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  • Laccase-mediated functionalization of fibre-forming polymers [Elektronski vir]
    Kokol, Vanja ...
    Laccases (benzenediol/oxygen oxidoreductase, EC 1.10.3.2) are multi-copper-containing enzymes which reduce molecular oxygen to water and simultaneously perform one-electron oxidation of various ... substrates such as diphenols, methoxy-substituted monophenols and aromatic and aliphatic amines, generating reactive radicals which can further produce dimmers, oligomers and/or polymers via a covalent bond between C-C, C-O or C-N. In the contribution, different strategies for laccasemediated modification and/or functionalization of various fibre-forming polymers, being induced by radical reactions under mild reactions conditions are presented: i) chitosan-based fibres with different phenolic acids, yielding a product with synergistic antioxidant and antimicrobial properties. Phenolic acids were oxidized by laccase via oxyor carbon-radical intermediate, which showed tendency for further polymerization as well as coupling with nucleophilic chitosan amino group, depending on pH. ii) lignin of lignocellulosic fibres, being natural branched aromatic polymer, mainly consisted of three typical monolignol units (guaiacyl, syringyl and/or p-hydroxyphenyl) with specific reactive groups on aromatic ring, presenting reactive sites for grafting of functional phenolic molecules. iii) hydrophobic polyethersulfone (PES) polymers with phenolic molecules as e.g. 4- hydroxybenzoic acid (HB) to increase their chemical reactivity via C-O and C-C linkages. Different strategies to reveal the laccase-mediated oxidation kinetics of various substrates as well as their functionalization are presented: using cyclic voltammetry to follow the redox potentials of oxidation intermediates, using oximetry to follow the oxygen consumption in the course of laccase oxidation, and using capialary electrophoresis to follow produced intermediates. The efficacy of grafting and consequently the new functional molecules/groups created on polymers surfaces are confirmed by color measurement, FTIR or XPS analysis, and/or polyelectrolyte titration. Finally, laccase-mediated reactions are shown to be effectively at producing polymeric materials with specific or multi-functional properties such as colouration, antimicrobial, antioxidant, flame retardant and biocompatibility.
    Source: Proceedings [Elektronski vir] (Str. 90-96)
    Type of material - conference contribution ; adult, serious
    Publish date - 2012
    Language - english
    COBISS.SI-ID - 16341526

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