Control of selectivity in the oxidation of 5-hydroxymethylfurfural to 5- formyl-2-furancarboxylic acid catalyzed by laccase in a multiphasic gas-liquid microbioreactor.

The selectivity of 5-formyl-2-furancarboxylic acid (FFCA) was studied in a batch bioreactor and microbioreactors with different internal diameters (ID). Using microbioreactors, the effect of the flow rate of the liquid and gas phase on the yield, space time yield (STYFFCA), and gas-liquid mixture velocity (UM) of the reaction was evaluated. The biooxidation in flow microbioreactors, a selectivity of 100 % for FFCA was achieved, while with the batch bioreactor at the same substrate concentration a selectivity of 6.7 % was obtained. The highest yield (30 %) with 15 mM of 5-hydroxymethylfurfural (HMF) was reached at a gas-liquid flow rate of 0.5 µL/min and the highest STYFFCA (0.07 mol m-3 min-1) was achieved at a gas-liquid flow rate of 1.5 µL/min with the microbioreactor with an ID of 0.5 mm. The UM values (0.5 to 1.6 cm min1) indicated that the reaction takes place under a kinetic regime without mass transfer limitations.

Immobilization of Lipases Using Poly(vinyl) Alcohol.

Lipases are very versatile enzymes because they catalyze various hydrolysis and synthesis reactions in a chemo-, regio-, and stereoselective manner. From a practical point of view, immobilization allows the recovery and stabilization of the biocatalyst for its application in different types of bioreactors. Among the various support options for immobilizing lipases is polyvinyl alcohol (PVA), which, when functionalized or combined with other materials, provides different characteristics and properties to the biocatalyst. This review analyzes the multiple possibilities that PVA offers as a material to immobilize lipases when combined with alginate, chitosan, and hydroxypropylmethylcellulose (HPMC), incorporating magnetic properties together with the formation of fibers and microspheres. The articles analyzed in this review were selected using the Scopus database in a range of years from 1999 to 2023, finding a total of 42 articles. The need to expand knowledge in this area is due to the great versatility and scaling possibilities that PVA has as a support for lipase immobilization and its application in different bioreactor configurations.

Upstream and Downstream Bioprocessing in Enzyme Technology.

The development of biotransformation must integrate upstream and downstream processes. Upstream bioprocessing will influence downstream bioprocessing. It is essential to consider this because downstream processes can constitute the highest cost in bioprocessing. This review comprehensively overviews the most critical aspects of upstream and downstream bioprocessing in enzymatic biocatalysis. The main upstream processes discussed are enzyme production, enzyme immobilization methodologies, solvent selection, and statistical optimization methodologies. The main downstream processes reviewed in this work are biocatalyst recovery and product separation and purification. The correct selection and combination of upstream and downstream methodologies will allow the development of a sustainable and highly productive system.

Robust and Continuous Lipase-Catalyzed Reactions in Deep Eutectic Solvents: Low Viscosity and Double CLEA-LentiKats Immobilization (CLEA-LK-Lipases).

Deep Eutectic Solvents (DES) are used as reaction media for lipase-catalyzed esterifications in continuous devices. In particular, DES may be useful for lipophilization-like reactions involving substrates with unpaired solubilities. Aspects to be considered are the viscosity of the solvent, as well as the stability of the enzyme in the non-conventional media. The viscosity can be decreased by adding buffer as cosolvent (up to 20% v/v) and keeping the non-conventional nature. Lipases can be stabilized by following a double immobilization pattern, comprising CLEA formation and entrapment in LentiKats®. The low viscosity and high stability of the CLEA-LK-lipase enable the use of DES under flow conditions.

Integrating Biocatalysis with Viscous Deep Eutectic Solvents in Lab-On-A-Chip Microreactors.

The combination of deep eutectic solvents (DESs, ChCl/glycerol 1 : 2) with buffer (up to 15 % v/v) leads to solvent mixtures that exert viscosities below 25 mPa s-1 at 45 °C while keeping their non-aqueous nature. This enables the setup of efficient enzymatic esterifications, which can also be applied in different continuous systems. Following those premises, the use of microreactors in biocatalytic reactions was explored using (low-viscous) DES-buffer media, showing that reactions could be performed efficiently. Under non-optimized conditions, the microreactor devices led to specific productivities considerably higher than those observed in the batch reactor (14 vs. 0.24 mgproduct min-1 mgbiocat -1 ) at the same enzyme loadings and conversion of 6 % (to assure a fair comparison). Looking beyond, the combination of several microchannels (e. g., in scale-out fashion) with DES-water media may lead to powerful, sustainable, and efficient tools for industrial synthesis.

Immobilization of Pseudomonas stutzeri lipase through Cross-linking Aggregates (CLEA) for reactions in Deep Eutectic Solvents.

The use of deep eutectic solvents (DES) with buffer as cosolvent (up to 10 % v/v) leads to low-viscous media in which lipases can perform synthetic reactions, instead of hydrolysis. This paper explores the immobilization of Pseudomonas stutzeri lipase (TL) in cross-linking aggregates (CLEA) to deliver robust derivatives that are active in media like choline chloride - glycerol DES with buffer as cosolvent. While the free TL enzyme was markedly inactive in these media, TL-CLEA derivatives perform esterifications and can be reused several times. Overall, results are consistent with previous experiments reported for other lipases in these DES-water media and confirm that CLEA immobilization turns out a very useful and straightforward alternative for generating active (bio)catalysts for DES-aqueous media systems. Immobilized systems open the possibility of performing continuous processes in low-viscous DES-buffer media.

Production of Bulk Chemicals with Biocatalysis: Drivers and Challenges Reflected in Recent Industrial Granted Patents (2015-2020).

The application of biocatalysis and White Biotechnology tools in chemical areas concerning the production of bulk compounds and other related low-added value products (with high volumes) has been gaining importance in recent years. The expected drivers of biocatalysis for these sectors are energy savings, regioselectivity (leading to cleaner products), the possibility of using thermolabile substrates, as well as the generation of less by-products and manageable wastes. This paper explores some recent industrial granted patents related to biocatalysis and bulk chemicals. Several patents have been identified in fields such as biodiesel and esterification reactions, and sugar or furan chemistry. Overall, innovative strategies involve the identification of novel enzymes, the set-up of improved immobilization methods, as well as novel reactor designs that can offer improved performances and economics. The reported examples indicate that biocatalysis can certainly offer opportunities for these areas as well, far from the typical pharmaceutical and fine chemical applications often reported in the literature.

Immobilized lipase-CLEA aggregates encapsulated in lentikats® as robust biocatalysts for continuous processes in deep eutectic solvents.

The immobilization of lipases in cross linked aggregates (CLEA) leads to a robust biocatalyst that remains very stable in low viscous non-conventional Deep Eutectic Solvents - Buffer mixtures. To reinforce that stability, and to facilitate the biocatalyst recovery, this paper explores the immobilization of Lipase-CLEA derivatives in Lentikats®. This double immobilization can be successfully used in esterifications in DES-buffer media, using substrates of unpaired solubilities (e.g. benzoic acid and glycerol), in batch and continuous processes, and reaching full conversion. Under these conditions, the derivatives display an improved stability (compared to the Lipase-CLEA derivatives) and enable the reuse of the reaction media in continuous devices for at least 6 cycles under non-optimized conditions, accumulating 10 g product L-1, enhancing the productivity, and opening exciting future options for sustainable chemistry.

From batch to fed-batch and to continuous packed-bed reactors: Lipase-catalyzed esterifications in low viscous deep-eutectic-solvents with buffer as cosolvent.

This work explores for the first time the use of Deep Eutectic Solvents (DES) with phosphate buffer 100 mM pH 7 as cosolvent (10% v/v) in biocatalytic reactions in fed-batch and packed-bed bioreactors. The lipase-catalyzed esterification of glycerol and benzoic acid is studied, as it involves two substrates with different polarities (for which DES are needed). In the fed-batch bioreactor, the highest conversion (90%) was obtained at a substrate flow rate of 0.01 mL/min. The fed-batch operation increased the conversion by 59% compared to the batch mode. Regarding productivity, semi-continuous and continuous bioreactors showed analogous results. Upon recirculation of the reaction media in the continuous bioreactor, a conversion of 67% was achieved in 7 cycles of operation. The stability of the biocatalyst in the packed-bed bioreactor decreased only 2% in 10 days, demonstrating the attractiveness that low viscous DES-water mixtures with continuous processes may have.

Lipases in Green Chemistry: Deep Eutectic Solvents (DES) as New Green Solvents.

Deep eutectic solvents (DES) may become important alternatives as versatile, biodegradable, and cost-effective solvents for biocatalysis. Especially for reactions where substrates and products of different polarities are combined, the design of a tailored solvent that may dissolve all compounds-while being enzyme-compatible at the same time-appears to be a strong ally in sustainable chemistry. Herein it is shown that the combination of DES with "water as cosolvent" (in a range from 5% to 20% water, v/v) leads to non-conventional solvents with significantly reduced viscosity. In these media, lipases and proteases can perform synthetic reactions efficiently, and hydrolytic side reactions remain suppressed (even at 20% water, v/v). The use of these less viscous non-conventional media could also provide options for hydrolase-catalyzed synthetic reactions even in continuous fashion.

Biocatalytic Valorization of Furans: Opportunities for Inherently Unstable Substrates.

Biogenic furans (furfural and 5-hydroxymethylfurfural) are expected to become relevant building blocks based on their high degree of functionality and versatility. However, the inherent instability of furans poses considerable challenges for their synthetic modifications. Valorization routes of furans typically generate byproducts, impurities, wastes, and a cumbersome downstream processing, compromising their ecological footprint. Biocatalysis may become an alternative, given the high selectivity of enzymes, together with the mild reaction conditions applied. This Review critically discusses the options for enzymes in the upgrading of furans. Based on previous reports, a variety of biocatalytic transformations have been applied to furans, with successful cases both in aqueous and in water-free media. Options comprise the biodetoxification of toxic furans in hydrolysates, selective syntheses based on oxidation-reduction processes, solvent-free esterifications, or carboligations to afford C12 derivatives. Reported strategies show in general promising but still modest productivities (2-30 gproduct L-1 d-1 , depending on the example). There are opportunities with high potential and deserving of further development, scale-up, and technoeconomic assessment, to entirely validate them as realistic alternatives.

Applications of Liquid/Liquid Biphasic Oxidations by Hydrogen Peroxide with Ionic Liquids or Deep Eutectic Solvents.

This Minireview focuses on recent applications of ionic liquids (ILs) and deep eutectic solvents (DESs) in biphasic oxidations in which the oxidizing agent corresponds to hydrogen peroxide. Biphasic reactions are accomplished when the substrate presents low or moderate solubility in aqueous (polar) systems and/or when separation of products and byproduct is an issue. The properties of the IL and DES allows the reaction activity to be intensified. On the other hand, the high chemical stability of the ionic solvents allows the use of hydrogen peroxide to minimize solvent degradation and unwanted byproducts. The experimental evidence presented herein shows that ILs and DESs can be used as cocatalysts, catalysts, and solvents to achieve enhanced yields and conversions. The process advantages, in terms of a reduction of volatile solvents, improve the safety and use of the oxidizing agent, which implies the possibility of developing new process improvements in the future.

Intervenciones terapéuticas para la conducta suicida en adolescentes / Therapeutic interventions in suicidal behavior teens

La conducta suicida presenta un amplio espectro de comportamientos que constituyen un continuo. En la población adolescente en Chile, las ideas de muerte llegan a presentarse hasta en el 62% y se ha observado que los trastornos del ánimo, esquizofrenia, consumo de sustancias, están fuertemente asociados a la conducta suicida tanto en la evidencia internacional como nacional. La conducta suicida tiene una naturaleza compleja y multifactorial, influyendo sobre ella aspectos biológicos, psicológicos, psiquiátricos, familiares y socio-culturales, lo cual complejiza el diseño de una intervención terapéutica eficiente. Este artículo presenta una revisión actualizada de las intervenciones terapéuticas para adolescentes con conducta suicida. Se expone la principal evidencia y el nivel de efectividad de las estrategias de intervención.

Suicidal behavior has a wide spectrum of behaviors that constitute a continuum. In the adolescent population in Chile, the ideas of death occur in up to 62% of adolescents, and it has been observed that mood disorders, schizophrenia, and substance abuse are strongly associated with suicidal behavior in both international and national evidence. Suicidal behavior is of a complex and multifactorial nature, influenced by biological, psychological, psychiatric, familiar and socio-cultural aspects, which complicate the design of efficient therapeutic intervention. This article presents a current review of therapeutic interventions for adolescents with suicidal behavior. The main evidence and the level of effectiveness of intervention strategies are presented.