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1 to 50 of 211 results
  • Sonochemically processed cationic nanocapsules: Efficient antimicrobials with membrane disturbing capacity

     Francesko, Antonio; Torrent Burgues, Juan; Carrión Fité, Francisco Javier; Macedo Fernandes, Margarida Maria; Tzanov, Tzanko; Heinze, Thomas
    Biomacromolecules
    Date of publication: 2014-03-08
    Journal article

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    Bacterial-mediated diseases are a major healthcare concern worldwide due to the rapid spread of antibiotic-resistant bacteria. One strategy to manage the bacterial infections while avoiding the emergence of resistant strains implies specific targeting and disruption of bacteria membranes. This work evaluates the potential of nanostructured biopolymer derivatives, nanocapsules (NCs), to disrupt the bacteria cell walls and effectively kill planktonic microorganisms. Two biopolymers, chitosan and cellulose, were chemically modified to synthesize derivatives with improved cationic character (thiolated chitosan and aminocellulose) prior to their processing into nanocapsules via a one-step sonochemical process. The interactions of NCs, displaying an average size of around 250 nm, with bacteria membrane were evaluated using two membrane models: Langmuir monolayers and liposome bilayers composed of a l-a-phosphatidylglycerol phospholipid extracted from Escherichia coli. NCs possessed improved membrane disturbing capacity in comparison to the nonprocessed biopolymer derivatives, by drastically increasing the monolayer fluidity and inducing more than 50% leakage of a dye inserted in the bilayered liposomes. In addition, membrane disturbance was directly proportional to the NCs cationic charge. Whereas evidence showed that thiolated chitosan and aminocellulose interacted with the bacteria membrane through a ¿carpet model¿, the NCs were found to induce larger surface defects and high local perturbance through a ¿detergent model¿. Importantly, the degree of disruption caused by the biopolymer derivatives and NCs correlated well with the antimicrobial capacity against Escherichia coli, selectively killing bacteria cells without imparting toxicity to human fibroblasts.

    Bacterial-mediated diseases are a major healthcare concern worldwide due to the rapid spread of antibiotic-resistant bacteria. One strategy to manage the bacterial infections while avoiding the emergence of resistant strains implies specific targeting and disruption of bacteria membranes. This work evaluates the potential of nanostructured biopolymer derivatives, nanocapsules (NCs), to disrupt the bacteria cell walls and effectively kill planktonic microorganisms. Two biopolymers, chitosan and cellulose, were chemically modified to synthesize derivatives with improved cationic character (thiolated chitosan and aminocellulose) prior to their processing into nanocapsules via a one-step sonochemical process. The interactions of NCs, displaying an average size of around 250 nm, with bacteria membrane were evaluated using two membrane models: Langmuir monolayers and liposome bilayers composed of a l-a-phosphatidylglycerol phospholipid extracted from Escherichia coli. NCs possessed improved membrane disturbing capacity in comparison to the nonprocessed biopolymer derivatives, by drastically increasing the monolayer fluidity and inducing more than 50% leakage of a dye inserted in the bilayered liposomes. In addition, membrane disturbance was directly proportional to the NCs cationic charge. Whereas evidence showed that thiolated chitosan and aminocellulose interacted with the bacteria membrane through a “carpet model”, the NCs were found to induce larger surface defects and high local perturbance through a “detergent model”. Importantly, the degree of disruption caused by the biopolymer derivatives and NCs correlated well with the antimicrobial capacity against Escherichia coli, selectively killing bacteria cells without imparting toxicity to human fibroblasts.

  • In situ chitosan gelation initiated by atmospheric plasma treatment

     Molina, Ricardo; Jovancic, P.; Vilchez, S.; Tzanov, Tzanko; Solans, C.
    Carbohydrate polymers
    Date of publication: 2014-01-06
    Journal article

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  • Sonochemical coating of textiles with hybrid ZnO/chitosan antimicrobial nanoparticles

     Petkova Petkova, Petya Stoyanova; Francesko, Antonio; Macedo Fernandes, Margarida Maria; Mendoza Gomez, Ernesto; Perelshtein, Ilana; Aharon, Gedanken; Tzanov, Tzanko
    ACS applied materials and interfaces
    Date of publication: 2014-01-09
    Journal article

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    Textiles are good substrates for growth of microorganisms especially under moisture and temperature conditions found in hospitals. Microbial shedding from the body occurs continuously at contact of the patient with textile materials used in medical practice, contributing to the occurrence of hospital acquired infections. Thus, the use of efficient antimicrobial textiles is necessary to prevent the transfer of pathogens and the infection incidence. In this work, hybrid antimicrobial coatings were generated on cotton fabrics by means of a one-step simultaneous sonochemical deposition of ZnO nanoparticles (NPs) and chitosan. The process was further optimized in terms of reagents concentration and processing time in order to improve the antibacterial properties of the fabric and ensure their biocompatibility. The highest antibacterial activity of the fabrics against two medically relevant bacterial species was achieved in a 30 min sonochemical coating process using 2 mM ZnO NPs suspension. When chitosan was simultaneously deposited with the same amount of ZnO, the obtained hybrid NPs coating displayed higher by 48 and 17 % antibacterial activity against Staphylococcus aureus and Escherichia coli, respectively. The presence of biopolymer also improved the durability of the antimicrobial effect of the coatings by 21 % for Staphylococcus aureus and 40 % for Escherichia coli, evaluated after applying multiple washing cycles at hospital laundering regimes. Finally, 87 % biocompatibility improvement supported by fibroblast viability was observed for the hybrid ZnO/chitosan coating compared to the steady decrease of cells viability over one week in contact with the fabrics coated with ZnO alone.

    Textiles are good substrates for growth of microorg anisms especially under moisture and temperature conditions found in hospitals. Microbia l shedding from the body occurs continuously at contact of the patient with textile materials used in medical practice, contributing to the occurrence of hospital acquired infections. Thus, the use of efficient antimicrobial textiles is necessary to prevent the transfer of pathogens a nd the infection incidence. In this work, hybrid antimicrobial coatings were generated on cotton fab rics by means of a one-step simultaneous sonochemical deposition of ZnO nanoparticles (NPs) and chitosan. The process was further optimized in terms of reagents concentration and pr ocessing time in order to improve the antibacterial properties of the fabric and ensure t heir biocompatibility. The highest antibacterial activity of the fabrics against two medically relev ant bacterial species was achieved in a 30 min sonochemical coating process using 2 mM ZnO NPs sus pension. When chitosan was simultaneously deposited with the same amount of Zn O, the obtained hybrid NPs coating displayed higher by 48 and 17 % antibacterial activ ity against Staphylococcus aureus and Escherichia coli , respectively. The presence of biopolymer also imp roved the durability of the antimicrobial effect of the coatings by 21 % for Staphylococcus aureus and 40 % for Escherichia coli , evaluated after applying multiple washing cycles at hospital laundering regimes. Finally, 87 % biocompatibility improvement supported by fibrobl ast viability was observed for the hybrid ZnO/chitosan coating compared to the steady decreas e of cells viability over one week in contact with the fabrics coated with ZnO alone.

  • An enzymatic approach to develop a lignin-based adhesive for wool floor coverings

     Aracri, Elisabetta; Diaz Blanco, Carlos; Tzanov, Tzanko
    Green Chemistry
    Date of publication: 2014-02-04
    Journal article

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    This work describes a novel enzymatic approach to develop a lignin-based adhesive aimed at replacing synthetic latex in wool floor coverings. The adhesive production consisted of a lignin pre-activation step to oxidise it by a laccase-enhancer system followed by a phenolation step where natural phenolic compounds were copolymerised with lignin in order to increase its content of quinone structures reactive towards wool. The electrochemical behaviour of the adhesive precursors and the influence of process conditions on the adhesive characteristics suggested that the phenolic compounds were able to autopolymerise and copolymerise between themselves and with lignin during the enzymatic reaction. Consequently, the flexibility and bonding strength of the adhesive increased. The latter showed strength performance similar to that of the traditional latex-based adhesive. Satisfactory level of flexibility was obtained using polyethylene glycol as an external plasticizer of lignin.

  • Building an antifouling zwitterionic coating on urinary catheters using an enzymatically triggered bottom-up approach

     Diaz Blanco, Carlos; Ortner, Andreas; Dimitrov, Radostin; Navarro Santañes, Antonio; Mendoza Gomez, Ernesto; Tzanov, Tzanko
    ACS applied materials and interfaces
    Date of publication: 2014-06-23
    Journal article

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    Catheter associated urinary tract infections are common during hospitalization due to the formation of bacterial biofilms on the indwelling device. In this study, we report an innovative biotechnology-based approach for the covalent functionalization of silicone catheters with antifouling zwitterionic moieties to prevent biofilm formation. Our approach combines the potential bioactivity of a natural phenolics layer biocatalytically conjugated to sulfobetaine-acrylic residues in an enzymatically initiated surface radical polymerization with laccase. To ensure sufficient coating stability in urine, the silicone catheter is plasma-activated. In contrast to industrial chemical methods, the methacrylate-containing zwitterionic monomers are polymerized at pH 5 and 50 °C using as an initiator the phenoxy radicals solely generated by laccase on the phenolics-coated catheter surface. The coated catheters are characterized by X-ray photoelectron spectroscopy (XPS), Fourier transformed infrared (FTIR) analysis, atomic force microscopy (AFM), and colorimetrically. Contact angle and protein adsorption measurements, coupled with in vitro tests with the Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus in static and dynamic conditions, mimicking the operational conditions to be faced by the catheters, demonstrate reduced biofilm formation by about 80% when compared to that of unmodified urinary catheters. The zwitterionic coating did not affect the viability of the human fibroblasts (BJ-5ta) over seven days, corresponding to the extended useful life of urinary catheters.

    Catheter associated urinary tract infections are common during hospitalization due to the formation of bacterial biofilms on the indwelling device. In this study, we report an innovative biotechnology-based approach for the covalent functionalization of silicone catheters with antifouling zwitterionic moieties to prevent biofilm formation. Our approach combines the potential bioactivity of a natural phenolics layer biocatalytically conjugated to sulfobetaine-acrylic residues in an enzymatically initiated surface radical polymerization with laccase. To ensure sufficient coating stability in urine, the silicone catheter is plasma-activated. In contrast to industrial chemical methods, the methacrylate-containing zwitterionic monomers are polymerized at pH 5 and 50 °C using as an initiator the phenoxy radicals solely generated by laccase on the phenolics-coated catheter surface. The coated catheters are characterized by X-ray photoelectron spectroscopy (XPS), Fourier transformed infrared (FTIR) analysis, atomic force microscopy (AFM), and colorimetrically. Contact angle and protein adsorption measurements, coupled with in vitro tests with the Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus in static and dynamic conditions, mimicking the operational conditions to be faced by the catheters, demonstrate reduced biofilm formation by about 80% when compared to that of unmodified urinary catheters. The zwitterionic coating did not affect the viability of the human fibroblasts (BJ-5ta) over seven days, corresponding to the extended useful life of urinary catheters.

  • One-step sonochemical preparation of redox-responsive nanocapsules for glutathione mediated RNA release

     Francesko, Antonio; Macedo Fernandes, Margarida Maria; Tzanov, Tzanko; Perelshtein, Illana; Benisvy Aharonovich, Lena; Gedanken, Aharon
    Journal of materials chemistry B
    Date of publication: 2014-07-09
    Journal article

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    Efficient RNA delivery to targeted cells requires the use of stable interactive carriers that provide RNA protection during the extracellular transit and trigger release once internalised. One strategy to avoid the premature extracellular RNA drain coupled to sufficient intracellular release is the use of stimuli-responsive delivery materials exploiting as a triggering mechanism the redox gradient between the extra- and intracellular compartments. This work describes a facile route for preparation of redox-active nanocarriers containing disulphides that combine RNA protection and delivery on demand based on intracellular glutathione (GSH) levels. A one-step sonochemical technology was employed to generate thiolated chitosan (TC) nanocapsules with diameter between 250 - 570 nm and simultaneously load them with RNA. Their size and physiological stability were directly proportional to the extent of disulphide cross-linking, which in turn could be ruled by adjusting the processing pH and degree of chitosan thiolation. The TC processing into nanocapsules showed to be advantageous in terms of RNA condensation and protection compared to the typically employed nanocomplexation. Fluorescence microscopy imaging revealed that: i) the nanocapsules enter the human fibroblasts and migrate to the perinuclear regions within 1 h, and ii) the cargo release occurs after the internalisation. These redox-responsive and biocompatible drug carriers demonstrated an effective (~60 %) and sustained (up to 72 h) RNA release at intracellular GSH concentrations (10 mM) in vitro, based on disulphide reduction and consequent capsules disassembly.

    Efficient RNA delivery to targeted cells requires the use of stable interactive carriers that provide RNA protection during the extracellular transit and trigger release once internalised. One strategy to avoid the premature extracellular RNA drain coupled to sufficient intracellular release is the use of stimuli-responsive delivery materials exploiting as a triggering mechanism the redox gradient between the extra- and intracellular compartments. This work describes a facile route for preparation of redox-active nanocarriers containing disulphides that combine RNA protection and delivery on demand based on intracellular glutathione (GSH) levels. A one-step sonochemical technology was employed to generate thiolated chitosan (TC) nanocapsules with diameter between 250 - 570 nm and simultaneously load them with RNA. Their size and physiological stability were directly proportional to the extent of disulphide cross-linking, which in turn could be ruled by adjusting the processing pH and degree of chitosan thiolation. The TC processing into nanocapsules showed to be advantageous in terms of RNA condensation and protection compared to the typically employed nanocomplexation. Fluorescence microscopy imaging revealed that: i) the nanocapsules enter the human fibroblasts and migrate to the perinuclear regions within 1 h, and ii) the cargo release occurs after the internalisation. These redox-responsive and biocompatible drug carriers demonstrated an effective (~60 %) and sustained (up to 72 h) RNA release at intracellular GSH concentrations (10 mM) in vitro, based on disulphide reduction and consequent capsules disassembly.

  • Upgrading the co-streams of fish processing industries through nanoparticles formation for skin conditioning purposes

     Tzanov, Tzanko; Macedo Fernandes, Margarida Maria; Aracri, Elisabetta; Rivera, Diana; ¿li¿yte, Rasa
    International Conference on Polymer and Fiber Biotechnology
    Presentation's date: 2014-05-25
    Presentation of work at congresses

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  • Laccase-catalysed functionalization of lignin to produce a novel, bio-based adhesive for wool floor coverings

     Aracri, Elisabetta; Diaz Blanco, Carlos; Tzanov, Tzanko
    International Conference on Biobased Materials and Composites
    Presentation's date: 2014-05-15
    Presentation of work at congresses

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  • Sonochemically processed cationic nanobiopolymers - efficient antimicrobials with membrane disturbant capacity

     Macedo Fernandes, Margarida Maria; Francesko, Antonio; Torrent Burgues, Juan; Heinze, Thomas; Tzanov, Tzanko
    International Conference on Polymer and Fiber Biotechnology
    Presentation's date: 2014-05-25
    Presentation of work at congresses

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  • Enzyme-based nanoparticles to inhibit bacterial biofilm formation in urinary catheters

     Ivanova, Kristina Dimitrova; Macedo Fernandes, Margarida Maria; Tzanov, Tzanko
    International Conference on Polymer and Fiber Biotechnology
    Presentation's date: 2014-05-27
    Presentation of work at congresses

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  • Development of a lignin-based adhesive for wool floor coverings using laccase and natural phenols

     Aracri, Elisabetta; Diaz Blanco, Carlos; Tzanov, Tzanko
    International Conference on Polymer and Fiber Biotechnology
    Presentation's date: 2014-05-27
    Presentation of work at congresses

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  • Rapeseed production industry¿s co-streams used as a raw material to develop value-added products: bioactivities and possible applications

     Rivera, Diana; Macedo Fernandes, Margarida Maria; Rommi, Katariina; Hakala, Terhi; Lantto, Raija; Tzanov, Tzanko
    International Conference on Polymer and Fiber Biotechnology
    Presentation's date: 2014-05-27
    Presentation of work at congresses

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  • Sonochemical formation and enzymatic stabilisation of functional hybrid nanocomposites

     Petkova Petkova, Petya Stoyanova; Francesko, Antonio; Tzanov, Tzanko
    International Conference on Polymer and Fiber Biotechnology
    Presentation's date: 2014-05-25
    Presentation of work at congresses

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  • Sonochemically generated bioconjugate nano/micro-capsules as non-viral vectors for efficient nucleic acid delivery

     Francesko, Antonio; Macedo Fernandes, Margarida Maria; Tzanov, Tzanko
    International Conference on Polymer and Fiber Biotechnology
    Presentation's date: 2014-05-25
    Presentation of work at congresses

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  • FUNCTIONAL MATERIALS FOR LAST DIAGNOSIS OF WOUND INFECTION

     Tzanov, Tzanko
    Participation in a competitive project

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  • Tannic Acid NPs - Synthesis and immobilization on to a solid surface in a one ¿ step process and their antibacterial and anti-inflammatory properties

     Perelshtein, Ilana; Ruderman, Elena; Francesko, Antonio; Tzanov, Tzanko; Macedo Fernandes, Margarida Maria; Gedanken, Aharon
    Ultrasonics sonochemistry
    Date of publication: 2013-12-14
    Journal article

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    Tannic acid nanoparticles were synthesized from an aqueous solution without the use of stabilizers via a sonochemical process. In order to avoid the dissolution of the formed nanoparticles, the sonochemical reaction was performed in the presence of a cotton fabric: following their formation, the tannic acid nanoparticles were embedded into the cotton substrate in a one-step process. The bioactive properties of the tannic acid coated surface were examined towards the inhibition of myeloperoxidase and collagenase, two major enzymes related with inflammatory processes. In addition, the antibacterial activity of the tannic acid nanoparticles coated textiles was evaluated against Staphylococcus aureus and Pseudomonas aeruginosa. © 2013 Elsevier B.V. All rights reserved.

    Tannic acid nanoparticles were synthesized from an aqueous solution without the use of stabilizers via a sonochemical process. In order to avoid the dissolution of the formed nanoparticles, the sonochemical reaction was performed in the presence of a cotton fabric: following their formation, the tannic acid nanoparticles were embedded into the cotton substrate in a one-step process. The bioactive properties of the tannic acid coated surface were examined towards the inhibition of myeloperoxidase and collagenase, two major enzymes related with inflammatory processes. In addition, the antibacterial activity of the tannic acid nanoparticles coated textiles was evaluated against Staphylococcus aureus and Pseudomonas aeruginosa.

  • Use of cyclic voltammetry as an effective tool for selecting efficient enhancers for oxidative bioprocesses: Importance of pH

     Aracri, Elisabetta; Tzanov, Tzanko; Vidal Llucia, Teresa
    Industrial & engineering chemistry research
    Date of publication: 2013-01-04
    Journal article

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    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

  • Chitosan and chitosan ZnO-based complex nanoparticles: formation, characterization, and antibacterial activity

     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
    Journal of materials chemistry B
    Date of publication: 2013-02-04
    Journal article

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  • A new approach to produce plant antioxidant-loaded chitosan for modulating proteolytic environment and bacterial growth

     Rocasalbas Lozano, Guillermo; Touriño Eirin, Sonia; Torres, Josep Lluis; Tzanov, Tzanko
    Journal of materials chemistry B
    Date of publication: 2013-01-14
    Journal article

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    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.

    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.

  • Effect of thiol-functionalisation on chitosan antibacterial activity: interaction with a bacterial membrane model

     Macedo Fernandes, Margarida Maria; Francesko, Antonio; Torrent Burgues, Juan; Tzanov, Tzanko
    Reactive and functional polymers
    Date of publication: 2013-01-12
    Journal article

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    The antibacterial activity of chitosan modified with the thiol-containing 2-iminothiolane HCl (TC-IMI) and N-acetyl- L -cysteine (TC-NAC) was studied by Langmuir film balance technique using a dipalmitoylphos- phatidylglycerol (DPPG) monolayer bacterial membrane model. The interactions of the biopolymer with the membrane model were assessed by monitoring the differences in the shape of the compression iso- therms recorded in the absence and presence of chitosan and thiolated conjugates in the subphase. A low molecularweightchitosan(15 kDa)shiftedthecompressionisothermsofDPPGmonolayerstowardslarger areas ( A 0,CS = 145 Å 2 ), confirming its membrane disturbance capacity. Further thiolation induced higher yield of expansion, more pronounced in the case of TC-IMI. The expansion of the monolayer increased sig- nificantly( A 0,TC-NAC = 150 Å 2 vs A 0,TC-IMI = 175 Å 2 )andtheelasticityatasurfacepressureof30 mN/m,typical for bio-membranes decreased to a greater extent C 1 s ; 30 TC NAC = 120 mN/m vs C 1 s ; 30 TC IMI = 87 mN/m) in presence of TC-IMI. Antibacterial tests against a Gram-negative Escherichia coli and a Gram-positive Staph- ylococcusaureus wereingoodagreementwiththesefindings,suggestingthatchitosanthiolatedwith2-imi- nothiolane HCl acts as a bactericide disrupting the integrity of the bacterial cell membrane

    The antibacterial activity of chitosan modified with the thiol-containing 2-iminothiolane HCl (TC-IMI) and N-acetyl- L -cysteine (TC-NAC) was studied by Langmuir film balance technique using a dipalmitoylphos- phatidylglycerol (DPPG) monolayer bacterial membrane model. The interactions of the biopolymer with the membrane model were assessed by monitoring the differences in the shape of the compression iso- therms recorded in the absence and presence of chitosan and thiolated conjugates in the subphase. A low molecularweightchitosan(15 kDa)shiftedthecompressionisothermsofDPPGmonolayerstowardslarger areas ( A 0,CS = 145 Å 2 ), confirming its membrane disturbance capacity. Further thiolation induced higher yield of expansion, more pronounced in the case of TC-IMI. The expansion of the monolayer increased sig- nificantly( A 0,TC-NAC = 150 Å 2 vs A 0,TC-IMI = 175 Å 2 )andtheelasticityatasurfacepressureof30 mN/m,typical for bio-membranes decreased to a greater extent C 1 s ; 30 TC NAC = 120 mN/m vs C 1 s ; 30 TC IMI = 87 mN/m) in presence of TC-IMI. Antibacterial tests against a Gram-negative Escherichia coli and a Gram-positive Staph- ylococcusaureus wereingoodagreementwiththesefindings,suggestingthatchitosanthiolatedwith2-imi- nothiolane HCl acts as a bactericide disrupting the integrity of the bacterial cell membrane

  • Myeloperoxidase: A paradoxical enzyme - from host defense to disease

     Díaz González, María; Francesko, Antonio; Macedo Fernandes, Margarida Maria; Tzanov, Tzanko
    Date of publication: 2013-01-30
    Book chapter

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  • Gallic acid implications in health: multi-therapeutic and protective agent

     Francesko, Antonio; Macedo Fernandes, Margarida Maria; Tzanov, Tzanko
    Date of publication: 2013-07-15
    Book chapter

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  • Formulation of hybrid biopolymer hydrogels containing phenolic nanoparticles

     Petkova Petkova, Petya Stoyanova; Francesko, Antonio; Tzanov, Tzanko
    American Chemical Society National Meeting
    Presentation's date: 2013-04-08
    Presentation of work at congresses

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  • Nanobiopolymers: efficient antimicrobials with membrane disturbant capacity

     Macedo Fernandes, Margarida Maria; Francesko, Antonio; Torrent Burgues, Juan; Tzanov, Tzanko
    American Chemical Society National Meeting
    Presentation's date: 2013-04-09
    Presentation of work at congresses

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    Nanoparticles possess unique physicochemical properties, important for the efficient transport through the cell membranes. The small and controllable size, large surface area to mass ratio, and high reactivity facilitate the intracellular delivery, thereby overcoming some of the limitations in traditional antimicrobial therapeutics. Chemically modified biopolymers (thiolated chitosan and aminocellulose) were processed into nanoparticles via a one-step sonochemical process and evaluated for their antibacterial activity against Escherichia coli and Staphyloccocus aureus. Thiolated chitosan and aminocellulose were shown to possess improved antimicrobial properties compared to the starting biopolymers and even higher bactericide effect was observed after processed into nanoparticles. The mechanistic insights were obtained by Langmuir monolayer technique using Escherichia coli phospholipids as membrane models. The high cationic character of the modified biopolymers and the obtained spherical structure were found to allow efficient interaction with the phospholipid heads and tails, crucial for their antibacterial activity and transport through cell membranes.

  • Simultaneous deposition of chitosan and ZnO NP¿s on textiles via one-step sonochemical reaction

     Perelshtein, Ilana; Gedanken, Aharon; Petkova Petkova, Petya Stoyanova; Touriño Eirin, Sonia; Traeger, K.; Tzanov, Tzanko
    IFATCC International Congress
    Presentation's date: 2013-05-08
    Presentation of work at congresses

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  • Simultaneous sonochemical-enzymatic coating of textiles with antimicrobial nanoparticles

     Petkova Petkova, Petya Stoyanova; Touriño Eirin, Sonia; Traeger, K.; Tzanov, Tzanko; Perelshtein, Ilana; Gedanken, Aharon
    IFATCC International Congress
    Presentation's date: 2013-05-08
    Presentation of work at congresses

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  • Combined antimicrobial/antifouling coatings using zwitterion-decorated phenolic nano-capsules

     Diaz Blanco, Carlos; Francesko, Antonio; Macedo Fernandes, Margarida Maria; Tzanov, Tzanko
    American Chemical Society National Meeting
    Presentation's date: 2013-04-08
    Presentation of work at congresses

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  • Enzymes to control bacterial biofilm formation

     Ivanova, Kristina Dimitrova; Macedo Fernandes, Margarida Maria; Tzanov, Tzanko
    American Chemical Society National Meeting
    Presentation's date: 2013-10-08
    Presentation of work at congresses

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  • Solid-liquid surface functionalization of biopolymeric platforms with plant-derived polyphenols

     Ivanova, Kristina Dimitrova; Petkova Petkova, Petya Stoyanova; Tzanov, Tzanko
    American Chemical Society National Meeting
    Presentation's date: 2013-04-08
    Presentation of work at congresses

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  • Nanostructured multilayer coatings with antibiofilm activity for biomedical applications

     Tzanov, Tzanko; Macedo Fernandes, Margarida Maria; Gamerith, Caroline
    American Chemical Society National Meeting
    Presentation's date: 2013-04-10
    Presentation of work at congresses

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  • Thiol/disulfide rationale to formulate therapeutic biopolymer nanomaterials

     Francesko, Antonio; Macedo Fernandes, Margarida Maria; Tzanov, Tzanko
    American Chemical Society National Meeting
    Presentation's date: 2013-04-08
    Presentation of work at congresses

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  • NOVEL COATINGS TO PREVENT BIOFILM FORMATION ON URINARY

     Tzanov, Tzanko
    Participation in a competitive project

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  • APOSITOS ACTIVOS PARA HERIDAS CRONICAS BASADOS EN BIOPOLIMEROS

     Tzanov, Tzanko
    Participation in a competitive project

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  • Inhibition of deleterious chronic wound enzymes with plant polyphenols

     Díaz-González, María; Rocasalbas Lozano, Guillem; Francesko, Antonio; Touriño Eirin, Sonia; Torres, Josep Lluis; Tzanov, Tzanko
    Biocatalysis and biotransformation
    Date of publication: 2012-01-18
    Journal article

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    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)

  • GAGs-thiolated chitosan assemblies for chronic wounds treatment: control of enzyme activity and cell attachment

     Francesko, Antonio; Soares da Costa, Diana; Lisboa, Patricia; Reis, Rui Luís; Tzanov, Tzanko; Iva Hristova, Pashkuleva
    Journal of materials chemistry B
    Date of publication: 2012-04-20
    Journal article

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    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.

  • Functional biopolymer-based matrices for modulation of chronic wound enzyme activities

     Francesko, Antonio; Soares da Costa, Diana; Reis, Rui Luís; Pashkuleva, Iva; Tzanov, Tzanko
    Acta biomaterialia
    Date of publication: 2012-10-13
    Journal article

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    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.

  • Enzymatic pre-treatment as a means of enhancing the antibacterial activity and stability of ZnO nanoparticles sonochemically coated on cotton fabrics

     Perelshtein, Ilana; Ruderman, Yelena; Perkas, Nina; Traeger, Kamelia; Tzanov, Tzanko; Beddow, Jamie; Joyce, Eadaoin; Mason, Timothy J.; Blanes, María; Mollá, Korina; Gedanken, Aharon
    Journal of materials chemistry B
    Date of publication: 2012
    Journal article

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  • Laccase-assisted formation of bioactive chitosan/gelatin hydrogel stabilized with plant polyphenols

     Rocasalbas Lozano, Guillermo; Francesko, Antonio; Touriño Eirin, Sonia; Fernández Francos, Xavier; Guebitz, Georg M.; Tzanov, Tzanko
    Carbohydrate polymers
    Date of publication: 2012-11-02
    Journal article

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    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.

    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.

  • Light harvesting amphiphiles boost the performance of lipase-based washing formulations

     Díaz Blanco, Carlos; Trifonov, Antoli; Georgiev, George; Tzanov, Tzanko
    Enzyme and microbial technology
    Date of publication: 2012-08-10
    Journal article

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  • Enzymatic functionalization of protein fibers to confer cationic dye absorption

     Gaffar Hossain, Kh. M.; Grabherl, Günter; Tzanov, Tzanko
    Melliand international
    Date of publication: 2012-03-31
    Journal article

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  • Hematoporphyrin-based amphiphiles boost the washing performance of protease-containing formulations in a biomimetic approach

     Díaz Blanco, Carlos; Trifonov, Antoli; Georgiev, G.; Tzanov, Tzanko
    Journal of molecular catalysis B. Enzymatic
    Date of publication: 2012-06
    Journal article

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  • Enzymatic pre-treament as a means of enhancing the antibacterial activity and stability of ZnO nanoparticles sonochemically coated on cotton fabrics

     Perelshtein, Ilana; Ruderman, Yelena; Perkas, Nina; Traeger, Kamelia; Tzanov, Tzanko; Beddow, Jamie; Joyce, Eadaoin; Mason, Timothy J.; Blanes, María; Mollá, Korina; Gedanken, Aharon
    Journal of materials chemistry B
    Date of publication: 2012-03-15
    Journal article

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    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.

  • Simultaneous hybrid chitosan/zinc oxide nanoparticles for imparting antimicrobial and UV protection to cotton fabrics using US

     Traeger, Kamelia; Touriño Eirin, Sonia; Tzanov, Tzanko
    E-MRS Fall Meeting
    Presentation's date: 2012-09-18
    Presentation of work at congresses

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  • Thiolation effect on the antibacterial activity of a low molecular weight chitosan: interactions with a bacterial membrane model

     Macedo Fernandes, Margarida Maria; Francesko, Antonio; Torrent Burgues, Juan; Tzanov, Tzanko
    E-MRS Fall Meeting
    Presentation's date: 2012-09-18
    Presentation of work at congresses

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  • A dual polyphenolic/zwitterionic coating prevents microbial biofilm formation on urinary catheters

     Diaz Blanco, Carlos; Tzanov, Tzanko
    E-MRS Fall Meeting
    Presentation's date: 2012-09-18
    Presentation of work at congresses

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  • Bioactive multilayer coatings for prevention of bacterial biofilm formation on indwelling medical devices

     Macedo Fernandes, Margarida Maria; Tzanov, Tzanko
    E-MRS Fall Meeting
    Presentation's date: 2012-09-18
    Presentation of work at congresses

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  • Enzymatic functionalization of chitosan with bakers yeast hexokinase

     Touriño Eirin, Sonia; Tzanov, Tzanko
    E-MRS Fall Meeting
    Presentation's date: 2012-09-20
    Presentation of work at congresses

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  • Ultrasound-induced formation of redox-responsive chitosan nancarriers

     Francesko, Antonio; Macedo Fernandes, Margarida Maria; Tzanov, Tzanko
    E-MRS Fall Meeting
    Presentation's date: 2012-09-20
    Presentation of work at congresses

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  • International Conference on Antimicrobial Research

     Macedo Fernandes, Margarida Maria; Diaz Blanco, Carlos; Tzanov, Tzanko
    International Conference on Antimicrobial Research
    Presentation's date: 2012-11-22
    Presentation of work at congresses

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