Biomedical Engineering Reference
In-Depth Information
1.4
1.0
1.2
0.5
1.0
0.0
0 5 10 15 20
Paraoxon concentration (ppm)
0.8
0.6
0.4
O
CH
3
CH
2
O
CH
3
CH
2
O
P O
NO
2
0.2
0.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Paraoxon concentration (ppm)
FIGURE 1.17
Calibration curve for paraoxon inhibitor using the alkaline phosphatase biosensor created by assembling Str-Alk
phosphatase onto the biotinylated polymer as presented in Figure 1.15. The conditions of 0.4 mM CSPD and 10%
enhancer were used as described in Ref. (44). Insets display the higher concentration range of paraoxon inhibition
effects as well as the chemical structure of paraoxon. Reprinted with permission from Pande, R., Kamtekar, S.,
Ayyagari, M.S., Kamath, M., Marx, K.A., Kumar, J., Tripathy, S.K., Kaplan, D.L. (1996). A Biotinylated
Undecylthiophene Copolymer Bioconjugate for Surface Immobilization: Creating an Alkaline Phosphatase
Chemileuminescence-Based Biosensor.
Bioconjugate Chem.
7:159-164. Copyright (1996) American Chemical Society.
the electrode potential and therefore selectivity over the analyte species to be quantitated,
typically by the current detected at the electrode. Another is that the electrochemical sens-
ing via potential control is confined to the electrode surface. And the electrode itself may be
whatever geometry and size is required, including microscale to nanoscale dimensions. As
a result, electrochemical methods are an attractive methodology for creating biosensors.
They provide an additional advantage in that electropolymerization is possible upon an
electrode, allowing the creation of thin polymeric films from monomers in solution through
controlled electron transfer. Such films can be utilized for both immobilization of biological
elements as well as the underlying signal transduction process of the biosensor, where elec-
tron transfer can be employed to generate a signal dependent upon analyte concentration.
Electrochemical-based biosensors were some of the earliest types of biosensors commer-
cialized (52,53). A good example is the glucose sensor developed for monitoring blood
glucose levels in diabetic and prediabetic patients. In the Center for Intelligent
Biomaterials, we have carried out basic studies of the electropolymerization of thin films,
as well as employed strategies utilizing these films and electrochemical signal transduction
in a number of studies of different biosensor systems. We describe some of these systems
in the following sections.
