Biology Reference
In-Depth Information
Figure 2.7.
The electrochemical detection system for oxyteracycline
(OTC)using aptamer-immobilized interdigitated array (IDA)gold electrode
chip. Left: An IDA gold electrode chip and the IDA gold electrode. Right: A
typical electrochemical reaction occurring after aptamer binds to its target
molecole.
A very interesting biosensor was developed based on a similar
principleforthedetectionofcancercells[34].Theaptamerselected
for acute leukaemia cells was fixed onto a gold electrode and elec-
trochemical impedance spectroscopy (EIS) technique was used to
characterizethesurfacewith[Fe(CN)
6
]
3
−
/
4
−
asaredoxprobe.Upon
binding of the aptamer-modified electrode with leukaemia cells,
the electron-transfer resistance of [Fe(CN)
6
]
3
−
/
4
−
on the sensor
surface increased substantially. A linear relationship was observed
between the electron-transfer resistance and the concentration of
the leukaemia cells in a range 1
×
10
4
to 1
×
10
7
cells/mL with a
detection limitof 6
×
10
3
cells/mL and high selectivity.
2.8 Electrochemical Aptasensors Based on the Aptamer
Conformational Changes
Aptamers bind their targets through adaptive recognition; in solu-
tionaptamersareunstructured,butfolduponassociatingwiththeir
molecular targets into molecular architectures in which the ligand