives, gold nanoparticles, as well as mediators for the construction of electrodes. Acetosyringone and promazine adsorbed on glassy carbon electrodes (GCEs) covered with multiwall carbon nanotubes (MWCNTs) and laccase were used as biocathodes. These mediators showed very efficient adsorption on modified glassy carbon electrodes covered with MWCNTs and enabled efficient and stable adsorption of laccase, which acts as the bioelectrocatalyst. Very good electrical contact between the electrode surface and the laccase enzymatic active sites made it possible to increase the catalytic current density of oxygen-reduction by about 82% compared to electrodes without mediators. Application of acetosyringone and promazine used in the construction of biocathode also improved the current and power of the biobattery ca. twice comparing to the system without mediators. The device output reached the power that equaled approximately 2 mW/cm2 at 0.8 V and open circuit potential (OCP) was 1.6 V. The systems elaborated proved also useful in oxygen sensing and allowed to determine lower oxygen concentrations in solution compared to the GCE modified with MWCNTs and laccase alone. The electrode showed also better stability in long-timescale measurements.

Smart Nanoparticles for Selective Immobilization of Acid Phosphatases

An easy to use method combining the selectivity of metal chelate affinity binding with strong covalent linking was developed for immobilization of non-specific acid phosphatases bearing a His-tag from crude cell lysate. Silica nanoparticles were grafted with aminopropyl functions which were partially transformed further with EDTA dianhydride to chelators. The heterofunctionalized nanoparticles charged with Ni2+ as the most appropriate metal ion were applied as support. First, the His-tagged phosphatases were selectively bound to the metal-chelate functions of the support. Then, the enzyme-charged silica nanoparticles were further stabilized by forming a covalent linkage between nucleophilic moieties at the enzyme surface and free amino groups of the support using neopentylglycol diglycidylether as the most effective bifunctional linking agent. The phosphatase biocatalysts obtained by this method exhibited better phosphate transfer activity with a range of alcohols and PPi as phosphate donor in aqueous medium applying batch and continuous-flow modes than the ones immobilized on conventional supports. Furthermore, this novel strategy opens up novel possibility for efficient immobilization of other His-tagged recombinant enzymes.

Nano-Immobilized Biocatalysts for Biodiesel Production from Renewable and Sustainable Resources

The cost of biodiesel production relies on feedstock cost. Edible oil is unfavorable as a biodiesel feedstock because of its expensive price. Thus, non-edible crop oil, waste oil, and microalgae oil have been considered as alternative resources. Non-edible crop oil and waste cooking oil are more suitable for enzymatic transesterification because they include a large amount of free fatty acids. Recently, enzymes have been integrated with nanomaterials as immobilization carriers. Nanomaterials can increase biocatalytic efficiency. The development of a nano-immobilized enzyme is one of the key factors for cost-effective biodiesel production. This paper presents the technology development of nanomaterials, including nanoparticles (magnetic and non-magnetic), carbon nanotubes, and nanofibers, and their application to the nano-immobilization of biocatalysts. The current status of biodiesel production using a variety of nano-immobilized lipase is also discussed.

Superiority of amino-modified chiral mesoporous silica nanoparticles in delivering indometacin

The present study established indometacin (IMC) delivery system with chiral mesoporous silica nanoparticles (CMSNs) and amino-modified chiral mesoporous silica nanoparticles (Amino-CMSNs) that previously reported as pharmaceutical excipients, and their systemic biological effects, mainly consisting of in vitro drug intestinal permeability, haemolysis assay, in vivo pharmacokinetics, anti-inflammation pharmacodynamics and gastric irritation, were addressed. It turned out that the two IMC delivery systems established by CMSN and Amino-CMSN significantly improved drug intestinal permeability due to the improved drug dissolution caused by conversion of drug crystalline state to amorphous phase. Further, IMC-loaded Amino-CMSN was the superior choice because of its higher dissolution rate. Furthermore, CMSN and Amino-CMSN were safe to be circulated in blood, and Amino-CMSN with significant lower haemolysis ratio than CMSN was better for the minimum haemolytic behaviour. Oral bioavailability and anti-inflammation effect of IMC delivery systems established by CMSN and Amino-CMSN were enhanced compared with IMC, which was attributed to the primary cause of the improvement of IMC dissolution, and Amino-CMSN exhibited better biological effect. As a result of these facts, it is believed that the effective delivery of IMC by Amino-CMSN will provide a new candidate to formulate poorly soluble drugs so as to significantly develop pharmaceutical application.