Buckypaper-Bilirubin Oxidase Biointerface for Electrocatalytic Applications: Buckypaper Thickness

Area of Science:

• Electrochemistry
• Materials Science
• Biocatalysis

Background:

• Direct electronic communication between electrodes and biocatalysts is crucial for efficient fuel cells and electrochemical devices.
• Conductive carbon nanostructures, like carbon nanotubes, improve electrode surface area and electrocatalytic currents.
• Freestanding buckypapers offer a support-free electrode solution, enabling device miniaturization.

Purpose of the Study:

• To investigate the impact of buckypaper thickness on the electrocatalytic properties of bilirubin oxidase (BOD).
• To optimize electrode design for enhanced biocatalytic performance in energy applications.
• To understand electron transfer mechanisms within BOD immobilized on carbon nanotube buckypapers.

Main Methods:

• Preparation of freestanding carbon nanotube buckypapers with varying thicknesses (87 μm to 380 μm).
• Immobilization of bilirubin oxidase (BOD) onto buckypapers via hydrophobic and π-π interactions.
• Electrochemical characterization using cyclic voltammetry and chronoamperometry in oxygenated and deoxygenated buffers.

Main Results:

• Lower buckypaper thickness (<220 μm) yielded improved sigmoidal electrocatalytic currents compared to thicker buckypapers.
• Achieved oxygen reduction current density up to 3 mA cm^-2 without redox mediators.
• Distinguishable peaks for all copper sites (T1, T2, T3) of BOD were identified on the 87 μm buckypaper, revealing distinct electron transfer rates.

Conclusions:

• Buckypaper thickness significantly influences the electrocatalytic efficiency of immobilized BOD.
• Optimized buckypaper electrodes facilitate direct electron transfer, enhancing performance in biosensors and energy devices.
• Understanding the electron transfer dynamics of enzyme active sites is vital for designing advanced biocatalytic systems.