Biomedical Engineering Reference
In-Depth Information
Fig. 4.3 a
ECL-potential curves and cyclic voltammograms (
CVs
) of the gGQDs (
1
,
3
) and
background (
2
,
4
) with concentration of 20 ppm in 0.05 M Tris-HCl (pH 7.4) buffer solution
containing 0.1 M K
2
S
2
O
8
. Scan rate: 100 mV s
−
1
.
b
PL (
λ
ex
=
340 nm) and ECL spectra for
the gGQDs-K
2
S
2
O
8
system.
c
ECL-potential
curves of the background
(
1
) and bGQDs (20 ppm)
(
2
,
3
) in 0.05 M Tris-HCl (pH 7.4) buffer solution containing 0.1 M K
2
S
2
O
8
. Reprinted with per-
mission from Ref. [
50
]. Copyright 2012 Wiley
radicals could react with GQDs
·−
via electron-transfer annihilation,
producing an excited state (GQDs*) that finally emitted light, which could be
described as the following equations:
·−
Then, SO
4
→
nGQDs
·−
(4.29)
GQDs + ne
−
S
2
O
8
2
−
+
E
−
→
S
2
O
8
·
2
−
(4.30)
S
2
O
8
·
2
−
→
SO
4
2
−
+ SO
4
·−
(4.31)
GQDs
·−
+ SO
4
·−
→
GQDs
∗
+ SO
4
2
−
(4.32)
GQDs
∗
→
GQDs +
HV
(4.33)
4.2 QDs ECL for DNA Biosensing
The combination for the sensitive ECL detection with extremely selective biological
interaction between DNA/aptamer-probe assays has attracted more and more inter-
est over the past years. ECL allows the detection of analytes at low concentrations
over a wide linear range. What is more, ECL could combine with many other analyt-
ical methods such as high-performance liquid chromatography (HPLC), liquid chro-
matography (LC), capillary electrophoresis (CE), and flow injection analysis (FIA).
4.2.1 QDs ECL for DNA Analysis
QD ECL technique was widely used in the field of DNA biosensing. Various QDs
of CdTe [
51
,
52
], CdS [
53
,
54
], and their composites [
55
-
59
] were employed as
