Nanoporous gold

The high surface areas of nanostructured electrodes can provide for significantly enhanced surface loadings of electroactive materials. The fabrication and characterization of nanoporous gold (np-Au) substrates as electrodes for bioelectrochemical applications is described. Robust np-Au electrodes were prepared by sputtering a gold–silver alloy onto a glass support and subsequent dealloying of the silver component.

>>>Nanoporous Gold Electrodes with Tuneable Pore Sizes for Bioelectrochemical Applications

In the recent paper, we were able to tune the pore size of np-Au via controlling the dealloy conditions in order to see their effects on the bioelectrochemical response of redox proteins was evaluated using cytochrome c as a model system.

np-Au based biosensors and biofuel cells have been developed in our group.

>>Immobilisation of redox enzymes on nanoporous gold electrodes: applications in biofuel cells

Diazonium salts can be electrochemically reduced on gold, resulting in monolayer or multilayer coverage depending on the chemical composition of the salt. After activation of carboxylic acid functional groups on the surface modified layer with carbodiimide, nucleophilic addition of primary amine groups on the surface of the enzyme can result in immobilisation in a manner that enables DET.

>> Robust and flexible nanoporous gold electrodes:

Nanoporous Gold Based Biofuel Cells on Contact Lenses

A lactate/O2 enzymatic biofuel cell (EBFC) was prepared as a potential power source for wearable micro-electronic devices. Mechanically stable and flexible nanoporous gold (NPG) electrodes were prepared using an electrochemical dealloying method consisting of a pre-anodization process and a subsequent electrochemical cleaning step. Bioanodes were prepared by the electrodeposition of an Os polymer and Pediococcus sp. lactate oxidase onto the electrode. The electrocatalytic response to lactate could be tuned by adjusting the deposition time. Bilirubin oxidase from Myrothecium verrucaria was covalently attached to a diazonium modified NPG surface. A flexible EBFC was prepared by placing the electrodes between two commercially available contact lenses to avoid direct contact with the eye.

>>A quasi-solid-state and self-powered biosupercapacitor based on flexible nanoporous gold electrodes

A quasi-solid-state and flexible biofuel cell using a hydrogel electrolyte preloaded with sugar as a fuel is described. The device can function as a self-powered biosupercapacitor delivering pulses for over 600 cycles, with a power density over 10 times higher than that from the biofuel cell alone.