Biology Reference
In-Depth Information
8.3 Use of Metal Nanoparticles as Electrochemical Labels
Metal nanoparticles were first introduced as labels for DNA
sensing by Mirkin and coworkers [26] in 1996. The gold-labeled
ssDNA probes were used to detect complementary DNA targets
by a colorimetric method based on particle aggregation [26-28].
In 2000, Limoges and coworkers [29] became the first group
to use metal nanoparticle labels for electrochemical detection,
in an immunoassay. The group then extended this concept to
electrochemical DNA hybridization detection, based on labeling an
oligonucleotide with gold nanoparticles [30]. The assay, depicted
in Fig. 8.2, consisted of four steps: (a) passive adsorption of the
amplified target DNA on the walls of a polystyrene microwell, (b)
hybridizationwithanoligonucleotideprobeconjugatedtoanAu-NP,
(c) oxidative gold metal dissolution in an acidic bromine-bromide
solution, and (d) anodic stripping voltammetry (ASV, see Sec. 8.4)
detection of the released Au
3
+
ions at a screen-printed microband
electrode (SPMBE) immersed in the microwell. The combination
of the sensitive Au
3
+
determination at a SPMBE with the large
number of Au
3
+
ions released from each gold nanoparticle allowed
detectiondownto5pMofanamplifiedhumancytomegalovirusDNA
fragment.
In the same year (three months after Limoges' work was
published), Wang's group also reported a DNA hybridization assay
Figure 8.2.
DNA detection scheme based on the capture and dissolution
of individual gold nanoparticles, followed by voltammetric detection at
a screen-printed microband electrode. Taken with permission from [30],
L. Authier, C. Grossiord, P. Brossier, and B. Limoges,
Anal. Chem
.
73
, 4450-
4456 (2001). c
American Chemical Society.
