Spray congealing for immobilization of biocatalysts

Spray congealing was investigated as new innovative immobilization technique for biocatalysts. The immobilization is realized by an atomization of a suspension or emulsion of a melted carrier and the enzyme, which is re-solidifyed due to temperature decrease. This method needs neither organic solvents nor a difficult downstream processing after preparation. For the encapsulation different matrices, like long chain alcohols and glyceryl derivatives, with melting points below 86 °C and environmentally friendly properties were chosen and tested for their suitability for enzyme encapsulation. Spray congealing is widely used for pharmaceutically active ingredients, but has not been described for enzymes so far [1]. The immobilization of a laccase, (Novozym 51003, from Myceliophthora thermophila), was investigated and the produced microparticles were characterized. The obtained particles showed a mean particle size around 40 µm and a spherical surface with different structures depending on the used matrix. Spray congealing with the laccase reached yields of 80 % and residual activities up to 56%. Furthermore 4 consecutive reactions with 20% retained activity of in cetyl alcohol immobilized enzyme were realized. Cetyl alcohol was found to be the most appropriate carrier for the immobilization of the investigated laccase, due to an easy handling and high yields. In addition, the best retained activities were obtained and a recycling of the biocatalyst could be realized [2]. Please click Additional Files below to see the full abstract

Una introducción a la traducción científica

Sección: Reseñas bibliográficas. Http://www.medtrad.orgEsta obra del traductor y profesor francés Jean Maillot (1905-1993) no es un tratado teórico de traducción ni un manual de metodología de la traducción, sino una exposición sencilla y clara de algunos de los problemas de la traducción científica y técnica a través de una abundante acumulación de casos concretos extraídos del francés, alemán, inglés y ruso.Peer reviewe

Oxidative Esterification of 5-Hydroxymethylfurfural under Flow Conditions Using a Bimetallic Co/Ru Catalyst

Furanic di-carboxylate derivatives of 5-Hydroxymethylfurfural (HMF) are nowadays important in the polymer industry as they are used as building blocks for bio-based polyesters. The high reactivity of HMF compels to avoid harsh synthetic conditions. Therefore, developing mild catalytic processes for its selective oxidation is a challenging task. Herein, we report the first oxidative esterification of HMF to dimethyl furan-2,5-dicarboxylate (FDCM) under flow conditions using oxygen as oxidant. For that purpose, a new series of nitrogen-doped carbon-supported bimetallic Co/Ru heterogeneous catalysts were prepared and characterized by XRD, XPS and N2 physisorption. These analyses revealed that the porosity of the materials and order of impregnation of the metals to the carbon supports lead to varying catalytic activities. Under optimized conditions the flow reactor showed a 15-fold increase on the production of FDCM compared to batch conditions. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA

3D printed and stimulus responsive drug delivery systems based on synthetic polyelectrolyte hydrogels manufactured via digital light processing

Hydrogels are three-dimensional hydrophilic polymeric networks absorbing up to and even more than 90 wt% of water. These superabsorbent polymers retain their shape during the swelling process while enlarging their volume and mass. In addition to their swelling behavior, hydrogels can possess other interesting properties, such as biocompatibility, good rheological behavior, or even antimicrobial activity. This versatility qualifies hydrogels for many medical applications, especially drug delivery systems. As recently shown, polyelectrolyte-based hydrogels offer beneficial properties for long-term and stimulus-responsive applications. However, the fabrication of complex structures and shapes can be difficult to achieve with common polymerization methods. This obstacle can be overcome by the use of additive manufacturing. 3D printing technology is gaining more and more attention as a method of producing materials for biomedical applications and medical devices. Photopolymerizing 3D printing methods offer superior resolution and high control of the photopolymerization process, allowing the fabrication of complex and customizable designs while being less wasteful. In this work, novel synthetic hydrogels, consisting of [2-(acryloyloxy) ethyl]trimethylammonium chloride (AETMA) as an electrolyte monomer and poly(ethylene glycol)-diacrylate (PEGDA) as a crosslinker, 3D printed via Digital Light Processing (DLP) using a layer height of 100 μm, are reported. The hydrogels obtained showed a high swelling degree q∞m,t ∼ 12 (24 h in PBS; pH 7; 37 °C) and adjustable mechanical properties with high stretchability (ϵmax ∼ 300%). Additionally, we embedded the model drug acetylsalicylic acid (ASA) and investigated its stimulus-responsive drug release behaviour in different release media. The stimulus responsiveness of the hydrogels is mirrored in their release behavior and could be exploited in triggered as well as sequential release studies, demonstrating a clear ion exchange behavior. The received 3D-printed drug depots could also be printed in complex hollow geometry, exemplarily demonstrated via an individualized frontal neo-ostium implant prototype. Consequently, a drug-releasing, flexible, and swellable material was obtained, combining the best of both worlds: the properties of hydrogels and the ability to print complex shapes

Swelling and Mechanical Characterization of Polyelectrolyte Hydrogels as Potential Synthetic Cartilage Substitute Materials

Hydrogels have become an increasingly interesting topic in numerous fields of application. In addition to their use as immobilization matrixes in (bio)catalysis, they are widely used in the medical sector, e.g., in drug delivery systems, contact lenses, biosensors, electrodes, and tissue engineering. Cartilage tissue engineering hydrogels from natural origins, such as collagen, hyaluronic acid, and gelatin, are widely known for their good biocompatibility. However, they often lack stability, reproducibility, and mechanical strength. Synthetic hydrogels, on the other hand, can have the advantage of tunable swelling and mechanical properties, as well as good reproducibility and lower costs. In this study, we investigated the swelling and mechanical properties of synthetic polyelectrolyte hydrogels. The resulting characteristics such as swelling degree, stiffness, stress, as well as stress-relaxation and cyclic loading behavior, were compared to a commercially available biomaterial, the ChondroFiller® liquid, which is already used to treat articular cartilage lesions. Worth mentioning are the observed good reproducibility and high mechanical strength of the synthetic hydrogels. We managed to synthesize hydrogels with a wide range of compressive moduli from 2.5 ± 0.1 to 1708.7 ± 67.7 kPa, which addresses the span of human articular cartilage

Low-melting manganese(II)-based ionic liquids: syntheses, structures, properties and influence of trace impurities

The synthesis of more than 10 new magnetic ionic liquids with [MnX4]2 anions, X = Cl, NCS, NCO, is presented. Detailed structural information through single-crystal X-ray di raction is given for (DMDIm)[Mn(NCS)4], (BnEt3N)2[Mn(NCS)4], and {(Ph3P)2N}2[Mn(NCO4)] 0.6H2O, respectively. All compounds consist of discrete anions and cations with tetrahedrally coordinated Mn(II) atoms. They show paramagnetic behavior as expected for spin-only systems. Melting points are found for several systems below 100 C classifying them as ionic liquids. Thermal properties are investigated using di erential scanning calorimetry (DSC) measurements. The physicochemical properties of density, dynamic viscosity, electrolytic conductivity, and surface tension were measured temperature-dependent of selected samples. These properties are discussed in comparison to similar Co containing systems. An increasing amount of bromide impurity is found to a ect the surface tension only up to 3.3%

Coagulation using organic carbonates opens up a sustainable route towards regenerated cellulose films

Due to their biodegradability, biocompatibility and sustainable nature, regenerated cellulose (RC) films are of enormous relevance for green applications including medicinal, environmental and separation technologies. However, the processes used so far are very hazardous to the environment and health. Here, we disclose a simple, fast, environmentally friendly, nontoxic and cost-effective processing method for preparing RC films. High quality non-transparent and transparent RC films and powders can be produced by dissolution with tetrabutylphosphonium hydroxide [TBPH]/[TBP]+[OH]− followed by coagulation with organic carbonates. Investigations on the coagulation mechanism revealed an extremely fast reaction between the carbonates and the hydroxide ions. The high-quality powders and films were fully characterized with respect to structure, surface morphology, permeation and selectivity. This method represents a future-oriented green alternative to known industrial processes. © 2020, The Author(s)