Wiring Gold Nanoparticles and Redox Enzymes: A Self‐Sufficient Nanocatalyst for the Direct Oxidation of Carbohydrates with Molecular Oxygen

Abstract

The development of artificial nanocatalysts, especially those incorporating the highly active biocatalysts (enzymes) present in nature, is a rapidly developing field in nanocatalysis and nanomaterials science. Dehydrogenases are exceptionally attractive, as they catalyze the oxidation of various cheap/common substrates to more expensive and desired products. However, their use in sustainable catalysis and/or their incorporation in advanced nanomaterials with catalytic functions are limited owing to one immense problem that can be formulated as a question: how can the electrons received from the oxidized substrate be removed? Here, a solution to this problem is demonstrated: we designed a unique nanomaterial composed of two redox enzymes (nonspecific glucose dehydrogenase and oxygen‐reducing laccase) and gold nanoparticles. Both enzymes were wired through the gold nanoparticles (10 nm) and direct electrochemical “communication” was achieved, allowing electron transfer from the redox center of glucose dehydrogenase to a copper center of laccase. As a result, self‐sufficient nanocatalysts were synthesized and shown to oxidize various carbohydrates directly with molecular oxygen.

Characterization of a Yellow Laccase from Botrytis cinerea 241

“…1.10.3.2) oxidize a great variety of aromatic compounds [ 1 , 2 ]. They can be applied for wide industrial applications: organic synthesis, biosensor construction, biofuel cells development, biomass valorization, and xenobiotic biodegradation [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. Typical laccases have four copper atoms, which form three different copper centers (type T1, T2 and T3) [ 13 , 14 ].…”

Nanocatalysts Containing Direct Electron Transfer-Capable Oxidoreductases: Recent Advances and Applications

“…Thus, it is important, when designing enzymatic nanocatalysts, to choose "pH compatible" enzymes, to ensure maximal activity of the newly formed nanocatalysts. For example, Ratautas et al [118] and Gružauskaitė et al [120] used GDH and LAC, which had similar activity dependence on pH ( Figure 5D). Thus, newly formed catalysts were relatively active in a solution that had a pH value relatively suitable for both oxidoreductases.…”

“…In this regard, our group has recently published a study, where metallic nanoparticles and DET-capable enzymes were incorporated, producing novel nanocatalysts [118]. In this work, efforts were made to produce a clean and efficient synthetic route towards the production of highly desired and economically valuable aldonic acids (e.g., lactobionic acid) [119].…”

“…Briefly, the redox potential of the reduction half-reaction must be more positive than the oxidation half-reaction for a process to occur [86,117]. The standard redox potentials at pH 7.0 and 25 °C for some catalytically relevant half-reactions are given in Figure 10 From Figure 10, one can see the importance of oxygen reduction reaction (ORR) [118]. Because oxygen reduction has a very high thermodynamic potential at pH 7.0, this process is sufficient to drive many other catalytically relevant reactions, and thus it comes as a no surprise why multicopper oxidases are usually used for biocathodes in biofuel cells.…”

Amplification of surface-enhanced Raman scattering by the oxidation of capping agents on gold nanoparticles

“…2,[16][17][18][19] These studies are particularly promising considering recent advances in redox "nanozymes" researchthese are biomolecule-nanoparticle complexes that display the catalytic or electron transfer properties of metal nanoparticles. [20][21][22] For SERS-controlled studies of redox reactions over a broad concentration range, high enhancement factors are required. The enhancement factor in its turn crucially depends on the accessibility of gold nanoparticle surfaces for the reactants or reaction products.…”