Anzahl der Treffer: 419
Erstellt: Sun, 24 Sep 2023 16:59:25 +0200 in 0.0494 sec

Täuscher, Eric; Freiberger, Emma
Cholesterin aus Hirn. - In: Nachrichten aus der Chemie, ISSN 1439-9598, Bd. 71 (2023), 1, S. 30-32

Cholesterin hat es bis in den Alltagssprachgebrauch gebracht. Allein deshalb ist es für Praktika im Chemiestudium ein interessanter Vertreter der Steroide. Zudem ist es einfach zu gewinnen.

Täuscher, Eric; Freiberger, Emma
Cholesterin aus Hirn. - In: Nachrichten aus der Chemie, ISSN 1868-0054, Bd. 71 (2023), 1, S. 30-32

Cholesterin hat es bis in den Alltagssprachgebrauch gebracht. Allein deshalb ist es für Praktika im Chemiestudium ein interessanter Vertreter der Steroide. Zudem ist es einfach zu gewinnen.
Tsierkezos, Nikos; Freiberger, Emma; Ritter, Uwe; Krischok, Stefan; Ullmann, Fabian; Köhler, Michael
Application of nitrogen-doped multi-walled carbon nanotubes decorated with gold nanoparticles in biosensing. - In: Journal of solid state electrochemistry, ISSN 1433-0768, Bd. 27 (2023), 10, S. 2645-2658

Novel films consisting of nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) were fabricated by means of chemical vapor deposition technique and decorated with gold nanoparticles (AuNPs) possessing diameter of 14.0 nm. Electron optical microscopy analysis reveals that decoration of N-MWCNTs with AuNPs does not have any influence on their bamboo-shaped configuration. The electrochemical response of fabricated composite films, further denoted as N-MWCNTs/AuNPs, towards oxidation of dopamine (DA) to dopamine-o-quinone (DAQ) in the presence of ascorbic acid (AA) and uric acid (UA) was probed in real pig serum by means of cyclic voltammetry (CV) and square wave voltammetry (SWV). The findings demonstrate that N-MWCNTs/AuNPs exhibit slightly greater electrochemical response and sensitivity towards DA/DAQ compared to unmodified N-MWCNTs. It is, consequently, obvious that AuNPs improve significantly the electrochemical response and detection ability of N-MWCNTs. The electrochemical response of N-MWCNTs/AuNPs towards DA/DAQ seems to be significantly greater compared to that of conventional electrodes, such as platinum and glassy carbon. The findings reveal that N-MWCNTs/AuNPs could serve as powerful analytical sensor enabling analysis of DA in real serum samples.
Tsierkezos, Nikos; Reddmann, Eike Felix; Ritter, Uwe
Synthesis and electrochemical properties of sulfur-nitrogen-doped multi-walled carbon nanotubes. - In: Fullerenes, nanotubes & carbon nanostructures, ISSN 1536-4046, Bd. 0 (2023), 0

Multi-walled carbon nanotubes doped with sulfur and nitrogen (S-N-MWCNTs) were grown onto silicon/silicon oxide wafer by means of chemical vapor deposition upon decomposition of dimethyl sulfoxide (DMSO) and acetonitrile (ACN) in presence of catalyst. The S-N-MWCNTs were characterized by scanning electron microscopy combined with energy dispersive X-ray spectroscopy. The findings demonstrate that S-N-MWCNTs exhibit bamboo-shaped nanostructure, quite similar to pure nitrogen-doped carbon nanotubes. The S-N-MWCNTs were investigated with respect to their electrochemical response to ferrocyanide/ferricyanide, [Fe(CN)6]^4-/3- in potassium chloride aqueous solutions by means of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. The recorded CVs demonstrate strong dependence of electrochemical response, electron transfer kinetics, and sensitivity of S-N-MWCNTs on concentration of decomposed DMSO precursor. Namely, upon increasing concentration of decayed DMSO up to 2% wt. the current density, the electron transfer kinetics, and the sensitivity of S-N-MWCNTs toward [Fe(CN)6]^4-/3- tend to enhance. The extracted EIS results approve that when DMSO reaches the optimum concentration of 2% wt. the barrier for electron transfer decreases significantly leading, consequently, to faster electron transfer kinetics. The S-N-MWCNTs exhibit considerable stability and excellent reproducibility, and thus it can be considered suitable analytical tool for detection of redox systems at micromolar level.
Ritter, Uwe; Nikolenko, Andrii; Alieksandrov, Maksim; Strelchuk, Viktor; Chumachenko, Vasyl; Kutsevol, Nataliya; Scharff, Peter; Prylutskyy, Yu I.
Structural and optical properties of C70 fullerenes in aqueous solution. - In: Fullerenes, nanotubes & carbon nanostructures, ISSN 1536-4046, Bd. 31 (2023), 10, S. 983-988

The simple method of preparation of highly stable and purified C70 fullerene aqueous solution (C70FAS) is proposed. The features of structural stabilization of C70 fullerenes in an aqueous solution by studying their structural and optical properties using Raman, photoluminescence, infrared reflection-absorption, UV-VIS absorption, and dynamic light scattering spectroscopy methods were analyzed. The experimental results showed that the most likely mechanism for C70 fullerenes stabilization in water is surface hydroxylation with covalent attachment of water hydroxyls to C70 fullerene carbons. Raman and infrared absorption spectra of C70FAS showed characteristic vibrational bands of C70 fullerenes with a slight broadening and low-frequency shift of ∼1 cm^−1, indicating the attachment of water hydroxyls to the C70 fullerene carbons. The photoluminescence spectra showed excitonic emission bands of C70 molecules with intensity depending on their content. UV-VIS absorption spectra demonstrate the absorption bands typical for monomeric C70 fullerene. Finally, the dynamic light scattering data confirmed that C70FAS is a typical colloidal fluid containing both individual C70 molecules and their nano aggregates up to 100 nm. These findings provide insights into the stabilization mechanism of C70 fullerenes in water and may have implications for their potential application in nanobiotechnology.
Adamopoulos, Nikolaos D.; Tsierkezos, Nikos; Ntziouni, Afroditi; Zhang, Fu; Terrones, Mauricio; Kordatos, Konstantinos V.
Synthesis, characterization, and electrochemical performance of reduced graphene oxide decorated with Ag, ZnO, and AgZnO nanoparticles. - In: Carbon, ISSN 0008-6223, 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.
Dorner-Reisel, Annett; Wang, Tao; Freiberger, Emma; Ritter, Uwe; Moje, Jens; Zhao, Mengya; Scharff, Peter
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.
Radivoievych, Aleksandar; Kolp, Benjamin; Grebinyk, Sergii; Prylutska, Svitlana; Ritter, Uwe; Zolk, Oliver; Glökler, Jörn Felix; Frohme, Marcus; Grebinyk, Anna
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.
Karagianni, Alexandra; Tsierkezos, Nikos; Prato, Maurizio; Terrones, Mauricio; Kordatos, Konstantinos V.
Application of carbon-based quantum dots in photodynamic therapy. - In: Carbon, ISSN 0008-6223, 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.
Prylutskyy, Yuriy; Nozdrenko, Dmytro; Gonchar, Olga; Prylutska, Svitlana; Bogutska, Kateryna; Täuscher, Eric; Scharff, Peter; Ritter, Uwe
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.