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.@en

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. @en

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.@en

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. @en

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. @en

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.@en

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.@en

The aerobic organocatalytic oxidation of alcohols was achieved by using water-soluble sodium anthraquinone sulfonate. Under visible-light activation, this catalyst mediated the aerobic oxidation of alcohols to aldehydes and ketones. The photo-oxyfunctionalization of alkanes was also possible under these conditions.@en

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.@en

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. @en

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).@en

The hydroxylation of fatty acids is an appealing reaction in synthetic chemistry, although the lack of selective catalysts hampers its industrial implementation. In this study, we have engineered a highly regioselective fungal peroxygenase for the ω-1 hydroxylation of fatty acids with quenched stepwise over-oxidation. One single mutation near the Phe catalytic tripod narrowed the heme cavity, promoting a dramatic shift toward subterminal hydroxylation with a drop in the over-oxidation activity. While crystallographic soaking experiments and molecular dynamic simulations shed light on this unique oxidation pattern, the selective biocatalyst was produced by Pichia pastoris at 0.4 g L−1 in a fed-batch bioreactor and used in the preparative synthesis of 1.4 g of (ω-1)-hydroxytetradecanoic acid with 95 % regioselectivity and 83 % ee for the S enantiomer.@en

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.@en

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.@en

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.@en

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.@en

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.@en

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.@en

Multimodal imaging techniques are emerging in medical diagnosis. The synergistic combination of imaging techniques, such as MRI and PET/SPECT, is highly useful to strengthen each of the individual imaging modalities while reducing any of their disadvantages. In recent years, the progress of technical integration of imaging scanners has led to a clear motivation to design multimodal agents by chemists that can be used simultaneously and hence profit optimally of the new hybrid imaging scanners. Nanoscaffolds combining discrete functions (e.g. magnetic, radioactive, optical or therapeutic) are particularly interesting in this regard. There has been an increasing endeavour to design and synthesize multifunctional nanocomposites for practical applications in dual imaging modalities such as MRI-optical, MRI-PET, PET-optical, PET-CT, MRI-SPECT. Chapter 1 of this thesis summarizes the state-of-the-art in the development of multimodal probes for medical imaging and therapy, in which the roles of metal ions are highlighted. Chapters 2-5 focus on the exploration of porous nanomaterials, e.g. zeolite LTL in particular, which is suitable for the above-mentioned purposes due to their ability to accommodate large amounts of lanthanide ions through ion-exchange of alkali cations that counterbalance the AlO4- of the crystalline framework. The surface chemistry and biocompatibility study are also included. Chapter 6 describes a facile methodology to synthesize the lanthanide-nanoparticles with controllable size and application of the synthesized materials as MRI contrast agents. Chapter 7 shows that these versatile materials are also applicable in a very different field: they are very efficient in the storage and release of oxygen. In conclusion, the findings of the thesis mainly provide insights into the merits and understanding of zeolite-based MR imaging probes. @en

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@en