Biology Reference
In-Depth Information
Figure 2.8.
(a) The microfluidic electrochemical aptamer-based sensor
chip. (b) The syringe pumps connected to a four-input, single-output mul-
tiplexed valve. (c)The detection mechanism of the switch on sensor.
2.9 Electrochemical Aptasensors Based on
Target-Induced Aptamer Displacement
This type of biosensor took advantage of the strong a
nity of the
aptamer for its specific analyte and used a competition scheme as
the detection methodology [6].
In the target-induced strand displacement strategy, the aptasen-
sor is usually assembled by fixing a complementary DNA-aptamer
duplex on an electrode (Fig. 2.9). Upon binding to their target mole-
cules, the aptamers or complementary DNA are displaced from the
electrode,resultinginasignificantchangeintheelectrochemicalsig-
nal. This strategy is particularly interesting since it is easy to gener-
alize for any aptamer without prior knowledge of its secondary or
tertiary structure, and it is well suited for the development of elec-
trochemical aptasensors.
This approach has been adopted for the development of biosen-
sorsforthedetectionofdifferenttargetsandsomeexampleswillbe
presented here.
Faradic impedance spectroscopy (FIS) was the electrochemi-
cal technique used in an aptasensor for the detection of lysozyme
[48]. The duplex formed by the lysozyme aptamer and a partial
