Biomedical Engineering Reference
In-Depth Information
Glucose
Gluconolactone
Glucose oxidase
(GOx)
O
2
H
2
O
2
OH
-
Prussian Blue (PB)
Transducer
Figure 12.6
Detection scheme for a Prussian Blue (PB)-modii ed electrode in
immunosensing. Glucose oxidase-labeled antibody converts glucose to gluconolactone on
the electrode surface. Secondary to this reaction is the production of hydrogen peroxide that
can be reduced amperometrically at low applied overpotentials, electrocatalyzed by the PB
.
being recommended for the development of enzymatic biosensors based
on oxidases, for working with microvolumes and for decentralized
assays.
12.4.1
Prussian Blue and Analogues Enzyme System
Due to the electrocatalytic properties of PB toward the reduction of H
2
O
2
at mild applied potentials (see
Figure 12.6
) most of the enzymes employed
with this approach have been oxido-reductases [11]. However, the recent
discovery of more generic electrocatalytic properties of PB for other com-
pounds [12] has led to new classes of enzymes being incorporated into
biosensors, such as hydrolases (
e.g.
, acetylcholinesterase and butyrylcho-
linesterase) (see
Section 12.4.1.8
).
12.4.1.1 Glucose Oxidase
Glucose oxidase enzyme (GOx) (EC 1.1.3.4) is an oxido-reductase that
catalyses the oxidation of glucose to H
2
O
2
and D-glucono-δ-lactone. In
cells, it aids in breaking the sugar down into its metabolites. It is highly
selective for β-D-glucose and does not act on α-D-glucose. GOx, which is
ot en extracted from
Aspergillus niger
, is widely used for the determination
