Biocompatible Catalysts Research Articles

Silicomolybdic Acid Cluster as Biocompatible Catalyst for One-Pot Tandem Synthesis of Orthogonally Protected Glycosides.

The present paper describes a new and practical approach for the one-pot preparation of O-isopropylidene derivatives and also orthogonally protected S- and O-glycosides from the corresponding unprotected saccharides by employing 2 mol % of a silicomolybdic acid (SMA) cluster as a versatile and biocompatible catalyst. The present protocol is applicable to two-step one-pot tandem transformations, which include the O-isopropylidation, spiroketal functionalization, 4,6-O-arylidene acetalations, and arylidene acetylation processes under relatively mild reaction conditions. One-pot sequential transformations, low catalyst loading, rapid transformation, high to excellent reaction yields, mild reaction conditions, and a nontoxic biocompatible workup procedure are the notable advantages of devised protocol.

Choline Halide-Based Deep Eutectic Solvents as Biocompatible Catalysts for the Alternating Copolymerization of Epoxides and Cyclic Anhydrides.

Aliphatic polyesters have received considerable attention in recent years due to their biodegradability and biocompatible, mechanical, and thermal properties that can make them a suitable alternative to today's commercialized polymers. The ring-opening copolymerization (ROCOP) of epoxides and cyclic anhydrides is a route to synthesize a diverse array of polyesters that could be useful in many applications. However, the catalysts used rarely consider biocompatible catalysts in the case that any are left in the polymer. To the best of our knowledge, we report the first example of using deep eutectic solvents (DESs) as biocompatible catalysts for this target ROCOP with polymerization activity for at least six diverse monomer pairs. Choline halide salts are active for this polymerization, with dried salts showing polymerization slower than that of those conducted in air. Hydrogen bonding with water is hypothesized to enhance the rate-determining step of epoxide ring opening. While the presence of water improves the rate of polymerization, it also acts as a chain transfer agent, leading to smaller molar mass polymers than intended. Combining the choline halide salts with urea or ethylene glycol hydrogen bond donors in air led to DES catalysts that reacted similarly to the salts exposed to air. However, when generating these DESs in air-free conditions, they showed similar rates of polymerization without a drop in polymer molar mass. The hydrogen bonding provided by urea and ethylene glycol seems to promote the rate increase without serving as a chain transfer agent. Results reported herein display the promising potential of biocompatible catalyst systems for this ROCOP process as well as introducing the use of hydrogen bonding to enhance polymerization rates.

Integrating Enzymes with Supramolecular Polymers for Recyclable Photobiocatalytic Catalysis

AbstractChemical modifications of enzymes excel in the realm of enzyme engineering due to its directness, robustness, and efficiency; however, challenges persist in devising versatile and effective strategies. In this study, we introduce a supramolecular modification methodology that amalgamates a supramolecular polymer with Candida antarctica lipase B (CalB) to create supramolecular enzymes (SupEnzyme). This approach features the straightforward preparation of a supramolecular amphiphilic polymer (β‐CD@SMA), which was subsequently conjugated to the enzyme, resulting in a SupEnzyme capable of self‐assembly into supramolecular nanoparticles. The resulting SupEnzyme nanoparticles can form micron‐scale supramolecular aggregates through supramolecular and electrostatic interactions with guest entities, thus enhancing catalyst recycling. Remarkably, these aggregates maintain 80 % activity after seven cycles, outperforming Novozym 435. Additionally, they can effectively initiate photobiocatalytic cascade reactions using guest photocatalysts. As a consequence, our SupEnzyme methodology exhibits noteworthy adaptability in enzyme modification, presenting a versatile platform for various polymer, enzyme, and biocompatible catalyst pairings, with potential applications in the fields of chemistry and biology.

Integrating Enzymes with Supramolecular Polymers for Recyclable Photobiocatalytic Catalysis.

Chemical modifications of enzymes excel in the realm of enzyme engineering due to its directness, robustness, and efficiency; however, challenges persist in devising versatile and effective strategies. In this study, we introduce a supramolecular modification methodology that amalgamates a supramolecular polymer with Candida antarctica lipase B (CalB) to create supramolecular enzymes (SupEnzyme). This approach features the straightforward preparation of a supramolecular amphiphilic polymer (β-CD@SMA), which was subsequently conjugated to the enzyme, resulting in a SupEnzyme capable of self-assembly into supramolecular nanoparticles. The resulting SupEnzyme nanoparticles can form micron-scale supramolecular aggregates through supramolecular and electrostatic interactions with guest entities, thus enhancing catalyst recycling. Remarkably, these aggregates maintain 80 % activity after seven cycles, outperforming Novozym 435. Additionally, they can effectively initiate photobiocatalytic cascade reactions using guest photocatalysts. As a consequence, our SupEnzyme methodology exhibits noteworthy adaptability in enzyme modification, presenting a versatile platform for various polymer, enzyme, and biocompatible catalyst pairings, with potential applications in the fields of chemistry and biology.

Polymerization of D,L-lactide in the presence of biocompatible catalyst bismuth subsalicylate

Polymerization of D,L-lactide was performed in bulk at 160°C in the presence of bismuth (III) subsalicylate catalyst. Kinetics of the reaction was studied by differential scanning calorimetry in isothermal mode at 160°C and catalyst concentrations of 2500, 5000, and 7500 ppm. It was shown that the catalyst has a high activity: under this conditions an equilibrium conversion of 96% was achieved in 20–30 min, and the molecular weight of the resulting poly(D,L-lactide) reached 118 kDa.

Composite of gum arabic and halloysite as a bio-based acidic catalyst for efficient synthesis of 5-hydroxymthylfurfural

A novel acidic bio-based composite has been synthesized via covalent conjugation of two acidic natural compounds, i.e. halloysite clay mineral and Gum Arabic. Measurement of the acidity of the composite confirmed that its acidity was higher than that of individual components. Halloysite-Gum Arabic composite was successfully applied as a biocompatible catalyst for the dehydration of fructose to 5-hydroxymthylfurfural. The reaction conditions were also optimized via Response Surface Method (RSM) and it was found that using 30 mg catalyst per 0.1 mmol fructose led to 99.2% product yield at 100 °C in 105 min. Gratifyingly, the as-prepared composite was recyclable for seven consecutive runs and only insignificant loss of activity was observed after each run. Notably, the recycled catalyst was structurally and morphologically stable.

One pot facile visible-light promoted synthesis of quinazolinones via Csp3-H oxidation in aqueous media

The utilization of biocompatible catalysts for the synthesis of biologically significant molecules in aqueous environments represents a pivotal and challenging aspect within the realm of green and sustainable chemistry. Herein, a KI-mediated Csp3-H oxidation reaction to synthesis heterogeneously of quinazolinones is reported in this study. Aldehydes, formed from the oxidation of alcohols, undergo amide attacks and subsequent cyclization, efficiently producing a variety of quinazolinones under sunlight and in aqueous media. The utilization of solar energy significantly reduces experimental costs and minimizes the occurrence of toxic effects. This approach proceeded smoothly to afford quniazolinones in high to excellent yields with a wide substrate scope.

Biosynthesis of Au/CuO catalyst with Syringa oblata Lindl. leaf extract for efficient selective oxidation of glycerol to 1,3-dihydroxyacetone

Efficient conversion of glycerol to 1,3-dihydroxyacetone (DHA) is the affirmation and guarantee of the feasible development of biodiesel industry, but the biocompatibility of catalyst must be considered due to the wide application of DHA in food and medicine industries. In this work, an environmentally benign biosynthesis approach with Syringa oblata Lindl. (SoL) leaf extract was employed to fabricate Au/CuO catalysts for the oxidation of glycerol to DHA. The biosynthesized SoL-Au/CuO catalysts were characterized and the effects of plant extracts concentration, gold loading, calcination temperature and reaction conditions on the catalytic performance were systematically analyzed. High catalytic performance with glycerol conversion rate of 95.7% and DHA selectivity of 77.9% can be attained under optimum conditions. This work provides the first example of preparing biocompatible catalyst for the thermal catalytic oxidation of glycerol to DHA, which can not only reach efficient conversion of glycerol and selectivity to DHA, but also is simple, green, environmentally friendly, and promising.

Tumor-targeted glycogen nanoparticles loaded with hemin and glucose oxidase to promote tumor synergistic therapy

Strategies which are used to address the low levels of intracellular hydrogen peroxide and the development of biocompatible catalysts still need to be fulfilled in tumor chemodynamic therapy. Therefore, a novel tumor-targeted glycogen-based nanoparticle system (GN/He/GOx/HA) was developed to co-deliver hemin (He) and GOx, which can self-supply glucose formed upon degradation of glycogen by α-glycosidase in the lysosome environment, in order to achieve synergistic antitumor therapy. Hyaluronic acid (HA) was selected as the outer shell to protect the activity of GOx, and to increase the uptake by tumor cells via CD44 receptor-mediated endocytosis. GN/He/GOx/HA NPs had a good stability in the blood circulation, but fast release of the therapeutic cargos upon intracellular uptake. Hemin had a cascade catalytic reaction with GOx. Furthermore, GN/He/GOx/HA NPs had the strongest cytotoxicity in Hela cells in a glucose concentration dependent manner. The NPs could efficiently produce reactive oxygen species in tumor cells, resulting in a decrease in the mitochondrial membrane potential and apoptosis of tumor cells. The in vivo results showed that the drug-loaded nanoparticles had good safety, biocompatibility, and efficacious antitumor effect. Therefore, the glycogen-based nanoparticle delivery system provides potential application for self-enhancing CDT, which can be used for effective antitumor therapy.

Ruthenium Catalysis in Biological Habitats

AbstractRecent years have witnessed a considerable progress in research aimed at merging transition metal catalysis with chemical and cell biology. Therefore, a crescent number of metal‐catalyzed transformations have been shown compatible with biological media and even with living settings. Of the different transition metals used to build these biocompatible catalysts, ruthenium has demonstrated to be particularly powerful, in part because the resulting complexes exhibit a very good balance between reactivity and biological stability. Indeed, ruthenium complexes have demonstrated utility to promote a great variety of reactions in biologically relevant contexts, from deprotection and redox processes to cycloadditions or photocatalytic transformations. Many of these reactions may enable the development of new type of biological tools and pharmacological strategies.

High-performance flower-like and biocompatible nickel-coated Fe3O4@SiO2 magnetic nanoparticles decorated on a graphene electrocatalyst for the oxygen evolution reaction.

The electrocatalytic oxygen evolution reaction (OER) plays a crucial role in renewable clean energy conversion technologies and has developed into an important direction in the field of advanced energy, becoming the focus of basic research and industrial development. Herein, we report the synthesis and application of flower-like nickel-coated Fe3O4@SiO2 magnetic nanoparticles decorated on a graphene electrocatalyst for the OER that exhibit high efficiency and robust durability. The catalysts were optimized using a rotating ring-disk electrode to test their oxygen evolution properties in 1.0 M KOH solution. Importantly, owing to the high specific surface area and conductivity of C3N4 and graphene, the as-synthesized Fe3O4@SiO2@NiO/graphene/C3N4 exhibits a small Tafel slope of 40.46 mV dec-1, low overpotential of 288 mV at 10 mA cm-2, and robust OER durability within a prolonged test period of 100 h. The cytotoxicity of Fe3O4@SiO2, Fe3O4@SiO2@NiO, and Fe3O4@SiO2@NiO/graphene/C3N4 was evaluated in HeLa and MC3T3-E1 cells, demonstrating that they are efficient and biocompatible catalysts for the OER. Owing to its excellent electrocatalytic efficiency and eco-friendliness, Fe3O4@SiO2@NiO/graphene/C3N4 has considerable potential as a new multifunctional composite for large-scale applications in catalysis, biology, medicine, and high-efficiency hydrogen production.

Multistep enzyme cascades as a route towards green and sustainable pharmaceutical syntheses.

Enzyme cascades are a powerful technology to develop environmentally friendly and cost-effective synthetic processes to manufacture drugs, as they couple different biotransformations in sequential reactions to synthesize the product. These biocatalytic tools can address two key parameters for the pharmaceutical industry: an improved selectivity of synthetic reactions and a reduction of potential hazards by using biocompatible catalysts, which can be produced from sustainable sources, which are biodegradable and, generally, non-toxic. Here we outline a broad variety of enzyme cascades used either in vivo (whole cells) or in vitro (purified enzymes) to specifically target pharmaceutically relevant molecules, from simple building blocks to complex drugs. We also discuss the advantages and requirements of multistep enzyme cascades and their combination with chemical catalysts through a series of reported examples. Finally, we examine the efficiency of enzyme cascades and how they can be further improved by enzyme engineering, process intensification in flow reactors and/or enzyme immobilization to meet all the industrial requirements.

Cytochrome C catalyzed oxygen tolerant atom-transfer radical polymerization

Atom-transfer radical polymerization (ATRP) is a well-known technique for controlled polymer synthesis. However, the ATRP usually employed toxic heavy metal ionas as the catalyst and was susceptible to molecular oxygen, which made it should be conducted under strictly anoxic condition. Conducting ATRP under ambient and biocompatible conditions is the major challenge. In this study, cytochrome C was explored as an efficient biocatalyst for ATRP under biocompatible conditions. The cytochrome C catalyzed ATRP showed a relatively low polymer dispersity index of 1.19. More interestingly, the cytochrome C catalyzed ATRP showed superior oxygen resistance as it could be performed under aerobic conditions with high dissolved oxygen level. Further analysis suggested that the Fe(II) embed in the cytochrome C might serve as the catalytic center and methyl radical was responsible for the ATRP catalysis. This work explored new biocompatible catalyst for aerobic ATRP, which might open new dimension for practical ATRP and application of cytochrome C protein.Graphical

A Schiff base complex of lanthanum on modified MCM-41 as a reusable nanocatalyst in the homoselective synthesis of 5-substituted 1H-tetrazoles.

In this work, mesoporous MCM-41 was modified by a new Schiff-base formed from the condensation of triethylenetatramine and 5-bromosalicylaldehyde. Then, it was used for the stabilization of lanthanum metal (La-Schiff base@MCM-41) as a homoselective, reusable, efficient and biocompatible catalyst in the synthesis of 5-substituted 1H-tetrazole derivatives. The synthesized tetrazoles were characterized using 1H NMR and FT-IR spectroscopy and methods to measure their physical properties. La-Schiff base@MCM-41 was characterized by using various techniques such as ICP, CHN, XRD, TGA, BET, FT-IR spectroscopy, SEM, EDS and WDX. This catalyst has good stability and a heterogeneous nature, enabling it to be easily recovered and reused several times without significant loss in catalytic activity. This present strategy has important advantages such as utilizing PEG as a green solvent, short reaction times, excellent yields, easy recycling of the catalyst and pure separation of the products. The recovered La-Schiff base@MCM-41 catalyst was characterized by using FT-IR spectroscopy, SEM and AAS.

Biocompatible Materials Enabled by Biobased Production of Pyomelanin Isoforms Using an Engineered Yarrowia lipolytica

AbstractMelanin‐like compounds have been studied in recent years for their electron transport and ultraviolet (UV) light absorbance properties as well as applications as functional, biocompatible catalysts, and material additives. Pyomelanin is a unique form of melanin compounds that has not received significant attention. Here, a strain of Yarrowia lipolytica suitable for the production of nearly 2.8 g L−1 of homogentisic acid (HGA) is metabolically engineered, which can then be oxidized to form pyomelanin either in situ or through altering pH. By using this biosourced material, a series of material traits including spectral analysis/UV–vis absorbance properties, electronic and metal interaction/chelation properties, and effectiveness in polymer dispersions with poly(l‐lactide) are evaluated. In all cases, biosourced pyomelanin performs on par with or better than a chemically sourced analog. In a performance application, it is explored how pyomelanin may be blended at low concentrations to increase the elasticity of a rigid commercial polymer. Collectively, this work establishes biosourced pyomelanin as a versatile compound for unique material applications.

Photo-oxygenation by a biocompatible catalyst reduces amyloid-β levels in Alzheimer's disease mice.

Amyloid formation and the deposition of the amyloid-β peptide are hallmarks of Alzheimer's disease pathogenesis. Immunotherapies using anti-amyloid-β antibodies have been highlighted as a promising approach for the prevention and treatment of Alzheimer's disease by enhancing microglial clearance of amyloid-β peptide. However, the efficiency of antibody delivery into the brain is limited, and therefore an alternative strategy to facilitate the clearance of brain amyloid is needed. We previously developed an artificial photo-oxygenation system using a low molecular weight catalytic compound. The photocatalyst specifically attached oxygen atoms to amyloids upon irradiation with light, and successfully reduced the neurotoxicity of aggregated amyloid-β via inhibition of amyloid formation. However, the therapeutic effect and mode of actions of the photo-oxygenation system in vivo remained unclear. In this study, we demonstrate that photo-oxygenation facilitates the clearance of aggregated amyloid-β from the brains of living Alzheimer's disease model mice, and enhances the microglial degradation of amyloid-β peptide. These results suggest that photo-oxygenation may represent a novel anti-amyloid-β strategy in Alzheimer's disease, which is compatible with immunotherapy.

Biocatalysts Based on Peptide and Peptide Conjugate Nanostructures.

Peptides and their conjugates (to lipids, bulky N-terminals, or other groups) can self-assemble into nanostructures such as fibrils, nanotubes, coiled coil bundles, and micelles, and these can be used as platforms to present functional residues in order to catalyze a diversity of reactions. Peptide structures can be used to template catalytic sites inspired by those present in natural enzymes as well as simpler constructs using individual catalytic amino acids, especially proline and histidine. The literature on the use of peptide (and peptide conjugate) α-helical and β-sheet structures as well as turn or disordered peptides in the biocatalysis of a range of organic reactions including hydrolysis and a variety of coupling reactions (e.g., aldol reactions) is reviewed. The simpler design rules for peptide structures compared to those of folded proteins permit ready ab initio design (minimalist approach) of effective catalytic structures that mimic the binding pockets of natural enzymes or which simply present catalytic motifs at high density on nanostructure scaffolds. Research on these topics is summarized, along with a discussion of metal nanoparticle catalysts templated by peptide nanostructures, especially fibrils. Research showing the high activities of different classes of peptides in catalyzing many reactions is highlighted. Advances in peptide design and synthesis methods mean they hold great potential for future developments of effective bioinspired and biocompatible catalysts.

One-Pot Chemo-bioprocess of PET Depolymerization and Recycling Enabled by a Biocompatible Catalyst, Betaine

Poly(ethylene terephthalate) (PET) has been widely used in various industries due to its unique physical properties. However, PET causes major environmental problems globally due to its low degrada...

Electrochemical synthesis of quinazolinone via I2-catalyzed tandem oxidation in aqueous solution.

The development of protocols for synthesizing quinazolinones using biocompatible catalysts in aqueous medium will help to resolve the difficulties of using green and sustainable chemistry for their synthesis. Herein, using I2 in coordination with electrochemical synthesis induced a C–H oxidation reaction which is reported when using water as the environmentally friendly solvent to access a broad range of quinazolinones at room temperature. The reaction mechanism strongly showed that I2 cooperates electrochemically promoted the oxidation of alcohols, then effectively cyclizing amides to various quinazolinones.

One‐pot Synthesis of 2‐Amino‐4H‐chromenes Derivatives in Aqueous Solution of Choline Hydroxide

Abstract2‐Amino‐4H‐chromenes have showed broad bioactivities and attracted great attention in synthetic chemistry. Here, the aqueous solution of choline hydroxide was found to be an efficient catalytic system for the one‐pot synthesis of 2‐amino‐4H‐chromenes under room temperature. Various aldehydes, malononitrile and phenols could be converted to the corresponding 2‐amino‐4H‐chromenes smoothly with good to excellent isolated yields. This catalytic system had high chemo‐selectivity with biocompatible catalyst in green solvents, water. Its operation and work‐up procedures were very simple, and importantly, the target compounds could be obtained from simple centrifugation and washing procedures, no column purification was needed. In addition, the catalytic system involving choline hydroxide and water could be easily reused for at least five cycles with high activity. The above advantages made this catalytic system promising in the industrial production of 2‐amino‐4H‐chromenes.