Intelligent hydrogel design: Towards more performing hydrogel processing

Despite their highly attractive properties, 3D printing of hydrogel materials can be rather challenging. Herein, we present a novel hydrogel material that can be easily processed into three-dimensional scaffolds using different 3D printing technologies. An acrylate-terminated, urethane-based PEG was prepared by reacting PEG 2000 with isophorone diisocyanate (IPDI) and monoacrylated PEG (336 g/mol) in a 1:2:2 molar ratio (WO 2017/005613 A1). For melt 3D-printing, pure polymer was used (Tm 38°C). For bioprinting, a 50 wt% solution with 3 wt% Laponite was used. Please click Additional Files below to see the full abstract

GSyellow, a multifaceted tag for functional protein analysis in monocot and dicot plants

The ability to tag proteins has boosted the emergence of generic molecular methods for protein functional analysis. Fluorescent protein tags are used to visualize protein localization, and affinity tags enable the mapping of molecular interactions by, for example, tandem affinity purification or chromatin immunoprecipitation. To apply these widely used molecular techniques on a single transgenic plant line, we developed a multifunctional tandem affinity purification tag, named GS(yellow), which combines the streptavidin-binding peptide tag with citrine yellow fluorescent protein. We demonstrated the versatility of the GS(yellow) tag in the dicot Arabidopsis (Arabidopsis thaliana) using a set of benchmark proteins. For proof of concept in monocots, we assessed the localization and dynamic interaction profile of the leaf growth regulator ANGUSTIFOLIA3 (AN3), fused to the GS(yellow) tag, along the growth zone of the maize (Zea mays) leaf. To further explore the function of ZmAN3, we mapped its DNA-binding landscape in the growth zone of the maize leaf through chromatin immunoprecipitation sequencing. Comparison with AN3 target genes mapped in the developing maize tassel or in Arabidopsis cell cultures revealed strong conservation of AN3 target genes between different maize tissues and across monocots and dicots, respectively. In conclusion, the GS(yellow) tag offers a powerful molecular tool for distinct types of protein functional analyses in dicots and monocots. As this approach involves transforming a single construct, it is likely to accelerate both basic and translational plant research

A semiempirical scaling model for the solid- and liquid-state photopolymerization kinetics of semicrystalline acrylated oligomers

The recent introduction of semicrystalline acrylated oligomers exhibiting fast photoinitiated free radical polymerization in the solid state calls for a deeper understanding of the mechanisms behind the reaction kinetics. The photoinduced polymerization of an acrylated urethane-based poly(ethylene glycol) precursor was studied in detail at temperatures below the melting point using differential photocalorimetry. In isothermal conditions, the exothermal heat flow profile is characterized by an acceleration step followed by a gradual deceleration. In contrast to liquid-state photopolymerization, the well-known gel effect cannot be invoked to account for the reaction acceleration in the crystallized resin. By revisiting the kinetics of free-radical polymerization, it appears that the acceleration results from the buildup of the radical concentration toward steady state in a reaction diffusion driven process. The kinetic behavior is examined in terms of conversion for which any structure-dependent kinetic effect is described by a power-law approximation based on scaling arguments from experimental evidence and polymer physics. This results in a closed-form analytical expression that compares well to experimental data for the photopolymerization kinetics of a semicrystalline acrylated urethane precursor upon adjustment of three parameters. The model is extended to include the additional kinetic complexity for liquid (meth)acrylates and provides a unified approach to free-radical polymerization built on fundamental insights

Postarachnoiditis anterior spinal arachnoid cyst formation with compressive myelopathy : report of 2 cases

BACKGROUND: Spinal cystic arachnoiditis is a rare complication of a subarachnoid haemorrhage or infectious meningitis. The inflammatory process leads to fibrosis, adhesions, and in severe cases cyst formation. Large arachnoid cysts are an uncommon cause of compressive myelopathy. The majority are located posterior of the spinal cord at the thoracic level. Anterior cyst formation is exceptional, especially at the cervical region. CASE DESCRIPTION: We present 2 cases of progressive myelopathy secondary to anterior arachnoid cyst formation. In a 54-year-old female a large anterior symptomatic thoracic cyst arose 4 years after rupture of a posterior inferior cerebellar artery aneurysm. The other 59-year-old-patient, however, developed an anterior cervical cyst only weeks after a varicella meningoencephalitis. Both female patients were treated with a decompressive laminectomy and wide fenestration of the cysts. Partial recovery was obtained in 1 patient, but there was no improvement in the other case. CONCLUSIONS: Spinal cystic arachnoiditis with anterior cyst formation is an extremely rare complication of subarachnoid haemorrhage and infectious meningitis but can cause severe neurologic deficits. Clinicians should be aware of this rare complication. Due to the risk of irreversible spinal cord injury, rapid surgical intervention is recommended in most cases

A Semiempirical Scaling Model for the Solid- and Liquid-State Photopolymerization Kinetics of Semicrystalline Acrylated Oligomers

The recent introduction of semicrystalline acrylated oligomers exhibiting fast photoinitiated free radical polymerization in the solid state calls for a deeper understanding of the mechanisms behind the reaction kinetics. The photoinduced polymerization of an acrylated urethane-based poly­(ethylene glycol) precursor was studied in detail at temperatures below the melting point using differential photocalorimetry. In isothermal conditions, the exothermal heat flow profile is characterized by an acceleration step followed by a gradual deceleration. In contrast to liquid-state photopolymerization, the well-known gel effect cannot be invoked to account for the reaction acceleration in the crystallized resin. By revisiting the kinetics of free-radical polymerization, it appears that the acceleration results from the buildup of the radical concentration toward steady state in a reaction–diffusion driven process. The kinetic behavior is examined in terms of conversion for which any structure-dependent kinetic effect is described by a power-law approximation based on scaling arguments from experimental evidence and polymer physics. This results in a closed-form analytical expression that compares well to experimental data for the photopolymerization kinetics of a semicrystalline acrylated urethane precursor upon adjustment of three parameters. The model is extended to include the additional kinetic complexity for liquid (meth)­acrylates and provides a unified approach to free-radical polymerization built on fundamental insights

Indirect solid freeform fabrication of an initiator-free photocrosslinkable hydrogel precursor for the creation of porous scaffolds

the present work, a photopolymerized urethane-based poly(ethylene glycol) hydrogel is applied as a porous scaffold material using indirect solid freeform fabrication (SFF). This approach combines the benefits of SFF with a large freedom in material selection and applicable concentration ranges. A sacrificial 3D poly(epsilon-caprolactone) structure is generated using fused deposition modeling and used as template to produce hydrogel scaffolds. By changing the template plotting parameters, the scaffold channel sizes vary from 280 to 360 m, and the strut diameters from 340 to 400 m. This enables the production of scaffolds with tunable mechanical properties, characterized by an average hardness ranging from 9 to 43 N and from 1 to 6 N for dry and hydrated scaffolds, respectively. Experiments using mouse calvaria preosteoblasts indicate that a gelatin methacrylamide coating of the scaffolds results in an increased cell adhesion and proliferation with improved cell morphology