Fibronectin Functionalized Electrospun Fibers by Using Benign Solvents: Best Way to Achieve Effective Functionalization

The aim of this study is to demonstrate the feasibility of different functionalization methods for electrospun fibers developed using benign solvents. In particular three different approaches were investigated to achieve the functionalization of poly(epsilon caprolactone) (PCL) electrospun fibers with fibronectin. Protein surface entrapment, chemical functionalization and coaxial electrospinning were performed and compared. Moreover, bilayered scaffolds, with a top patterned and functionalized layer with fibronectin and a randomly oriented not functionalized layer were fabricated, demonstrating the versatility of the use of benign solvents for electrospinning also for the fabrication of complex graded structures. Besides the characterization of the morphology of the obtained scaffolds, ATR-FTIR and ToF-SIMS were used for the surface characterization of the functionalized fibers. Cell adhesion and proliferation were also investigated by using ST-2 cells. Positive results were obtained from all functionalized scaffolds and the most promising results were obtained with bilayered scaffolds, in terms of cells infiltration inside the fibrous structure

Single-Atom-Based Catalysts for Photocatalytic Water Splitting on TiO2 Nanostructures

H2 generation from photocatalytic water splitting is one of the most promising approaches to producing cost-effective and sustainable fuel. Nanostructured TiO2 is a highly stable and efficient semiconductor photocatalyst for this purpose. The main drawback of TiO2 as a photocatalyst is the sluggish charge transfer on the surface of TiO2 that can be tackled to a great extent by the use of platinum group materials (PGM) as co-catalysts. However, the scarcity and high cost of the PGMs is one of the issues that prevent the widespread use of TiO2/PGM systems for photocatalytic H2 generation. Single-atom catalysts which are currently the frontline in the catalysis field can be a favorable path to overcome the scarcity and further advance the use of noble metals. More importantly, single-atom (SA) catalysts simultaneously have the advantage of homogenous and heterogeneous catalysts. This mini-review specifically focuses on the single atom decoration of TiO2 nanostructures for photocatalytic water splitting. The latest progress in fabrication, characterization, and application of single-atoms in photocatalytic H2 generation on TiO2 is reviewed

Protein interactions with corroding metal surfaces: comparison of Mg and Fe

The influence of bovine serum albumin (BSA) on the electrochemical behaviour of pure Mg and Fe was studied in simulated body fluid (SBF), in view of the possible application of these materials as biodegradable metals. Results indicate a different trend for the BSA-effect on corrosion for the two metals: for Mg, a strong corrosion-inhibiting effect is observed in the presence of BSA in solution, especially for short-term exposure, whereas for Fe only a slight acceleration of corrosion is caused by the addition of BSA to the solution. For both metals, the protein-effect on the electrochemical behaviour shows a complex time-dependence. Surface analysis indicates that stronger BSA adsorption takes place on Mg than on Fe. Moreover, adsorption experiments with BSA and a second protein (lysozyme) were conducted. The results are discussed in view of electrostatic interactions between differently charged metal oxide/hydroxide surfaces and proteins

EVALITA Evaluation of NLP and Speech Tools for Italian - December 17th, 2020

Welcome to EVALITA 2020! EVALITA is the evaluation campaign of Natural Language Processing and Speech Tools for Italian. EVALITA is an initiative of the Italian Association for Computational Linguistics (AILC, http://www.ai-lc.it) and it is endorsed by the Italian Association for Artificial Intelligence (AIxIA, http://www.aixia.it) and the Italian Association for Speech Sciences (AISV, http://www.aisv.it)

Genomic investigations of unexplained acute hepatitis in children

Since its first identification in Scotland, over 1,000 cases of unexplained paediatric hepatitis in children have been reported worldwide, including 278 cases in the UK1. Here we report an investigation of 38 cases, 66 age-matched immunocompetent controls and 21 immunocompromised comparator participants, using a combination of genomic, transcriptomic, proteomic and immunohistochemical methods. We detected high levels of adeno-associated virus 2 (AAV2) DNA in the liver, blood, plasma or stool from 27 of 28 cases. We found low levels of adenovirus (HAdV) and human herpesvirus 6B (HHV-6B) in 23 of 31 and 16 of 23, respectively, of the cases tested. By contrast, AAV2 was infrequently detected and at low titre in the blood or the liver from control children with HAdV, even when profoundly immunosuppressed. AAV2, HAdV and HHV-6 phylogeny excluded the emergence of novel strains in cases. Histological analyses of explanted livers showed enrichment for T cells and B lineage cells. Proteomic comparison of liver tissue from cases and healthy controls identified increased expression of HLA class 2, immunoglobulin variable regions and complement proteins. HAdV and AAV2 proteins were not detected in the livers. Instead, we identified AAV2 DNA complexes reflecting both HAdV-mediated and HHV-6B-mediated replication. We hypothesize that high levels of abnormal AAV2 replication products aided by HAdV and, in severe cases, HHV-6B may have triggered immune-mediated hepatic disease in genetically and immunologically predisposed children

Organische Modifizierung von TiO2 und anderen Metalloxiden mit SAMs und Proteinen – Charakterisierung mittels Oberflächenanalytik

The controlled modification of surfaces by organic molecules has a high potential to improve material properties in advanced applications (e.g., biomedical devices, sensor arrays, dye-sensitized solar cells or micro- and nanoreactors) as the majority of the interaction of the material and the environment is related to the surface properties. Self-assembled monolayers (SAMs) provide a particularly flexible means to engineer the surface chemistry, as they are available with a large chemical variety and interact with the substrate in specific ways. This thesis comprises a detailed surface analytical investigation about the surface modification of native and anodic metal oxides (with a focus on TiO2, ZrO2 and MgO) by self-assembly of organic molecules and proteins. The adsorbed coatings were investigated mainly by ToF-SIMS and XPS. The first section deals with the self-assembly of siloxanes to metal oxide surfaces. The bifunctional siloxane 3-aminopropyltriethoxysilane (APTES) and a porphyrin comprising APTES as functional group (Zn-TESP) are adsorbed to the metal oxide substrates under variation of the reaction temperature. The adsorption strength, i.e., physisorption or chemisorption, coverage and kinetics are evaluated with respect to the substrate and reaction temperature. Even though a lower amount of molecules adsorb to the magnesium oxide surfaces in comparison to TiO2, the results show that MgO seems to be more prone to covalent silanization than the latter. Understanding the adsorption processes of SAMs to metal oxides allows the modification of these surfaces in a controlled fashion. Inherent differences in the adsorption behavior to different substrates may be used to selectively modify them with monolayers of different functionality. Whereas such procedures are established for noble metal – metal oxide composites, no route for the selective monolayer adsorption to mixed metal oxide composite materials was previously reported. The second section of this thesis is dedicated to the selective modification of anodic metal oxide substrates, particularly TiO2 and ZrO2, with SAMs. Composites of these metal oxides are used, e.g., in medical alloys (Ti-13Nb-13Zr). Several routes to produce selectively modified mixed titanium and zirconium metal oxide substrates are evaluated. The adsorption and desorption of various functional groups (amine, carboxylic acid, phosphonic acid and siloxane) to TiO2 and ZrO2 is investigated in order to determine preferential interactions with one of the substrates. The selective modification by using inherent material contrasts like conductivity and photocatalytic activity is also explored. A protocol for selective functionalization of mixed metal oxide substrates of TiO2 and ZrO2 with SAMs of two different organic molecules, octadecylphosphonic acid (OPA) and Zn-TESP is developed. The phosphonic acid initially adsorbs to both oxide substrates and is photodecomposed on TiO2, resulting in phosphate terminated TiO2. The second functionalization with the siloxane Zn-TESP requires an intermediate treatment that restores the reactivity of the photo-cleaned area towards condensation reactions. The parameters were optimized for improved selectivity of the treatment. This thesis consequently is the first to report on the successful selective SAM modification of composite TiO2 (Zn-TESP) and ZrO2 (OPA) anodic metal oxide surfaces. The self-assembly of organic molecules is particularly important for metal oxide surfaces in contact with biological tissue. The third section considers the modification of metal oxide substrates via self-assembly of functional protein coatings. The controlled adsorption of the latter (e.g., via siloxane linker SAMs) can modify the interaction of a physiological system and the metal implant material. Effects of protein coatings are explored with regard to the corrosion resistance of self-degrading Mg substrates and the cellular differentiation of mesenchymal stem cells on protein coated TiO2 nanotubes. An in-depth mechanistic understanding of the interaction between the oxide surface and proteins is essential when protein coatings are used in surgical implants, sensors and in food applications. Particularly the retention of the protein functionality is important, which is directly related to the tertiary structure of the molecule. The present thesis explores the stability of the protein coating and the tertiary structure retention by the surface analytical methods ToF-SIMS and XPS. The disulfide bond signal in ToF-SIMS is found to be directly related to the activity of adsorbed protein coatings. Furthermore, the influence of the choice of linker molecule on protein adsorption, orientation and functionality is discussed. Carbonyldiimidazole (CDI) and 11-hydroxyundecylphosphonic acid (HUPA) show superior protein adsorption properties than APTES based coatings, emphasizing that the choice of linker is vitally important to the performance of a protein coating.Die kontrollierte Modifizierung von Oberflächen mit organischen Molekülen besitzt ein hohes Potential die Eigenschaften des Materials für fortschrittliche Anwendungen (z.B. in biomedizinischen Instrumenten, Sensoren, Farbstoff-Solarzellen sowie in Mikro- und Nanoreaktoren) zu verbessern, da der Hauptteil der Wechselwirkungen des Materials mit der Umwelt von den Eigenschaften der Materialoberfläche abhängt. Eine besondes vielfältige Methode zur Gestaltung der Oberflächenchemie ist die Verwendung von selbstorganisierende Monolagen (SAMs). Diese sind mit einem breiten Spektrum an Funktionalitäten erhältlich und gehen spezifische Wechselwirkungen mit dem Substrat ein. Diese Dissertation beinhaltet eine detaillierte oberflächenanalytische Untersuchung der Oberflächenmodifikation nativer und anodischer Metalloxide (mit dem Schwepunkt auf TiO2, ZrO2 und MgO) durch selbstorganisierte Anordung von organischen Molekülen und Proteinen. Die erzielten Beschichtungen werden hauptsächlich mit Flugzeit-Sekundärionen-Massenspektrometrie (ToF-SIMS) und Röntgenphotoelektronenspektroskopie (XPS) analysiert. Der erste Abschnitt bearbeitet die Selbstorgnisation von Siloxanen auf Metalloxidoberflächen. Das bifunktionale Siloxan 3-Aminopropyltriethoxysilan (APTES) und ein Porphyrin, welches APTES als funktionelle Gruppe beinhaltet (Zn-TESP), werden bei unterschiedlichen Temperaturen auf die Metalloxidoberflächen adsorbiert. Die Stärke der gebildeten Bindung, d.h. Physi- oder Chemisorption, der Bedeckungsgrad und die Kinetik der Adsorption wird in Abhängigkeit der Adsorptionstemperatur und des Substrats evaluiert. Obwohl im Vergleich zu Titandioxid eine geringere Anzahl an Molekülen auf Magnesiumoxid adsorbiert, zeigen die Ergebnisse, dass die Silanisierung des letzteren einen höheren Anteil kovalent adsorbierter Moleküle ergibt. Das Verständnis der Adsorptionsprozesse von SAMs auf Metalloxiden erlaubt die kontrollierte Modifizierung dieser Oberflächen. Ein inherent unterschiedliches Adsorptionsverhalten zu verschiedenen Oxiden kann dazu benutzt werden, diese mit Monolagen unterschiedlicher Funktionalitäten zu modifizieren. Verfahren zur selektiven Modifikation sind für Edelmetall-Metalloxid Kompositstrukturen bekannt, jedoch wurde bisher nicht über die selektive Adsorption organischer Monolagen auf Strukturen aus mehreren Metalloxiden berichtet. Der zweite Abschnitt dieser Dissertation ist der selektiven Modifikation anodischer Metalloxide, insbesondere TiO2 und ZrO2, mit SAMs gewidmet. Die Kombination dieser Materialien wird z.B. in medizinischen Legierungen verwendet (Ti-13Nb-13Zr). Mehrere Wege zur Produktion selektiv beschichteter, gemischter Titan- und Zirkondioxidoberflächen werden evaluiert. Die Adsorption unterschiedlicher funktioneller Gruppen (Amine, Carboxylsäuren, phosphonische Säuren und Siloxane) auf TiO2 und ZrO2 wird verglichen, um bevorzugte Wechselwirkungen einzelner funktioneller Gruppe mit einem Substrat zu ermitteln. Ausserdem wird die selektive Modifikation durch der Natur der Oxide entspringende Kontraste, z.B. elektrische Leitfähigkeit und photokatalytische Aktivität, erforscht. In dieser Dissertation wird eine Anleitung zur selektiven Funktionalisierung gemischter Metalloxidoberflächen aus TiO2 und ZrO2 mit SAMs zweier organischer Moleküle, Octadecylphosphonische Säure (OPA) und Zn-TESP, präsentiert. Zunächst adsorbiert die phosphonische Säure gleichermaßen auf beide Oxidoberflächen. Daraufhin wird das Molekül auf TiO2 photokatalytisch zersetzt, was in einer Terminierung des TiO2 mit Phosphatgruppen resultiert. Um das zweite Molekül, das Siloxan Zn-TESP, auf TiO2 adsorbieren zu können, ist ein weiterer Behandlungsschritt nötig, welcher die Reaktivität der photokatalytisch gereinigten Bereiche zu Kondensationsrektionen wiederherstellt. Die Parameter werden im Hinblick auf optimierte Selektivität optimisiert. Diese Dissertation ist somit die erste Abhandlung über die erfolgreiche, selektive Modifikation von Kompositstrukturen aus den anodischen Oxiden TiO2 (Zn-TESP) und ZrO2 (OPA). Die Selbstorganisation organischer Moleküle ist insbesondere für Metalloxidoberflächen in Kontakt mit biologischem Gewebe von Bedeutung. Im dritten Abschnitt wird daher die Modifikation von Implantatmaterialien durch selbstorganisierte Adsorption funktioneller Proteinbeschichtungen bearbeitet. Die kontrollierte Beschichtung mit letzteren (z.B. durch SAMs aus Kopplungsmolekülen mit Siloxanfunktionalitäten) kann die Wechselwirkung des Implantatmaterials mit der physiologischen Umgebung maßgeblich beeinflussen. Die Auswirkungen von Proteinbeschichtungen werden einerseits anhand der Korrosionsbeständigkeit von selbst-zersetzenden Magnesiumimplantaten und andererseits anhand der Differentation mesenchymaler Stammzellen auf proteinbeschichteten TiO2-Nanoröhren diskutiert. Ein grundlegendes Verständnis der Wechselwirkung der Oxidoberfläche mit Proteinen is essentiell für die Verwendung von proteinbeschichteten Oberflächen in Implantatmaterialien, Sensoren und der Lebensmittelindustrie. Insbesondere der Erhalt der Proteinfunktionalität, welche direkt mit der Tertiärstruktur des Proteins zusammenhängt, ist von Bedeutung. Diese Dissertation untersucht die Stabilität und den Erhalt der Tertiärstruktur von immobilisierten Proteinen mittels der oberflächenanalytischen Methoden ToF-SIMS und XPS. Als Indikator für die enzymatische Aktivität der Proteinbeschichtung wird das Disulfid-Fragment ermittelt, welches in den Massenspektren detektiert werden kann. Des weiteren wird der Einfluss der Wahl des Kopplungsmoleküls auf die Proteinadsorption, -orientierung und -aktivität diskutiert. Im Vergleich zu APTES-basierten Kopplungssystemen resultieren SAMs aus Carbonyldiimidazol (CDI) und 11-Hydroxyundecylphosphonische Säure (HUPA) in herausragenden Proteinbeschichtungen, was betont dass die Wahl des Kopplungsmoleküls äußerst wichtig für die Effizienz immobilisierter Proteine ist

Zirconia Nanotube Coatings - UV-Resistant Superhydrophobic Surfaces

Surface modifications influence material interactions such as wettability, imparting hydrophobicity or hydrophilicity. Mainstream research focused on enhancing product shelf-life, directs attention towards superhydrophobic surfaces (SHS). SHS offer several benefits for outdoor applications such as self-cleaning, anti-soiling, anti-mist etc. In this manuscript, we explore the possibility of combining structural and chemical modifications to metal substrates in order to create superhydrophobic metal oxide surfaces. ZrO2-nanotubes are evaluated with regard to their application as transparent UV-stable superhydrophobic coatings. Nanostructured oxide surfaces are created via single-step electrochemical anodization. The absence of HF acid-based pre-etching steps offer a safe and alternatively a green synthesis route. Anodized oxides are modified using octadecylphosphonic acid self-assembled monolayers, demonstrate superhydrophobicity and are evaluated for their mechanical stability under a jet of water, chemical stability under indirect sunlight irradiation in air/water and direct UV exposure. Zirconia nanotubular films were evaluated for optical transparency using light microscopy and surface wettability of the different zirconia-composites was compared to the model system-titania. Structural and compositional differences of the SAM layer upon time dependent decay were analyzed with X-ray photoelectron spectroscopy. <br /

Strategy facilitating the transfer of zirconium-oxide nanotubes onto zirconia-based ceramic implants

We report on the synthesis route for metal-oxide nanotubes via electro-chemical anodization of zirconium foil resulting in the formation of zirconia nanotubular (ZrNT) films, subsequently transferred onto pre-formed zirconia (ZrO2) implant material. The approach was based on a direct transfer of ZrNT films onto the ceramic implant via an acetone bath. The ZrNT film was detached from the metal-foil using regular adhesive-tape prior to transfer. This simple technique allows to impart a robust micro-nanoscale structure to bulk-ceramics that can potentially offer enhanced surface-reaction sites and functionality in the field of ceramic-biomaterial applications

Protein interactions with corroding metal surfaces: comparison of Mg and Fe

The influence of bovine serum albumin (BSA) on the electrochemical behaviour of pure Mg and Fe was studied in simulated body fluid (SBF), in view of the possible application of these materials as biodegradable metals. Results indicate a different trend for the BSA-effect on corrosion for the two metals: for Mg, a strong corrosion-inhibiting effect is observed in the presence of BSA in solution, especially for short-term exposure, whereas for Fe only a slight acceleration of corrosion is caused by the addition of BSA to the solution. For both metals, the protein-effect on the electrochemical behaviour shows a complex time-dependence. Surface analysis indicates that stronger BSA adsorption takes place on Mg than on Fe. Moreover, adsorption experiments with BSA and a second protein (lysozyme) were conducted. The results are discussed in view of electrostatic interactions between differently charged metal oxide/hydroxide surfaces and proteins

Electropolymerization and Characterization of Poly-N-methylpyrrole Coatings on AZ91D Magnesium Alloy

We report the growth of a poly-N-methylpyrrole coating on a Mg alloy AZ91D in aqueous sodium salicylate solution using cyclic voltammetry (CV). The electropolymerization of poly-N-methylpyrrole coating was carried out in a one step process without any further pretreatment of the AZ91D surface. The polymeric coatings were analyzed using x-ray photoelectron spectroscopy (XPS), time-of-flight secondary-ion-mass-spectrometry (ToF-SIMS) and scanning electron microscopy (SEM). The adhesion of poly-N-methylpyrrole coatings was tested applying ASTM D33359-09 standard, which showed good adhesion properties. Electrochemical impedance spectroscopy (EIS) in aqueous 0.1 M Na2SO4 solution indicates improved corrosion resistance of the coated samples compared to the bare AZ91D surface; the efficiency of protection was found to depend on the concentration of sodium salicylate used during electropolymerization