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The Latest Trends in Catalyst Immobilization

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Organic Chemistry".

Deadline for manuscript submissions: closed (31 December 2022) | Viewed by 27014

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Prof. Dr. Alessandra Puglisi

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Dipartimento di Chimica, Università degli Studi di Milano, Via Golgi 19, 20133 Milano, Italy
Interests: organic synthesis; stereoselective catalysis; supported catalysts and catalytic reactors; flow chemistry; 3D printing technologies for organic synthesis
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Dear Colleagues,

Immobilized catalysts represent a key tool for the development of a modern and sustainable chemistry. The anchoring of a catalyst into a (solid) support with the aim of facilitating its recovery and, ultimately, its recycling, is a well-established methodology with a long history. However, research in this field is still very active and attractive, since heterogenized catalysts can contribute to the realization of more environmentally friendly processes. This Special Issue has the goal to include the latest trends in the field of immobilized catalysts: chiral and achiral catalysts and organo- and metal-based catalysts. In this very broad topic, a special mention goes to biocatalysis: The use of (supported) enzymes as “special” catalysts is a powerful methodology in the hands of the synthetic organic chemist who wants to develop efficient and highly stereoselective catalytic reactions. The chosen (solid) support often plays a fundamental role in the success of the catalyst itself. Not only does it dictate the possible recovery (and recycle) of the catalytic species, but it often influences the catalyst performances, either in a positive or in a negative way. In other words, the support can enhance the stability of the immobilized catalyst, leading to a more active catalyst, or it can depress its reactivity. This is the reason the development of new and “smart” materials is a topic strictly related to the development of new supported catalysts. Moreover, the support itself may have catalytic properties. This Special Issue on “The Latest Trends in Catalyst Immobilization” will serve as an opportunity to bring together the different aspects of catalyst heterogenization: the design of new, modified catalytic species ready for the anchoring, the development of new materials that can act as a support or a catalyst, the characterization of the catalytic system, and the studies on catalyst activity and recyclability.

You may choose our Joint Special Issue in Chemistry.

Prof. Dr. Alessandra Puglisi
Guest Editor

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Keywords

immobilized catalysts
solid support
organocatalysis
metal catalysis
biocatalysis
enzymes
recyclable catalyst
smart materials
sustainable process

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The Latest Trends in Catalyst Immobilization in Chemistry (1 article)

Published Papers (11 papers)

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28 pages, 4553 KiB

Open AccessArticle

(Magnetic) Cross-Linked Enzyme Aggregates of Cellulase from T. reesei: A Stable and Efficient Biocatalyst

by Dušica Ifko, Katja Vasić, Željko Knez and Maja Leitgeb

Molecules 2023, 28(3), 1305; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules28031305 - 30 Jan 2023

Cited by 6 | Viewed by 2089

Abstract

Cross-linked enzyme aggregates (CLEAs) represent an effective tool for carrier-free immobilization of enzymes. The present study promotes a successful application of functionalized magnetic nanoparticles (MNPs) for stabilization of cellulase CLEAs. Catalytically active CLEAs and magnetic cross-linked enzyme aggregates (mCLEAs) of cellulase from Trichoderma reesei were prepared using glutaraldehyde (GA) as a cross-linking agent and the catalytic activity and stability of the CLEAs/mCLEAs were investigated. The influence of precipitation agents, cross-linker concentration, concentration of enzyme, addition of bovine serum albumin (BSA), and addition of sodium cyanoborohydride (NaBH₃CN) on expressed activity and immobilization yield of CLEAs/mCLEAs was studied. Particularly, reducing the unsaturated Schiff’s base to form irreversible linkages is important and improved the activity of CLEAs (86%) and mCLEAs (91%). For increased applicability of CLEAs/mCLEAs, we enhanced the activity and stability at mild biochemical process conditions. The reusability after 10 cycles of both CLEAs and mCLEAs was investigated, which retained 72% and 65% of the initial activity, respectively. The thermal stability of CLEAs and mCLEAs in comparison with the non-immobilized enzyme was obtained at 30 °C (145.65% and 188.7%, respectively) and 50 °C (185.1% and 141.4%, respectively). Kinetic parameters were determined for CLEAs and mCLEAs, and the K_M constant was found at 0.055 ± 0.0102 mM and 0.037 ± 0.0012 mM, respectively. The maximum velocity rate (V_max) was calculated as 1.12 ± 0.0012 µmol/min for CLEA and 1.17 ± 0.0023 µmol/min for mCLEA. Structural characterization was studied using XRD, SEM, and FT-IR. Catalytical properties of immobilized enzyme were improved with the addition of reducent NaBH₃CN by enhancing the activity of CLEAs and with addition of functionalized aminosilane MNPs by enhancing the activity of mCLEAs. Full article

(This article belongs to the Special Issue The Latest Trends in Catalyst Immobilization)

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12 pages, 2100 KiB

Open AccessArticle

Simple Enzyme Immobilization for Flow Chemistry? An Assessment of Available Strategies for an Acetaldehyde-Dependent Aldolase

by Martin Wäscher, Thomas Classen and Jörg Pietruszka

Molecules 2022, 27(19), 6483; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27196483 - 01 Oct 2022

Viewed by 1367

Abstract

Enzyme immobilization is a technology that enables (bio-)catalysts to be applied in continuous-flow systems. However, there is a plethora of immobilization methods available with individual advantages and disadvantages. Here, we assessed the influence of simple and readily available methods with respect to the performance of 2-deoxy-d-ribose-5-phosphate aldolase (DERA) in continuous-flow conditions. The investigated immobilization strategies cover the unspecific attachment to carriers via epoxides, affinity-based attachment via metal ion affinity, StrepTag™-StrepTactin™ interaction as well as the covalent affinity attachment of an enzyme to a matrix tethered by the HaloTag^®. The metal-ion-affinity-based approach outperformed the other methods in terms of immobilized activity and stability under applied conditions. As most enzymes examined today already have a HisTag for purification purposes, effective immobilization may be applied, as simple as a standard purification, if needed. Full article

(This article belongs to the Special Issue The Latest Trends in Catalyst Immobilization)

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10 pages, 1536 KiB

Open AccessArticle

Supported Eosin Y as a Photocatalyst for C-H Arylation of Furan in Batch and Flow

by Sergio Rossi, Fabian Herbrik, Simonetta Resta and Alessandra Puglisi

Molecules 2022, 27(16), 5096; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27165096 - 10 Aug 2022

Cited by 7 | Viewed by 1646

Abstract

Eosin Y is one of the most popular organic dyes used as a photoredox catalyst and is largely employed in photochemical reactions both as a homogeneous and heterogeneous photocatalyst after immobilization. Immobilization of Eosin Y onto a solid support has many advantages, such as the possibility of recovery and reuse of the photocatalyst and the possibility of its use under flow conditions. In this paper, we report our findings on the immobilization of Eosin Y onto Merrifield resin and its application in the direct photochemical arylation of furan with aryldiazonium salts. The synthesized supported photocatalyst was used in batch reactions under heterogeneous conditions with different aryl diazonium salts, and its recovery and recycle were demonstrated for up to three times. The immobilized photocatalyst was then loaded in a packed-bed reactor and used under continuous flow conditions. The flow reaction allowed the arylated products to be obtained with higher productivity and space-time-yield than the batch in a very short reaction time. Full article

(This article belongs to the Special Issue The Latest Trends in Catalyst Immobilization)

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14 pages, 2508 KiB

Open AccessArticle

Co-Immobilization of RizA Variants with Acetate Kinase for the Production of Bioactive Arginyl Dipeptides

by Sven Bordewick, Ralf G. Berger and Franziska Ersoy

Molecules 2022, 27(14), 4352; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27144352 - 07 Jul 2022

Cited by 2 | Viewed by 1381

Abstract

The biocatalytic system comprised of RizA and acetate kinase (AckA) combines the specific synthesis of bioactive arginyl dipeptides with efficient ATP regeneration. Immobilization of this coupled enzyme system was performed and characterized in terms of activity, specificity and reusability of the immobilisates. Co-immobilization of RizA and AckA into a single immobilisate conferred no disadvantage in comparison to immobilization of only RizA, and a small addition of AckA (20:1) was sufficient for ATP regeneration. New variants of RizA were constructed by combining mutations to yield variants with increased biocatalytic activity and specificity. A selection of RizA variants were co-immobilized with AckA and used for the production of the salt-taste enhancers Arg-Ser and Arg-Ala and the antihypertensive Arg-Phe. The best variants yielded final dipeptide concentrations of 11.3 mM Arg-Ser (T81F_A158S) and 11.8 mM Arg-Phe (K83F_S156A), the latter of which represents a five-fold increase in comparison to the wild-type enzyme. T81F_A158S retained more than 50% activity for over 96 h and K83F_S156A for over 72 h. This study provides the first example of the successful co-immobilization of an l-amino acid ligase with an ATP-regenerating enzyme and paves the way towards a bioprocess for the production of bioactive dipeptides. Full article

(This article belongs to the Special Issue The Latest Trends in Catalyst Immobilization)

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13 pages, 2419 KiB

Open AccessArticle

Improvement in the Thermostability of a Recombinant β-Glucosidase Immobilized in Zeolite under Different Conditions

by Luis Gerardo Ramírez-Ramírez, David Enrique Zazueta-Álvarez, Héctor Alonso Fileto-Pérez, Damián Reyes-Jáquez, Cynthia Manuela Núñez-Núñez, Juan de Dios Galindo-De la Rosa, Javier López-Miranda and Perla Guadalupe Vázquez-Ortega

Molecules 2022, 27(13), 4105; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules27134105 - 26 Jun 2022

Cited by 4 | Viewed by 1523

Abstract

β-Glucosidase is part of the cellulases and is responsible for degrading cellobiose into glucose, a compound that can be used to produce biofuels. However, the use of the free enzyme makes the process more expensive. Enzyme immobilization improves catalytic characteristics and supports, such as zeolites, which have physical-chemical characteristics and ion exchange capacity that have a promising application in the biotechnological industry. This research aimed to immobilize by adsorption a recombinant β-glucosidase from Trichoderma reesei, obtained in Escherichia coli BL21 (DE3), in a commercial zeolite. A Box Behnken statistical design was applied to find the optimal immobilization parameters, the stability against pH and temperature was determined, and the immobilized enzyme was characterized by SEM. The highest enzymatic activity was determined with 100 mg of zeolite at 35 °C and 175 min. Compared to the free enzyme, the immobilized recombinant β-glucosidase presented greater activity from pH 2 to 4 and greater thermostability. The kinetic parameters were calculated, and a lower K_M value was obtained for the immobilized enzyme compared to the free enzyme. The obtained immobilization parameters by a simple adsorption method and the significant operational stability indicate promising applications in different fields. Full article

(This article belongs to the Special Issue The Latest Trends in Catalyst Immobilization)

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11 pages, 5053 KiB

Open AccessArticle

Synthesis of Chitosan-La₂O₃ Nanocomposite and Its Utility as a Powerful Catalyst in the Synthesis of Pyridines and Pyrazoles

by Khaled D. Khalil, Sayed M. Riyadh, Mariusz Jaremko, Thoraya A. Farghaly and Mohamed Hagar

Molecules 2021, 26(12), 3689; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26123689 - 17 Jun 2021

Cited by 7 | Viewed by 2239

Abstract

Recently, the development of nanocatalysts based on naturally occurring polysaccharides has received a lot of attention. Chitosan (CS), as a biodegradable and biocompatible polysaccharide, is considered to be an excellent template for the design of a hybrid biopolymer-based metal oxide nanocomposite. In this case, lanthanum oxide nanoparticles doped with chitosan at different weight percentages (5, 10, 15, and 20 wt% CS/La₂O₃) were prepared via a simple solution casting method. The prepared CS/La₂O₃ nanocomposite solutions were cast in a Petri dish in order to produce the developed catalyst, which was shaped as a thin film. The structural features of the hybrid nanocomposite film were studied by FTIR, SEM, and XRD analytical tools. FTIR spectra confirmed the presence of the major characteristic peaks of chitosan, which were modified by interaction with La₂O₃ nanoparticles. Additionally, SEM graphs showed dramatic morphological changes on the surface of chitosan, which is attributed to surface adsorption with La₂O₃ molecules. The prepared CS/La₂O₃ nanocomposite film (15% by weight) was investigated as an effective, recyclable, and heterogeneous base catalyst in the synthesis of pyridines and pyrazoles. The nanocomposite used was sufficiently stable and was collected and reused more than three times without loss of catalytic activity. Full article

(This article belongs to the Special Issue The Latest Trends in Catalyst Immobilization)

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14 pages, 1670 KiB

Open AccessArticle

Recoverable Phospha-Michael Additions Catalyzed by a 4-N,N-Dimethylaminopyridinium Saccharinate Salt or a Fluorous Long-Chained Pyridine: Two Types of Reusable Base Catalysts

by Eskedar Tessema, Vijayanath Elakkat, Chiao-Fan Chiu, Jing-Hung Zheng, Ka Long Chan, Chia-Rui Shen, Peng Zhang and Norman Lu

Molecules 2021, 26(4), 1159; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26041159 - 22 Feb 2021

Cited by 9 | Viewed by 2505

Abstract

Phospha-Michael addition, which is the addition reaction of a phosphorus-based nucleophile to an acceptor-substituted unsaturated bond, certainly represents one of the most versatile and powerful tools for the formation of P-C bonds, since many different electrophiles and P nucleophiles can be combined with each other. This offers the possibility to access many diversely functionalized products. In this work, two kinds of basic pyridine-based organo-catalysts were used to efficiently catalyze phospha-Michael addition reactions, the 4-N,N-dimethylaminopyridinium saccharinate (DMAP·Hsac) salt and a fluorous long-chained pyridine (4-R_f-CH₂OCH₂-py, where R_f = C₁₁F₂₃). These catalysts have been synthesized and characterized by Lu’s group. The phospha-Michael addition of diisopropyl, dimethyl or triethyl phosphites to α, β-unsaturated malonates in the presence of those catalysts showed very good reactivity with high yield at 80–100 °C in 1–4.5 h with high catalytic recovery and reusability. With regard to significant catalytic recovery, sometimes more than eight cycles were observed for DMAP·Hsac adduct by using non-polar solvents (e.g., ether) to precipitate out the catalyst. In the case of the fluorous long-chained pyridine, the thermomorphic method was used to efficiently recover the catalyst for eight cycles in all the reactions. Thus, the easy separation of the catalysts from the products revealed the outstanding efficacy of our systems. To our knowledge, these are good examples of the application of recoverable organo-catalysts to the DMAP·Hsac adduct by using non-polar solvent and a fluorous long-chained pyridine under the thermomorphic mode in phospha-Michael addition reactions. Full article

(This article belongs to the Special Issue The Latest Trends in Catalyst Immobilization)

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13 pages, 2331 KiB

Open AccessArticle

Characterization of Cross-Linked Enzyme Aggregates of the Y509E Mutant of a Glycoside Hydrolase Family 52 β-xylosidase from G. stearothermophilus

by Gabriela Romero, Lellys M. Contreras, Carolina Aguirre, Jeff Wilkesman, Josefa María Clemente-Jiménez, Felipe Rodríguez-Vico and Francisco Javier Las Heras-Vázquez

Molecules 2021, 26(2), 451; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26020451 - 16 Jan 2021

Cited by 6 | Viewed by 1952

Abstract

Cross-linked enzyme aggregates (CLEAs) of the Y509E mutant of glycoside hydrolase family 52 β-xylosidase from Geobacillus stearothermophilus with dual activity of β-xylosidase and xylanase (XynB2^Y509E) were prepared. Ammonium sulfate was used as the precipitant agent, and glutaraldehyde as cross-linking agent. The optimum conditions were found to be 90% ammonium sulfate, 12.5 mM glutaraldehyde, 3 h of cross-linking reaction at 25 °C, and pH 8.5. Under these (most effective) conditions, XynB2^Y509E-CLEAs retained 92.3% of their original β-xylosidase activity. Biochemical characterization of both crude and immobilized enzymes demonstrated that the maximum pH and temperature after immobilization remained unchanged (pH 6.5 and 65 °C). Moreover, an improvement in pH stability and thermostability was also found after immobilization. Analysis of kinetic parameters shows that the K_m value of XynB2^Y509E-CLEAs obtained was slightly higher than that of free XynB2^Y509E (1.2 versus 0.9 mM). Interestingly, the xylanase activity developed by the mutation was also conserved after the immobilization process. Full article

(This article belongs to the Special Issue The Latest Trends in Catalyst Immobilization)

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15 pages, 2722 KiB

Open AccessArticle

Short-Chained Platinum Complex Catalyzed Hydrosilylation under Thermomorphic Conditions: Heterogeneous Phase Separation at Ice Temperature

by Chiao-Fan Chiu, Jinn-Hsuan Ho, Eskedar Tessema, Yijing Lu, Chia-Rui Shen, Chang-Wei Lin and Norman Lu

Molecules 2021, 26(2), 378; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26020378 - 13 Jan 2021

Cited by 3 | Viewed by 2028

Abstract

Homogeneous catalysts PtCl₂[5,5′-bis-(n-ClCF₂(CF₂)₃CH₂OCH₂)-2,2′-bpy] (2A) and PtCl₂[5,5′-bis-(n-HCF₂(CF₂)₃CH₂OCH₂)-2,2′-bpy] (2B), which contained short fluorous chains, were synthesized and used in catalysis of hydrosilylation of alkynes. In these reactions the thermomorphic mode was effectively used to recover these catalysts from the reaction mixture up to eight cycles by taking advantage of heterogeneous phase separation at ice temperature. This kind of catalysis had previously been observed in fluorous catalysts of platinum containing about 50% F-content, but in this work the percentage of F-content is decreased to only about 30%, by which we termed them as “very light fluorous”. Our new type of catalyst with limited number of F-content is considered as the important discovery in the fluorous technology field as the reduced number of fluorine atoms will help to be able to comply the EPA 8-carbon rule. The metal leaching after the reaction has been examined by ICP-MS, and the testing results show the leaching of residual metal to be minimal. Additionally, comparing these results to our previous work, fluorous chain assisted selectivity has been observed when different fluorous chain lengths of the catalysts are used. It has been found that there exists fluorous chain assisted better selectivity towards β-(E) form in the Pt-catalyzed hydrosilylation of non-symmetric terminal alkyne when the Pt catalyst contains short fluorous chain (i.e., 4 Cs). Phenyl acetylenes showed the opposite regioselectivity due to pi-pi interaction while using the same catalyst via Markovnikov’s addition to form terminal vinyl silane, which is then a major product for Pt-catalyzed hydrosilylation of terminal aryl acetylene with triethylsilane. Finally, the kinetic studies indicate that the insertion of alkyne into the Pt-H bond is the rate-determining step. Full article

(This article belongs to the Special Issue The Latest Trends in Catalyst Immobilization)

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19 pages, 2864 KiB

Open AccessArticle

Semi-Continuous Flow Biocatalysis with Affinity Co-Immobilized Ketoreductase and Glucose Dehydrogenase

by Michal Plž, Tatiana Petrovičová and Martin Rebroš

Molecules 2020, 25(18), 4278; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25184278 - 18 Sep 2020

Cited by 12 | Viewed by 3298

Abstract

The co-immobilization of ketoreductase (KRED) and glucose dehydrogenase (GDH) on highly cross-linked agarose (sepharose) was studied. Immobilization of these two enzymes was performed via affinity interaction between His-tagged enzymes (six histidine residues on the N-terminus of the protein) and agarose matrix charged with nickel (Ni²⁺ ions). Immobilized enzymes were applied in a semicontinuous flow reactor to convert the model substrate; α-hydroxy ketone. A series of biotransformation reactions with a substrate conversion of >95% were performed. Immobilization reduced the requirement for cofactor (NADP+) and allowed the use of higher substrate concentration in comparison with free enzymes. The immobilized system was also tested on bulky ketones and a significant enhancement in comparison with free enzymes was achieved. Full article

(This article belongs to the Special Issue The Latest Trends in Catalyst Immobilization)

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14 pages, 2421 KiB

Open AccessFeature PaperReview

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

by Hans-Jürgen Federsel, Thomas S. Moody and Steve J.C. Taylor

Molecules 2021, 26(9), 2822; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26092822 - 10 May 2021

Cited by 69 | Viewed by 5802

Abstract

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. Full article

(This article belongs to the Special Issue The Latest Trends in Catalyst Immobilization)

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