Immobilized photosensitizers for antimicrobial applications

Photodynamic antimicrobial chemotherapy (PACT) is a very promising alternative to conventional antibiotics for the efficient inactivation of pathogenic microorganisms; this is due to the fact that it is virtually impossible for resistant strains to develop due to the mode of action employed. PACT employs a photosensitizer, which preferentially associates with the microorganism, and is then activated with non-thermal visible light of appropriate wavelength(s) to generate high localized concentrations of reactive oxygen species (ROS), inactivating the microorganism. The concept of using photosensitizers immobilized on a surface for this purpose is intended to address a range of economic, ecological and public health issues. Photosensitising molecules that have been immobilized on solid support for PACT applications are described herein. Different supports have been analyzed as well as the target microorganism and the effectiveness of particular combinations of support and photosensitiser

In-situ steel solidification imaging in continuous casting using magnetic induction tomography

: Solidification process in continuous casting is a critical part of steel production. The speed and quality of the solidification process determines the quality of final product. Computational fluid dynamics (CFD) simulations are often used to describe the process and design of its control system, but so far, there is no any tool that provides an on-line measurement of the solidification front of hot steel during the continuous casting process. This paper presents a new tool based on magnetic induction tomography (MIT) for real time monitoring of this process. The new MIT system was installed at the end of the secondary cooling chamber of a casting unit and tested during several days in a real production process. MIT is able to create an internal map of electrical conductivity of hot steel deep inside the billet. The image of electrical conductivity is then converted to temperature profile that allows the measurement of the solid, mushy and liquid layers. In this study, such a conversion is done by synchronizing in one time step the MIT measurement and the thermal map generated with the actual process parameters available at that time. The MIT results were then compared with the results obtained of the CFD and thermal modelling of the industrial process. This is the first in-situ monitoring of the interior structure during a real continuous casting.The SHELL-THICK project has received funding from EU Research Fund for Coal and Steel under grant number 709830. This study reflects only the author's views and the European Commission is not responsible for any use that may be made of the information contained therein

Sviluppo e sperimentazione di metodi innovativi per l'analisi del segnale con applicazioni alla geofisica ed ai controlli non distruttivi.

2013/2014La produzione dei semilavorati di acciaio è realizzata attraverso fasi diverse, che comprendono la fusione, la solidificazione e la deformazione a caldo. La fase di solidificazione avviene normalmente nella macchina di colata continua. In questo processo l’acciaio liquido, posto in un grande contenitore chiamato siviera, viene travasato in un polmone, chiamato paniera, che lo distribuisce alle linee di colata. Nella siviera l’acciaio è ricoperto di scoria liquida per proteggerlo dall’ossidazione, per ridurre la dispersione termica e per catturare le impurità flottanti. Quando lo svuotamento sta per completarsi, aumenta il rischio di trascinamento verso la paniera della scoria. Attualmente l’operatore umano attraverso l’uso dei propri sensi decide autonomamente di interrompere il flusso. Sarebbe invece utile disporre di sistemi automatici in grado di sostituirsi all’uomo in modo affidabile. Questa ricerca si pone l’obiettivo di esplorare sperimentalmente la possibilità di applicare tecniche di analisi comunemente applicate in geofisica per identificare l’evento catastrofico rappresentato dal passaggio della scoria. Per comprendere in maggior dettaglio gli spetti fisici coinvolti nel fenomeno è stato intrapreso anche lo studio di tecniche computazionali tipiche della CFD. L’attività di ricerca si è articolata nella realizzazione di un sistema hardware e software in tempo reale che è stato impiegato sia in impianti reali, sia in un modello in scala ad acqua. I risultati ottenuti, applicando la trasformata wavelet e il metodo degli attributi istantanei mediante la trasformata di Hilbert, hanno dimostrato la validità dell’approccio e aprono la strada a futuri approfondimenti.XXVII Ciclo197

Synthesis and evaluation of new metal-porphyrin conjugates for biomedical application

2010/2011This thesis reports the synthesis, the characterization and the biological evaluation of new classes of metal-porphyrin conjugates for potential bio-medical applications. [Ru([9]aneS3)(N-N)(L)][X]n where N-N = nitrogen chelating ligand such as ethane-1,2- diamine (en) orbpy, L = S-dmso, Cl and X = CF3SO3 or PF6, n = 2 or 1 respectively), [Ru([9]aneN3)(dmso-S)2Cl]Cl, fac-[99mTc (CO)3(H2O)3]+ and [NEt4]2 fac-[ReBr3(CO)3] were chosen as metal fragments. In the first section we describe different synthetic approaches to the preparation of porphyrin conjugates with Ru(II) coordination compounds. Ru (II) fragments were chosen they have shown a promising anticancer activity both in vitro and in vivo, in murine models. Water solubility in an important feature for biomedical application but usually porphyrins are fairly or not water soluble. The conjugation of a metal fragment to a porphyrin, beside increasing the solubility of the porphyrin macrocycle, is an intriguing alternative for making water soluble compounds that are expected to combine the cytotoxicity to the metal fragment to the phototoxicity of the porphyrins for an additive antitumor effect. We varied the number and charge of the peripheral Ru fragments, and described conjugates whose total charge ranges from +4 to +8. We showed that the connection can occur through a single coordination bond (N(pyridyl)–Ru) or through multiple coordination bond (through a chelating bpy unit). We demonstrated that meso-pyridylporphyrins (PyPs), besides being synthetically more affordable, allow to tune the geometry of the conjugates. We showed that in the series of porphyrins with peripheral bpy units at meso positions, it is possible to vary the metal fragment and the length and the flexibility of the connectors between the bpyAc peripheral moieties and the meso C atoms to obtain compounds with different solubility Finally some or those conjugates were evaluated as potential PDT agents. Singlet oxygen quantum yield was evaluated for all of them as useful parameter. The in vitro cell growth inhibition of some of such conjugates toward MDA-MB-231 human breast cancer cells and HBL-100 human non tumorigenic epithelial cells are reported, together with their phototoxic effects onMDAMB-231 cells. All conjugates have IC50 values in the low micromolar range that decrease by 1 order of magnitude upon irradiation of cell cultures with visible light. This make them promising for PDT of cancer. In the second section we describe the first example of 99mTc – porphyrins conjugates where the connection between the metal fragment and the porphyrins macrocycle occurred at the periphery of the cromophore, at meso position. In radiopharmaceutical chemistry it is common to compare the retention time in the HPLC in the radiochromatogram of the 99mTc conjugate with the UV-vis trace of the corresponding non-radioactive Re congener to confirm the success of the labeling and to characterize unambiguously the 99mTc-conjugate. By an accurate characterization of the water soluble porphyrinic precursors and of the Re(I) congeners, we were able to establish, for the first time, that only one [99mTc (CO)3]+ fragment is bounded at the periphery of the porphyrins. Furthermore, all the 99mTc/Re-porphyrin conjugates were obtained with high purity level and reasonable to good yields. The total charge ranges from +1 to +3. Stability studies performed by HPLC on the 99mTc-conjugates revealed an high stability under air at room temperature, in absence or presence of cells up to 30 minutes to 24 hours. Since natural and synthetic porphyrins and metalloporphyrins are the most useful photosensitizers for PDT, we decided to evaluate the water soluble porphyrinic precursors and the Re(I)-porphyrins conjugates as potential photosensitizers for PDT. The in vitro cell uptake, the cell growth inhibition toward HeLa cells are reported, together with their phototoxic effects on the same cell line. All conjugates revealed a negligible cytotoxicity (IC50 values higher than 100 mM) after 24 h of exposure. Those value decrease by 1 order or magnitude upon irradiation with visible light (590-700 nm) at mild light doses ( 5 J/cm2). We found that compounds uptake after 24h exposure is significantly different, and it does not affect appreciably their cytotoxicity. On the contrary, the phototoxicity is directly related to the ability of the compounds to penetrate cells. They proved to have from moderate to good singlet oxygen quantum yields and high photostability. Taken together, those results make them promising for PDT of cancer.XXIV Ciclo198

Synthesis, characterization and biological evaluation of a new photoactive hydrogel against Gram-positive and Gram-negative bacteria

In 2013, the World Health Organization reported that 884 million people lack access to clean potable water. Photodynamic antimicrobial chemotherapy (PACT) is a very promising alternative to conventional antibiotics for the efficient inactivation of pathogenic microorganisms. We report the synthesis, characterization and antibacterial activity of a polyacrylamide-based hydrogel (7), with a new photoactive phenothiazinium compound (6) immobilized on it, to be used as a novel water-sterilizing device. The hydrogel was characterized by IR and scanning electron microscopy and incorporation of the dye confirmed by UV-visible spectroscopy. Antibacterial tests using the recombinant bioluminescent Gram-positive Staphylococcus aureus RN4220 and Gram-negative Escherichia coli DH5α were performed to assess the ability of the hydrogel to inactivate bacterial strains in solution. The hydrogel is characterized by a non-ordered microporous structure and is able to generate reactive oxygen species. The hydrogel is able to inactivate planktonic cells of the S. aureus and E. coli (3.3 log and 2.3 log killing, respectively) after 25 min of irradiation with white light at 14.5 mW cm−2. The contact surface does not influence the kill rates while the killing rate increased by increasing the total amount of the hydrogel (0.27 log drop to 1.65 log drop with 0.5 mg cm−3 to 2.5 mg cm−3 of total amount of dye). The hydrogel was found to be active for four cycles, suggesting the possibility of reuse and it was shown to be active against both Gram-positive and Gram-negative species with no leaching of the active molecule

Metal Solidification Imaging Process by Magnetic Induction Tomography

Abstract There are growing number of important applications that require a contactless method for monitoring an object surrounded inside a metallic enclosure. Imaging metal solidification is a great example for which there is no real time monitoring technique at present. This paper introduces a technique - magnetic induction tomography - for the real time in-situ imaging of the metal solidification process. Rigorous experimental verifications are presented. Firstly, a single inductive coil is placed on the top of a melting wood alloy to examine the changes of its inductance during solidification process. Secondly, an array of magnetic induction coils are designed to investigate the feasibility of a tomographic approach, i.e., when one coil is driven by an alternating current as a transmitter and a vector of phase changes are measured from the remaining of the coils as receivers. Phase changes are observed when the wood alloy state changes from liquid to solid. Thirdly, a series of static cold phantoms are created to represent various liquid/solid interfaces to verify the system performance. Finally, a powerful temporal reconstruction method is applied to realise real time in-situ visualisation of the solidification and the measurement of solidified shell thickness, a first report of its kind

Synthesis and bactericidal properties of porphyrins immobilized in a polyacrylamide support: influence of metal complexation on photoactivity

Spectroscopic and photodynamic properties of three novel polymeric hydrogels bearing porphyrins have been studied in vitro on the recombinant bioluminescent Gram-negative Escherichia coli DH5α to assess their ability to inactivate bacterial strains in solution. The three different hydrogels were formed by polymerization of 5-[4-2-(2-(2-acrylamidoethoxy)ethoxy)ethyl]carboxyphenyl-10,15,20-tris(4-N-methylpyridyl)porphyrin trichloride (5) and its complexes with Pd(II) (6) and Cu(II) (7) respectively, to form three optically transparent polyacrylamide hydrogels. All of the porphyrins are tricationic and they bear at the meso positions three N-methylpyridyl rings and one terminal acryloyl group connected through a flexible hydrophilic linker, particularly suitable for the later polymerization and incorporation into a hydrogel. The hydrogels were characterized by IR and scanning electron microscopy and incorporation of the dye was confirmed by UV-visible spectroscopy. All the hydrogels are characterized by a non-ordered microporous structure. The E. coli exhibited a decrease of 1.87 log after 25 min irradiation when the porphyrin hydrogel 9 was evaluated. When the Pd(II) and Cu(II)porphyrin hydrogels were tested (10, 11), they showed a 2.93 log decrease and 1.26 log decrease in the survival of the E. coli after 25 min irradiation, respectively. Similar results were obtained when the porphyrins were tested in solution. Of the three hydrogels, the Pd(II)porphyrin hydrogel (10) proved to be the one with the highest photokilling ability under illumination, and also exhibited the lowest toxicity in the absence of light. Hydrogels 9 and 10 were found to be active for five cycles, suggesting the possibility of reuse

Rheological Studies Dedicated to the Development of a Novel Injectable Polymeric Blend for Viscosupplementation Treatment

Viscosupplementation is an intra-articular symptomatic treatment of mild osteoarthritis. The treatment involves the injection of high-molecular-weight hyaluronan (HA), and especially of cross-linked HA to restore the lubricating and cushioning properties of the synovial fluid. This work involves the development of a novel viscosupplementation fluid based on amidated carboxymethylcellulose and obtained by blending the soluble polymer with its crosslinked derivative. Rheological analyses carried out under both oscillatory and continuous shear provided a rationale to assess the viscosupplement formulation and the production process. The hydrogel fraction content and the total polymer concentration can be properly selected in order to ensure an optimal combination of flowability and viscoelastic properties

Développement d une forme pharmaceutique véhiculant un calixarène destinée au traitement d une peau saine ou lésée contaminée par de l uranium

Les accidents de contamination par voie cutanée représentent la seconde cause de contamination des travailleurs de l industrie nucléaire, après l inhalation. La contamination cutanée par l uranium est particulièrement préoccupante car elle peut conduire à une forte exposition interne des individus et les traitements actuellement employés, c est-à-dire le rinçage de la zone cutanée contaminée et l administration de décorporants, sont peu efficaces. Il apparaît alors important de développer de nouveaux traitements. La stratégie adoptée dans ces travaux de thèse a consisté à mettre au point un traitement local de la contamination cutanée par l uranium basé sur l utilisation d un chélateur de la famille des calixarènes, le 1,3,5-OCH3-2,4,6-OCH2COOH-p-tertbutylcalix[6]arène, permettant de piéger le radioélément au niveau de la zone cutanée contaminée afin d empêcher sa pénétration dans l organisme, et ainsi d éviter la manifestation de ses effets toxiques.Notre premier objectif a été de développer une forme galénique adaptée à l usage cutané contenant le calixarène tricarboxylique d intérêt et capable de le rendre disponible pour la chélation de l uranium présent dans une solution aqueuse contaminée. Une nanoémulsion de type huile dans eau présentant des molécules de calixarène à la surface des gouttelettes huileuses dispersées a ainsi été formulée.Notre second objectif a consisté à évaluer l intérêt de la nanoémulsion de calixarène en tant que traitement d urgence des contaminations cutanées par l uranium. Dans un premier temps, nous avons démontré par des expérimentations in vitro utilisant la technique d ultrafiltration que la nanoémulsion de calixarene est capable d extraire rapidement, en moins de 5 minutes, plus de 80 % des ions uranyle d une solution aqueuse contaminée. L étude ex vivo de la diffusion percutanée de l uranium à travers des explants de peau d oreille de porc montés en cellule de Franz a ensuite montré que le traitement de la contamination par la nanoémulsion de calixarène permet d empêcher le passage de l uranium à travers la peau. En effet, l application de la nanoémulsion de calixarène immédiatement après la contamination cutanée permet de réduire la quantité d uranium diffusée à travers la peau au bout de 24 heures de respectivement 94 % et 98 % sur peau saine et peau excoriée.Ce système montre donc de réelles potentialités et ouvre de nouvelles perspectives dans le traitement des contaminations cutanées par l uranium.CHATENAY M.-PARIS 11-BU Pharma. (920192101) / SudocSudocFranceF