Direct electron transfer of trametes hirsuta laccase adsorbed at unmodified nanoporous gold electrodes

The enzyme Trametes hirsuta laccase undergoes direct electron transfer at unmodified nanoporous gold electrodes, displaying a current density of 28 mu A/cm(2). The response indicates that ThLc was immobilised at the surface of the nanopores in a manner which promoted direct electron transfer, in contrast to the absence of a response at unmodified polycrystalline gold electrodes. The bioelectrocatalytic activity of ThLc modified nanoporous gold electrodes was strongly dependent on the presence of halide ions. Fluoride completely inhibited the enzymatic response, whereas in the presence of 150 mM Cl-, the current was reduced to 50% of the response in the absence of Cl-. The current increased by 40% when the temperature was increased from 20 degrees C to 37 degrees C. The response is limited by enzymatic and/or enzyme electrode kinetics and is 30% of that observed for ThLc co-immobilised with an osmium redox polymer. (C) 2012 Elsevier B.V. All rights reserved

Direct electron transfer of bilirubin oxidase (Myrothecium verrucaria) at an unmodified nanoporous gold biocathode

Well defined mediatorless bioelectrocatalytic reduction of oxygen with high current densities of 0.8 mA cm(-2) was obtained on nanoporous gold electrodes modified with Myrothecium verrucaria bilirubin oxidase. A stable faradaic response was observed when the enzyme modified electrode was coated with a specifically designed electrodeposition polymer layer. The response of the enzyme electrode was only slightly inhibited by the addition of F-. (C) 2011 Elsevier B.V. All rights reserved

Charge pump design.

<p>Overall scheme of the charge pump design divided into different modules connected to electronics for sensing, sampling, and wireless radio transmission of data.</p

Bench-top device test.

<p>Photographs of the set-up for the bench-top device test, showing (A) the oxygen sensitive wireless self-powered biodevice, <i>i.e.</i> an EFC (electrochemical cell containing the anodes, 1, and cathodes, 2) connected to the wireless operational unit (white box, 3) and a control device (voltmeter, 4) and (B) a computer with the developed control software and receiver (CC2530 radio highlighted with the white arrow, 5), placed roughly 4 m from the device.</p

Wireless carbohydrate sensing.

<p>Recorded signal from the carbohydrate sensitive self-contained biodevice in buffers with varying lactose concentrations.</p

Wireless oxygen sensing.

<p>Recorded signal from the self-contained biodevice for oxygen monitoring in buffers with varying oxygen concentrations.</p