Biomedical Engineering Reference
In-Depth Information
600
500
R
2
= 0.9778
400
300
200
100
0
0
10
20
30
40
50
60
Concentration (ppm)
FIGURE 20.10
Calibration curve in the association phase (Biacore). This curve was constructed for IgE binding in the associa-
tion phase at concentrations from 5 to 50 ppm. Standard deviations were calculated based on three samples at 5
ppm, three at 10 ppm, and four at 20 ppm, giving a CV
ave
of 22%. Binding experiments at higher concentrations
were only carried out once to conserve reagents.
yet been optimized and is not sufficient for the detection of IgE in real samples. For meas-
urements of very low concentrations of target analyte to be feasible, a high association con-
stant of the aptamer and IgE is necessary. This constant is very much dependent upon the
three-dimensional stability of the aptamer and further developments in the design and
selection of theses aptamers needs to be made.
20.5
Future Prospects
If an aptasensor for the detection of IgE were to be developed for routine clinical use, the
aptamer selected would need to form a very stable complex with the target analyte to
withstand the numerous washing steps, which would be necessary for its detection in a
complex solution such as blood. Selection of an aptamer known to form a stable complex
with IgE when immobilized to a solid support would therefore appear to be necessary.
Further work would also be needed to test the aptamer in complex protein solutions
which would undoubtedly be necessary to develop an aptasensor capable of clinical appli-
cation.
The ultimate aim would be to develop allergen-specific IgE aptamers and incorporate
them into a commercially viable aptasensor that could be used by an individual to diag-
nose precisely to which allergen they are allergic.
References
(1)
Mayer G. 2004.
The structure and function of immunoglobulins
. Available at http:// www.
med.sc.edu:85/mayer/IgTypes2000.htm
(2)
Stefan R-I, van Staden J and Aboul-Enein H. 2000. Immunosensors in clinical analysis.
Fresenius
Journal of Analytical Chemistry
366: 659-668.
