Gold Electrodes for Detection of Enzyme Assays with 3‐Indoxylphosphate as Substrate

Abstract

The advantageous characteristics of gold not only for its electrochemical behavior but also for the unique adsorptive protein characteristics are the basis of this paper. 3-Indoxyl phosphate (3-IP) has previously been demonstrated to be a very convenient substrate for the electrochemical detection, using carbon-based electrodes, of enzymeimmunoassays (EIAs) that employ not only alkaline phosphatase (AP) but also horseradish peroxidase (HRP) as label. Combination of both: gold electrodes and 3-IP has not been studied and it produces a very suitable detection for EIAs. The electrochemical behavior of indigo, product of the enzymatic hydrolisis of 3-IP, has been thoroughly studied for the first time on disk and band gold electrodes. The possibility of electrodepositing gold on the bands and automation has also been considered. The detection has been applied for the determination of osteocalcin with an HRP-based ELISA (enzyme-linked immunosorbent assay).

Electrochemical characterization of different screen-printed gold electrodes

“…Indigo carmine (IC) is the sulphonated product that can be used with characterization purposes. The electrochemical behaviour of IC has been previously studied on gold electrodes: disk and band [30]. In 0.1 M H 2 SO 4 it presents two anodic processes as shown in Fig.…”

Oriented immobilisation of anti-pneumolysin Fab through a histidine tag for electrochemical immunosensors

“…Addition of concentrated sulphuric acid stops the enzymatic reaction and produces indigo blue solubilisation. The electrochemical behaviour of indigo blue on gold films has been previously studied (Castaño-Álvarez et al, 2004). From the two processes that present this molecule, the first one has been chosen since it is reversible and appears at low potentials.…”

Chapter 26 Thick- and thin-film DNA sensors

“…Moreover, compared with other substrates, kinetic constants resulted more favourable. The electrochemical behaviour of IC on gold electrodes has been studied [52].…”