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The drive toward miniaturization of enzyme-based bioelectronics established a need for three-dimensional (3D) microstructured electrodes, which are difficult to implement using conventional manufacturing processes. Additive manufacturing coupled with electroless metal plating enables the production of 3D conductive microarchitectures with high surface area for potential applications in such devices. However, interfacial delamination between the metal layer and the polymer structure is a major reliability concern, which leads to device performance degradation and eventually device failure. This work demonstrates a method to produce a highly conductive and robust metal layer on a 3D printed polymer microstructure with strong adhesion by introducing an interfacial adhesion layer. Prior to 3D printing, multifunctional acrylate monomers with alkoxysilane (-Si-(OCH 3 ) 3 ) were synthesized via the thiol-Michael addition reaction between pentaerythritol tetraacrylate (PETA) and 3-mercaptopropyltrimethoxysilane (MPTMS) with a 1:1 stoichiometric ratio. Alkoxysilane functionality remains intact during photopolymerization in a projection micro-stereolithography (PμSLA) system and is utilized for the sol-gel reaction with MPTMS during postfunctionalization of the 3D printed microstructure to build an interfacial adhesion layer. This leads to the implementation of abundant thiol functional groups on the surface of the 3D printed microstructure, which can act as a strong binding site for gold during electroless plating to improve interfacial adhesion. The 3D conductive microelectrode prepared by this technique exhibited excellent conductivity of 2.2 × 10 7 S/m (53% of bulk gold) with strong adhesion between a gold layer and a polymer structure even after harsh sonication and an adhesion tape test. As a proof-of-concept, we examined the 3D gold diamond lattice microelectrode modified with glucose oxidase as a bioanode for a single enzymatic biofuel cell. The lattice-structured enzymatic electrode with high catalytic surface area was able to generate a current density of 2.5 μA/cm 2 at 0.35 V, which is an about 10 times increase in current output compared to a cube-shaped microelectrode.

The use of magnetic biocatalysts is highly beneficial in bioprocesses technology, as it allows their easy recovering and enhances biocatalyst lifetime. Thus, it simplifies operational processing and increases efficiency, leading to more cost-effective processes. The use of small-size matrices as carriers for enzyme immobilization enables to maximize surface area and catalysts loading, also reducing diffusion limitations. As highly expensive nanoparticles (nm size) usually aggregate, their application at large scale is not recommended. In contrast, the use of magnetic micro-macro (µm-mm size) matrices leads to more homogeneous biocatalysts with null or very low aggregation, which facilitates an easy handling and recovery. The present review aims to highlight recent trends in the application of medium-to-high size magnetic biocatalysts in different areas (biodiesel production, food and pharma industries, protein purification or removal of environmental contaminants). The advantages and disadvantages of these above-mentioned magnetic biocatalysts in bioprocess technology will be also discussed., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Due to the problems raised by the use of animal or microbial recombinant proteases, the use of proteases from vegetable origin is becoming increasingly popular.. Among them, sulfidryl proteases have a special interest. Ficin is an outstanding example of this kind of proteases. This paper aims to be to make a comprehensive review of the recent uses of this enzyme, including for example protein hydrolysis, the production of bioactive peptides and antibodies fragments (researchers point that ficin results are more reproducible than using other proteases), meat tenderization, milk coagulations in cheese making or peptide synthesis. Efforts to get industrial immobilized biocatalysts of the enzyme will be also described. The review shows the huge potential and brilliant prospect that this enzyme can have in the near future., (Copyright © 2020 Elsevier B.V. All rights reserved.)

To exploit the hydrolytic activity and high selectivity of immobilized lipase B from Candida antarctica on octyl agarose (CALB-OC) in the hydrolysis of triacetin and also to produce new value-added compounds from glycerol, this work describes a chemoenzymatic methodology for the synthesis of the new dimeric glycerol ester 3-((2,3-diacetoxypropanoyl)oxy)propane-1,2-diyl diacetate. According to this approach, triacetin was regioselectively hydrolyzed to 1,2-diacetin with CALB-OC. The diglyceride product was subsequently oxidized with pyridinium chlorochromate (PCC) and a dimeric ester was isolated as the only product. It was found that the medium acidity during the PCC treatment and a high 1,2-diacetin concentration favored the formation of the ester. The synthesized compounds were characterized using IR, MS, HR-MS, and NMR techniques. The obtained dimeric ester was evaluated at 100 ppm against seven bacterial strains and two Candida species to identify its antimicrobial activity. The compound has no inhibitory activity against the bacterial strains used but decreased C. albicans and C. parapsilosis growth by 49% and 68%, respectively. Hemolytic activity was evaluated, and the results obtained support the use of the dimeric ester to control C. albicans and C. parapsilosis growth in non-intravenous applications because the compound shows hemolytic activity.

A strategy to obtain biocatalysts formed by three enzyme layers has been designed using lipases A and B from Candida antarctica (CALA and CALB), the lipases from Rhizomucor miehei (RML) and Thermomyces lanuginosus (TLL), and the artificial chimeric phospholipase Lecitase Ultra (LEU). The enzymes were initially immobilized via interfacial activation on octyl-agarose beads, treated with polyethylenimine (PEI) and a new enzyme layer was immobilized on the octyl-enzyme-PEI composite by ion exchange, producing octyl-enzyme-PEI-enzyme biocatalysts. Except when using LEU, when the two-layer biocatalysts, a large percentage of the PEI-immobilized enzyme was released when a new batch of PEI was added. This was prevented by glutaraldehyde crosslinking. The enzyme modifications produced more active preparations in some cases while in other cases, the effect of the modifications was negative for enzyme activity. These effects of the enzymes modifications were also different when the enzyme was immobilized by interfacial activation or by ion exchange. In all cases, the 3-layer biocatalysts were more active than the single- or bi-layer biocatalysts with some of the assayed substrates. However, as the substrate diffusion problems increased when new enzyme layers were added, even a decrease in enzyme activity with some substrates was found after increasing the number of enzyme layers., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Conjugated linolenic acid (CLA) has important health effects, and their phospholipids forms (PL) are advantageous vehicles of this bioactive agent. Acidolysis of soybean phosphatidylcholine (PC) with conjugated linolenic acid (CLA) catalyzed by Lecitase® Ultra immobilized on Duolite A658 was studied. This reaction is typically limited by hydrolysis, producing 60-90 % of lyso- and glycero-PC and yielding low the process efficiency. Drying the amphiphilic PC material was found the key factor for maximal diacylglycerol phosphatidylcholines (PC) production and different drying approaches were studied to maximize the formation of PC rich in CLA in a solvent free process. PC lyophilization for 24 h getting dry solid appearance (PC; 783 ± 11 mg water/Kg PC) or other standard protocols to reduce water content/activity of reaction medium, did not improve the reaction performance. However, adding 4 extra days to the second step of lyophilization at high vacuum (1 Pa) and moderate temperature (20 °C), followed by further PC dehydration with molecular sieves, drastically reduced the hydrolysis process by achieving a extensive PC dehydration (279 ± 4 mg water/Kg PC), obtaining for the first time >99% molar yield of diacyl-PC product. After 24 h of reaction, a diacyl-PC product with 72.3% CLA content was obtained. PC molecules containing two CLA were the major species formed., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Phospholipids (PL) rich in conjugated linolenic acid (CLA) have important health effects. Yields of phosphatidylcholine (PC) acidolysis with CLA use to be limited to <30%, due to competitive side-hydrolysis. Duolite A658-Lecitase is a very suitable biocatalyst for this reaction. In this study, PC hydrolysis has been practically eliminated using extremely dried lyophilized PC (279 ± 4 mg water/Kg PC), obtaining close to 100% molar yield of modified PC (72.3% CLA) with Duolite-Lecitase in 24 h, the highest yield reported in the literature for this reaction. It has been better improved by changing the immobilization support, using three food grade hydrophobic supports (Styrene, and two Octadecyl methacrylates (OM and OMC)). In only 2 h, with a 1/12 PC/CLA molar ratio at 50 °C, similar almost quantitative yields of PC with 74.4% CLA content has been obtained using OM-Lecitase. The fatty acid composition of modified PCs is not affected by the enzyme immobilization protocol., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

NiZnFe 2 O 4 superparamagnetic nanoparticles were coated with silica by impregnation with tetraethoxysilane (TEOS) and further activated with divinylsulfone (DVS) and p-benzoquinone (BQ) for covalent immobilization lipase from Pseudomonas fluorescens (PFL), producing the biocatalysts TEOS-NANO-DVS-PFL and TEOS-NANO-BQ-PFL. The optimal conditions for enzyme immobilization were found to be pH 7 and 0.1 M of both activating reagents. PFL was also immobilized on TEOS nanoparticles without any activation as a reference (TEOS-NANO-PFL). Results indicated that TEOS could be released from the nanoparticles at alkaline pH value. Optimal TEOS-NANO-PFL exhibited a recovered activity of 55% and a t 1/2(60°C) of just over 150 min; while TEOS-NANO-DVS-PFL showed 82% of activity recovered and t 1/2(60°C) of 225 min; being the TEOS-NANO-BQ-PFL the biocatalyst offering the best results (89% of recovered activity and a half-life over 1440 min), the maximum enzyme load was ≈300 U/g., (Copyright © 2019 Elsevier B.V. All rights reserved.)