In Vitro Cytotoxicity of D18 and Y6 as Potential Organic Photovoltaic Materials for Retinal Prostheses

Millions of people worldwide are diagnosed with retinal dystrophies such as retinitis pigmentosa and age-related macular degeneration. A retinal prosthesis using organic photovoltaic (OPV) semiconductors is a promising therapeutic device to restore vision to patients at the late onset of the disease. However, an appropriate cytotoxicity approach has to be employed on the OPV materials before using them as retinal implants. In this study, we followed ISO standards to assess the cytotoxicity of D18, Y6, PFN-Br and PDIN individually, and as mixtures of D18/Y6, D18/Y6/PFN-Br and D18/Y6/PDIN. These materials were proven for their high performance as organic solar cells. Human RPE cells were put in direct and indirect contact with these materials to analyze their cytotoxicity by the MTT assay, apoptosis by flow cytometry, and measurements of cell morphology and proliferation by immunofluorescence. We also assessed electrophysiological recordings on mouse retinal explants via microelectrode arrays (MEAs) coated with D18/Y6. In contrast to PFN-Br and PDIN, all in vitro experiments show no cytotoxicity of D18 and Y6 alone or as a D18/Y6 mixture. We conclude that D18/Y6 is safe to be subsequently investigated as a retinal prosthesis.     

Synthesis,Structure, Molecular Orbital and Valence Bond Calculations for Tetrazole Azide,CHN7

The synthesis, NMR spectroscopic characterization and structure determination of highly explosive tetrazole azide, a very nitrogen‐rich material (88.3% N) is reported. Tetrazole azide was prepared in high yield from the diazotation reaction of aminotetrazole, followed by treatment of the formed diazonium salt with sodium azide. Synthesis in diethylether/methanol and recrystallization from diethylether afforded colorless cubes: CHN₇ ( 1 ): monoclinic, P1 2₁/n₁, a=1346.6(5), b=499.6(2), c=1360.9(5) pm, β=105.14(1)⁰, V=0.884(2) nm³, Z=8, ϱ=1.670 g cm⁻³. The observed structural parameters (X‐ray) are in good accordance with the results from molecular orbital (MO) calculations. The computed electrostatic potential (B3LYP) suggests a pronounced shock and friction sensitivity which was confirmed experimentally. Quantitative valence bond (VB) calculations were performed for the most important 21 VB structures in order to obtain the structural weights and to obtain an assessment for the importance of the various individual VB structures considered.     

Eine neue,breit anwendbare Synthese für aromatische Aldehyde

Diformamide ( 1 ) reacts with activated aromatic compounds like toluene, anisole, m‐xylene, 1,2‐dimethoxybenzene in the presence of AlCl₃ to give N‐(diarylmethyl)‐formamides 2a—d , the corresponding aromatic aldehydes 3—6 are formed as by‐products in low yields. From N,N‐dimethylaniline and 1 /AlCl₃ the triphenylmethane derivative 7 can be obtained. The reaction of anisole with N‐methyl‐diformamide ( 9 ) affords the formamide 10 . The mixture of formamide, P₄O₁₀ and AlCl₃ reveals to be a reagent which is capable to formylate toluene and anisole, resp. Triformamide ( 14 )/AlCl₃ is an effective formylating system which allows the preparation of aromatic aldehydes (e.g. 3,4,17—32 ) from the corresponding aromatic hydrocarbons. Aluminiumchloride can be replaced by borontrichloride. The yields of the formylation reactions depend strongly from the reaction conditions (molar ratio: aromatic hydrocarbon/AlCl₃/ 14 ; solvent, reaction temperature). The scope of the reaction covers nearly complete those of the Gattermann‐Koch‐, Gattermann‐ and Vilsmeier—Haack‐reaction.     

Validation of a method based on polymerase chain reaction for the detection of genetically modified organisms in various processed foodstuffs

A qualitative screening method was validated for the detection of genetically modified organisms (GMOs) in various processed food matrices (cooked maize grit, infant formula, biscuits, meal of acidified soybeans). The prepared food matrices contained each 0%, 2%, 100% (10% instead of 100% in the case of biscuits) of Roundup-Ready© soybeans and/or of Bt-176 maize. The method was based on the detection of the introduced DNA sequences by using the polymerase chain reaction (PCR) for amplification of DNA. Two different detection systems were applied: one based on the 35S promoter fragment which is present in GM-soybeans and in GM-maize and one based on the nos terminator sequence which is present only in GM-soybeans. Prior to the validation study, it was demonstrated that the food matrices were homogenous and that there was no cross-contamination between GMO-containing and GMO-free samples. Some laboratories had a high portion of false positive results probably due to laboratory contamination whereas all others reported nearly always correct data for all matrices investigated. Statistical analysis showed that after exclusion of the outliers, an average of 97% correct results was obtained for non-GMO containing samples (3% false positive results) and an average of 98% correct results for GMO-containing samples (2% false negative results). The validated method was shown to be suitable for screening of GMOs in processed food matrices also when extreme physical stress was applied (e.g., heating for 45 min at 100vv°C or 10 min at 180vv°C) or when multiple components were present, as in the case of biscuit preparations.     

Direct observation of a noncatalytic growth regime for GaAs nanowires

We identify a new noncatalytic growth regime for molecular beam epitaxially grown GaAs nanowires (NWs) that may provide a route toward axial heterostructures with discrete material boundaries and atomically sharp doping profiles. Upon increase of the As/Ga flux ratio, the growth mode of self-induced GaAs NWs on SiO(2)-masked Si(111) is found to exhibit a surprising discontinuous transition in morphology and aspect ratio. For effective As/Ga ratios <1, in situ reflection high-energy electron diffraction measurements reveal clear NW growth delay due to formation of liquid Ga droplets since the growth proceeds via the vapor-liquid-solid mechanism. In contrast, for effective As/Ga ratios >1 an immediate onset of NW growth is observed indicating a transition to droplet-free, facet-driven selective area growth with low vertical growth rates. Distinctly different microstructures, facet formation and either the presence or absence of Ga droplets at the apex of NWs, are further elucidated by transmission electron microscopy. The results show that the growth mode transition is caused by an abrupt change from As- to Ga-limited conditions at the (111)-oriented NW growth front, allowing precise tuning of the dominant growth mode.     

Development of a Raman method to follow the evolution of coating thickness of pellets

Context: Although several methods have been investigated to measure the film thickness of tablets and its correlation with the dissolution behavior, much fewer such investigations exist for pharmaceutical pellets.

Objective: To study the possibility of measuring the film thickness and predicting the dissolution behavior of pellets produced in different fluid bed equipments with Raman spectroscopy.

Materials and methods: Pyridoxine hydrochloride-layered pellets were produced and coated in two different Strea-1 equipments. Raman spectra were collected and analysed to set up a calibration model based on the film thickness data calculated from Camsizer analysis results. Dissolution tests were done according to Ph. Eur. standards.

Results: Raman spectroscopy proved to be a good tool in the measurement of film thickness. Polymer weight gain showed a linear correlation with film thickness but was a poor predictor of dissolution results below a threshold value.

Conclusion: The Raman spectroscopic measurement of a small sample can provide accurate data of the film thickness. The investigation suggests that a threshold value might exist for the film thickness above which it can be used to judge future dissolution results.     

Polyclonal Aptamer Libraries from a FluRoot-SELEX for the Specific Labeling of the Apical and Elongation/Differentiation Zones of Arabidopsis thaliana Roots

In more than 30 years of aptamer research, it has become widely accepted that aptamers are fascinating binding molecules for a vast variety of applications. However, the majority of targets have been proteins, although special variants of the so-called SELEX process for the molecular evolution of specific aptamers have also been developed, allowing for the targeting of small molecules as well as larger structures such as cells and even cellular networks of human (tumor) tissues. Although the provocative thesis is widely accepted in the field, that is, in principle, any level of complexity for SELEX targets is possible, the number of studies on whole organs or at least parts of them is limited. To pioneer this thesis, and based on our FluCell-SELEX process, here, we have developed polyclonal aptamer libraries against apices and the elongation/differentiation zones of plant roots as examples of organs. We show that dedicated libraries can specifically label the respective parts of the root, allowing us to distinguish them in fluorescence microscopy. We consider this achievement to be an initial but important evidence for the robustness of this SELEX variant. These libraries may be valuable tools for plant research and a promising starting point for the isolation of more specific individual aptamers directed against root-specific epitopes.     

Preclinical Evaluation of CRISPR-Edited CAR-NK-92 Cells for Off-the-Shelf Treatment of AML and B-ALL

Acute myeloid leukemia (AML) and B-cell acute lymphocytic leukemia (B-ALL) are severe blood malignancies affecting both adults and children. Chimeric antigen receptor (CAR)-based immunotherapies have proven highly efficacious in the treatment of leukemia. However, the challenge of the immune escape of cancer cells remains. The development of more affordable and ready-to-use therapies is essential in view of the costly and time-consuming preparation of primary cell-based treatments. In order to promote the antitumor function against AML and B-ALL, we transduced NK-92 cells with CD276-CAR or CD19-CAR constructs. We also attempted to enhance cytotoxicity by a gene knockout of three different inhibitory checkpoints in NK cell function (CBLB, NKG2A, TIGIT) with CRISPR-Cas9 technology. The antileukemic activity of the generated cell lines was tested with calcein and luciferase-based cytotoxicity assays in various leukemia cell lines. Both CAR-NK-92 exhibited targeted cytotoxicity and a significant boost in antileukemic function in comparison to parental NK-92. CRISPR-Cas9 knock-outs did not improve B-ALL cytotoxicity. However, triple knock-out CD276-CAR-NK-92 cells, as well as CBLB or TIGIT knock-out NK-92 cells, showed significantly enhanced cytotoxicity against U-937 or U-937 CD19/tag AML cell lines. These results indicate that the CD19-CAR and CD276-CAR-NK-92 cell lines’ cytotoxic performance is suitable for leukemia killing, making them promising off-the-shelf therapeutic candidates. The knock-out of CBLB and TIGIT in NK-92 and CD276-CAR-NK-92 should be further investigated for the treatment of AML.     

The Black Box of Cellular and Molecular Events of Plasmodium vivax Merozoite Invasion into Reticulocytes

Plasmodium vivax is the most widely distributed malaria parasite affecting humans worldwide, causing ~5 million cases yearly. Despite the disease’s extensive burden, there are gaps in the knowledge of the pathophysiological mechanisms by which P. vivax invades reticulocytes. In contrast, this crucial step is better understood for P. falciparum, the less widely distributed but more often fatal malaria parasite. This discrepancy is due to the difficulty of studying P. vivax’s exclusive invasion of reticulocytes, which represent 1–2% of circulating cells. Its accurate targeting mechanism has not yet been clarified, hindering the establishment of long-term continuous in vitro culture systems. So far, only three reticulocyte invasion pathways have been characterised based on parasite interactions with DARC, TfR1 and CD98 host proteins. However, exposing the parasite’s alternative invasion mechanisms is currently being considered, opening up a large field for exploring the entry receptors used by P. vivax for invading host cells. New methods must be developed to ensure better understanding of the parasite to control malarial transmission and to eradicate the disease. Here, we review the current state of knowledge on cellular and molecular mechanisms of P. vivax’s merozoite invasion to contribute to a better understanding of the parasite’s biology, pathogenesis and epidemiology.