Characterization method for new resist formulations for HAR patterns made by X-ray lithography

At the Karlsruhe Institute of Technology (KIT), Institute of Micro Structure Technology (IMT) high aspect ratio (HAR) micro structures are manufactured by means of deep X-ray lithography and gold electroplating (LIGA technology). The technology is used to fabricate grating structures for differential phase contrast X-ray imaging (DPCI). Using an epoxy based negative resist material; electroplated grating structures are fabricated having absorber lamellas with heights up to 100 μm and a period down to 2.4 μm. However, in DPCI there is an increasing demand for improved quality gratings with periods down to 1 μm, areas larger than 50 mm × 50 mm with a high homogeneity in terms of the lamella height distribution and defect-free grating patterns. Pattern deformations are due to limited mechanical stability of the resist during the development process as well as to resist shrinkage during crosslinking, affecting mostly gratings with small periods and HARs. The purpose of this contribution is to present a methodology for the characterization of different epoxy based negative resist formulations, aiming to increase the quality of the HAR free standing grating lamellas by increased mechanical stability of the resist.     

Analytical methods for the determination of alkylpolyglucosides

This paper describes the repertoire of analytical methods which is currently available for the determination of Alkylpolyglucosides (APGs). The methods range from chromatographic techniques (hightemperature gas chromatography, high-performance liquid chromatography, thin-layer chromatography) to methods which allow a fast and easy (but unselective) determination of sum parameters. For the first time a derivatization method is described which converts APGs into anionic compounds that can be titrated potentiometrically.     

Ozonation of Exhausted Reactive Dye-Bath Analogues: the Use of Atrazine as an OH* Probe Compound

Ozonation and O₃/H₂O₂ treatment of a spent reactive dye–bath analogue containing aminofluorotriazine type reactive dyestuffs were examined in semi–batch experiments at different pH (2, 7 and 12), bicarbonate (0.18 M at pH7) and carbonate (0.19 M at pHl2) alkalinity. Atrazine (23.2 µM) was added as an OH* – sensitive probe compound to the reactive dye–bath analogue to evaluate the individual contributions of both direct molecular (O₃) and indirect radical (OH*) type reaction pathways for the treatment of spent dye–bath ingredients. From the obtained results it was evident that particularly de–aromatization (expressed in terms of UV₂₅₄ and UV₂₇₀ removal) kinetics were significantly retarded in the presence of HCO₃, CO₃ ^2‐ and particularly H₂O₂. O₃ decomposition and consumption increased appreciably when H₂O₂ (0.125 mM at pH7) was added as compared in the presence of carbonate/bicarbonate alkalinity when H₂O₂ was added indicating that H₂O₂ and alkalinity could act as radical chain reaction promoters (carriers) and inhibitors, respectively. Atrazine degradation and UV₂₇₀ abatement rates paralleled each other revealing that particularly de–aromatization of the spent dye–bath constituents mainly involves the action of OH*. Nitrate formation was distinctly higher at pH7 than at pH 12 as a consequence of the stronger OH* scavenging effect of carbonate alkalinity at pH12.     

S1P Lyase siRNA Dampens Malignancy of DLD-1 Colorectal Cancer Cells

Sphingosine-1-phosphate lyase 1 (S1P lyase or SGPL1) is an essential sphingosine-1-phosphate-degrading enzyme. Its manipulation favors onset and progression of colorectal cancer and others in vivo. Thus, SGPL1 is an important modulator of cancer initiation. However, in established cancer, the impact of retrospective SGPL1 modulation is elusive. Herein, we analyzed how SGPL1 siRNA affects malignancy of the human colorectal cancer cells DLD-1 and found that in parallel to the reduction of SGPL1 expression levels, migration, invasion, and differentiation status changed. Diminished SGPL1 expression was accompanied with reduced cell migration and cell invasion in scratch assays and transwell assays, whereas metabolic activity and proliferation was not altered. Decreased migration was attended by increased cell–cell-adhesion through upregulation of E-cadherin and formation of cadherin-actin complexes. Spreading cell islets showed lower vimentin abundance in border cells. Furthermore, SGPL1 siRNA treatment induced expression of epithelial cell differentiation markers, such as intestinal alkaline phosphatase and cytokeratin 20. Hence, interference with SGPL1 expression augmented a partial redifferentiation of colorectal cancer cells toward normal colon epithelial cells. Our investigation showed that SGPL1 siRNA influenced tumorigenic activity of established colorectal cancer cells. We therefore suggest SGPL1 as a target for lowering malignant potential of already existing cancer.     

Exposing Differences in Monomer Exchange Rates of Multicomponent Supramolecular Polymers in Water

The formation of multicomponent and bioactive supramolecular polymers is a promising strategy for the formation of biomaterials that match the dynamic and responsive nature of biological systems. In order to fully realize the potential of this strategy, knowledge of the location and behavior of bioactive components within the system is crucial. By employing synthetic strategies to create multifunctional monomers, coupled with FRET and STORM techniques, we have investigated the formation and behavior of a bioactive and multicomponent supramolecular polymer. By creating a peptide‐dye‐monomer conjugate, we were able to measure high degrees of monomer incorporation and to visualize the equal distribution of monomers within the supramolecular polymer. Furthermore, by tracking the movement of monomers, we uncovered small differences in the dynamics of the bioactive monomers.     

Microscopic Cascading Devices for Boosting Mucus Penetration in Oral Drug Delivery—Micromotors Nesting Inside Microcontainers

In the case of macromolecules and poorly permeable drugs, oral drug delivery features low bioavailability and low absorption across the intestinal wall. Intestinal absorption can be improved if the drug formulation could be transported close to the epithelium. To achieve this, a cascade delivery device comprising Magnesium-based Janus micromotors (MMs) nesting inside a microscale containers (MCs) has been conceptualized. The device aims at facilitating targeted drug delivery mediated by MMs that can lodge inside the intestinal mucosa. Loading MMs into MCs can potentially enhance drug absorption through increased proximity and unidirectional release. The MMs will be provided with optimal conditions for ejection into any residual mucus layer that the MCs have not penetrated. MMS confined inside MCs propel faster in the mucus environment as compared to non-confined MMs. Upon contact with a suitable fuel, the MM-loaded MC itself can also move. An in vitro study shows fast release profiles and linear motion properties in porcine intestinal mucus compared to more complex motion in aqueous media. The concept of dual-acting cascade devices holds great potential in applications where proximity to epithelium and deep mucus penetration are needed.     

The Age of Cortical Neural Networks Affects Their Interactions with Magnetic Nanoparticles

Despite increasing use of nanotechnology in neuroscience, the characterization of interactions between magnetic nanoparticles (MNPs) and primary cortical neural networks remains underdeveloped. In particular, how the age of primary neural networks affects MNP uptake and endocytosis is critical when considering MNP‐based therapies for age‐related diseases. Here, primary cortical neural networks are cultured up to 4 weeks and with CCL11/eotaxin, an age‐inducing chemokine, to create aged neural networks. As the neural networks are aged, their association with membrane‐bound starch‐coated ferromagnetic nanoparticles (fMNPs) increases while their endocytic mechanisms are impaired, resulting in reduced internalization of chitosan‐coated fMNPs. The age of the neurons also negates the neuroprotective effects of chitosan coatings on fMNPs, attributing to decreased intracellular trafficking and increased colocalization of MNPs with lysosomes. These findings demonstrate the importance of age and developmental stage of primary neural cells when developing in vitro models for fMNP therapeutics targeting age‐related diseases.