Michaela Patila

Graphene-based nanobiocatalytic systems: recent advances and future prospects.

Graphene-based nanomaterials are particularly useful nanostructured materials that show great promise in biotechnology and biomedicine. Owing to their unique structural features, exceptional chemical, electrical, and mechanical properties, and their ability to affect the microenvironment of biomolecules, graphene-based nanomaterials are suitable for use in various applications, such as immobilization of enzymes. We present the current advances in research on graphene-based nanomaterials used as novel scaffolds to build robust nanobiocatalytic systems. Their catalytic behavior is affected by the nature of enzyme-nanomaterial interactions and, thus, the availability of methods to couple enzymes with nanomaterials is an important issue. We discuss the implications of such interactions along with future prospects and possible challenges in this rapidly developing area.

Graphene oxide derivatives with variable alkyl chain length and terminal functional groups as supports for stabilization of cytochrome c

In this study we report the ability of reduced and non-reduced graphene oxide-based nanomaterials (GONs), modified with variable alkyl chain length and terminal functional groups, to act as effective scaffolds for the immobilization of cytochrome c (cyt c) using different immobilization procedures. The GONs/cyt c conjugates are characterized by a combination of techniques, namely atomic force microscopy, X-ray photoelectron and FT-IR spectroscopies as well as thermo-gravimetric and differential thermal analysis. The effect of the structure of functional groups and the surface chemistry of GONs on the immobilization efficiency, the peroxidase activity and the stability of the cyt c was investigated and correlated with conformational changes on the protein molecule upon immobilization. The enhanced thermal stability (up to 2-fold) and increased tolerance (up to 25-fold) against denaturing agents observed for immobilized cyt c, indicates that these functionalized GONs are suitable as nanoscaffolds for the development of robust nanobiocatalysts.

Laccase-Functionalized Graphene Oxide Assemblies as Efficient Nanobiocatalysts for Oxidation Reactions

Multi-layer graphene oxide-enzyme nanoassemblies were prepared through the multi-point covalent immobilization of laccase from Trametes versicolor (TvL) on functionalized graphene oxide (fGO). The catalytic properties of the fGO-TvL nanoassemblies were found to depend on the number of the graphene oxide-enzyme layers present in the nanostructure. The fGO-TvL nanoassemblies exhibit an enhanced thermal stability at 60 °C, as demonstrated by a 4.7-fold higher activity as compared to the free enzyme. The multi-layer graphene oxide-enzyme nanoassemblies can efficiently catalyze the oxidation of anthracene, as well as the decolorization of an industrial dye, pinacyanol chloride. These materials retained almost completely their decolorization activity after five reaction cycles, proving their potential as efficient nano- biocatalysts for various applications.

Hybrid Nanomaterials of Magnetic Iron Nanoparticles and Graphene Oxide as Matrices for the Immobilization of beta-Glucosidase: Synthesis, Characterization, and Biocatalytic Properties

Hybrid nanostructures of magnetic iron nanoparticles and graphene oxide were synthesized and used as nanosupports for the covalent immobilization of β-glucosidase. This study revealed that the immobilization efficiency depends on the structure and the surface chemistry of nanostructures employed. The hybrid nanostructure-based biocatalysts formed exhibited a 2 to 4-fold higher thermostability as compared to the free enzyme, as well as an enhanced performance at higher temperatures (up to 70 °C) and in a wider pH range. Moreover, these biocatalysts retained a significant part of their bioactivity (up to 40 %) after 12 repeated reaction cycles.

Stabilization of Laccase Through Immobilization on Functionalized GO-Derivatives

This chapter deals with the use of functionalized derivatives of graphene oxide as nanoscaffolds for the immobilization and stabilization of laccase from Trametes versicolor. Covalent and noncovalent immobilization approaches are described, while a novel method for the development of laccase-based multilayer nanoassemblies is also presented. Various biochemical, spectroscopic, and microscopic techniques were applied to characterize the nanobiocatalytic systems in respect to their microstructure and catalytic performance. Laccase-GO nanosystems were characterized with FTIR spectroscopy in order to confirm the functionalization of the nanomaterials, as well as to interpret the nanomaterial-enzyme interactions, while the multilayer structure of laccase-based multilayer nanoassemblies was confirmed by atomic force microscopy. The nanobiocatalytic systems presented here demonstrated exceptional stability and reusability compared with the free enzyme form, leading to robust biocatalytic systems appropriate for various applications of industrial interest.