Fabrication and Characterization of Ultrathin-ring Electrodes for Pseudo-steady-state Amperometric Detection.

The fabrication of ultrathin-ring electrodes with a diameter of 2 mm and a thickness of 100 nm is established. The ultrathin-ring electrodes provide a large density of pseudo-steady-state currents, and realize pseudo-steady-state amperometry under quiescent conditions without a Faraday cage. Under the limiting current conditions, the current response at the ultrathin-ring electrode can be well explained by the theory of the microband electrode response.

Characteristics of fast mediated bioelectrocatalytic reaction near microelectrodes.

The pseudo-steady-state current due to a mediated enzymatic reaction on a microelectrode is characterized on the basis of theoretical analysis and numerical simulation. The steady-state current is proportional to substrate concentration when the enzymatic reaction is considerably faster than substrate mass transport via nonlinear diffusion. Under such conditions, the reaction plane, where the mass flow of the substrate is converted to that of the mediator, exists near the electrode surface.

Diffusion-controlled detection of glucose with microelectrodes in mediated bioelectrocatalytic oxidation.

This paper describes a diffusion-controlled electrolysis of glucose with mediated bioelectrocatalysis at microdisk-electrodes. Under conditions of an extremely fast enzyme reaction, compared with the diffusion of glucose, the current in potential-step chronoamperometry reaches an almost steady state within 10 s, and is proportional to the glucose concentration. The current can be detected at +0.

Nano-molar level hydrogen peroxide detection by horseradish peroxidase adsorbed cup-stacked carbon nanotube electrodes and applications to L-glutamate detection.

We have developed a simple fabrication method of a highly sensitive direct electron transfer-type electrochemical biosensor for hydrogen peroxide by use of cup-stacked carbon nanotubes (CSCNTs). The CSCNTs, formed by stacking of cup-shaped carbon units, has larger internal space and more hydrophilic edges, thanks to the presence of functional groups containing oxygen (e.g.