Biomedical Engineering Reference
In-Depth Information
Table 4.2
QDs ECL employed in the field of Aptamer biosensing
QD
Target
Linear range
References
CdSe/ZnS
AT P
0.018-90.72 mM
Huang et al. [
62
]
−
8
-8.0
×
10
−
7
M
CdSe-CdS
AT P
1.0
×
10
Jie et al. [
63
]
TiO
2
-N
Adenosine
10 nM-1.0 mM
Tian et al. [
64
]
−
1
CdSe-ZnS
Cancer cell
4
×
102-104 cells mL
Jie et al. [
65
]
CdS-ZnS
Cancer cell
60-1,000 cells
Jie et al. [
66
]
CdSe/ZnS
Lysozyme
/
Huang et al. [
67
]
CdSe/ZnS
Thrombin
27.2-545 nM
Chen et al. [
68
]
CdSe/ZnS
Thrombin
0.01-50 nM
Xie et al. [
69
]
−
1
CdSe
Thrombin
0-64
μ
g mL
Li et al. [
70
]
CdTe/SiO2
Thrombin
5.0 aM-5.0 fM
Shan et al. [
71
]
CdTe
Thrombin
0.5-800 pM
Huang and Zhu [
72
]
−
15
-1.0
×
10
−
13
M
CdS
Thrombin
1.0
×
10
Guo et al. [
73
]
Pb
2
+
−
10
-1.0
×
10
−
8
M
CdTe
2.0
×
10
Hai et al. [
74
]
In our group, using the QDs as the signal tranducers, a series of aptasensors
were developed for the detection of lysozyme [
67
], thrombin [
72
], and adenosine
5′-triphosphate (ATP) [
62
]. Through the aptamer-target-specific affinity and the
rules of Watson-Crick base pairing, aptasensors for lysozyme and ATP detection
were fabricated, respectively.
Take ATP detection as an example [
62
], after the thiol modified anti-ATP
probes were immobilized onto the pretreated Au electrode, ATP solution was
dropped for the formation of aptamer-ATP bioaffinity complexes. The biotin-
modified complementary DNA (biotin-cDNA, in terms of the probe) oligonucleo-
tides were hybridized with the remnant-free probes. At last, the avidin-modified
QDs were bound to the aptasensor through the biotin-avidin system in the exist-
ence of biotin-cDNA. The ECL intensity, as the readout signal for the aptasen-
sor, was responsive to the amount of QDs bonded to the cDNA oligonucleotides,
which was inversely proportional to the combined target analyte indirectly. Later,
Jie et al. [
63
] employed superstructural dendrimeric CdSe-CdS-QDs as the emit-
ter and successfully applied to amplified ECL assays of ATP using DNA cycle
amplification technique. The whole fabrication process was given in Fig.
4.5
.
Compared with the pure QDs, the superstructure exhibits highly enhanced ECL
signal and could be easily labeled, separated, and immobilized onto a magnetic
electrode.
In the case that thrombin owned two different aptamers, we ingeniously grafted
the concept of sandwich immunoreaction into the aptamer field and constructed a
sandwich aptasensor by using QDs ECL technique for thrombin detection [
72
]. The
thiol-terminated aptamer with 15 nucleotides (probe I) was first immobilized on Au
electrode, and then, thrombin and another 5′-biotin-modified aptamer (29 nucleo-
tides, probe II) were incubated to the above electrode, respectively, in order to form
the sandwich structure of probe I/thrombin/probe II. Streptavidin-modified QDs
(avidin-QDs) were bound to probe II via the biotin-avidin system. Thrombin was
