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A chemoenzymatic method for the synthesis of haloethers is presented. A combination of enzymatic hypohalite synthesis with spontaneous oxidation of alkenes and nucleophilic attack by various alcohols enabled the synthesis of a wide range of haloethers. The reaction system has been characterised and current imitations have been worked out. In the present, aqueous reaction system, hydroxyhalide formation represents the main undesired side reaction. Nevertheless, semi-preparative scale synthesis of a range of haloethers is demonstrated., BT/Biocatalysis

Propargylic alcohols and amines are versatile building blocks in organic synthesis. We demonstrate a straightforward enzymatic cascade to synthesize enantiomerically pure propargylic alcohols and amines from readily available racemic starting materials. In the first step, the peroxygenase from Agrocybe aegerita converted the racemic propargylic alcohols into the corresponding ketones, which then were converted into the enantiomerically pure alcohols using the (R)-selective alcohol dehydrogenase from Lactobacillus kefir or the (S)-selective alcohol dehydrogenase from Thermoanaerobacter brokii. Moreover, an enzymatic Mitsunobu-type conversion of the racemic alcohols into enantiomerically enriched propargylic amines using (R)-selective amine transaminase from Aspergillus terreus or (S)-selective amine transaminase from Chromobacterium violaceum was established. The one-pot two-step cascade reaction yielded a broad range of enantioenriched alcohol and amine products in 70-99% yield., BT/Biocatalysis

Porous materials, such as zeolites, have great potential for biomedical applications, thanks to their ability to accommodate positively charged metal-ions and their facile surface functionalization. Although the latter aspect is important to endow the nanoparticles with chemical/colloidal stability and desired biological properties, the possibility for simple ion-exchange enables easy switching between imaging modalities and/or combination with therapy, depending on the envisioned application. In this study, the nanozeolite Linde type L (LTL) with already confirmed magnetic resonance imaging properties, generated by the paramagnetic gadolinium (GdIII) in the inner cavities, was successfully radiolabeled with a positron emission tomography (PET)-tracer zirconium-89 (89Zr). Thereby, exploiting 89Zr-chloride resulted in a slightly higher radiolabeling in the inner cavities compared to the commonly used 89Zr-oxalate, which apparently remained on the surface of LTL. Intravenous injection of PEGylated 89Zr/GdIII-LTL in healthy mice allowed for PET-computed tomography evaluation, revealing initial lung uptake followed by gradual migration of LTL to the liver and spleen. Ex vivo biodistribution confirmed the in vivo stability and integrity of the proposed multimodal probe by demonstrating the original metal/Si ratio being preserved in the organs. These findings reveal beneficial biological behavior of the nanozeolite LTL and hence open the door for follow-up theranostic studies by exploiting the immense variety of metal-based radioisotopes., BT/Biocatalysis

Propargylic alcohols and amines are versatile building blocks in organic synthesis. We demonstrate a straightforward enzymatic cascade to synthesize enantiomerically pure propargylic alcohols and amines from readily available racemic starting materials. In the first step, the peroxygenase from Agrocybe aegerita converted the racemic propargylic alcohols into the corresponding ketones, which then were converted into the enantiomerically pure alcohols using the (R)-selective alcohol dehydrogenase from Lactobacillus kefir or the (S)-selective alcohol dehydrogenase from Thermoanaerobacter brokii. Moreover, an enzymatic Mitsunobu-type conversion of the racemic alcohols into enantiomerically enriched propargylic amines using (R)-selective amine transaminase from Aspergillus terreus or (S)-selective amine transaminase from Chromobacterium violaceum was established. The one-pot two-step cascade reaction yielded a broad range of enantioenriched alcohol and amine products in 70-99% yield., BT/Biocatalysis

A chemoenzymatic method for the synthesis of haloethers is presented. A combination of enzymatic hypohalite synthesis with spontaneous oxidation of alkenes and nucleophilic attack by various alcohols enabled the synthesis of a wide range of haloethers. The reaction system has been characterised and current imitations have been worked out. In the present, aqueous reaction system, hydroxyhalide formation represents the main undesired side reaction. Nevertheless, semi-preparative scale synthesis of a range of haloethers is demonstrated., BT/Biocatalysis

Submarine slope instabilities are considered one of the major threats for offshore buried pipelines. This paper presents a novel method to evaluate the ultimate pressure acting on a buried pipeline during the liquefaction of an inclined seabed. Small-scale model tests with pipes buried at three different embedment ratios have been conducted at an enhanced centrifugal acceleration condition. A high-speed, high-resolution imaging system was developed to quantify the soil displacement field of the soil body and to visualize the development of the liquefied zone. The measured lateral pressures were compared with the hybrid approach proposed for the landslide–pipeline interaction in clay-rich material by Randolph and White (2012) and Sahdi et al. (2014). The hybrid approach is proved to be able to predict later pressures induced by the movement of (partially) liquefied sand on buried pipelines. It is found that the fluid inertia (fluid dynamics) component plays an important role when the non-Newtonian Reynolds number >~2 or the shear strain rate > 4.5 × 10−2 sec−1., Geo-engineering

Aromatic hydroxylation reactions catalyzed by heme-thiolate enzymes proceed via an epoxide intermediate. These aromatic epoxides could be valuable building blocks for organic synthesis giving access to a range of chiral trans-disubstituted cyclohexadiene synthons. Here, we show that naphthalene epoxides generated by fungal peroxygenases can be subjected to nucleophilic ring opening, yielding non-racemic trans-disubstituted cyclohexadiene derivates, which in turn can be used for further chemical transformations. This approach may represent a promising shortcut for the synthesis of natural products and APIs., BT/Biocatalysis, BT/Environmental Biotechnology

Submarine slope instabilities are considered one of the major threats for offshore buried pipelines. This paper presents a novel method to evaluate the ultimate pressure acting on a buried pipeline during the liquefaction of an inclined seabed. Small-scale model tests with pipes buried at three different embedment ratios have been conducted at an enhanced centrifugal acceleration condition. A high-speed, high-resolution imaging system was developed to quantify the soil displacement field of the soil body and to visualize the development of the liquefied zone. The measured lateral pressures were compared with the hybrid approach proposed for the landslide–pipeline interaction in clay-rich material by Randolph and White (2012) and Sahdi et al. (2014). The hybrid approach is proved to be able to predict later pressures induced by the movement of (partially) liquefied sand on buried pipelines. It is found that the fluid inertia (fluid dynamics) component plays an important role when the non-Newtonian Reynolds number >~2 or the shear strain rate > 4.5 × 10−2 sec−1., Geo-engineering

Aromatic hydroxylation reactions catalyzed by heme-thiolate enzymes proceed via an epoxide intermediate. These aromatic epoxides could be valuable building blocks for organic synthesis giving access to a range of chiral trans-disubstituted cyclohexadiene synthons. Here, we show that naphthalene epoxides generated by fungal peroxygenases can be subjected to nucleophilic ring opening, yielding non-racemic trans-disubstituted cyclohexadiene derivates, which in turn can be used for further chemical transformations. This approach may represent a promising shortcut for the synthesis of natural products and APIs., BT/Biocatalysis, BT/Environmental Biotechnology

Peroxygenases have long inspired the selective oxyfunctionalization of various aliphatic and aromatic compounds, because of their broad substrate spectrum and simplicity of catalytic mechanism. This study provides a proof-of-concept of piezobiocatalysis by demonstrating peroxygenase-catalyzed oxyfunctionalization reactions fueled by piezocatalytically generated H2O2. Bismuth oxychloride (BiOCl) generated H2O2 in situ via an oxygen reduction reaction under ultrasonic wave conditions. Through the simple combination of water, ultrasound, recombinant, evolved unspecific peroxygenase from Agrocybe aegerita (rAaeUPO), and BiOCl, the piezobiocatalytic platform accelerated selective hydroxylation of ethylbenzene to enantiopure (R)-1-phenylethanol [total turnover number of rAaeUPO (TTNrAaeUPO), 2002; turnover frequency, 77.7 min-1 >99% enantiomeric excess (ee)]. The BiOCl-rAaeUPO couple also catalyzed other representative substrates (e.g., propylbenzene, 1-chloro-4-ethylbenzene, cyclohexane, and cis-β-methylstyrene) with high turnover frequency and selectivity. We alleviated the oxidative stress of piezocatalytically generated OH- on rAaeUPO by spatial separation of rAaeUPO and BiOCl, which resulted in greatly enhanced TTNrAaeUPO of >3900 and the notable prolongation of reaction time. Overall, the BiOCl-rAaeUPO couple serves as a mechanical-to-chemical energy conversion platform for driving peroxygenase-catalyzed reactions under ultrasonic conditions., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., BT/Biocatalysis

It is well-known that energy-rich radiation induces water splitting, eventually yielding hydrogen peroxide. Synthetic applications, however, are scarce and to the best of our knowledge, the combination of radioactivity with enzyme-catalysis has not been considered yet. Peroxygenases utilize H2O2 as an oxidant to promote highly selective oxyfunctionalization reactions but are also irreversibly inactivated in the presence of too high H2O2 concentrations. Therefore, there is a need for efficient in situ H2O2 generation methods. Here, we show that radiolytic water splitting can be used to promote specific biocatalytic oxyfunctionalization reactions. Parameters influencing the efficiency of the reaction and current limitations are shown. Particularly, oxidative inactivation of the biocatalyst by hydroxyl radicals influences the robustness of the overall reaction. Radical scavengers can alleviate this issue, but eventually, physical separation of the enzymes from the ionizing radiation will be necessary to achieve robust reaction schemes. We demonstrate that nuclear waste can also be used to drive selective, peroxygenase-catalyzed oxyfunctionalization reactions, challenging our view on nuclear waste in terms of sustainability., BT/Biocatalysis, RST/Applied Radiation & Isotopes, RST/Radiation, Science and Technology

A photobiocatalytic cascade transforming natural triglycerides into alkanes/alkenes is proposed. Starting from natural triglycerides, free fatty acids have been obtained using lipases. The free fatty acids were then, in a photoenzymatic step, decarboxylated into the C1-shortened alkanes using a recently described photodecarboxylase from Chlorella variabilis NC64A. This cascade produced alkanes from various natural (waste) oils in significant amounts (up to 24 g L−1) and may provide a basis for valorisation of waste oils into a next generation of biodiesel., BT/Biocatalysis

The assessment of the potentially destructive impacts of subaqueous landslides on offshore pipelines is required when the pipeline route passes through zones with a risk of mass movements. Therefore, quantifying and evaluating the ultimate load/pressure acting on the pipeline is one of the key factors in geotechnical safety design of the pipeline. One of the triggers of subaqueous soil mass movements is the monotonic loads, which induce the trigger relative displacement between a soil layer and a pipe under both drained and (partially) undrained conditions. Two approaches based on geotechnical and fluid dynamics perspectives have been proposed for estimating the ultimate load/pressure for different stages of a submarine landslide. Traditionally, the former method focuses on the analysis of pipelines installed under flat seabed experiencing relative movements to the surrounding soil, whereas, the latter method focuses on the behaviour of pipelines laid on the surface of the seabed and subjected to debris flows. However, offshore pipelines are often buried under the seabed, which is not always flat and has a modest inclination in some cases. This engineering condition normally differs from that of the simplifying assumptions and boundary conditions (such as seabed inclination, and soil strength) commonly imposed to the geotechnical and fluid dynamics approaches. Accordingly, a better understanding of the soilpipeline interaction when the pipelines are buried in subaqueous slopes is essential for evaluating the ultimate load/pressure that would be caused by the slope failures. This thesis presents a research effort on investigating the soilpipeline interaction during subaqueous slope failures using advanced physical modelling. In this research, the experiments can be divided into two main groups according to the soil drainage conditions. The first group of tests were carried out in the drained condition by using dry sand as the soil material for the slopes. The pip, Geo-engineering

En route to a bio-based chemical industry, the conversion of fatty acids into building blocks is of particular interest. Enzymatic routes, occurring under mild conditions and excelling by intrinsic selectivity, are particularly attractive. Here we report photoenzymatic cascade reactions to transform unsaturated fatty acids into enantiomerically pure secondary fatty alcohols. In a first step the C=C-double bond is stereoselectively hydrated using oleate hydratases from Lactobacillus reuteri or Stenotrophomonas maltophilia. Also, dihydroxylation mediated by the 5,8-diol synthase from Aspergillus nidulans is demonstrated. The second step comprises decarboxylation of the intermediate hydroxy acids by the photoactivated decarboxylase from Chlorella variabilis NC64A. A broad range of (poly)unsaturated fatty acids can be transformed into enantiomerically pure fatty alcohols in a simple one-pot approach., BT/Biocatalysis

It is well-known that energy-rich radiation induces water splitting, eventually yielding hydrogen peroxide. Synthetic applications, however, are scarce and to the best of our knowledge, the combination of radioactivity with enzyme-catalysis has not been considered yet. Peroxygenases utilize H2O2 as an oxidant to promote highly selective oxyfunctionalization reactions but are also irreversibly inactivated in the presence of too high H2O2 concentrations. Therefore, there is a need for efficient in situ H2O2 generation methods. Here, we show that radiolytic water splitting can be used to promote specific biocatalytic oxyfunctionalization reactions. Parameters influencing the efficiency of the reaction and current limitations are shown. Particularly, oxidative inactivation of the biocatalyst by hydroxyl radicals influences the robustness of the overall reaction. Radical scavengers can alleviate this issue, but eventually, physical separation of the enzymes from the ionizing radiation will be necessary to achieve robust reaction schemes. We demonstrate that nuclear waste can also be used to drive selective, peroxygenase-catalyzed oxyfunctionalization reactions, challenging our view on nuclear waste in terms of sustainability., BT/Biocatalysis, RST/Applied Radiation & Isotopes, RST/Radiation, Science and Technology

A photobiocatalytic cascade transforming natural triglycerides into alkanes/alkenes is proposed. Starting from natural triglycerides, free fatty acids have been obtained using lipases. The free fatty acids were then, in a photoenzymatic step, decarboxylated into the C1-shortened alkanes using a recently described photodecarboxylase from Chlorella variabilis NC64A. This cascade produced alkanes from various natural (waste) oils in significant amounts (up to 24 g L−1) and may provide a basis for valorisation of waste oils into a next generation of biodiesel., BT/Biocatalysis

The assessment of the potentially destructive impacts of subaqueous landslides on offshore pipelines is required when the pipeline route passes through zones with a risk of mass movements. Therefore, quantifying and evaluating the ultimate load/pressure acting on the pipeline is one of the key factors in geotechnical safety design of the pipeline. One of the triggers of subaqueous soil mass movements is the monotonic loads, which induce the trigger relative displacement between a soil layer and a pipe under both drained and (partially) undrained conditions. Two approaches based on geotechnical and fluid dynamics perspectives have been proposed for estimating the ultimate load/pressure for different stages of a submarine landslide. Traditionally, the former method focuses on the analysis of pipelines installed under flat seabed experiencing relative movements to the surrounding soil, whereas, the latter method focuses on the behaviour of pipelines laid on the surface of the seabed and subjected to debris flows. However, offshore pipelines are often buried under the seabed, which is not always flat and has a modest inclination in some cases. This engineering condition normally differs from that of the simplifying assumptions and boundary conditions (such as seabed inclination, and soil strength) commonly imposed to the geotechnical and fluid dynamics approaches. Accordingly, a better understanding of the soilpipeline interaction when the pipelines are buried in subaqueous slopes is essential for evaluating the ultimate load/pressure that would be caused by the slope failures. This thesis presents a research effort on investigating the soilpipeline interaction during subaqueous slope failures using advanced physical modelling. In this research, the experiments can be divided into two main groups according to the soil drainage conditions. The first group of tests were carried out in the drained condition by using dry sand as the soil material for the slopes. The pip, Geo-engineering

En route to a bio-based chemical industry, the conversion of fatty acids into building blocks is of particular interest. Enzymatic routes, occurring under mild conditions and excelling by intrinsic selectivity, are particularly attractive. Here we report photoenzymatic cascade reactions to transform unsaturated fatty acids into enantiomerically pure secondary fatty alcohols. In a first step the C=C-double bond is stereoselectively hydrated using oleate hydratases from Lactobacillus reuteri or Stenotrophomonas maltophilia. Also, dihydroxylation mediated by the 5,8-diol synthase from Aspergillus nidulans is demonstrated. The second step comprises decarboxylation of the intermediate hydroxy acids by the photoactivated decarboxylase from Chlorella variabilis NC64A. A broad range of (poly)unsaturated fatty acids can be transformed into enantiomerically pure fatty alcohols in a simple one-pot approach., BT/Biocatalysis

The consecutive photooxidation and reductive amination of various alcohols in a cascade reaction were realized by the combination of a photocatalyst and several enzymes. Whereas the photocatalyst (sodium anthraquinone-2-sulfonate) mediated the light-driven, aerobic oxidation of primary and secondary alcohols, the enzymes (various ω-transaminases) catalyzed the enantio-specific reductive amination of the intermediate aldehydes and ketones. The system worked in a one-pot one-step fashion, whereas the productivity was significantly improved by switching to a one-pot two-step procedure. A wide range of aliphatic and aromatic compounds was transformed into the enantiomerically pure corresponding amines via the photo-enzymatic cascade., BT/Biocatalysis

Enzymatic methods for the polymerisation of vinyl monomers are presented and critically discussed. Vinyl monomers can be polymerised initiated by enzyme-catalysed radical formation. The most widely used initiators for this purpose are β-diketo compounds, which can be transformed into the corresponding radicals via peroxidase- or laccase-catalysed oxidation. For this, peroxidases use hydrogen peroxide as oxidant, while laccases rely on molecular oxygen. Both enzyme classes comprise specific advantages and disadvantages that are discussed in this chapter. Also, parameters to control the polymer properties are introduced and discussed, Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., BT/Biocatalysis

Natural deep eutectic solvents (NADES) are proposed as alternative solvents for peroxygenase-catalysed oxyfunctionalization reactions. Choline chloride-based NADES are of particular interest as they can serve as solvent, enzyme-stabiliser and sacrificial electron donor for the in situ H2O2 generation. This report provides the first proof-of-concept and basic characterisation of this new reaction system. Highly promising turnover numbers for the biocatalysts of up to 200,000 have been achieved., BT/Biocatalysis

Peroxygenases catalyze selective oxyfunctionalization of hydrocarbons with high conversion efficiencies using H2O2 as a key cosubstrate. Here, we report an unbiased photoelectrochemical (PEC) tandem structure consisting of a FeOOH/BiVO4 photoanode, a Cu(In,Ga)Se2 solar absorber, and a graphitic carbon nitride/reduced graphene oxide hybrid cathode for light-driven peroxygenase catalysis. Powered by sufficient photovoltage generated by the solar absorber, the PEC platform generates H2O2 in situ through reductive activation of molecular oxygen using water as an electron donor in the absence of external bias. The peroxygenase from Agrocybe aegerita catalyzed the stereoselective hydroxylation of ethylbenzene to (R)-1-phenylethanol with total turnover numbers over 43 300 and high enantioselectivity (ee > 99%) in the unbiased PEC tandem system., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., BT/Biocatalysis

Various enzymes utilize hydrogen peroxide as an oxidant. Such “peroxizymes” are potentially very attractive catalysts for a broad range of oxidation reactions. Most peroxizymes, however, are inactivated by an excess of H2O2. The electrochemical reduction of oxygen can be used as an in situ generation method for hydrogen peroxide to drive the peroxizymes at high operational stabilities. Using conventional electrode materials, however, also necessitates significant overpotentials, thereby reducing the energy efficiency of these systems. This study concerns a method to coat a gas-diffusion electrode with oxidized carbon nanotubes (oCNTs), thereby greatly reducing the overpotential needed to perform an electroenzymatic halogenation reaction. In comparison to the unmodified electrode, with the oCNTs-modified electrode the overpotential can be reduced by approximately 100 mV at comparable product formation rates., BT/Biocatalysis

Peroxygenases are very interesting catalysts for specific oxyfunctionalization chemistry. Instead of relying on complicated electron transport chains, they rely on simple hydrogen peroxide as the stoichiometric oxidant. Their poor robustness against H2O2 can be addressed via in situ generation of H2O2. Here we report that simple graphitic carbon nitride (g-C3N4) is a promising photocatalyst to drive peroxygenase-catalyzed hydroxylation reactions. The system has been characterized by outlining not only its scope but also its current limitations. In particular, spatial separation of the photocatalyst from the enzyme is shown as a solution to circumvent the undesired inactivation of the biocatalyst. Overall, very promising turnover numbers of the biocatalyst of more than 60.000 have been achieved., BT/Biocatalysis

We report the use of commercial laundry powder as a biocatalyst for a range of lipase-catalysed reactions including (trans)esterification, ester hydrolysis and chemoenzymatic epoxidation reactions. The enzymatic laundry powder exhibited excellent stability and recyclability, making it a readily available and cheap biocatalyst for chemical transformations., BT/Biocatalysis

Sand erosion and scouring caused by waves and marine currents result in gradual increase of local seabed inclination and formation of slopes around hydraulic structures and offshore foundations. During this process, shear stresses in the soil body increase monotonically which may lead to static liquefaction and damage of the adjacent offshore infrastructure. This paper presents the details of a newly developed static liquefaction triggering actuator to be used at an enhanced gravity condition in a geotechnical centrifuge. This actuator simulates the steeping process of submarine sand layers due to scouring and enables the investigation of failure mechanisms in submerged slopes. The details of the centrifuge test set-up designed and constructed to simulate the process of triggering static liquefaction in loose sand layers are presented. Furthermore, the performance of the novel integrated model preparation facility using sand fluidization is explained. The set-up was used to conduct several centrifuge tests at four different slope steepening rates to investigate the slope steepening rate effects. Moreover, the effect of viscosity of the submerging pore fluid on the behaviour of the slopes at the onset of failure is investigated. The Coriolis effect on loose saturated sand samples during increase of g-level is examined as well. Results show that the built-up of pore pressure due to local shear deformations can be detected and considered as one of the triggering mechanisms of this kind of submarine slope instabilities., Geo-engineering

An increasing number of biocatalytic oxidation reactions rely on H 2 O 2 as a clean oxidant. The poor robustness of most enzymes towards H 2 O 2 , however, necessitates more efficient systems for in situ H 2 O 2 generation. In analogy to the well-known formate dehydrogenase to promote NADH-dependent reactions, we here propose employing formate oxidase (FOx) to promote H 2 O 2 -dependent enzymatic oxidation reactions. Even under non-optimised conditions, high turnover numbers for coupled FOx/peroxygenase catalysis were achieved., BT/Biocatalysis

A recently discovered photodecarboxylase from Chlorella variabilis NC64A ( CvFAP) bears the promise for the efficient and selective synthesis of hydrocarbons from carboxylic acids. CvFAP, however, exhibits a clear preference for long-chain fatty acids thereby limiting its broad applicability. In this contribution, we demonstrate that the decoy molecule approach enables conversion of a broad range of carboxylic acids by filling up the vacant substrate access channel of the photodecarboxylase. These results not only demonstrate a practical application of a unique, photoactivated enzyme but also pave the way to selective production of short-chain alkanes from waste carboxylic acids under mild reaction conditions., BT/Biocatalysis, ChemE/Materials for Energy Conversion & Storage, ChemE/Inorganic Systems Engineering, ChemE/Algemeen

The use of natural deep eutectic solvents (NADES) as multifunctional solvents for limonene bioprocessing was reported. NADES were used for the extraction of limonene from orange peel wastes, as solvent for the chemoenzymatic epoxidation of limonene, and as sacrificial electron donor for the in situ generation of H 2 O 2 to promote the epoxidation reaction. The proof-of-concept for this multifunctional use was provided, and the scope and current limitations of the concept were outlined., BT/Biocatalysis

Natural deep eutectic solvents (NADES) are proposed as alternative solvents for peroxygenase-catalysed oxyfunctionalization reactions. Choline chloride-based NADES are of particular interest as they can serve as solvent, enzyme-stabiliser and sacrificial electron donor for the in situ H2O2 generation. This report provides the first proof-of-concept and basic characterisation of this new reaction system. Highly promising turnover numbers for the biocatalysts of up to 200,000 have been achieved., BT/Biocatalysis

Various enzymes utilize hydrogen peroxide as an oxidant. Such “peroxizymes” are potentially very attractive catalysts for a broad range of oxidation reactions. Most peroxizymes, however, are inactivated by an excess of H2O2. The electrochemical reduction of oxygen can be used as an in situ generation method for hydrogen peroxide to drive the peroxizymes at high operational stabilities. Using conventional electrode materials, however, also necessitates significant overpotentials, thereby reducing the energy efficiency of these systems. This study concerns a method to coat a gas-diffusion electrode with oxidized carbon nanotubes (oCNTs), thereby greatly reducing the overpotential needed to perform an electroenzymatic halogenation reaction. In comparison to the unmodified electrode, with the oCNTs-modified electrode the overpotential can be reduced by approximately 100 mV at comparable product formation rates., BT/Biocatalysis

Photoenzymatic cascades can be used for selective oxygenation of C−H-Bonds under mild conditions circumventing the hydrogen peroxide mediated peroxygenase inactivation via in situ H2O2 generation. Here, we report the “on demand” production of hydrogen peroxide via methanol assisted reduction of molecular oxygen using UV-illuminated titanium dioxide (Aeroxide P25) combined with the enantioselective hydroxylation of ethylbenzene to (R)-1-phenylethanole catalyzed by the Unspecific Peroxygenase from Agrocybe Aegerita. For the application of the system it is important to understand the influence of the reaction parameters to be able to optimize the system. Therefore, we systematically investigated product formation and enzyme inactivation as well as ROS formation (H2O2, .OH and .O2−) applying different light intensities and temperatures. As a result, Turnover Numbers up to 220 000, photonic efficiencies up to 13.6 % and production rates up to 0.9 mM h−1 were achieved., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., BT/Biocatalysis

Peroxygenases catalyze selective oxyfunctionalization of hydrocarbons with high conversion efficiencies using H2O2 as a key cosubstrate. Here, we report an unbiased photoelectrochemical (PEC) tandem structure consisting of a FeOOH/BiVO4 photoanode, a Cu(In,Ga)Se2 solar absorber, and a graphitic carbon nitride/reduced graphene oxide hybrid cathode for light-driven peroxygenase catalysis. Powered by sufficient photovoltage generated by the solar absorber, the PEC platform generates H2O2 in situ through reductive activation of molecular oxygen using water as an electron donor in the absence of external bias. The peroxygenase from Agrocybe aegerita catalyzed the stereoselective hydroxylation of ethylbenzene to (R)-1-phenylethanol with total turnover numbers over 43 300 and high enantioselectivity (ee > 99%) in the unbiased PEC tandem system., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., BT/Biocatalysis

Sand erosion and scouring caused by waves and marine currents result in gradual increase of local seabed inclination and formation of slopes around hydraulic structures and offshore foundations. During this process, shear stresses in the soil body increase monotonically which may lead to static liquefaction and damage of the adjacent offshore infrastructure. This paper presents the details of a newly developed static liquefaction triggering actuator to be used at an enhanced gravity condition in a geotechnical centrifuge. This actuator simulates the steeping process of submarine sand layers due to scouring and enables the investigation of failure mechanisms in submerged slopes. The details of the centrifuge test set-up designed and constructed to simulate the process of triggering static liquefaction in loose sand layers are presented. Furthermore, the performance of the novel integrated model preparation facility using sand fluidization is explained. The set-up was used to conduct several centrifuge tests at four different slope steepening rates to investigate the slope steepening rate effects. Moreover, the effect of viscosity of the submerging pore fluid on the behaviour of the slopes at the onset of failure is investigated. The Coriolis effect on loose saturated sand samples during increase of g-level is examined as well. Results show that the built-up of pore pressure due to local shear deformations can be detected and considered as one of the triggering mechanisms of this kind of submarine slope instabilities., Geo-engineering

Peroxygenases are very interesting catalysts for specific oxyfunctionalization chemistry. Instead of relying on complicated electron transport chains, they rely on simple hydrogen peroxide as the stoichiometric oxidant. Their poor robustness against H2O2 can be addressed via in situ generation of H2O2. Here we report that simple graphitic carbon nitride (g-C3N4) is a promising photocatalyst to drive peroxygenase-catalyzed hydroxylation reactions. The system has been characterized by outlining not only its scope but also its current limitations. In particular, spatial separation of the photocatalyst from the enzyme is shown as a solution to circumvent the undesired inactivation of the biocatalyst. Overall, very promising turnover numbers of the biocatalyst of more than 60.000 have been achieved., BT/Biocatalysis

We report the use of commercial laundry powder as a biocatalyst for a range of lipase-catalysed reactions including (trans)esterification, ester hydrolysis and chemoenzymatic epoxidation reactions. The enzymatic laundry powder exhibited excellent stability and recyclability, making it a readily available and cheap biocatalyst for chemical transformations., BT/Biocatalysis

An increasing number of biocatalytic oxidation reactions rely on H 2 O 2 as a clean oxidant. The poor robustness of most enzymes towards H 2 O 2 , however, necessitates more efficient systems for in situ H 2 O 2 generation. In analogy to the well-known formate dehydrogenase to promote NADH-dependent reactions, we here propose employing formate oxidase (FOx) to promote H 2 O 2 -dependent enzymatic oxidation reactions. Even under non-optimised conditions, high turnover numbers for coupled FOx/peroxygenase catalysis were achieved., BT/Biocatalysis

A recently discovered photodecarboxylase from Chlorella variabilis NC64A ( CvFAP) bears the promise for the efficient and selective synthesis of hydrocarbons from carboxylic acids. CvFAP, however, exhibits a clear preference for long-chain fatty acids thereby limiting its broad applicability. In this contribution, we demonstrate that the decoy molecule approach enables conversion of a broad range of carboxylic acids by filling up the vacant substrate access channel of the photodecarboxylase. These results not only demonstrate a practical application of a unique, photoactivated enzyme but also pave the way to selective production of short-chain alkanes from waste carboxylic acids under mild reaction conditions., BT/Biocatalysis, ChemE/Materials for Energy Conversion and Storage, ChemE/Inorganic Systems Engineering, ChemE/Algemeen

The use of natural deep eutectic solvents (NADES) as multifunctional solvents for limonene bioprocessing was reported. NADES were used for the extraction of limonene from orange peel wastes, as solvent for the chemoenzymatic epoxidation of limonene, and as sacrificial electron donor for the in situ generation of H 2 O 2 to promote the epoxidation reaction. The proof-of-concept for this multifunctional use was provided, and the scope and current limitations of the concept were outlined., BT/Biocatalysis

In this study, we combined photo-organo redox catalysis and biocatalysis to achieve asymmetric C–H bond functionalization of simple alkane starting materials. The photo-organo catalyst anthraquinone sulfate (SAS) was employed to oxyfunctionalise alkanes to aldehydes and ketones. We coupled this light-driven reaction with asymmetric enzymatic functionalisations to yield chiral hydroxynitriles, amines, acyloins and α-chiral ketones with up to 99 % ee. In addition, we demonstrate functional group interconversion to alcohols, esters and carboxylic acids. The transformations can be performed as concurrent tandem reactions. We identified the degradation of substrates and inhibition of the biocatalysts as limiting factors affecting compatibility, due to reactive oxygen species generated in the photocatalytic step. These incompatibilities were addressed by reaction engineering, such as applying a two-phase system or temporal and spatial separation of the catalysts. Using a selection of eleven starting alkanes, one photo-organo catalyst and 8 diverse biocatalysts, we synthesized 26 products and report for the model compounds benzoin and mandelonitrile > 97 % ee at gram scale., BT/Biocatalysis, BN/Greg Bokinsky Lab

Oxidation chemistry using enzymes is approaching maturity and practical applicability in organic synthesis. Oxidoreductases (enzymes catalysing redox reactions) enable chemists to perform highly selective and efficient transformations ranging from simple alcohol oxidations to stereoselective halogenations of non‐activated C−H bonds. For many of these reactions, no “classical” chemical counterpart is known. Hence oxidoreductases open up shorter synthesis routes based on a more direct access to the target products. The generally very mild reaction conditions may also reduce the environmental impact of biocatalytic reactions compared to classical counterparts. In this Review, we critically summarise the most important recent developments in the field of biocatalytic oxidation chemistry and identify the most pressing bottlenecks as well as promising solutions., BT/Biocatalysis, BN/Greg Bokinsky Lab

Oxidoreductases have become useful tools in the hands of chemists to perform selective and mild oxidation and reduction reactions. Instead of mimicking native catalytic cycles, generally involving costly and unstable nicotinamide cofactors, more direct, NAD(P)-independent methodologies are being developed. The promise of these approaches not only lies with simpler and cheaper reaction schemes but also with higher selectivity as compared to whole cell approaches and their mimics., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., BT/Biocatalysis

Peroxygenases offer an attractive means to address challenges in selective oxyfunctionalization chemistry. Despite this, their application in synthetic chemistry remains challenging due to their facile inactivation by the stoichiometric oxidant H2O2. Often atom-inefficient peroxide generation systems are required, which show little potential for large-scale implementation. Here, we show that visible-light-driven, catalytic water oxidation can be used for in situ generation of H2O2 from water, rendering the peroxygenase catalytically active. In this way, the stereoselective oxyfunctionalization of hydrocarbons can be achieved by simply using the catalytic system, water and visible light., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., BT/Biocatalysis, BN/Greg Bokinsky Lab

The photoenzymatic decarboxylation of fatty acids to alkanes is proposed as an alternative approach for the synthesis of biodiesel. By using a recently discovered photodecarboxylase from Chlorella variabilis NC64A (CvFAP) we demonstrate the irreversible preparation of alkanes from fatty acids and triglycerides. Several fatty acids and their triglycerides are converted by CvFAP in near-quantitative yield and exclusive selectivity upon illumination with blue light. Very promising turnover numbers of up to 8000 were achieved in this proof-of-concept study., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., BT/Biocatalysis

Oxidoreductases have become useful tools in the hands of chemists to perform selective and mild oxidation and reduction reactions. Instead of mimicking native catalytic cycles, generally involving costly and unstable nicotinamide cofactors, more direct, NAD(P)-independent methodologies are being developed. The promise of these approaches not only lies with simpler and cheaper reaction schemes but also with higher selectivity as compared to whole cell approaches and their mimics., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., BT/Biocatalysis

Peroxygenases offer an attractive means to address challenges in selective oxyfunctionalization chemistry. Despite this, their application in synthetic chemistry remains challenging due to their facile inactivation by the stoichiometric oxidant H2O2. Often atom-inefficient peroxide generation systems are required, which show little potential for large-scale implementation. Here, we show that visible-light-driven, catalytic water oxidation can be used for in situ generation of H2O2 from water, rendering the peroxygenase catalytically active. In this way, the stereoselective oxyfunctionalization of hydrocarbons can be achieved by simply using the catalytic system, water and visible light., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., BT/Biocatalysis, BN/Greg Bokinsky Lab

The photoenzymatic decarboxylation of fatty acids to alkanes is proposed as an alternative approach for the synthesis of biodiesel. By using a recently discovered photodecarboxylase from Chlorella variabilis NC64A (CvFAP) we demonstrate the irreversible preparation of alkanes from fatty acids and triglycerides. Several fatty acids and their triglycerides are converted by CvFAP in near-quantitative yield and exclusive selectivity upon illumination with blue light. Very promising turnover numbers of up to 8000 were achieved in this proof-of-concept study., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., BT/Biocatalysis

Carbon-nanodot-doped g-C3N4 is used as a photocatalyst to promote the aerobic oxidation of alcohols and oxyfunctionalisation of activated hydrocarbons. A critical E-factor analysis of the current reaction system reveals its limitations en route to environmentally acceptable oxidation procedures., BT/Biocatalysis

Surface PEGylation of nanoparticles designed for biomedical applications is a common and straightforward way to stabilize the materials for in vivo administration and to increase their circulation time. This strategy becomes less trivial when MRI active porous nanomaterials are concerned as their function relies on water/proton-exchange between the pores and bulk water. Here we present a comprehensive study on the effects of PEGylation on the relaxometric properties of nanozeolite LTL (dimensions of 20 × 40 nm) ion-exchanged with paramagnetic GdIII ions. We evidence that as long as the surface grafting density of the PEG chains does not exceed the “mushroom” regime (conjugation of up to 6.2 wt % of PEG), Gd-LTL retains a remarkable longitudinal relaxivity (38 s–1 mM–1 at 7 T and 25 °C) as well as the pH-dependence of the longitudinal and transverse relaxation times. At higher PEG content, the more compact PEG layer (brush regime) limits proton/water diffusion and exchange between the interior of LTL and the bulk, with detrimental consequences on relaxivity. Furthermore, PEGylation of Gd-LTL dramatically decreases the leakage of toxic GdIII ions in biological media and in the presence of competing anions, which together with minimal cytotoxicity renders these materials promising probes for MRI applications., BT/Biocatalysis

Selective oxyfunctionalizations of inert C−H bonds can be achieved under mild conditions by using peroxygenases. This approach, however, suffers from the poor robustness of these enzymes in the presence of hydrogen peroxide as the stoichiometric oxidant. Herein, we demonstrate that inorganic photocatalysts such as gold–titanium dioxide efficiently provide H2O2 through the methanol-driven reductive activation of ambient oxygen in amounts that ensure that the enzyme remains highly active and stable. Using this approach, the stereoselective hydroxylation of ethylbenzene to (R)-1-phenylethanol was achieved with high enantioselectivity (>98 % ee) and excellent turnover numbers for the biocatalyst (>71 000)., BT/Biocatalysis