Modulation of quinone PCET reaction by Ca2+ ion captured by calix[4]quinone in water.

Calix[4]arene-triacid-monoquinone (CTAQ), a quinone-containing water-soluble ionophore, was utilized to investigate how proton-coupled electron transfer (PCET) reactions of quinones were influenced by redox-inactive metal ions in aqueous environment. This ionophoric quinone derivative captured a Ca(2+) ion that drastically altered the voltammetric behavior of quinone, showing a characteristic response to pH and unique redox wave separation. Spectroelectrochemistry verified significant stabilization of the semiquinone, and electrocatalytic currents were observed in the presence of Ca(2+)-free CTAQ.

Glucose sensor based on glucose oxidase immobilized by zirconium phosphate.

Amperometric glucose sensors were fabricated using glucose oxidase (GOx) entrapped in zirconium hydrogenphosphate (ZrP), and their performance was evaluated. Reportedly, alpha-ZrP is one of the candidates that are expected to improve the stability of enzymes immobilized on solid surfaces. We intercalated GOxs into ZrP (GOx/ZrP), cast the GOx/ZrP suspension in polyvinylalcohol on a platinum electrode, and dried it in a vacuum oven.

An iridium oxide reference electrode for use in microfabricated biosensors and biochips.

In this paper we argue for the use of iridium oxide (IrO(x)) electrodes as quasi-reference electrodes in microfabricated biosensors and biochips that operate in buffered solutions. The simple microfabrication of these electrodes consists of a one-step electrodeposition of IrO(x) onto a microfabricated platinum (Pt) electrode. The IrO(x) electrode potential was found to vary less than 20 mV over 9 days after stabilization for 1 day in a phosphate-buffered saline (PBS) solution; this behavior of the electrode potential was found to be easily reproduced.

In vitro and short-term in vivo characteristics of a Kel-F thin film modified glucose sensor.

A new outer layer composition, consisting of polytetrafluoroethylene (PTFE), Kel-F oil, and Nafion, is suggested to minimize the detrimental effect of dissolved oxygen and to extend the linear response range of a glucose oxidase(GOx)-based sensor using nonconducting polymer. The morphology of Kel-F/PTFE/Kel-F/Nafion polymeric laminate was followed during fabrication by SEM. When Kel-F film was formed on the PTFE outer layer, the linear response was extended to 21 mM, at a sensitivity of 2.

In vivo calibration of the subcutaneous amperometric glucose sensors using a non-enzyme electrode.

A new two-point calibration method for the subcutaneous amperometric continuous glucose sensor is reported. The proposed method is based on direct measurement of the background current (I(o)) using a non-enzyme electrode. For in vivo test, three electrodes were implanted in rabbits.