| 1. |
- Gupta, G., et al.
(author)
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Exploiting Mass Spectrometry to Unlock the Mechanism of Nanoparticle-Induced Inflammasome Activation
- 2023
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In: Acs Nano. - : AMER CHEMICAL SOC. - 1936-0851 .- 1936-086X. ; 17:17, s. 17451-17467
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Journal article (peer-reviewed)abstract
- Nanoparticles (NPs) elicit sterile inflammation, but the underlying signaling pathways are poorly understood. Here, we report that human monocytes are particularly vulnerable to amorphous silica NPs, as evidenced by single-cell-based analysis of peripheral blood mononuclear cells using cytometry by time-of-flight (CyToF), while silane modification of the NPs mitigated their toxicity. Using human THP-1 cells as a model, we observed cellular internalization of silica NPs by nanoscale secondary ion mass spectrometry (nanoSIMS) and this was confirmed by transmission electron microscopy. Lipid droplet accumulation was also noted in the exposed cells. Furthermore, time-of-flight secondary ion mass spectrometry (ToF-SIMS) revealed specific changes in plasma membrane lipids, including phosphatidylcholine (PC) in silica NP-exposed cells, and subsequent studies suggested that lysophosphatidylcholine (LPC) acts as a cell autonomous signal for inflammasome activation in the absence of priming with a microbial ligand. Moreover, we found that silica NPs elicited NLRP3 inflammasome activation in monocytes, whereas cell death transpired through a non-apoptotic, lipid peroxidation-dependent mechanism. Together, these data further our understanding of the mechanism of sterile inflammation.
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| 2. |
- Galkina, Olga, et al.
(author)
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Antibacterial and photochemical properties of cellulose nanofiber-titania nanocomposites loaded with two different types of antibiotic medicines
- 2015
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In: Journal of materials chemistry. B. - : Royal Society of Chemistry (RSC). - 2050-750X .- 2050-7518. ; 3:35, s. 7125-7134
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Journal article (peer-reviewed)abstract
- Nanocomposite dermal drug delivery systems based on cellulose nanofibers with grafted titania nanoparticles loaded by two antibiotic medicines from different classes, i.e. tetracycline (TC) and phosphomycin (Phos), were successfully produced by a "green chemistry'' approach in aqueous media. The influence of a different surface binding mechanism between the drug molecule and modified cellulose nanofibers on the release of the drug and, as a result, on antimicrobial properties against common pathogens Gram-positive, Staphylococcus aureus and Gram-negative Escherichia coli was investigated. The disk diffusion method and broth culture tests using varying concentrations of drugs loaded to nanocomposites were carried out to investigate the antibacterial effects. The influence of UV irradiation on the stability of the obtained nanocomposites and their antibacterial properties after irradiation were also investigated, showing enhanced stability especially for the TC loaded materials. These findings suggest that the obtained nanocomposites are promising materials for the development of potentially useful antimicrobial patches.
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| 3. |
- Ahniyaz, Anwar, et al.
(author)
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Preparation of iron oxide nanocrystals by surfactant-free or oleic acid-assisted thermal decomposition of a Fe(III) alkoxide
- 2008
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In: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 320:6, s. 781-787
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Journal article (peer-reviewed)abstract
- A new non-hydrolytic, alkoxide-based route was developed to synthesize iron oxide nanocrystals. Surfactant-free thermal decomposition of the iron 2-methoxy-ethoxide precursors results in the formation of uniform iron oxide nanocrystals with an average size of 5.6 nm. Transmission electron microscope study shows that the nanocrystals are protected against aggregation by a repulsive surface layer, probably originating from the alkoxy-alkoxide ligands. Addition of oleic acid resulted in monodisperse nanocrystals with an average size of 4 nm. Mössbauer analysis confirmed that the nanocrystals mainly consisted of maghemite. Analysis of the magnetic hysteresis loop measurements and the zero field and field cooled measurements displayed an excellent fit to established theories for single-domain superparamagnetic nanocrystals and the size of the magnetic domains correlated well to the crystallite size obtained from transmission electron microscope.
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| 4. |
- Bedin, Michele, PhD, 1984-
(author)
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Iron, Manganese and Iridium Complexes From Models of RNR and Catalase to Water Oxidation
- 2020
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Doctoral thesis (other academic/artistic)abstract
- The focus of this thesis has been synthesise and study metal complexes that mimic the structure and function of the active site in two particular metalloenzymes, ribonucleotide reductase (RNR) and manganese catalase (MnCAT). These two metalloenzymes both have two transition metals ions in the cofactor: two manganese ions in MnCAT and either two iron, iron-manganese or two manganese ions in RNR.Three different ligands were synthetized to make model complexes for these cofactors. The first ligand, BPMP, can bind two metal ions and provides two symmetric pockets with two pyridine groups and one amine each, plus a phenolate group that can bridge the two metals. The second ligand DPCPMP had one carboxylate group instead of a pyridine group in one pocket, creating an asymmetric ligand, and the third ligand BPCPMP, had two carboxylate groups, one in each pocket. From the first and the second ligands it was possible to obtain six complexes: low-valent homometallic Mn/Mn and Fe/Fe complexes and a heterometallic complex for each ligand. For the third ligand, only the Fe/Fe complex was synthetized.All seven complexes were characterized by a number of spectroscopic methods. The presence of carboxylate groups in the ligand shifted the redox potential for the metal complexes towards more negative values, particularly in the case of the homometallic Fe/Fe complexes. Surprisingly, for the asymmetric ligand the placement of the metal ions in the two pockets was not dictated by the asymmetry. Additionally, the relative stability of the homometallic complexes versus the heterometallic complexes and the possibility to transform a homometallic complex into a heterometallic complex were investigated. By titrating one metal into a solution containing the other homometallic dimer it was possible to observe that Fe2+ added to a solution of a Mn/Mn complex led to the replacement of one Mn ion in the complex with a Fe ion.The manganese complex of DPCPMP was investigated as a functional model for MnCAT, catalysing the disproportionation of H2O2 to oxygen and water. In the presence of H2O2 this complex also forms a high-valent species with a di-µ-oxo bridge similar to the MnCAT and RNR.Finally, the methodology used for the study of these complexes was also applied to a set of Ir complexes that act as water oxidation catalysts, and we could show that the presence of a pendant group stabilizes the metal at higher oxidation states leading to higher activity for the catalyst.
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| 5. |
- Gaio, Servane, et al.
(author)
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Nanoceria-nanocellulose hybrid materials for delayed release of antibiotic and anti-inflammatory medicines
- 2022
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In: Materials Advances. - : Royal Society of Chemistry. - 2633-5409. ; 3:19, s. 7228-7234
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Journal article (peer-reviewed)abstract
- A novel nanoceria-nanocellulose hybrid material has been developed and evaluated as a potential drug delivery system. Crystalline nanoceria was synthesized in situ in the nanocellulose to obtain a homogenous distribution without extensive particle aggregation. The hybrid materials were loaded with two antibiotic drugs, triclosan and ampicillin, and one anti-inflammatory drug, diclofenac. The bacteriostatic effect on the gram-negative bacteria Escherichia coli was evaluated for the hybrid materials containing triclosan and ampicillin. The nanoceria-nanocellulose hybrid displayed a better retention of ampicillin than triclosan in the disc diffusion test, which is likely due to the presence of the carboxylic acid group in ampicillin that has better affinity for ceria compared to the phenolic group in triclosan. However, drug release studies in solution revealed rapid release of ampicillin and diclofenac, indicative of outer-sphere complexes between ceria and the drugs.
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| 6. |
- Ghosh, Sourav, et al.
(author)
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Investigating the stable operating voltage for the MnFe2O4 Li-ion battery anode
- 2021
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In: Sustainable Energy & Fuels. - : Royal Society of Chemistry. - 2398-4902. ; 5:6, s. 1904-1913
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Journal article (peer-reviewed)abstract
- Template-free synthesis of MnFe2O4 nanopowder is carried out by co-precipitation in a basic medium, evaluating the effects of cation ratio and reaction temperature on the phase composition crystallinity of the resulting powder. Single-phase samples of the target spinel are obtained at the stoichiometric Mn : Fe = 1 : 2 ratio under reflux conditions (100 degrees C), as confirmed by X-ray diffraction (XRD) and Fourier Transformed Infrared (FTIR) spectroscopy. Transmission electron microscopy (TEM) images confirmed that nanostructured MnFe2O4 particles are obtained, which is further supported by Debye-Scherrer calculations from XRD data and by AFM measurements. The produced oxide demonstrated considerable thermal stability according to TGA data. Magnetic characteristics are strongly dependent on the content of magnetic phase and phase composition, achieving a maximum of 54 emu g(-1) for single-phase stoichiometric MnFe2O4. Further, the electrochemical stability of this material as the anode is investigated in Li-ion batteries (LIBs). When the MnFe2O4 electrode is operated in the potential window of 0.01-3.0 V, the reversible capacity is enhanced by almost 45% (802 mA h g(-1)) after the 100(th) cycle with reference to the 2(nd) cycle reversible capacity (548 mA h g(-1)). Methodically dQ/dV plots are analyzed and compared to understand processes behind the evolution of extra capacity beyond its theoretical limit. Further, the upper cut-off potential is tuned to identify a stable operating potential window for the MnFe2O4 anode in LIBs.
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| 7. |
- Greco, Gabriele, et al.
(author)
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Tyrosine residues mediate supercontraction in biomimetic spider silk
- 2021
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In: Communications materials. - : Springer Science and Business Media LLC. - 2662-4443. ; 2:1
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Journal article (peer-reviewed)abstract
- Exposing spider silk to wet conditions can cause supercontraction. Here, tyrosine amino acid residues within the amorphous regions are found to contribute to supercontraction, which can be controlled by protein engineering. Water and humidity severely affect the material properties of spider major ampullate silk, causing the fiber to become plasticized, contract, swell and undergo torsion. Several amino acid residue types have been proposed to be involved in this process, but the complex composition of the native fiber complicates detailed investigations. Here, we observe supercontraction in biomimetically produced artificial spider silk fibers composed of defined proteins. We found experimental evidence that proline is not the sole residue responsible for supercontraction and that tyrosine residues in the amorphous regions of the silk fiber play an important role. Furthermore, we show that the response of artificial silk fibers to humidity can be tuned, which is important for the development of materials for applications in wet environments, eg producing water resistant fibers with maximal strain at break and toughness modulus.
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| 8. |
- Nikonova, Olesya A, et al.
(author)
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Electrochemical Synthesis, Structural Characterization, and decomposition of Rhenium Oxoethoxide, Re4O4(OEt)12. Ligand Influence on the Structure and Bonding in the High-Valent Tetranuclear Planar Rhenium Alkoxide Clusters
- 2008
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In: Inorganic Chemistry. ; 47, s. 1295-1300
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Journal article (peer-reviewed)abstract
- Anodic oxidation of rhenium in ethanol in the presence of LiCl as a conductive additive results with high yield information of a new oxoethoxide cluster, Re4O4(OEt)12. The structure of the planar centrosymmetric metal–oxygencore of this molecule is composed of four edge-sharing Re(V)O6 octahedra. Eight electrons are available for theformation of metal-metal bonds indicated by five relatively short Re-Re distances within the Re4-rhombus, a“planar butterfly” type cluster. The theoretical calculations are indicating relatively low contribution of metal-metalbonding in the stability of the core. The stability of the +V-oxidation state, unusual for rhenium alkoxides can beat least partially attributed to the size effects in the packing of ligands. The X-ray powder study indicates thattreatment of Re4O4(OEt)12 in ambient atmosphere rapidly transforms it into a mixed-valence derivativeRe4O6(OEt)10swith a structure related to the earlier investigated cluster Re4O6(OiPr)10. Thermal decomposition ofthe latter rhenium oxoethoxide results in reduction to rhenium metal at as low temperatures as 380 °C, producingaggregates of metal nanoparticles with the average size of 3 nm.
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