Publikationen am Institut für Chemie und Biotechnik

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Huang, Tianbai; Geitner, Robert; Croy, Alexander; Gräfe, Stefanie
Tailoring phosphine ligands for improved C-H activation: insights from Δ-machine learning. - In: Digital discovery, ISSN 2635-098X, Bd. 0 (2024), 0, insges. 15 S.

Transition metal complexes have played crucial roles in various homogeneous catalytic processes due to their exceptional versatility. This adaptability stems not only from the central metal ions but also from the vast array of choices of the ligand spheres, which form an enormously large chemical space. For example, Rh complexes, with a well-designed ligand sphere, are known to be efficient in catalyzing the C-H activation process in alkanes. To investigate the structure-property relation of the Rh complex and identify the optimal ligand that minimizes the calculated reaction energy ΔE of an alkane C-H activation, we have applied a Δ-machine learning method trained on various features to study 1743 pairs of reactants (Rh(PLP)(Cl)(CO)) and intermediates (Rh(PLP)(Cl)(CO)(H)(propyl)). Our findings demonstrate that the models exhibit robust predictive performance when trained on features derived from electron density (R2 = 0.816), and SOAPs (R2 = 0.819), a set of position-based descriptors. Leveraging the model trained on xTB-SOAPs that only depend on the xTB-equilibrium structures, we propose an efficient and accurate screening procedure to explore the extensive chemical space of bisphosphine ligands. By applying this screening procedure, we identify ten newly selected reactant-intermediate pairs with an average ΔE of 33.2 kJ mol−1, remarkably lower than the average ΔE of the original data set of 68.0 kJ mol−1. This underscores the efficacy of our screening procedure in pinpointing structures with significantly lower energy levels.
Motuziuk, Olexandr; Nozdrenko, Dmytro; Prylutska, Svitlana; Vareniuk, Igor; Cherepanov, Vsevolod; Bogutska, Kateryna; Rudenko, Sergii; Prylutskyy, Yuriy; Piosik, Jacek; Ritter, Uwe
C60 fullerene reduces the level of liver damage in chronic alcohol intoxication of rats. - In: Molecules, ISSN 1420-3049, Bd. 29 (2024), 13, 2951, S. 1-15

The liver is the main organ responsible for the metabolism of ethanol, which suffers significantly as a result of tissue damage due to oxidative stress. It is known that C60 fullerenes are able to efficiently capture and inactivate reactive oxygen species in in vivo and in vitro systems. Therefore, the purpose of this study is to determine whether water-soluble C60 fullerene reduces the level of pathological process development in the liver of rats induced by chronic alcohol intoxication for 3, 6, and 9 months, depending on the daily dose (oral administration; 0.5, 1, and 2 mg/kg) of C60 fullerene throughout the experiment. In this context, the morphology of the C60 fullerene nanoparticles in aqueous solution was studied using atomic force microscopy. Such biochemical parameters of experimental animal blood as ALT (alanine aminotransferase), AST (aspartate aminotransferase), GGT (gamma-glutamyl transferase) and ALP (alkaline phosphatase) enzyme activities, CDT (carbohydrate-deficient transferrin) level, values of pro-antioxidant balance indicators (concentrations of H2O2 (hydrogen peroxide) and GSH (reduced glutathione), activities of CAT (catalase), SOD (superoxide dismutase) and GPx (selenium-dependent glutathione peroxidase)), and pathohistological and morphometric features of liver damage were analyzed. The most significant positive change in the studied biochemical parameters (up to 29 ± 2% relative to the control), as markers of liver damage, was recorded at the combined administration of alcohol (40% ethanol in drinking water) and water-soluble C60 fullerenes in the optimal dose of 1 mg/kg, which was confirmed by small histopathological changes in the liver of rats. The obtained results prove the prospective use of C60 fullerenes as powerful antioxidants for the mitigation of pathological conditions of the liver arising under prolonged alcohol intoxication.
Kronfeld, Klaus-Peter; Köhler, Michael; Ellinger, Thomas
Microfluidic synthesis and properties of thermoresponsive hydrogel core-shell particles. - In: Journal of composites science, ISSN 2504-477X, Bd. 8 (2024), 5, 162, S. 1-9

An approach is demonstrated for the generation of swellable core-shell particles in the sub-millimeter range using a one-step microfluidic method. Particles are made of an agarose gel core and a shell consisting of hydrogel based on crosslinked poly-(N-isopropylacrylamide) (PNIPAM). Solidification of the core was achieved by cooling below the sol-gel temperature, while the shell was cured by photoinitiated co-polymerization. The shell of the particles is reversibly thermoresponsive; it contracts upon heating, releasing water, and becomes hydrophobic. The transition temperature as well as the stability of the particles are mainly affected by the shell monomer composition, while they are less affected by the type of the core material. Such composite particles remain swellable after drying.
Endres, Patrick; Schütt, Timo; Bode, Stefan; Hager, Martin; Geitner, Robert; Schubert, Ulrich Sigmar
Investigation of the cooperative-effects of Lewis- and Brønstedt acids in homogeneously catalyzed OME fuel synthesis by inline-NMR monitoring. - In: RSC Advances, ISSN 2046-2069, Bd. 14 (2024), 21, S. 14942-14948

Via inline-nuclear magnetic resonance measurements, the homogeneously catalyzed poly(oxymethylene dimethyl ether) fuel synthesis using trioxane and dimethoxy methane is investigated. Besides the Brønsted acid (BA) catalyst triflic acid (TfOH) different metal halides are studied as Lewis-acidic (LA) catalysts. Among the used LAs, MgCl2, the weakest based on electronegativity, reveals the highest catalytical activity. Additionally, the influence of the concentration of BA and LA is investigated. An increase in BA concentration leads to an exponential increase of the reaction rate, while increasing the concentration of the LA leads to a volcano plot with its optimum at a LA : BA ratio of 1 : 3. The influence of the LA on the electron density of the intermediate formaldehyde is concluded as the main factor for this behavior.
Saupe, Mario; Wiedemeier, Stefan; Gastrock, Gunter; Römer, Robert; Lemke, Karen
Flexible toolbox of high-precision microfluidic modules for versatile droplet-based applications. - In: Micromachines, ISSN 2072-666X, Bd. 15 (2024), 2, 250, S. 1-19

Although the enormous potential of droplet-based microfluidics has been successfully demonstrated in the past two decades for medical, pharmaceutical, and academic applications, its inherent potential has not been fully exploited until now. Nevertheless, the cultivation of biological cells and 3D cell structures like spheroids and organoids, located in serially arranged droplets in micro-channels, has a range of benefits compared to established cultivation techniques based on, e.g., microplates and microchips. To exploit the enormous potential of the droplet-based cell cultivation technique, a number of basic functions have to be fulfilled. In this paper, we describe microfluidic modules to realize the following basic functions with high precision: (i) droplet generation, (ii) mixing of cell suspensions and cell culture media in the droplets, (iii) droplet content detection, and (iv) active fluid injection into serially arranged droplets. The robustness of the functionality of the Two-Fluid Probe is further investigated regarding its droplet generation using different flow rates. Advantages and disadvantages in comparison to chip-based solutions are discussed. New chip-based modules like the gradient, the piezo valve-based conditioning, the analysis, and the microscopy module are characterized in detail and their high-precision functionalities are demonstrated. These microfluidic modules are micro-machined, and as the surfaces of their micro-channels are plasma-treated, we are able to perform cell cultivation experiments using any kind of cell culture media, but without needing to use surfactants. This is even more considerable when droplets are used to investigate cell cultures like stem cells or cancer cells as cell suspensions, as 3D cell structures, or as tissue fragments over days or even weeks for versatile applications.
Szántó, Géza; Pritzke, Pia; Kluitmann, Jonas; Köhler, Michael; Csáki, Andrea; Fritzsche, Wolfgang; Csarnovics, István; Bonyár, Attila
Optimization of the bulk refractive index sensitivity of silver nanoprisms. - In: Advanced optical materials, ISSN 2195-1071, Bd. 12 (2024), 15, 2302967, S. 1-11

The sensitivity and optical properties of silver nanoprisms (triangular plates with round-truncated corners) are investigated in this paper. Results of boundary element method simulations are compared with experimental results and literature data. Based on electron microscopy images of the synthesized nanoprisms, a single-particle model is set up for simulations with three running parameters: edge length, thickness, and roundness (defined as the radius of the circumscribed circle divided by the edge length). These geometric parameters can be optimized during chemical synthesis to create sensors with improved sensitivity. The effect of biomolecular layers is also investigated. As a novel approach to improve the agreement between the simulated and experimentally measured extinction spectra, the single-particle model is extended to consider the variation of the prisms' parameters in the form of distributions. The resulting extinction cross-section spectra correspond well with the experimental data. The calculated bulk refractive index sensitivity is 670 nm/RIU (RIU stands for refractive index unit) for the single particle model (length = 150 nm, thickness = 10 nm, and roundness = 0.1), while (690 ± 5) nm/RIU for the extended model. The presented model and obtained relations between sensitivity and geometry can be effectively used to design and optimize the fabrication technologies for silver nanoprism-based sensing applications.
Zeußel, Lisa; Chowdhary, Shefali; Wu, Haocheng; Kumar, Vipan; Singh, Sukhdeep
Sustainable harnessing of waste polycarbonate for synthesizing activated furans to generate Stenhouse adducts on polymer surface. - In: Chemistry, ISSN 1861-471X, Bd. 19 (2024), 13, e202400369, S. 1-11

Plastics are versatile materials, offering lightweight, durable, and affordable solutions across various industries. However, their non-degradable nature poses challenges by end of their life. This study presented an innovative carbonyl extraction method to utilize waste poly(bisphenol A carbonate) (PC) as reaction precursor to synthesis of activated furan as precursor for photoswitchable Stenhouse adducts. This innovative chemical strategy not only generated N,N’-functionalized barbiturates but also provided an eco-friendly and cost-effective alternative to traditional synthesis methods. The method presented hereby not only promotes sustainability by repurposing waste polycarbonate as carbonyl equivalent under green conditions but also yielded reusable bisphenol A (BPA). Furthermore, the derived activated furans exhibited their functionality by forming colored donor-acceptor Stenhouse adducts (DASAs) on aminated polymer surfaces. This work demonstrated a transition from a linear plastics economy toward a circular one, highlighting the potential of plastic waste as a resource for creating materials with improved properties.
Prylutska, Svitlana; Grebinyk, Anna; Ponomarenko, Stanislav; Gövem, Defne; Chumachenko, Vasyl; Kutsevol, Nataliya; Petrovsky, Mykola; Ritter, Uwe; Frohme, Marcus; Piosik, Jacek; Prylutskyy, Yuriy
Toxicity of water-soluble D-g-PNIPAM polymers in a complex with chemotherapy drugs and mechanism of their action in vitro. - In: International journal of molecular sciences, ISSN 1422-0067, Bd. 25 (2024), 5, 3069, S. 1-15

The application of a biocompatible polymer nanocarrier can provide target delivery to tumor tissues, improved pharmacokinetics, controlled drug release, etc. Therefore, the proposed strategy was to use the water-soluble star-like copolymers with a Dextran core and Poly(N-isopropylacrylamide) grafts (D-g-PNIPAM) for conjugation with the widely used chemotherapy drugs in oncology-Cisplatin (Cis-Pt) and Doxorubicin (Dox). The molecular characteristics of the copolymer were received using size-exclusion chromatography. The physicochemical characterization of the D-g-PNIPAM-Cis-Pt (or Dox) nanosystem was conducted using dynamic light scattering and FTIR spectroscopy. Using traditional biochemical methods, a comparative analysis of the enhancement of the cytotoxic effect of free Cis-Pt and Dox in combination with D-g-PNIPAM copolymers was performed in cancer cells of the Lewis lung carcinoma line, which are both sensitive and resistant to Dox; in addition, the mechanism of their action in vitro was evaluated.
Nguyen, Thi-Huong; Chen, Li-Yu; Khan, Nida Zaman; Lindenbauer, Annerose; Bui, Van-Chien; Zipfel, Peter F.; Heinrich, Doris
The binding of the SARS-CoV-2 spike protein to platelet factor 4: a proposed mechanism for the generation of pathogenic antibodies. - In: Biomolecules, ISSN 2218-273X, Bd. 14 (2024), 3, 245, S. 1-14

Pathogenic platelet factor 4 (PF4) antibodies contributed to the abnormal coagulation profiles in COVID-19 and vaccinated patients. However, the mechanism of what triggers the body to produce these antibodies has not yet been clarified. Similar patterns and many comparable features between the COVID-19 virus and heparin-induced thrombocytopenia (HIT) have been reported. Previously, we identified a new mechanism of autoimmunity in HIT in which PF4-antibodies self-clustered PF4 and exposed binding epitopes for other pathogenic PF4/eparin antibodies. Here, we first proved that the SARS-CoV-2 spike protein (SP) also binds to PF4. The binding was evidenced by the increase in mass and optical intensity as observed through quartz crystal microbalance and immunosorbent assay, while the switching of the surface zeta potential caused by protein interactions and binding affinity of PF4-SP were evaluated by dynamic light scattering and isothermal spectral shift analysis. Based on our results, we proposed a mechanism for the generation of PF4 antibodies in COVID-19 patients. We further validated the changes in zeta potential and interaction affinity between PF4 and SP and found that their binding mechanism differs from ACE2-SP binding. Importantly, the PF4/SP complexes facilitate the binding of anti-PF4/Heparin antibodies. Our findings offer a fresh perspective on PF4 engagement with the SARS-CoV-2 SP, illuminating the role of PF4/SP complexes in severe thrombotic events.
Köhler, Michael; Ehrhardt, Linda; Günther, Mike; Böhme, Manfred; Cao-Riehmer, Jialan
Low abundant bacteria reflect soil specificity - analysis of bacterial communities from archaeological investigation of pre-industrial saline ash deposits of Bad Dürrenberg (Germany). - In: Environments, ISSN 2076-3298, Bd. 11 (2024), 3, 42, S. 1-20

Six soil samples from three layers of an archaeological investigation profile from a pre-industrial ash deposit place have been investigated by NGS analyses of 16 S rRNA. The three pairs of sample originate from top soil (internal reference), from an intermediate ash layer and from a lower ash layer, formed about two centuries ago. In addition to general abundant bacteria, special genera known as halophilic or alkaline-tolerant have been found as expected from the history of the place and from the measured pH-value and conductivity measurements. The close relations between samples of pairs and the differences between the three soil layers are clearly indicated by abundance correlation and PCA-diagrams. Comparative PCA correlation plots including samples from an archaeological excavation site dedicated to pre-industrial coal mining illustrate the high distinguishability of investigated soils. These relations are particular clearly shown when lower abundant bacteria are regarded. The investigations are a further example for the “ecological memory of soil” reflecting the strong human impact on this pre-industrial embossed place.