Biology Reference
In-Depth Information
Figure9.14.
Schematicrepresentationofgenosensordesign.Reproduced
with permission from Wiley InterScience [11].
This decrease could be because the amount of probe strand on
the electrode surface is too high so hampering the hybridization
reaction by stearic impediments and/or because high amounts of
strands on the electrode surface blocksthe electrodic surface.
The effect of the thiol group was tested using non labeled probe
strands following a similar procedure. In this case signals obtained
were significantly lower than those obtained with the thiol group,
and due to the unspecific adsorption ofthe probes.
S-AP concentration was also tested, comparing the analytical
signalobtainedwiththatobtainedduetounspecificadsorptionofS-
AP.Inthiscase,5
×
10
−
10
MofS-APwasthemaximumconcentration
where the unspecific adsorption was notobserved.
Once the parameters that affect the procedure had been studied,
acalibrationcurveforthebiotinylatedtargetstrandwasperformed.
The peak current was linear with the concentration of the target
strandintherangecomprisedbetween5and100pM.Thedetection
limit, calculated as the concentration corresponding to a signal that
is three times the standard deviation of the intercept, was found to
be4.6 pM.
In addition, and in order to test the stability of the genosensor,
and minimize the analysis time, the sensing phase was formed and
