Spinelle als Anodenmaterialien für Lithium-Ionen-Akkumulatoren

In dieser Arbeit wird die hydrothermale Synthese von Li4 Ti5 O12 durch gezielte Variation der Syntheseparameter untersucht. Das aus der hydrothermalen Behandlung von Titandioxid in Hydroxiden resultierende Produkt ist von dem eingesetzten Lösungsmittel, den Hydroxiden und dem Verhältnis der Reaktanden abhängig. In dieser Arbeit wird der Einfluss mehrerer Alkohole und Wasser, der Lithium- und Natriumhydroxidmenge und des Titan-Lithiumhydroxid-Verhältnisses untersucht. Insbesondere die Partikelgröße des Produkts sinkt mit abnehmender Lösungsmittelpolarität. Weiterhin zeigen Spinelle sehr unterschiedliche Einlagerungsmechanismen mit Lithium-Ionen. Die untersuchten Spinelle Li4 Ti5 O12 , CuCr2 Se4 und MnFe2 O4 zeigen einen Insertions-, einen kombinierten Ersetzungs- und Insertions- sowie einen Konversionsmechanismus. Zudem zeigt Li4 Ti5 O12 bei der Einlagerung bei niedrigen Potentialen eine starke strukturelle Unordnung. Für diese Untersuchungen werden in situ-Methoden wie XRD und XAS in dieser Arbeit verwendet. Die Möglichkeiten dieser Methoden werden insbesondere an den Materialien LiMn1/3 Fe1/3 Co1/3 PO4 und Y2 Ti2 O5 S2 gezeigt. Dabei ist es möglich, an LiMn1/3 Fe1/3 Co1/3 PO4 XAS-Spektren für alle drei Metalle simultan zu messen. Bei Y2 Ti2 O5 S2 gelang nach Optimierung des Messaufbaus auch die Messung der XAS-Spektren der Schwefelabsorptionskante

Suzuki coupling activity of an aqueous phase Pd nanoparticle dispersion and a carbon nanotube/Pd nanoparticle composite

An aqueous phase dispersion of Pd nanoparticles stabilised by 4-dimethylaminopyridine (DMAP) promotes model Suzuki coupling reactions. The dispersion contains Pd nanoparticles of 3.4 ± 0.5 nm and a Pd(II) species (Pd(DMAP)4(OH)2) which forms following aerobic oxidation of the nanoparticles. The activity of the nanoparticle dispersion in promoting the Suzuki reactions is directly proportional to the size of the halogen on the substrate (as is usual for these coupling reactions) and also to the age of the nanoparticle dispersion. The Pd(DMAP)4(OH)2 complex can be isolated from the dispersion and is found to be very active in promoting the reactions. Its formation following aerobic oxidation of the nanoparticles is proposed as the reason for the improved activity of the dispersion with age. The nanoparticles present in the dispersion can, through displacement of the stabilising ligand, be immobilised onto functionalised multi-walled carbon nanotubes (MWCNTs) and the composite formed is an active and recyclable catalyst. The MWCNT/Pd-DMAP NP composite acts as a reservoir of dissolved Pd species, which function as homogeneous catalysts under reaction conditions.DG 15/11/201

Systematic control of α-Fe 2 O 3 crystal growth direction for improved electrochemical performance of lithium-ion battery anodes

α-Fe2O3 nanomaterials with an elongated nanorod morphology exhibiting superior electrochemical performance were obtained through hydrothermal synthesis assisted by diamine derivatives as shape-controlling agents (SCAs) for application as anodes in lithium-ion batteries (LIBs). The physicochemical characteristics were investigated via XRD and FESEM, revealing well-crystallized α-Fe2O3 with adjustable nanorod lengths between 240 and 400 nm and aspect ratios in the range from 2.6 to 5.7. The electrochemical performance was evaluated by cyclic voltammetry and charge–discharge measurements. A SCA test series, including ethylenediamine, 1,2-diaminopropane, 2,3-diaminobutane, and N-methylethylenediamine, was implemented in terms of the impact on the nanorod aspect ratio. Varied substituents on the vicinal diamine structure were examined towards an optimized reaction center in terms of electron density and steric hindrance. Possible interaction mechanisms of the diamine derivatives with ferric species and the correlation between the aspect ratio and electrochemical performance are discussed. Intermediate-sized α-Fe2O3 nanorods with length/aspect ratios of ≈240 nm/≈2.6 and ≈280 nm/≈3.0 were found to have excellent electrochemical characteristics with reversible discharge capacities of 1086 and 1072 mAh g−1 at 0.1 C after 50 cycles.Published versio

Surface Nanobubbles Studied by Time-Resolved Fluorescence Microscopy Methods Combined with AFM: The Impact of Surface Treatment on Nanobubble Nucleation

The impact of surface treatment and modification on surface nanobubble nucleation in water has been addressed by a new combination of fluorescence lifetime imaging microscopy (FLIM) and atomic force microscopy (AFM). In this study, rhodamine 6G (Rh6G)-labeled surface nanobubbles nucleated by the ethanol–water exchange were studied on differently cleaned borosilicate glass, silanized glass as well as self-assembled monolayers on transparent gold by combined AFM-FLIM. While the AFM data confirmed earlier reports on surface nanobubble nucleation, size, and apparent contact angles in dependence of the underlying substrate, the colocalization of these elevated features with highly fluorescent features observed in confocal intensity images added new information. By analyzing the characteristic contributions to the excited state lifetime of Rh6G in decay curves obtained from time-correlated single photon counting (TCSPC) experiments, the characteristic short-lived (<600 ps) component of could be associated with an emission at the gas–water interface. Its colocalization with nanobubble-like features in the AFM height images provides evidence for the observation of gas-filled surface nanobubbles. While piranha-cleaned glass supported nanobubbles, milder UV-ozone or oxygen plasma treatment afforded glass–water interfaces, where no nanobubbles were observed by combined AFM-FLIM. Finally, the number density of nanobubbles scaled inversely with increasing surface hydrophobicity

Abstract 111: Head and neck cancer cells can differentiate and resemble their tissue of origin

Oppel F, Shao S, Gendreizig S, et al. Abstract 111: Head and neck cancer cells can differentiate and resemble their tissue of origin. Cancer Research. 2022;82(12_Supplement):111-111.**Abstract** Head and neck squamous cell carcinoma (HNSCC) is a highly malignant disease with a mortality rate of about 50%. It represents the sixth most common type of malignant tumor in the world. Risk factors include tobacco and alcohol usage and infection with the human papilloma virus (HPV). HPV-negative HNSCCs frequently display areas of cornification evident by keratin pearls in the tumor tissue. Cornification represents a natural differentiation path of keratinocytes in the normal epidermis and oral mucosa. To investigate the mechanisms of HNSCC cell differentiation we have established spheroid cell cultures from patient-derived HNSCC and parotid gland adenoid cystic carcinoma (ACC) tissue that grow in suspension under serum-free conditions. The use of a specific differentiation medium induced striking adhesion, loss of proliferation, and differentiation in tumor cells. Spheroid cells grew as single cell clones under serum-free conditions with a cloning efficiency of 40-60%, which was fully diminished under differentiating conditions. HNSCC cells cornified as indicated by the formation of lamellar bodies in the cytoplasm of adherent cells and an upregulation of cornification markers SPRR3 and involucrin. ACC cells upregulated parotid gland differentiation markers including α-amylase. RNA-seq analysis in HNSCC cells confirmed an upregulation of signaling pathways associated with cornification and epithelial cell differentiation. Conversely, pathways regulating the three-dimensional organization of the genome were downregulated upon differentiation. This was accompanied by the formation of ATRX-positive heterochromatin foci in the nucleus of differentiated ACC and HNSCC cells resembling those previously described to arise during therapy-induced senescence. Moreover, gas chromatography mass spectrometry analysis revealed a lack of essential amino acids including leucine to be implicated in the differentiation process. Altogether, our spheroid model of HNSCC and ACC cells is suitable to analyze the mechanisms underlying tumor cell differentiation and might lead to new therapeutic approaches that can drive long-term repopulating HNSCC and ACC cells into differentiation. Citation Format: Felix Oppel, Senyao Shao, Sarah Gendreizig, Philipp Kühnel, Vivien Przybycin, Carsten Hain, Pascal Schmidt, Matthias Schürmann, Peter Goon, Karsten Niehaus, Jörn Kalinowski, Holger Sudhoff. Head and neck cancer cells can differentiate and resemble their tissue of origin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 111

Enzyme Degradable Polymersomes from Hyaluronic Acid-<i>block</i>-poly(ε-caprolactone) Copolymers for the Detection of Enzymes of Pathogenic Bacteria

We introduce a new hyaluronidase-responsive amphiphilic block copolymer system, based on hyaluronic acid (HYA) and polycaprolactone (PCL), that can be assembled into polymersomes by an inversed solvent shift method. By exploiting the triggered release of encapsulated dye molecules, these HYA-<i>block</i>-PCL polymersomes lend themselves as an autonomous sensing system for the detection of the presence of hyaluronidase, which is produced among others by the pathogenic bacterium Staphylococcus aureus. The synthesis of the enzyme-responsive HYA-<i>block</i>-PCL block copolymers was carried out by copper-catalyzed Huisgen 1,3-dipolar cycloaddition of ω-azide-terminated PCL and ω-alkyne-functionalized HYA. The structure of the HYA-<i>block</i>-PCL assemblies and their enzyme-triggered degradation and concomitant cargo release were investigated by dynamic light scattering, fluorescence spectroscopy, confocal laser-scanning microscopy, scanning and transmission electron, and atomic force microscopy. As shown, a wide range of reporter dye molecules as well as antimicrobials can be encapsulated into the vesicles during formation and are released upon the addition of hyaluronidase

Determinants of FIV and HIV Vif sensitivity of feline APOBEC3 restriction factors

International audienceBackground: Feline immunodeficiency virus (FIV) is a global pathogen of Felidae species and a model system for Human immunodeficiency virus (HIV)-induced AIDS. In felids such as the domestic cat (Felis catus), APOBEC3 (A3) genes encode for single-domain A3Z2s, A3Z3 and double-domain A3Z2Z3 anti-viral cytidine deaminases. The feline A3Z2Z3 is expressed following read-through transcription and alternative splicing, introducing a previously untrans-lated exon in frame, encoding a domain insertion called linker. Only A3Z3 and A3Z2Z3 inhibit Vif-deficient FIV. Feline A3s also are restriction factors for HIV and Simian immunodeficiency viruses (SIV). Surprisingly, HIV-2/SIV Vifs can counteract feline A3Z2Z3.Results: To identify residues in feline A3s that Vifs need for interaction and degradation, chimeric human-feline A3s were tested. Here we describe the molecular direct interaction of feline A3s with Vif proteins from cat FIV and present the first structural A3 model locating these interaction regions. In the Z3 domain we have identified residues involved in binding of FIV Vif, and their mutation blocked Vif-induced A3Z3 degradation. We further identified additional essential residues for FIV Vif interaction in the A3Z2 domain, allowing the generation of FIV Vif resistant A3Z2Z3. Mutated feline A3s also showed resistance to the Vif of a lion-specific FIV, indicating an evolutionary conserved Vif-A3 binding. Comparative modelling of feline A3Z2Z3 suggests that the residues interacting with FIV Vif have, unlike Vif-interacting residues in human A3s, a unique location at the domain interface of Z2 and Z3 and that the linker forms a homeobox-like domain protruding of the Z2Z3 core. HIV-2/SIV Vifs efficiently degrade feline A3Z2Z3 by possible targeting the linker stretch connecting both Z-domains.Conclusions: Here we identified in feline A3s residues important for binding of FIV Vif and a unique protein domain insertion (linker). To understand Vif evolution, a structural model of the feline A3 was developed. Our results show that HIV Vif binds human A3s differently than FIV Vif feline A3s. The linker insertion is suggested to form a homeo-box domain, which is unique to A3s of cats and related species, and not found in human and mouse A3s. Together, these findings indicate a specific and different A3 evolution in cats and human

Primary head and neck cancer cell cultures are susceptible to proliferation of Epstein-Barr virus infected lymphocytes

Shao S, Scholtz LU, Gendreizig S, et al. Primary head and neck cancer cell cultures are susceptible to proliferation of Epstein-Barr virus infected lymphocytes. BMC Cancer. 2023;23(1): 47.**Background** New concepts for a more effective anti-cancer therapy are urgently needed. Experimental flaws represent a major counter player of this development and lead to inaccurate and unreproducible data as well as unsuccessful translation of research approaches into clinics. In a previous study we have created epithelial cell cultures from head and neck squamous cell carcinoma (HNSCC) tissue. **Methods** We characterize primary cell populations isolated from human papillomavirus positive HNSCC tissue for their marker expression by RT-qPCR, flow cytometry, and immunofluorescence staining. Their sensitivity to MDM2-inhibition was measured using cell viability assays. **Results** Primary HNSCC cell cultures showed the delayed formation of spheroids at higher passages. These spheroids mimicked the morphology and growth characteristics of other established HNSCC spheroid models. However, expression of epithelial and mesenchymal markers could not be detected in these cells despite the presence of the HNSCC stem cell marker aldehyde dehydrogenase 1 family member A1. Instead, strong expression of B- and T-lymphocytes markers was observed. Flow cytometry analysis revealed a heterogeneous mixture of CD3 + /CD25 + T-lymphocytes and CD19 + B-lymphocytes at a ratio of 4:1 at passage 5 and transformed lymphocytes at late passages (≥ passage 12) with CD45 + CD19 + CD20 + , of which around 10 to 20% were CD3 + CD25 + CD56 + . Interestingly, the whole population was FOXP3-positive indicative of regulatory B-cells (Bregs). Expression of transcripts specific for the Epstein-Barr-virus (EBV) was detected to increase in these spheroid cells along late passages, and this population was vulnerable to MDM2 inhibition. HPV + HNSCC cells but not EBV + lymphocytes were detected to engraft into immunodeficient mice. **Conclusions** In this study we present a primary cell culture of EBV-infected tumor-infiltrating B-lymphocytes, which could be used to study the role of these cells in tumor biology in future research projects. Moreover, by describing the detailed characteristics of these cells, we aim to caution other researchers in the HNSCC field to test for EBV-infected lymphocyte contaminations in primary cell cultures ahead of further experiments. Especially researchers who are interested in TIL-based adopted immunotherapy should exclude these cells in their primary tumor models, e.g. by MDM2-inhibitor treatment. BI-12-derived xenograft tumors represent a suitable model for in vivo targeting studies

Selective H-D exchange catalysed by aqueous phase and immobilised Pd nanoparticles

Pd nanoparticles (with a mean diameter of 3.4 ± 0.5 nm) prepared through BH4− reduction of Na2PdCl4 can catalyse selective H–D exchange (through reaction with D2O) at the carbon α to the N atom of a pyridine ring. Oxidised Pd(II) complex species also present as dissolved species in the nanoparticle dispersion play no part in the exchange. We have studied the effects of several different variables on the rate of the selective H–D exchange activity for a model pyridine, i.e. 4-dimethylaminopyridine (DMAP). These variables include temperature, nanoparticle aging, nanoparticle re-reduction with H2 and nanoparticle immobilisation onto multi-walled carbon nanotubes (MWCNTs). We have also extended the study to related pyridine containing molecules.DG 15/11/1