Hydration of triethylenetetramine based inhibitor film accelerates the chloride-induced corrosion in concrete: a molecular dynamics study

Abstract. Organic corrosion inhibitors can be used to prevent chloride-induced corrosion in reinforced concrete structures. In this theoretical study Molecular Mechanics (MM) and Molecular Dynamics (MD) simulations are performed in order to better understand the interaction mechanisms with the passive film present on steel [1], in particular considering γ-FeOOH surface as solid surface which can be subject to chloride-induced corrosion process and the dimethylethanolamine (TETA) film [2]. The MD simulations are a very useful tool because they describe at atomistic level both the solid surface and organic inhibitors molecules in presence of chloride ions [2] and water molecules [3]. Hydration of organic TETA inhibitor film in presence of chloride ions always accelerate the corrosion process, as experimentally well known. In this theoretical work water molecules in fact induce chloride ions to adsorb on γ-FeOOH surface more quickly and in greater numbers respect with to the same simulations study without water molecules. This kind of organic film cannot exhibit a good behavior to prevent the chloride-induced corrosion process not displaying the so important repulsion to chloride ions. The hydration accelerates the corrosion process. This theoretical work permit to compare these results with another organic inhibitors films studied in previous work [1] in order to prevent the corrosion. References [1] M.V. Diamanti, E. A. Pérez-Rosales, G. Raffaini, F. Ganazzoli, A. Brenna, M. Pedeferri, M. Ormellese, Corrosion Science, 100, 231-241 (2015). [2] G. Raffaini, M. Catauro, F. Ganazzoli, F. Bolzoni, M. Ormellese, Macromolecular Symposia, 395, Article Number: 2000231, pp. 1-3 (2021). [3] G. Raffaini, F. Ganazzoli, J. of Biomed. Mat. Res. PART A, 92A, 1382-1391 (2006)

Surface Interactions between Ketoprofen and Silica‐Based Biomaterials as Drug Delivery System Synthesized Via Sol–Gel: A Molecular Dynamics Study

Biomaterial‐based drug delivery systems for a controlled drug release are drawing in‐ creasing attention thanks to their possible pharmaceutical and biomedical applications. It is im‐ portant to control the local administration of drugs, especially when the drug exhibits problems diffusing across biological barriers. Thus, in an appropriate concentration, it would be released in situ, reducing side effects due to interactions with the biological environment after implantation. A theoretical study based on Molecular Mechanics and Molecular Dynamics methods is performed to investigate possible surface interactions between the amorphous SiO2 surface and the ketoprofen molecules, an anti‐inflammatory drug, considering the role of drug concentration. These theoretical results are compared with experimental data obtained by analyzing, through Fourier transform infrared spectroscopy (FT‐IR), the interaction between the SiO2 amorphous surface and two per‐ centages of the ketoprofen drug entrapped in a silica matrix obtained via the sol–gel method and dried materials. The loaded drug in these amorphous bioactive material forms hydrogen bonds with the silica surface, as found in this theoretical study. The surface interactions are essential to have a new generation of biomaterials not only important for biocompatibility, with specific structural and functional properties, but also able to incorporate anti‐inflammatory agents for re‐ lease into the human bod

Aggregation behaviour of amphiphilic cyclodextrins: The nucleation stage by atomistic molecular dynamics simulations

Amphiphilically modified cyclodextrins may form various supramolecular aggregates. Here we report a theoretical study of the aggregation of a few amphiphilic cyclodextrins carrying hydrophobic thioalkyl groups and hydrophilic ethylene glycol moieties at opposite rims, focusing on the initial nucleation stage in an apolar solvent and in water. The study is based on atomistic molecular dynamics methods with a “bottom up” approach that can provide important information about the initial aggregates of few molecules. The focus is on the interaction pattern of amphiphilic cyclodextrin (aCD), which may interact by mutual inclusion of the substituent groups in the hydrophobic cavity of neighbouring molecules or by dispersion interactions at their lateral surface. We suggest that these aggregates can also form the nucleation stage of larger systems as well as the building blocks of micelles, vesicle, membranes, or generally nanoparticles thus opening new perspectives in the design of aggregates correlating their structures with the pharmaceutical properties

Molecular Dynamics Study of Sorafenib Anti-Cancer Drug: Inclusion Complex in Amphiphilic Cyclodextrin

Cyclodextrins (CDs) are cyclic oligosaccharides able to solubilize hydrophobic drugs in water enhancing their bioavailability. Sorafenib (SOR) is a lipophilic oral multikinase inhibitor that impedes proliferation, angiogenesis, and invasion of cancer cells with low water-solubility. Recently, amphiphilic cyclodextrins (aCDs) have been investigated as possible nanocarrier for systemic administration of SOR increasing its bio-availability. A theoretical study about inclusion complexes of SOR drug and a model of aCD system using molecular mechanics (MM) and molecular dynamics (MD) methods is here reported. At first, the single molecule aCD (SC6OH, heptakis(2-O-oligo(ethylene oxide)-6-hexylthio)-β-CD bearing 14 units of ethylene-oxide at the CD secondary rim) and SOR drug are studied. Then, the interaction between aCD and SOR is investigated. The theoretical results display different types of interaction geometries. The most stable geometry of the host-guest complex showed the lowest potential and favorable interaction energy and the fluorine atoms of SOR drug molecule are directed toward the hydrophobic primary rim of the aCD, while the part of the SOR rich in oxygen atoms is directed toward the hydrophilic secondary rim. This theoretical result is in a good agreement with NMR data in literature about same aCD as host of Sorafenib anti-cancer drug

Molecular dynamics study of Sorafenib anti-cancer drug

Sorafenib (SOR) is an oral multikinase inhibitor which impedes proliferation, angiogenesis and invasion of cancer cells with low water-solubility. Amphiphilic cyclodextrins (aCD) have been investigated as a possible nanocarrier for systemic administration of SOR increasing its bio-availability [1]. A theoretical study about inclusion complexes of SOR drug and a model of aCD system using a simulation protocol based on Molecular Mechanics (MM) and Molecular Dynamics (MD) methods [2] is here reported. In this work we have studied at first the single model aCD (SC6OH, heptakis(2-O-oligo(ethylene oxide)-6-hexylthio)-β-CD bearing 14 units of ethylene-oxide at the CD secondary rim ) and the single molecule of SOR, then the formation of the complex in the dielectric environment [3]. The results data of final most stable geometry of the inclusion complex anticancer-cyclodextrin which showed the lowest potential and interaction energy were reported. The most stable host-guest geometry shows that the fluorine atoms of SOR drug are directed toward the hydrophobic primary rim of the aCD, while the part of the SOR rich in oxygen atoms is directed towards the hydrophilic secondary rim. References [1] M. L. Bondì, A. Scala, G. Sortino, E. Amore, C. Botto, A. Azzolina, D. Balasus, M. Cervello and A. Mazzaglia, Biomacromolecules, 2015, 16, 3784-3791. [2] G. Raffaini, F. Ganazzoli, L. Malpezzi, C. Fuganti, G. Fronza, W. Panzeri and A. Mele J. Phys. Chem B., 2009,113, 9110-9122

Self-­‐ordering in solution of a novel polyamidoaminoacid with a chiral arginine side chain

Polyamidoaminoacids (PAAC) are a new class of bioinspired polymers obtained by polyaddition of selected aminoacids with N,N'-methylenebisacrylamide. Here we report some results obtained for the first such polymer, ARGO7, obtained with arginine stereoisomers. The CD spectra of the ARGO7 isomers showed an important and unexpected indication of a self-ordered pH-dependent secondary structure that was however nearly unaffected by temperature, ionic strength and denaturating agents. Theoretical modeling studies of L-ARGO7 carried out with classical Molecular Dynamical simulations showed that it assumed a folded structure with a transoid arrangement of the main chain reminiscent of the protein hairpin motif due to the intramolecular interactions. Torsion angles along the backbone showed a similar distribution at pH 6 and 14 consistent with the similarity of the CD spectra from pH 6 onwards

Chemical functionalization of graphene surface as filler for rubber compounds

Over the last few years, the surface modification of fillers for high-level technological applications such as polymer composites for tyre industry, conductive inks and coatings has seen a considerable increase in interest since it can increase mechanical, electrical, and thermal properties of the final material. Nano-sized carbon allotropes such as graphene and carbon nanotubes are a suitable class of compounds for these purposes: high thermal and electrical conductivity along with considerable mechanical reinforcement are the main improvements that these fillers bring to the composite and their elevated surface area allows to reduce the filler volume ratio compared to more common alternatives. An efficient and reliable method to modify the surface of these nano-fillers is the so-called pyrrole methodology, a mild procedure that involves bio-sourced reagents to introduce functional groups on the graphitic planes and that has been recently employed in the fabrication of elastomeric composites with improved mechanical properties. In order to understand the mechanism beneath the interaction between the pyrrole and the substrate and thus the behavior of the functionalized filler, a more in-depth analysis is requested. A theoretical work based on molecular dynamics simulations and a DFT study were performed in order to investigate the interaction energy, the geometry of interaction and the mobility of N-substituted pyrrole molecules adsorbed on the graphene planes. This theoretical study at atomistic level can help design a new class of high-performance fillers by better understanding the interaction mechanism given the important role of supramolecular interactions

Figurative Landscapes dimension. The Survey of Vegetal Architectures in Parma

La tesi si articola in quattro parti principali, a queste si aggiungono l’introduzione, le considerazioni finali sulla ricerca compiuta in merito di botanica e di gestione, il repertorio delle fonti bibliografiche e l’abaco delle essenze. L’obiettivo è di indagare il rilievo e la rappresentazione nel caso applicativo delle aree verdi della città di Parma. Possiamo dire che oggi il linguaggio figurativo ha acquisito grande importanza ed è parte integrante di molte riflessioni analitiche e progettuali, la dimensione rappresentativa assume un ruolo non più di tramite ma di mezzo attraverso il quale si può giungere alla conoscenza del paesaggio. Questo può essere considerato il punto di partenza e il filo conduttore di questa ricerca. Nell’introduzione si sottolinea l’importanza della salvaguardia del paesaggio del verde urbano, e del rapporto che c’è tra questo e la sua rappresentazione, copia o originale che sia. La prima parte affronta uno studio di testi teorici selezionati, appartenenti al XX e al XXI secolo, di architetti e paesaggisti che hanno descritto e rappresentato il paesaggio. Con la lettura, la descrizione e la comparazione dei contenuti teorici consultati si vogliono impostare le linee guida per le attività successive. La seconda parte si occupa della nascita del verde nella città storica attraverso lo studio di testi scelti per il loro apporto significativo sul tema. Si vuole passare da un’analisi storica per arrivare a capire funzioni e tipologie che il verde assume nella città di oggi. Nella terza parte ci soffermeremo sulla storia della rappresentazione del paesaggio attraverso un’analisi iconografica e una valutazione critica dei problemi che stanno alla base della sua rappresentazione. Cercare di ricostruire le molteplici rappresentazioni di elementi vegetali esistenti è un campo molto ampio, e ci ha portato a quelle che sono le rappresentazioni scientifiche d’iconografia botanica. L’obiettivo è di stabilire dei simboli precisi, dei codici grafici, per rappresentare tipologie vegetali: alberi, arbusti, manti erbosi e masse vegetali, che non hanno una loro definita simbologia. Nella quarta parte applicheremo il metodo scelto al caso di studio e ci porremo direttamente di fronte alle problematiche relative al rilievo e alla rappresentazione del verde urbano. Lo studio delle aree verdi di Parma ha come obiettivo ultimo, attraverso un’analisi critica del risultato ottenuto dalla restituzione grafica, di tracciare delle linee guida per future rappresentazioni attraverso quello che potrebbe essere definito un codice di rappresentazione