Efficient magnetic recycling of covalently attached enzymes on carbon-coated metallic nanomagnets

Proteases: Importance, Immobilization Protocols, Potential of Activated Carbon as Support, and the Importance of Modifying Supports for Immobilization

Although enzymes have been used for thousands of years, their application in industrial processes has gained importance since the 20th century due to technological and scientific advances in several areas, including biochemistry [...].

Multipoint Immobilization at Inert Center of Papain on Homo-Functional Diazo-Activated Silica Support: A Way of Restoring "Above Room-Temperature" Bio-Catalytic Sustainability

Although enzymes play a significant role in industrial applications, their potential usage at high-level efficiency, particularly above room temperature, has not yet been fully harnessed. It brings above room-temperature catalytic sustainability of an immobilized (imm.) bio-catalyst as a long pending issue to improve enzyme stability, activity, specificity, or selectivity, particularly the enantio-selectivity over the native-enzymes. At this juncture, in a robust methodology, a heterogeneous solid phase bio-catalyst, {Si(OSi)₄(H₂O)_1.03}_n=328{OSi(CH₃)₂-NH-C₆H₄-N═N}₄{papain}(H₂O)₂₅₁, has efficiently been prepared by immobilizing papain on homo-functionalized SG (silica-gel) via multipoint covalent attachment. The bio-catalyst is easy to be recovered and reused multiple times. The homo-functional -N═N⁺, which appears on the SG-surface, makes the multipoint diazo-links with the inert center of the tyrosine-moiety to couple the enzyme where all the amino, thiol, phenol, and so forth, groups of the protein, including those that belong to the active-site, remain intact. The immobilized enzyme (13.9 μmol g^-1) swims in pore-water within the pore-channel, remains stable up to 70 ± 5 °C, and exhibits wider temperature adaptability in performing its hydrolyzing activities. The relative activity, 78 ± 2% at 27 °C, remains quantitative for 60 days and can be reused for 60 cycles with 53% activity at room-temperature. The thermal (relative activity: 87%; incubated at 70 ± 5 °C for 24 h) and mechanical (relative activity: 92%; incubated at 2500 rpm for 2 h at 27 °C) stability was outstanding.

A Convenient U-Shape Microreactor for Continuous Flow Biocatalysis with Enzyme-Coated Magnetic Nanoparticles-Lipase-Catalyzed Enantiomer Selective Acylation of 4-(Morpholin-4-yl)butan-2-ol

This study implements a convenient microreactor for biocatalysis with enzymes immobilized on magnetic nanoparticles (MNPs). The enzyme immobilized onto MNPs by adsorption or by covalent bonds was lipase B from Candida antarctica (CaLB). The MNPs for adsorption were obtained by covering the magnetite core with a silica shell and later with hexadecyltrimethoxysilane, while for covalent immobilization, the silica-covered MNPs were functionalized by a layer forming from mixtures of hexadecyl- and 3-(2-aminoethylamino)propyldimethoxymethylsilanes in 16:1 molar ratio, which was further activated with neopentyl glycol diglycidyl ether (NGDE). The resulting CaLB-MNPs were tested in a convenient continuous flow system, created by 3D printing to hold six adjustable permanent magnets beneath a polytetrafluoroethylene tube (PTFE) to anchor the MNP biocatalyst inside the tube reactor. The anchored CaLB-MNPs formed reaction chambers in the tube for passing the fluid through and above the MNP biocatalysts, thus increasing the mixing during the fluid flow and resulting in enhanced activity of CaLB on MNPs. The enantiomer selective acylation of 4-(morpholin-4-yl)butan-2-ol (±)-1, being the chiral alcohol constituent of the mucolytic drug Fedrilate, was carried out by CaLB-MNPs in the U-shape reactor. The CaLB-MNPs in the U-shape reactor were compared in batch reactions to the lyophilized CaLB and to the CaLB-MNPs using the same reaction composition, and the same amounts of CaLB showed similar or higher activity in flow mode and superior activity as compared to the lyophilized powder form. The U-shape permanent magnet design represents a general and easy-to-access implementation of MNP-based flow microreactors, being useful for many biotransformations and reducing costly and time-consuming downstream processes.

Surface-coated magnetic nanostructured materials for robust bio-catalysis and biomedical applications-A review

BACKGROUND

Enzymes based bio-catalysis has wide range of applications in various chemical and biological processes. Thus, the process of enzymes immobilization on suitable support to obtain highly active and stable bio-catalysts has great potential in industrial applications. Particularly, surface-modified magnetic nanomaterials have garnered a special interest as versatile platforms for biomolecules/enzyme immobilization.

AIM OF REVIEW

This review spotlights recent progress in the immobilization of various enzymes onto surface-coated multifunctional magnetic nanostructured materials and their derived nano-constructs for multiple applications. Conclusive remarks, technical challenges, and insightful opinions on this field of research which are helpful to expand the application prospects of these materials are also given with suitable examples.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Nanostructured materials, including surface-coated magnetic nanoparticles have recently gained immense significance as suitable support materials for enzyme immobilization, due to their large surface area, unique functionalities, and high chemical and mechanical stability. Besides, magnetic nanoparticles are less expensive and offers great potential in industrial applications due to their easy recovery and separation form their enzyme conjugates with an external magnetic field. Magnetic nanoparticles based biocatalytic systems offer a wide-working temperature, pH range, increased storage and thermal stabilities. So far, several studies have documented the application of a variety of surface modification and functionalization techniques to circumvent the aggregation and oxidation of magnetic nanoparticles. Surface engineering of magnetic nanoparticles (MNPs) helps to improve the dispersion stability, enhance mechanical and physicochemical properties, upgrade the surface activity and also increases enzyme immobilization capabilities and biocompatibility of the materials. However, several challenges still need to be addressed, such as controlled synthesis of MNPs and clinical aspects of these materials require consistent research from multidisciplinary scientists to realize its practical applications.

Recent Trends in Enzyme Immobilization-Concepts for Expanding the Biocatalysis Toolbox

Enzymes have been exploited by humans for thousands of years in brewing and baking, but it is only recently that biocatalysis has become a mainstream technology for synthesis. Today, enzymes are used extensively in the manufacturing of pharmaceuticals, food, fine chemicals, flavors, fragrances and other products. Enzyme immobilization technology has also developed in parallel as a means of increasing enzyme performance and reducing process costs. The aim of this review is to present and discuss some of the more recent promising technical developments in enzyme immobilization, including the supports used, methods of fabrication, and their application in synthesis. The review highlights new support technologies such as the use of well-established polysaccharides in novel ways, the use of magnetic particles, DNA, renewable materials and hybrid organic–inorganic supports. The review also addresses how immobilization is being integrated into developing biocatalytic technology, for example in flow biocatalysis, the use of 3D printing and multi-enzymatic cascade reactions.

Building Tailored Interfaces through Covalent Coupling Reactions at Layers Grafted from Aryldiazonium Salts

Aryldiazonium ions are widely used reagents for surface modification. Attractive aspects of their use include wide substrate compatibility (ranging from plastics to carbons to metals and metal oxides), formation of stable covalent bonding to the substrate, simplicity of modification methods that are compatible with organic and aqueous solvents, and the commercial availability of many aniline precursors with a straightforward conversion to the active reagent. Importantly, the strong bonding of the modifying layer to the surface makes the method ideally suited to further on-surface (postfunctionalization) chemistry. After an initial grafting from a suitable aryldiazonium ion to give an anchor layer, a target species can be coupled to the layer, hugely expanding the range of species that can be immobilized. This strategy has been widely employed to prepare materials for numerous applications including chemical sensors, biosensors, catalysis, optoelectronics, composite materials, and energy conversion and storage. In this Review our goal is first to summarize how a target species with a particular functional group may be covalently coupled to an appropriate anchor layer. We then review applications of the resulting materials.

Armoring bio-catalysis via structural and functional coordination between nanostructured materials and lipases for tailored applications

Nanostructured materials represent an interesting and novel class of support matrices for the immobilization of different enzymes. Owing to the high surface area, robust mechanical stability, outstanding optical, thermal, and electrical properties, nanomaterials have been rightly perceived as desired immobilization matrices for lipases immobilization with a wide array of biotechnological applications such as dairy, food technology, fine chemical, pharmaceutical, detergent, and oleochemical industries. Lipases immobilized on nanomaterials have demonstrated superior attributes than free counterparts, such as aggrandized pH and thermal stability, robustness, long-term stability, and the possibility of reuse and recycling in several times. Here we review current and state-of-the-art literature on the use of nanomaterials as novel platforms for the immobilization of lipase enzymes. The physicochemical properties and exploitation of a large number of new nanostructured materials such as carbon nanotubes, nano-silica, graphene/graphene oxide, metal nanoparticles, magnetic nanostructures, metal-organic frameworks, and hybrid nanoflowers as a host matrix to constitute robust lipases-based nanobiocatalytic systems are discussed. Conclusive remarks, trends, and future recommendations for nanomaterial immobilized enzymes are also given.

Advances in Recombinant Lipases: Production, Engineering, Immobilization and Application in the Pharmaceutical Industry

Lipases are one of the most used enzymes in the pharmaceutical industry due to their efficiency in organic syntheses, mainly in the production of enantiopure drugs. From an industrial viewpoint, the selection of an efficient expression system and host for recombinant lipase production is highly important. The most used hosts are Escherichia coli and Komagataella phaffii (previously known as Pichia pastoris) and less often reported Bacillus and Aspergillus strains. The use of efficient expression systems to overproduce homologous or heterologous lipases often require the use of strong promoters and the co-expression of chaperones. Protein engineering techniques, including rational design and directed evolution, are the most reported strategies for improving lipase characteristics. Additionally, lipases can be immobilized in different supports that enable improved properties and enzyme reuse. Here, we review approaches for strain and protein engineering, immobilization and the application of lipases in the pharmaceutical industry.

Biochemical functionality of magnetic particles as nanosensors: how far away are we to implement them into clinical practice?

Magnetic nanosensors have become attractive instruments for the diagnosis and treatment of different diseases. They represent an efficient carrier system in drug delivery or in transporting contrast agents. For such purposes, magnetic nanosensors are used in vivo (intracorporeal application). To remove specific compounds from blood, magnetic nanosensors act as elimination system, which represents an extracorporeal approach. This review discusses principles, advantages and risks on recent advances in the field of magnetic nanosensors. First, synthesis methods for magnetic nanosensors and possibilities for enhancement of biocompatibility with different coating materials are addressed. Then, attention is devoted to clinical applications, in which nanosensors are or may be used as carrier- and elimination systems in the near future. Finally, risk considerations and possible effects of nanomaterials are discussed when working towards clinical applications with magnetic nanosensors.

Development of a reusable and sustainable biocatalyst by immobilization of soybean peroxidase onto magnetic adsorbent

In this work we synthesized an activated carbon/magnetite composite by a simple co-precipitation method. The activated carbon (AC) was synthesized from the solid waste obtained in the extraction process of the peroxidase enzyme and the magnetic composite was used as support for the immobilization of soybean peroxidase (SP). After the determination of the optimal immobilization parameters, a 100% yield was achieved under the following conditions: support:enzyme proportion of 1.0:0.05 g, equilibration time of 7 h, pH 3.0 (citrate buffer phosphate 0.1 mol L-1) and temperature of 50 °C. The determination of pH to the point of zero charge was also done to assist in the understanding of the immobilization process at different pH values. Several characterization techniques were used, such as thermogravimetric analysis, elemental analysis composition, X-ray powder diffraction, Fourier transform infrared spectroscopy and Scanning electron microscopy. The biocatalyst presented excellent operational stability and was reused for 11 consecutive cycles. The magnetic properties inserted in the AC contributed to the removal of the biocatalyst from the reaction medium without interfering in the adsorptive characteristics of the AC. Thus, the activated carbon/magnetite composite can be applied to different research fields with high performance.

Kinase-loaded magnetic beads for sequentialin vitrophosphorylation of peptides and proteins

Kinases ERK2 and GSK-3β loaded magnetic beads for sequentialin vitrophosphorylation of peptides and proteins.

Sulfonated carbon-encapsulated iron nanoparticles as an efficient magnetic nanocatalyst for highly selective synthesis of benzimidazoles

Various benzimidazoles were obtained by applying sulfonated carbon-encapsulated iron nanoparticles as the nanocatalyst.

Advances in biotechnological synthetic applications of carbon nanostructured systems

In the last few years carbon nanostructures have been applied for the immobilization of enzymes and biomimetic organo-metallic species useful for biotechnological applications. The nature of the support and the method of immobilization are responsible for the stability, reactivity and selectivity of the system. In this review, we focus on the recent advances in the use of carbon nanostructures, carbon nanotubes, carbon nanorods, fullerene and graphene for the preparation of biocatalytic and biomimetic systems and for their application in the development of green chemical processes.

Click and release: fluoride cleavable linker for mild bioorthogonal separation

Herein, we present a water dispersable, magnetic nanoparticle supported "click and release" system. The cleavable linker has been synthesized by using a strain-promoted copper-free "click" reagent to establish the specific link and a fluoride cleavable silane moiety for mild cleavage. Small organic molecules, azide-bearing dyes and functionalized enzymes have been bound to the magnetic particle and released in a bioorthogonal way.

Immobilization of Cellulase on Magnetic Nanocarriers

The constant increase in the number of sustainable products on the global markets demands new biotechnological processing strategies such as the purification and recovery of biocatalysts. Superparamagnetic iron oxide nanoparticles exhibit excellent recovery properties as carrier materials in enzyme catalysis. We present the simple and fast electrostatic assembly of cellulase (CEL) and low-priced silica-coated magnetic nanoparticles, which demonstrates stable enzyme bonding and excellent colloidal stability. The high CEL loading (0.43 g g-1), without leaching of biocatalyst and high recovery yields (75 %), could be sustained over ten magnetic recycling steps. The highlight of this study is the preservation of a high enzymatic activity and, therefore, the outstandingly high lifecycle stability.

Plasmonic Enzyme-Linked Immunosorbent Assay Using Nanospherical Brushes as a Catalase Container for Colorimetric Detection of Ultralow Concentrations of Listeria monocytogenes

Plasmonic enzyme-linked immunosorbent assay (pELISA) based on catalase (CAT)-mediated gold nanoparticle growth exhibits ultrahigh sensitivity for detecting disease-related biomarkers using sandwich formats. However, the limit of detection (LOD) of this strategy for Listeria monocytogenes is only around 10(3) CFU/mL, which considerably exceeds the amount of L. monocytogenes commonly present in food products (<100 CFU/g). Herein, we report an improved pELISA method for detection of L. monocytogenes at ultralow concentrations with the sandwich formats using silica nanoparticles carrying poly(acrylic acid) brushes as a "CAT container" to increase enzyme loading for enhancing the detection signal. Under optimal conditions, the proposed pELISA exhibits good specificity and excellent sensitivity for L. monocytogenes with a LOD of 8 × 10(1) CFU/mL in 0.01 M phosphate-buffered saline, via a reaction that can be discriminated by the naked eye. The LOD obtained by this method was 2 and 5 orders of magnitude lower than that of conventional CAT-based pELISA and horseradish peroxidase (HRP)-based conventional ELISA, respectively. Coupled with large-volume immunomagnetic separation, the LOD for L. monocytogenes-spiked lettuce samples reached 8 × 10(1) CFU/g. The improved pELISA also exhibited a great potential in detecting a single cell of L. monocytogenes in 100 μL of solution.

Stable dispersions of azide functionalized ferromagnetic metal nanoparticles

Stable dispersions of azide functionalized ferromagnetic metal nanoparticles were synthesized by covalent attachment of a block-copolymer to the nanoparticles surface via SI-ATRP and subsequent post-modification.