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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. [ABSTRACT FROM AUTHOR]

As renewable lignin building blocks, hydroxystyrenes are particularly appealing as either a replacement or addition to styrene-based polymer chemistry. These monomers are obtained by decarboxylation of phenolic acids and often subjected to chemical modifications of their phenolic hydroxy groups to improve polymerization behaviour. Despite efforts, a simple, scalable, and purely (chemo)catalytic synthesis of acetylated hydroxystyrenes remains elusive. We thus propose a custom-made chemoenzymatic route that utilizes a phenolic acid decarboxylase (PAD). Our process development strategy encompasses a computational solvent assessment informing about solubilities and viable reactor operation modes, experimental solvent screening, cascade engineering, heterogenization of biocatalyst, tailoring of acetylation conditions, and reaction upscale in a rotating bed reactor. By this means, we established a clean one-pot two-step process that uses the renewable solvent CPME, bio-based phenolic acid educts and reusable immobilised PAD. The overall chemoenzymatic reaction cascade was demonstrated on a 1 L scale to yield 18.3 g 4-acetoxy-3-methoxystyrene in 96% isolated yield. [ABSTRACT FROM AUTHOR]

For a knowledge-based design of enzyme catalysis in deep eutectic solvents (DESs), the influence of the DES properties (e.g., water activity and viscosity) and the impact of DESs and their individual components must be assessed. This paper investigates three different DESs: choline chloride–glycerol (ChCl–Gly), choline chloride–ethylene glycol (ChCl–EG), and ethyl ammonium chloride–glycerol (EACl–Gly). The specific activity and half-life time of horse liver alcohol dehydrogenase (HLADH) were experimentally determined in these DESs with water contents ranging from 0%–100%. HLADH showed limited activity in neat DESs, which was enhanced by adding water. Experiments with individual DES components of ChCl–Gly were carried out to clarify their individual influence. Glycerol acts as a strong stabilizer for the enzyme, whereas choline chloride's results are deleterious. To understand the experimental findings, molecular dynamics (MD) simulations were carried out to quantify the solvation layer and calculate the spatial distribution of the solvent molecules around HLADH. The experimental and the in silico approach suggests that designing novel DESs with higher glycerol loadings would result in improved media for biocatalysis. This is demonstrated by performing the reduction of cinnamaldehyde to cinnamyl alcohol—a relevant compound for the food industry and cosmetics—in ChCl–Gly (1 : 9 molar ratio), with 20 vol% water to decrease the viscosity. HLADH is highly active and stable under these new conditions, giving promising productivity (15.3 g L−1 d−1). This paper demonstrates that DESs can be designed to be both substrate-solubilizers and enzyme-compatible, opening new research lines for green chemistry and biocatalysis. [ABSTRACT FROM AUTHOR]

Correction for '3D printed and stimulus responsive drug delivery systems based on synthetic polyelectrolyte hydrogels manufactured via digital light processing' by Sonja Vaupel et al., J. Mater. Chem. B, 2023, DOI: https://doi.org/10.1039/d3tb00285c. [ABSTRACT FROM AUTHOR]

One-pot combinations of sequential catalytic reactions can offer practical and ecological advantages over classical multi-step synthesis schemes. In this context, the integration of enzymatic and chemo-catalytic transformations holds particular potential for efficient and selective reaction sequences that would not be possible using either method alone. Here, we report the one-pot combination of alcohol dehydrogenase-catalysed asymmetric reduction of 2-azido ketones and Pd nanoparticle-catalysed hydrogenation of the resulting azido alcohols, which gives access to both enantiomers of aromatic 1,2-amino alcohols in high yields and excellent optical purity (ee ＞99%). Furthermore, we demonstrate the incorporation of an upstream azidolysis and a downstream acylation step into the one-pot system, thus establishing a highly integrated synthesis of the antiviral natural product (S)-tembamide in 73% yield (ee ＞99%) over 4 steps. Avoiding the purification and isolation of intermediates in this synthetic sequence leads to an unprecedentedly low ecological footprint, as quantified by the E-factor and solvent demand. [ABSTRACT FROM AUTHOR]

1,4-Butanediol is shown to be an efficient cosubstrate to promote NAD(P)H-dependent redox biocatalysis. The thermodynamically and kinetically inert lactone coproduct makes the regeneration reaction irreversible. Thereby not only the molar surplus of cosubstrate is dramatically reduced but also faster reaction rates are obtained. [ABSTRACT FROM AUTHOR]

Hydrogels have gained significant interest in the last decades, especially in the medical sector, due to their versatile properties. While hydrogels from naturally occurring polysaccharides ( e.g. cellulose) are well-known, those produced from polymerizable carbohydrate-based monomers remain underexplored. However, these semi-synthetic hydrogels offer the great advantage of having adjustable properties for customization depending on their application. The objective of this study was to characterize semi-synthetic carbohydrate-based ionic hydrogels produced from GVIM-I (glucosyl vinyl imidazolium iodide). The antimicrobial activity was evaluated using the disk diffusion method, which demonstrated that all samples exhibit inhibitory effects on the growth of Candida auris . In vitro biocompatibility was determined by cell viability studies with L929 mouse fibroblasts, and a correlation was observed between eluate concentration and cell viability. In particular, the type of initiator system employed for polymerization was found to affect cell viability. The direct contact assessments showed that specific pre-treatments of the hydrogels resulted in higher cell viability than non-treated hydrogels. The results also revealed the impact of crosslinker concentration and type and identified poly(ethylene glycol)diacrylate (PEGDA) 575 as a promising crosslinker for future medical applications. LC-MS analysis of the wash medium identified unreacted GVIM-I as the leached material, which is presumed to be the cause of the observed cytotoxicity. Overall, the study provides valuable insights into the characteristics of GVIM-I based hydrogels and sheds light on the factors that influence their cytotoxicity and potential for medical application., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)