http://hdl.handle.net/2117/629 2013-06-19T22:50:50Z http://hdl.handle.net/2117/19096 Title: Chitosan and chitosan ZnO-based complex nanoparticles: formation, characterization, and antibacterial activity Authors: Perelshtein, Ilana; Ruderman, Yelena; Perkas, Nina; Tzanov, Tzanko; Beddow, Jamie; Joyce, Eadaoin; Mason, Timothy J.; Blanes, María; Mollá, Korina; Patlolla, Anitha; Frenkel, Anatoly I.; Gedanken, Aharon 2013-05-03T13:19:06Z http://hdl.handle.net/2117/17932 Title: Use of cyclic voltammetry as an effective tool for selecting effcient enhancers for oxidative bioprocesses: importance of pH Authors: Aracri, Elisabetta; Tzanov, Tzanko; Vidal Lluciá, Teresa Abstract: Seven natural phenols and two synthetic compounds were evaluated by means of cyclic voltammetry as enhancers for the oxidation of the lignin model compound veratryl alcohol (VAl) and a sulfonated lignin (SL). Their electrochemical behaviors and catalytic efficiencies (CEs) against both substrates were assessed as a function of pH. A general increase in CE of the phenols was for the first time observed in the oxidation of VAl at pH 7 and 8. Methyl syringate (MS), syringic acid (SRC), and syringaldehyde (SRD) exhibited the highest CEs against VAl among the studied phenolic compounds despite the reduced stabilities of their phenoxy radicals. This was a result of favorable stability−reactivity balances, which were apparently influenced by both the chemical structures of the enhancers and the experimental conditions. Violuric acid (VAc) proved the most efficient compound in oxidizing lignin, followed by SRD and MS, which showed regeneration in the interval of pHs studied 2013-02-22T11:50:22Z http://hdl.handle.net/2117/17583 Title: GREDIQ-RIMA: The evolution of a teaching project of experimentation in chemistry Authors: Grau Vilalta, Maria Dolors; Guaus Guerrero, Ester; Martínez Martínez, María del Rosario; Calvet Tarragona, Aureli; Farran Marsà, Adriana; Salán Ballesteros, Maria Núria; Álvarez del Castillo, María Dolores; Gorchs Altarriba, Roser; Almajano Pablos, María Pilar; Morillo Cazorla, Margarita; Garrido Soriano, Núria Abstract: Authors of this project belong to the Resources Chemistry Teaching Group (GReDiQ) involved in RIMA (Research and innovation in learning methodologies). The audiovisual and multimedia material productions realized have been grouped into three themes: Basic Techniques of Experimentation in Chemistry, Safety in Chemistry Laboratories and Advanced Techniques of Experimentation in Chemistry. This work has been awarded a prize of the Universitat Politècnica de Catalunya (UPC–BARCELONATECH), one of the Autonomous Region of Catalunya and another one of a State scope 2013-02-05T15:33:21Z http://hdl.handle.net/2117/17291 Title: A new approach to produce plant antioxidants-loaded chitosan for medical applications Authors: Rocasalbas Lozano, Guillem; Touriño Eirín, Sonia; Tzanov, Tzanko; Torres, Josep Lluís Abstract: This work reports a straightforward approach for incorporation of plant-derived flavonoid-based antioxidants into an intrinsically antimicrobial chitosan platform in order to generate chitosan-based materials suitable for biomedical applications. The novelty of this approach consists in the use of thioacidolysis – a common analytical method for the characterization of proanthocyanidins – to covalently functionalize natural macromolecules such as chitosan with bioactive phenolic moieties. It is known that proanthocyanidins undergo depolymerization in acid medium, where in the presence of nucleophiles they form stable flavan-3-ol derivatives. Based on this reaction, flavan-3-ol moieties from the polyphenol extract of Hamamelis virginiana are incorporated covalently into a previously thiolated chitosan matrix. The phenolics-functionalized chitosan possesses improved antioxidant and antimicrobial properties, and inhibitory efficiency over deleterious wound enzymes in vitro. 2013-01-14T10:12:09Z http://hdl.handle.net/2117/17193 Title: Functional biopolymer-based matrices for modulation of chronic wound enzyme activities Authors: Francesko, Antonio; Soares da Costa, Diana; Reis, Rui L.; Pashkuleva, Iva; Tzanov, Tzanko Abstract: Collagen, collagen/hyaluronic acid (HA) and collagen/HA/chitosan (CS) sponges loaded with epigallocatechin gallate (EGCG), catechin (CAT) and gallic acid (GA) were developed and evaluated as active chronic wound dressings. Their physico-mechanical properties, biostability, biocompatibility and ability to inhibit in vitro myeloperoxidase (MPO) and collagenase—major enzymes related with the persistent inflammation in chronic wounds—were investigated as a function of the biopolymer composition and the polyphenolic compound used. The results demonstrated that the molecular weight of HA influences significantly the bulk properties of the obtained materials: higher elastic modulus, swelling ability and biostability against collagenase were measured when HA with higher molecular weights (830 and 2000 kDa) were added to the collagen matrices. The addition of CS and the polyphenols increased further the biostability of the sponges. Preliminary in vitro tests with fibroblasts revealed that the cells were able to adhere to all sponges. Cell viability was not affected significantly by the addition of the polyphenols; however, the presence of CS or high molecular weight HA in the sponge composition was associated with lower cellular viability. Finally, all specimens containing polyphenols efficiently inhibited the MPO activity. The highest inhibition capacity was observed for EGCG (IC50 = 15 ± 1 μM) and it was coupled to the highest extent of binding to the biopolymers (>80%) and optimal release profile from the sponges that allowed for prolonged (up to 3–5 days) effects. 2013-01-07T09:09:56Z http://hdl.handle.net/2117/17113 Title: Laccase-assisted formation of bioactive chitosan/gelatin hydrogel stabilized with plant polyphenols Authors: Rocasalbas Lozano, Guillem; Francesko, Antonio; Touriño Eirín, Sonia; Fernández Francos, Xavier; Guebitz, Georg M.; Tzanov, Tzanko Abstract: Laccase-assisted simultaneous cross-linking and functionalization of chitosan/gelatin blends with phenolic compounds from Hamamelis virginiana was investigated for the development of bioactive hydrogel dressings. The potential of these hydrogels for chronic wound treatment was evaluated in vitro, assessing their antibacterial and inhibitory effect on myeloperoxidase and collagenase. Rheological studies revealed that the mechanical properties of the hydrogels were a function of the enzymatic reaction time. Stable hydrogels and resistant to lysozyme degradation were achieved after 2 h laccase reaction. The inhibitory capacity of the hydrogel for myeloperoxidase and collagenase was 32% and 79% respectively after 24 h incubation. Collagenase activity was additionally suppressed by adsorption (20%) of the enzyme onto the hydrogel. Therefore, the bioactive properties of the hydrogels were due to the effect of both released phenolic compounds and the permanently functionalized platform itself. The hydrogels showed antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus. 2012-12-12T10:28:13Z http://hdl.handle.net/2117/17072 Title: GAGs-thiolated chitosan assemblies for chronic wounds treatment: control of enzyme activity and cell attachment Authors: Francesko, Antonio; Soares da Costa, Diana; Lisboa, Patricia; Reis, Rui L.; Tzanov, Tzanko; Iva Hristova, Pashkuleva Abstract: Multilayered polyelectrolyte coatings comprising thiolated chitosan (TC) and glycosaminoglycans (GAGs), chondroitin sulphate and hyaluronic acid, were built using a layer-by-layer approach. The surface activity of these coatings for binding and inhibition of enzymes related to chronic inflammation, such as collagenase and myeloperoxidase, was assessed. The build-up of five bi-layers of TC/GAGs onto gold surfaces was monitored in situ by QCM-D. All experimental groups showed exponential growth of the coatings controlled by the degree of chitosan thiolation and the molecular weight of the GAGs. The degree of chitosan modification was also the key parameter influencing the enzyme activity: increasing the thiols content led to more efficient myeloperoxidase inhibition and was inversely proportional to the adsorption of collagenase. Enhanced fibroblast attachment and proliferation were observed when the multilayered polyelectrolyte constructs terminated with GAGs. The possibility to control either the activity of major wound enzymes by the thiolation degree of the coating or the cell adhesion and proliferation by proper selection of the ultimate layer makes these materials potentially useful in chronic wounds treatment and dermal tissue regeneration. 2012-12-04T12:03:01Z http://hdl.handle.net/2117/15998 Title: Enzymatic pre-treament as a means of enhancing the antibacterial activity and stability of ZnO nanoparticles sonochemically coated on cotton fabrics Authors: Gedanken, Aharon; Mollá, Korina; Blanes, María; Perelshtein, Ilana; Ruderman, Yelena; Perkas, Nina; Traeger, Kamelia; Tzanov, Tzanko; Beddow, Jamie; Joyce, Eadaoin; Mason, Timothy J. Abstract: Zinc oxide nanoparticles (ZnO NP’s) are known for their excellent antibacterial properties. This paper describes a method for enhancing the stability and the antibacterial activity of ZnO NPs synthesized and embedded sonochemically on cotton fabrics, by pre-treating the fabric surface with cellulase enzyme. The enzymatic pre-treatment resulted in the deposition of smaller sized NPs with improved adhesion. The reduction in particle size brought about better antibacterial performance against several types of bacteria. The sonochemically produced ZnO coating withstood 10 laundry cycles at 92º C retaining its antibacterial activity. 2012-06-09T12:11:47Z http://hdl.handle.net/2117/15330 Title: Inhibition of deleterious chronic wound enzymes with plant polyphenols Authors: Díaz González, María; Rocasalbas Lozano, Guillem; Francesko, Antonio; Touriño Eirín, Sonia; Torres, Josep Lluis; Tzanov, Tzanko Abstract: The chronic wound environment is characterized by high concentrations of reactive oxygen species (ROS) and elevated levels of myeloperoxidase (MPO) and collagenases, together impairing the healing process. Therefore, the management of chronic wounds at a molecular level requires the synergistic use of antioxidants, MPO and collagenase inhibitors to simultaneously target multiple factors from wound pathogenesis. In this study, a polyphenolic extract from Hamamelis virginiana plant, rich in condensed and hydrolysable oligomeric tannins, was evaluated as an inhibitor of MPO and collagenase.In addition to efficient scavengers of radical and non-radical reactive species, H. virginiana polyphenols were found to act as substrates in the MPO peroxidase cycle, preventing the accumulation of ROS in the chronic wound site. Furthermore, it was also found that the plant exerts an irreversible inhibitory effect on collagenase activity (IC50 = 75 ± 10 μg/mL) 2012-02-23T12:40:47Z http://hdl.handle.net/2117/13880 Title: The M-5 muscarinic acetylcholine receptor third intracellular loop regulates receptor function and oligomerization Authors: Borroto Escuela, Dasiel Óscar; Garcia Negredo, G.; Garriga Solé, Pere; Fuxe, Kjell; Ciruela, Francisco 2011-11-14T16:00:22Z http://hdl.handle.net/2117/13861 Title: Overproduction of human M3 muscarinic acetylcholine receptor: An approach toward structural studies Authors: Romero Fernandez, Wilber; Garriga Solé, Pere; Borroto Escuela, Dasiel Óscar 2011-11-11T13:35:26Z http://hdl.handle.net/2117/13857 Title: Differential expression of muscarinic acetylcholine receptor subtypes in Jurkat cells and their signaling Authors: Alea, M.P.; Borroto Escuela, Dasiel Óscar; Romero Fernandez, Wilber; Fuxe, Kjell; Garriga Solé, Pere 2011-11-11T12:23:40Z http://hdl.handle.net/2117/13237 Title: Hydrophobic amino acids at the cytoplasmic ends of helices 3 and 6 of rhodopsin conjointly modulate transducin activation Authors: Bosch Presegué, Laia; Iarriccio Silva, Laura; Aguila Cerda, Mónica; Toledo, Darwin; Ramon Portés, Eva; Cordomí Montoya, Arnau; Garriga Solé, Pere Abstract: Rhodopsin is the visual photoreceptor responsible for dim light vision. This receptor is located in the rod cell of the retina and is a prototypical member of the G-protein-coupled receptor superfamily. The structural details underlying the molecular recognition event in transducin activation by photoactivated rhodopsin are of key interest to unravel the molecular mechanism of signal transduction in the retina. We constructed and expressed rhodopsin mutants in the second and third cytoplasmic domains of rhodopsin –where the natural amino acids were substituted by the human M3 acetylcholine muscarinic receptor homologous residues– in order to determine their potential involvement in G-protein recognition. These mutants showed normal chromophore formation and a similar photobleaching behavior than WT rhodopsin, but decreased thermal stability in the dark state. The single mutant V1383.53 and the multiple mutant containing V2275.62 and a combination of mutations at the cytoplasmic end of transmembrane helix 6 caused a reduction in transducin activation upon rhodopsin photoactivation. Furthermore, combination of mutants at the second and third cytoplasmic domains revealed a cooperative role, and partially restored transducin activation. The results indicate that hydrophobic interactions by V1383.53, V2275.62, V2506.33, V2546.37 and I2556.38 are critical for receptor activation and/or efficient rhodopsin–transducin interaction. 2011-09-19T11:07:52Z http://hdl.handle.net/2117/13132 Title: Alterations in the photoactivation pathway of rhodopsin mutants associated with retinitis pigmentosa Authors: Bosch Presegué, Laia; Ramon Portés, Eva; Toledo, Darwin; Cordomí Montoya, Arnau; Garriga Solé, Pere Abstract: The visual photoreceptor rhodopsin undergoes a series of conformational changes upon light activation, eventually leading to the active metarhodopsin II conformation, which is able to bind and activate the G-protein, transducin. We have previously shown that mutant rhodopsins G51V and G89D, associated with retinitis pigmentosa, present photobleaching patterns characterized by the formation of altered photointermediates whose nature remained obscure. Our current detailed UV–visible spectroscopic analysis, together with functional characterization, indicate that these mutations influence the relative stability of the different metarhodopsin photointermediates by altering their equilibria and maintaining the receptor in a nonfunctional light-induced conformation that may be toxic to photoreceptor cells. We propose that G51V and G89D shift the equilibrium from metarhodopsin I towards an intermediate, recently named as metarhodopsin Ib, proposed to interact with transducin without activating it. This may be one of the causes contributing to the molecular mechanisms underlying cell death associated with some retinitis pigmentosa mutations. 2011-08-29T17:38:17Z http://hdl.handle.net/2117/12710 Title: Sensor materials for the detection of human neutrophil elastase and cathepsin G activity in wound ¿uid Authors: Wehrschuetz-Sigl, Eva; Guebitz, George M.; Van der Palen, Job; Hasmann, Andrea; Gewessler, Ulrike; Hulla, Elisabet; Schneider, Konstantin P.; Binder, Barbara; Francesko, Antonio; Tzanov, Tzanko; Schintler, Michael Abstract: Human neutrophil elastase (HNE) and cathepsin G (CatG) are involved in the pathogenesis of a number of inflammatory disorders. These serine proteinases are released by neutrophils and monocytes in case of infection. Wound infection is a severe complication regarding wound healing causing diagnostic and therapeutic problems. In this study we have shown the potential of HNE and CatG to be used as markers for early detection of infection. Significant differences in HNE and CatG levels in infected and non-infected wound fluids were observed. Peptide substrates for these two enzymes were successfully immobilised on different surfaces, including collagen, modified collagen, polyamide polyesters and silica gel. HNE and CatG activities were monitored directly in wound fluid via hydrolysis of the chromogenic substrates. Infected wound fluids led to significant higher substrate hydrolysis compared with non-infected ones. These different approaches could be used for the development of devices which are able to detect elevated enzyme activities before manifestation of infection directly on bandages. This would allow a timely intervention by medical doctors thus preventing severe infections. 2011-06-06T12:00:58Z