Gold nanoparticles as electronic bridges for laccase-based biocathodes

Area of Science:

• Electrochemistry
• Nanotechnology
• Biocatalysis

Background:

• Direct electron transfer (DET) between redox enzymes and electrodes is crucial for biosensor and biofuel cell applications.
• Optimizing DET requires oriented immobilization of enzyme molecules onto electroactive surfaces.
• Functionalized gold nanoparticles (AuNPs) offer a promising platform for enzyme immobilization and electron mediation.

Purpose of the Study:

• To develop a direct electron transfer-based laccase (Lc) cathode for efficient oxygen electroreduction.
• To achieve oriented immobilization of Lc molecules onto functionalized AuNPs for enhanced DET.
• To investigate the electrocatalytic performance of the nanostructured enzymatic electrode at low overpotentials.

Main Methods:

• Step-by-step covalent attachment of AuNPs and Lc molecules to porous graphite electrodes.
• Utilized diazonium salt reduction strategy for electrode modification.
• Employed oriented immobilization of Lc on functionalized AuNPs via their Cu T1 site.

Main Results:

• A stable, nanostructured enzymatic electrode was successfully fabricated.
• Oriented Lc immobilization facilitated very fast DET with the electrode.
• Oxygen electroreduction exhibited two catalytic contributions, with one at low overpotentials attributed to efficiently wired Lc molecules (k(0) ≫ 400 s(-1)).

Conclusions:

• The developed strategy enables highly efficient direct electron transfer for laccase-based oxygen electroreduction.
• Oriented immobilization on functionalized AuNPs is key to achieving low overpotential electrocatalysis.
• This approach holds promise for advanced electrochemical devices utilizing redox enzymes.