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10 pages, 1925 KiB

Open AccessArticle

Spatial Control over Catalyst Positioning for Increased Micromotor Efficiency

by Shauni Keller, Serena P. Teora, Arif Keskin, Luuk J. C. Daris, Norman A. P. E. Samuels, Moussa Boujemaa and Daniela A. Wilson

Gels 2023, 9(2), 164; https://doi.org/10.3390/gels9020164 - 18 Feb 2023

Cited by 3 | Viewed by 2702

Abstract

Motion is influenced by many different aspects of a micromotor’s design, such as shape, roughness and the type of materials used. When designing a motor, asymmetry is the main requirement to take into account, either in shape or in catalyst distribution. It influences both speed and directionality since it dictates the location of propulsion force. Here, we combine asymmetry in shape and asymmetry in catalyst distribution to study the motion of soft micromotors. A microfluidic method is utilized to generate aqueous double emulsions, which upon UV-exposure form asymmetric microgels. Taking advantage of the flexibility of this method, we fabricated micromotors with homogeneous catalyst distribution throughout the microbead and micromotors with different degrees of catalyst localization within the active site. Spatial control over catalyst positioning is advantageous since less enzyme is needed for the same propulsion speed as the homogeneous system and it provides further confinement and compartmentalization of the catalyst. This proof-of-concept of our new design will make the use of enzymes as driving forces for motors more accessible, as well as providing a new route for compartmentalizing enzymes at interfaces without the need for catalyst-specific functionalization. Full article

(This article belongs to the Special Issue Hydrogels, Microgels, and Nanogels: From Fundamentals to Applications)

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23 pages, 4355 KiB

Open AccessArticle

3D-Printing of Capsule Devices as Compartmentalization Tools for Supported Reagents in the Search of Antiproliferative Isatins

by Camilla Malatini, Carlos Carbajales, Mariángel Luna, Osvaldo Beltrán, Manuel Amorín, Christian F. Masaguer, José M. Blanco, Silvia Barbosa, Pablo Taboada and Alberto Coelho

Pharmaceuticals 2023, 16(2), 310; https://doi.org/10.3390/ph16020310 - 16 Feb 2023

Cited by 4 | Viewed by 3107

Abstract

The application of high throughput synthesis methodologies in the generation of active pharmaceutical ingredients (APIs) currently requires the use of automated and easily scalable systems, easy dispensing of supported reagents in solution phase organic synthesis (SPOS), and elimination of purification and extraction steps. The recyclability and recoverability of supported reagents and/or catalysts in a rapid and individualized manner is a challenge in the pharmaceutical industry. This objective can be achieved through a suitable compartmentalization of these pulverulent reagents in suitable devices for it. This work deals with the use of customized polypropylene permeable-capsule devices manufactured by 3D printing, using the fused deposition modeling (FDM) technique, adaptable to any type of flask or reactor. The capsules fabricated in this work were easily loaded “in one step” with polymeric reagents for use as scavengers of isocyanides in the work-up process of Ugi multicomponent reactions or as compartmentalized and reusable catalysts in copper-catalyzed cycloadditions (CuAAC) or Heck palladium catalyzed cross-coupling reactions (PCCCRs). The reaction products are different series of diversely substituted isatins, which were tested in cancerous cervical HeLa and murine 3T3 Balb fibroblast cells, obtaining potent antiproliferative activity. This work demonstrates the applicability of 3D printing in chemical processes to obtain anticancer APIs. Full article

(This article belongs to the Special Issue 3D Printing of Drug Formulations)

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16 pages, 3870 KiB

Open AccessArticle

Process Intensification of 2,2′-(4-Nitrophenyl) Dipyrromethane Synthesis with a SO₃H-Functionalized Ionic Liquid Catalyst in Pickering-Emulsion-Based Packed-Bed Microreactors

by Hong Zhang, Minjing Shang, Yuchao Zhao and Yuanhai Su

Micromachines 2021, 12(7), 796; https://doi.org/10.3390/mi12070796 - 5 Jul 2021

Cited by 4 | Viewed by 3258

Abstract

A stable water-in-oil Pickering emulsion was fabricated with SO₃H-functionalized ionic liquid and surface-modified silica nanoparticles and used for 2,2′-(4-nitrophenyl) dipyrromethane synthesis in a packed-bed microreactor, exhibiting high reaction activity and product selectivity. The compartmentalized water droplets of the Pickering emulsion had an excellent ability to confine the ionic liquid against loss under continuous-flow conditions, and the excellent durability of the catalytic system without a significant decrease in the reaction efficiency and selectivity was achieved. Compared with the reaction performance of a liquid–liquid slug-flow microreactor and batch reactor, the Pickering-emulsion-based catalytic system showed a higher specific interfacial area between the catalytic and reactant phases, benefiting the synthesis of 2,2′-(4-nitrophenyl) dipyrromethane and resulting in a higher yield (90%). This work indicated that an increase in the contact of reactants with catalytic aqueous solution in a Pickering-emulsion-based packed-bed microreactor can greatly enhance the synthetic process of dipyrromethane, giving an excellent yield of products and a short reaction time. It was revealed that Pickering-emulsion-based packed-bed microreactors with the use of ionic liquids as catalysts for interfacial catalysis have great application potential in the process of intensification of organic synthesis. Full article

(This article belongs to the Special Issue Micromachines for Chemical Process Intensification)

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13 pages, 4076 KiB

Open AccessArticle

In Situ Growth of ZIF-8 Nanocrystals on the Pore Walls of 3D Ordered Macroporous TiO₂ for a One-Pot Cascade Reaction

by Jing Chen, Yingchun Guo, Tengteng Kang, Xingchi Liu, Xiaomei Wang and Xu Zhang

Catalysts 2021, 11(5), 533; https://doi.org/10.3390/catal11050533 - 21 Apr 2021

Cited by 8 | Viewed by 2733

Abstract

It is wise to mimic a bioinspired system to design a nanoreactor as a catalyst containing multiple components for a cascade reaction. Here, we report the uniform growth of well-dispersed nano-scale ZIF-8 crystals on the pore walls of 3DOM TiO₂ via the TEA-assisted crystallization process. The UV-vis spectra indicate that the ZIF-8 photosensitizer can extend the visible-light absorption of 3DOM TiO₂. The obtained nanoreactor can efficiently catalyze the one-pot aromatic alcohol oxidization and Knoevenagel condensation cascade reaction for larger molecules. This work offers an important strategy for preparing semiconductor–MOF multifunctional composites with a spatially separated compartmentation for the cascade reaction. Full article

(This article belongs to the Section Nanostructured Catalysts)

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13 pages, 3143 KiB

Open AccessReview

The Impact of Single-Cell Genomics on Adipose Tissue Research

by Alana Deutsch, Daorong Feng, Jeffrey E. Pessin and Kosaku Shinoda

Int. J. Mol. Sci. 2020, 21(13), 4773; https://doi.org/10.3390/ijms21134773 - 5 Jul 2020

Cited by 44 | Viewed by 9265

Abstract

Adipose tissue is an important regulator of whole-body metabolism and energy homeostasis. The unprecedented growth of obesity and metabolic disease worldwide has required paralleled advancements in research on this dynamic endocrine organ system. Single-cell RNA sequencing (scRNA-seq), a highly meticulous methodology used to dissect tissue heterogeneity through the transcriptional characterization of individual cells, is responsible for facilitating critical advancements in this area. The unique investigative capabilities achieved by the combination of nanotechnology, molecular biology, and informatics are expanding our understanding of adipose tissue’s composition and compartmentalized functional specialization, which underlie physiologic and pathogenic states, including adaptive thermogenesis, adipose tissue aging, and obesity. In this review, we will summarize the use of scRNA-seq and single-nuclei RNA-seq (snRNA-seq) in adipocyte biology and their applications to obesity and diabetes research in the hopes of increasing awareness of the capabilities of this technology and acting as a catalyst for its expanded use in further investigation. Full article

(This article belongs to the Special Issue Adipogenesis and Adipose Tissue Metabolism 2.0)

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42 pages, 13978 KiB

Open AccessReview

Artificial Metalloenzymes: From Selective Chemical Transformations to Biochemical Applications

by Tomoki Himiyama and Yasunori Okamoto

Molecules 2020, 25(13), 2989; https://doi.org/10.3390/molecules25132989 - 30 Jun 2020

Cited by 15 | Viewed by 7334

Abstract

Artificial metalloenzymes (ArMs) comprise a synthetic metal complex in a protein scaffold. ArMs display performances combining those of both homogeneous catalysts and biocatalysts. Specifically, ArMs selectively catalyze non-natural reactions and reactions inspired by nature in water under mild conditions. In the past few years, the construction of ArMs that possess a genetically incorporated unnatural amino acid and the directed evolution of ArMs have become of great interest in the field. Additionally, biochemical applications of ArMs have steadily increased, owing to the fact that compartmentalization within a protein scaffold allows the synthetic metal complex to remain functional in a sea of inactivating biomolecules. In this review, we present updates on: (1) the newly reported ArMs, according to their type of reaction, and (2) the unique biochemical applications of ArMs, including chemoenzymatic cascades and intracellular/in vivo catalysis. We believe that ArMs have great potential as catalysts for organic synthesis and as chemical biology tools for pharmaceutical applications. Full article

(This article belongs to the Special Issue Hybrid Catalysts for Asymmetric Catalysis)

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16 pages, 2024 KiB

Open AccessArticle

Hydrogel Microvalves as Control Elements for Parallelized Enzymatic Cascade Reactions in Microfluidics

by Franziska Obst, Anthony Beck, Chayan Bishayee, Philipp J. Mehner, Andreas Richter, Brigitte Voit and Dietmar Appelhans

Micromachines 2020, 11(2), 167; https://doi.org/10.3390/mi11020167 - 5 Feb 2020

Cited by 19 | Viewed by 4463

Abstract

Compartmentalized microfluidic devices with immobilized catalysts are a valuable tool for overcoming the incompatibility challenge in (bio) catalytic cascade reactions and high-throughput screening of multiple reaction parameters. To achieve flow control in microfluidics, stimuli-responsive hydrogel microvalves were previously introduced. However, an application of this valve concept for the control of multistep reactions was not yet shown. To fill this gap, we show the integration of thermoresponsive poly(N-isopropylacrylamide) (PNiPAAm) microvalves (diameter: 500 and 600 µm) into PDMS-on-glass microfluidic devices for the control of parallelized enzyme-catalyzed cascade reactions. As a proof-of-principle, the biocatalysts glucose oxidase (GOx), horseradish peroxidase (HRP) and myoglobin (Myo) were immobilized in photopatterned hydrogel dot arrays (diameter of the dots: 350 µm, amount of enzymes: 0.13–2.3 µg) within three compartments of the device. Switching of the microvalves was achieved within 4 to 6 s and thereby the fluid pathway of the enzyme substrate solution (5 mmol/L) in the device was determined. Consequently, either the enzyme cascade reaction GOx-HRP or GOx-Myo was performed and continuously quantified by ultraviolet-visible (UV-Vis) spectroscopy. The functionality of the microvalves was shown in four hourly switching cycles and visualized by the path-dependent substrate conversion. Full article

(This article belongs to the Special Issue Selected papers from the APMM 2019–Active Polymeric Materials and Microsystems Conference)

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