Oxymethylene ether (OME) fuel catalyst screening using in situ NMR spectroscopy. - In: Chemistry - a European journal, ISSN 1521-3765, Bd. 29 (2023), 33, e202203776, S. 1-9
Online NMR measurements are introduced in the current study as a new analytical setup for investigation of the oxymethylene dimethyl ether (OME) synthesis. For the validation of the setup, the newly established method is compared with state-of-the-art gas chromatographic analysis. Afterwards, the influence of different parameters, such as temperature, catalyst concentration and catalyst type on the OME fuel formation based on trioxane and dimethoxymethane is investigated. As catalysts, AmberlystTM 15 (A15) and trifluoromethanesulfonic acid (TfOH) are utilized. A kinetic model is applied to describe the reaction in more detail. Based on these results, the activation energy (A15: 48.0 kJ mol^-1 and TfOH: 72.3 kJ mol^-1) and the order in catalyst (A15: 1.1 and TfOH: 1.3) are calculated and discussed.
https://doi.org/10.1002/chem.202203776
Synthesis, characterization, and electrochemical performance of reduced graphene oxide decorated with Ag, ZnO, and AgZnO nanoparticles. - In: Carbon, ISSN 1873-3891, Bd. 213 (2023), 118178
Graphene oxide (GO) derived from the oxidization of graphite exhibits high specific surface area with potential in electrochemical applications. Furthermore, silver and zinc oxide nanoparticles, further denoted as AgNPs and ZnONPs, respectively, display superior physicochemical and electronic properties, that would significantly improve the electrocatalytic properties by being applied in electrochemical sensing. Consequently, in the present work, three different hybrid nanomaterials consisting of reduced graphene oxide (rGO) modified with either AgNPs, ZnONPs, or combined AgZnONPs were synthesized and characterized. The synthesis of GO was performed by a modified Hummer's method, while the decoration of GO with the nanoparticles was carried out by self-assembly solvothermal processes. The Ag-rGO, ZnO-rGO, and AgZnO-rGO nanocomposite hybrid materials were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) combined with energy-dispersive X-ray spectroscopy (EDX). Furthermore, the electrochemical responses of the fabricated nanocomposites towards the standard ferrocyanide/ferricyanide [Fe(CN)6]3-/4- redox system were investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. The results have been explained in terms of structural differences between the nanoparticles formed on the surface of the fabricated nanocomposite materials. Namely, the improved electrochemical performance of ZnO-rGO can be attributed to the high surface to volume ratio of ZnO, which provides greater area of electrode/electrolyte junction and consequently, large number of sites at the electrolyte-ZnO interface. The aim of the present work is the fabrication of novel high-performance rGO-based nanomaterials for applications in electrochemical sensing.
https://doi.org/10.1016/j.carbon.2023.118178
NMR and GPC analysis of alkyd resins: influence of synthesis method, vegetable oil and polyol content. - In: Polymers, ISSN 2073-4360, Bd. 15 (2023), 9, 1993, S. 1-14
Alkyd resins are oil-based polymers that have been widely used for generations in the surface coating industry and beyond. Characterization of these resins is of high importance to understand the influence of its components on its behavior, compatibility with other resins, and final quality to ensure high durability. Here, NMR spectroscopy and GPC were used for characterizing differences in the chemical structure, molecular distribution, and dispersity between oil-based and fatty acid-based alkyd polymers made from sacha inchi and linseed oils. Sancha inchi (Plukentia volubilis L.) is a fruit-bearing plant native to South America and the Caribbean, and has a rich unsaturated fatty acid content. The effect of vegetable oil and polyol selection on the synthesis of alkyd resins for coating applications was analyzed. The influence of two different synthesis methods, monoglyceride and fatty acid processes, was also compared. Important structural differences were observed using NMR: one-dimensional spectra revealed the degree of unsaturated fatty acid chains along the polyester backbone, whereas, 2D NMR experiments facilitated chemical shift assignments of all signals. GPC analysis suggested that alkyd resins with homogeneous and high molecular weights can be obtained with the fatty acid process, and that resins containing pentaerythritol may have uniform chain lengths.
https://doi.org/10.3390/polym15091993
Fullerene C60 films on dental implants: durability study after in vitro short-term exposure. - In: Diamond and related materials, ISSN 0925-9635, Bd. 135 (2023), 109886
The carbon fullerene C60 is an anti-inflammatory substance that reduces cellular stress levels. In this study, C60 fullerenes were deposited on complex dental implants to improve cell attachment and vitality. For the first time, fullerene C60 films were deposited via high-vacuum sublimation on complex-shaped Ti-6Al-4V dental implants with a threaded-screw design. The “as-deposited” fullerene C60 films were compared with fullerene C60 films on dental Ti-6Al-4V implants using a threaded-screw design after three weeks of incubation in Hank's balanced salt solution (HBSS). It was proven by Raman spectroscopy that the incubation in potassium and alkali-ion rich HBSS at 37 ˚C resulted in a reduction of monomeric fullerene C60 fraction and an increase in dimer, linear chain and polymerized C60 molecules. Furthermore, the structure of the C60 films differed depending on the measurement position on dental implants with a threaded-screw design. The fraction of monomeric fullerene C60 was highest on top of the trapezoidal thread, which had a micropatterned topography. Nano-indentations were performed at this position with a maximum load of 1000 μN. The fullerene C60 films showed a nano-hardness of 0.3 ± 0.1 GPa and a Young's modulus of 7.6 ± 3.6 GPa at this position, which is typical for monomeric fullerene C60 with weak interatomic interaction in the face-centred-cubic crystal structure. The murine embryonal calvarial stem-cell line MC3T3-E1 (ECACC, UK), which is driven toward osteogenic differentiation, spread out extremely well on the fullerene C60 film, with improved cell morphology compared to uncoated Ti-6Al-4V. Cell nuclei density were determined to be 237.5 cell nuclei per mm2 for the Ti-6Al-4V dental implants with a threaded-screw design with fullerene C60 coating in “as-deposited” condition. This was approximately 40 % better than that of uncoated Ti-6Al-4V dental implants with a threaded-screw design.
https://doi.org/10.1016/j.diamond.2023.109886
Archaeal and extremophilic bacteria from different archaeological excavation sites. - In: International journal of molecular sciences, ISSN 1422-0067, Bd. 24 (2023), 6, 5519, S. 1-18
Beside natural factors, human activities are important for the development of microbiomes. Thus, local soil bacterial communities are affected by recent activities such as agriculture, mining and industry. In addition, ancient human impacts dating back centuries or millennia have changed soils and can emboss the recent bacterial communities up to now, representing a certain long-term "memory of soil". Soil samples from five different archaeological excavation places were investigated for the presence of Archaea with a Next Generation Sequencing (NGS) analysis of the DNA coding for 16S r-RNA sequences. It was found that the abundance of Archaea differs strongly between less than one and more than 40 percent of bacteria. A Principal Component Analysis (PCA) of all samples shows that the archaeological excavation places can be distinguished from each other by the archaeal component of soil bacterial communities, which presents a typical pattern for each place. Most samples are marked by the dominance of Crenarchaeota, which are presented mainly by ammonia-related types. High contents of Nanoarchaeaota have been observed in one ash deposit of a historical saline and all samples of a historical tannery area. These samples are also marked by a significant presence of Dadabacteria. The specific abundancies of special Archaea - among them ammonia-oxidizing and sulphur-related types - are due obviously to former human activities and support the concept of the "ecological memory of soil".
https://doi.org/10.3390/ijms24065519
Silent death by sound: C60 fullerene sonodynamic treatment of cancer cells. - In: International journal of molecular sciences, ISSN 1422-0067, Bd. 24 (2023), 2, 1020, S. 1-17
The acoustic pressure waves of ultrasound (US) not only penetrate biological tissues deeper than light, but they also generate light emission, termed sonoluminescence. This promoted the idea of its use as an alternative energy source for photosensitizer excitation. Pristine C60 fullerene (C60), an excellent photosensitizer, was explored in the frame of cancer sonodynamic therapy (SDT). For that purpose, we analyzed C60 effects on human cervix carcinoma HeLa cells in combination with a low-intensity US treatment. The time-dependent accumulation of C60 in HeLa cells reached its maximum at 24 h (800 ± 66 ng/106 cells). Half of extranuclear C60 is localized within mitochondria. The efficiency of the C60 nanostructure’s sonoexcitation with 1 MHz US was tested with cell-based assays. A significant proapoptotic sonotoxic effect of C60 was found for HeLa cells. C60′s ability to induce apoptosis of carcinoma cells after sonoexcitation with US provides a promising novel approach for cancer treatment.
https://doi.org/10.3390/ijms24021020
A user-guide for polymer purification using dialysis. - In: Polymer chemistry, ISSN 1759-9962, Bd. 14 (2023), 1, S. 92-101
Dialysis diffusion kinetics are investigated via in situ NMR spectroscopy for numerous different raw polymeric solutions to result in a general guideline for polymer purification using dialysis. In several approaches, a polymer was on purpose contaminated with its respective monomer, regenerated conducting conventional dialysis and monitored online utilizing in situ NMR spectroscopy. Consequently, polymer type and molar mass, monomer type, molar mass cut-off of the dialysis tubing and type of solvent were varied resulting in 29 different purification approaches and over 40 000 NMR-spectra. As a result, several major parameters were identified affecting the purification process significantly such as the chosen solvent, viscosity and alpha value. On the contrary, parameters such as dialysis tubing molar mass cut-off and molar mass of the polymer did not affect the purification in a significant manner. Furthermore, physical properties such as density, viscosity, alpha value, and dipole moment of the ingredients were combined in a principal component analysis in order to identify the most important parameters.
https://doi.org/10.1039/D2PY00972B
Application of carbon-based quantum dots in photodynamic therapy. - In: Carbon, ISSN 1873-3891, Bd. 203 (2023), S. 273-310
Photodynamic Therapy (PDT) is a non-invasive therapeutic modality that can treat a wide variety of cancer types by means of photosensitizer drug, light, and oxygen. Due to enhanced specificity and fewer side effects, PDT can be an alternative approach for cancer treatments. However, conventional photosensitizers (PSs) exhibit low selectivity, hydrophobicity, and limited photophysical properties. Nanotechnology emerges as a potential solution to these issues and improves PDT efficiency. Nanomaterials such as Carbon Quantum Dots (CQDs) and Graphene Quantum Dots (GrQDs) have been widely applied on PDT research recently, regarding their excellent photoluminescence properties, biocompatibility, as well as their hydrophilicity. The present review article summarizes the main features of PDT and carbon-based quantum dots with an emphasis on used PSs and methods for synthesis of carbon dots. Additionally, the most recent applications of CQDs and GrQDs in PDT have been extensively discussed. The main conclusion that arises is that carbon-based quantum dots seem to be a powerful tool in cancer diagnosis and treatment.
https://doi.org/10.1016/j.carbon.2022.11.026
The residual effect of C60 fullerene on biomechanical and biochemical markers of the muscle soleus fatigue development in rats. - In: Journal of nanomaterials, ISSN 1687-4129, Bd. 2023 (2023), e2237574, S. 1-11
Muscle fatigue as a defense body mechanism against overload is a result of the products of incomplete oxygen oxidation such as reactive oxygen species. Hence, C60 fullerene as a powerful nanoantioxidant can be used to speed up the muscle recovery process after fatigue. Here, the residual effect of C60 fullerene on the biomechanical and biochemical markers of the development of muscle soleus fatigue in rats for 2 days after 5 days of its application was studied. The known antioxidant N-acetylcysteine (NAC) was used as a comparison drug. The atomic force microscopy to determine the size distribution of C60 fullerenes in an aqueous solution, the tensiometry of skeletal muscles, and the biochemical analysis of their tissues and rat blood were used in this study. It was found that after the cessation of NAC injections, the value of the integrated muscle power is already slightly different from the control (5%-7%) on the first day, and on the second day, it does not significantly differ from the control. At the same time, after the cessation of C60 fullerene injections, its residual effect was 45%-50% on the first day, and 17%-23% of the control on the second one. A significant difference (more than 25%) between the pro- and antioxidant balance in the studied muscles and blood of rats after the application of C60 fullerene and NAС plays a key role in the long-term residual effect of C60 fullerene. This indicates prolonged kinetics of C60 fullerenes elimination from the body, which contributes to their long-term (at least 2 days) compensatory activation of the endogenous antioxidant system in response to muscle stimulation, which should be considered when developing new therapeutic agents based on these nanoparticles.
https://doi.org/10.1155/2023/2237574
FluidFM-based fabrication of nanopatterns: promising surfaces for platelet storage application. - In: ACS applied materials & interfaces, ISSN 1944-8252, Bd. 14 (2022), 21, S. 24133-24143
Platelets are cell fragments from megakaryocytes devoid of the cell nucleus. They are highly sensitive and easily activated by nonphysiological surfaces. Activated platelets have an intrinsic mechanism to release various proteins that participate in multiple pathways, initiating the platelet activation cascade. Surface-induced platelet activation is a challenge encountered during platelet storage, which eventually leads to aggregation of platelets and can thereby result in the degradation of the platelet concentrates. We have previously reported that surface-induced platelet activation can be minimized by either modifying their contact surfaces with polymers or introducing nanogroove patterns underneath the platelets. Here, we investigated the response of platelets to various nanotopographical surfaces printed using fluidic force microscopy (FluidFM). We found that the hemispherical array (grid) and hexagonal tile (hive) structures caused a reduction of surface stiffness, which leads to an inhibition of platelet adhesion. Our results reveal that nanopatterns enable the inhibition of platelet activation on surfaces, thus implying that development in nanotexturing of storage bags can extend the lifetime of platelet concentrates.
https://doi.org/10.1021/acsami.2c03459