Browsing by Author

  • Publication
    Efficient decolorization of recalcitrant dyes at neutral/alkaline pH by a new bacterial laccase-mediator system
    (Academic Press, 2021-07-01)
    Coria-Oriundo L.L.
    ;
    Battaglini F.
    ;
    Wirth S.A.
    Laccases and laccase-mediator systems (LMS) are versatile catalysts that can oxidize a broad range of substrates coupled to the sole reduction of dioxygen to water. They possess many biotechnological applications in paper, textile, and food industries, bioethanol production, organic synthesis, detection and degradation of pollutants, and biofuel cell development. In particular, bacterial laccases are getting relevance due to their activity in a wide range of pH and temperature and their robustness under harsh conditions. However, the enzyme and the redox mediator's availability and costs limit their large-scale commercial use. Here we demonstrate that β-(10-phenothiazyl)-propionic acid can be used as an efficient and low-cost redox mediator for decolorizing synthetic dyes by the recombinant laccase SilA from Streptomyces ipomoeae produced in E. coli. This new LMS can decolorize more than 80% indigo carmine and malachite green in 1 h at pH = 8.0 and 2 h in tap water (pH = 6.8). Furthermore, it decolorized more than 40% of anthraquinone dye remazol brilliant blue R and 80% of azo dye xylidine ponceau in 5 h at 50 °C, pH 8.0. It supported at least 3 decolorization cycles without losing activity, representing an attractive candidate for a cost-effective and environmentally friendly LMS functional at neutral to alkaline pH.
  • Publication
    Flexible conducting platforms based on PEDOT and graphite nanosheets for electrochemical biosensing applications
    (Elsevier B.V., 2020-09-30)
    Scotto J.
    ;
    Piccinini E.
    ;
    von Bilderling C.
    ;
    Coria-Oriundo L.L.
    ;
    Battaglini F.
    ;
    Knoll W.
    ;
    Marmisolle W.A.
    ;
    Azzaroni O.
    Carbon nanomaterials are usually employed for improving the electrical and electrochemical properties of conducting polymer electrodes. However, low-cost of production, scalable simple procedures and adequate integration of the components at the molecular level within the composites become a challenge when dealing with real life applications. In this work, we present a novel strategy for producing graphite nanosheets (GNS) dispersed in the solvent employed then for the chemical synthesis of PEDOT, which allows producing composite nanofilms on plastic substrates for the construction of transparent and flexible all-polymer electrodes. By an optimized experimental procedure, we achieved a proper integration of PEDOT and GNS within ultrathin (<100 nm) composite films and good enough conductivity to ensure adequate electrochemical response without the requirement of conducting base electrodes. We tested the performance of these platforms for real applications by developing glucose biosensors by molecular integration of supramolecular assembly of glucose oxidase and an electroactive polyelectrolyte on top of the PEDOT-GNS coatings. The incorporation of GNS does not only improve the voltammetric response of the resulting all-polymer electrodes but also produces a better integration of the electrochemically active assembly.
  • Publication
    Functionalized hierarchical wrinkled-silica spheres for laccases immobilization
    (Springer, 2021-02-01)
    Fuentes K.M.
    ;
    Coria-Oriundo L.L.
    ;
    Wirth S.
    ;
    Bilmes S.A.
    Functionalized mesoporous SiO2 are common supports for some enzymes of industrial interest, such as laccases. However, the incorporation of specific functionalities and the loading of enzymes with dimensions close to the diameters of the pores obstructs the porous system. For biotechnological applications, tailored porous supports are still needed to enhance the laccase loading. The hierarchical meso/macroporous system in wrinkled-SiO2 spheres (w-SiO2) is a suitable option to overcome this issue. Herein, (3-aminopropyl) triethoxysilane and glutaraldehyde were use as functionalizing agents for the immobilization of laccase on w-SiO2. The functionalization occurs in the mesopores of the wrinkled walls and the preservation of the macroporous entries facilitates the diffusion of the laccase inside the particle. The enzyme performance was evaluated by means of the crystal violet bleaching. The enzyme is stabilized through the imine groups provided by glutaraldehyde, allowing the retention of the activity after several reaction cycles. The bleaching can be boosted by acetosyringone, highlighting the possibility of using redox mediators to expand the range of oxidizable substrates. Understanding the effect of w-SiO2 functionalization on laccases loading and performance could be extrapolated to other enzymes with biotechnological interest that requires this type of hierarchical porous silica.