Environmental Engineering Reference
In-Depth Information
plasmon resonance (SPR)-based sensor can be increased. Several different mate-
rials are also used to support AuNPs such as optical fibres, ITO glass, sol-gel matrix
for the detection of human IgG [
50
], streptavidin [
51
], interleukin-1
[
52
] and
propanethiol [
53
]. Similarly, waveguide-mode sensor, which mimic the principle of
SPR, has been generated with higher sensitive sensing using AuNP conjugation for
the detection of influenza viruses [
10
-
12
].
β
11.5 Sensing Applications of AuNPs
11.5.1 Detection of Proteins
The state of a disease can be diagnosed by detecting the presence of certain
biomarkers related to the disease. In this case, AuNP-based detection can play an
important role for the detection of the target protein. In one example, AuNP was
utilized for the detection of
Ricinis communis
agglutinin (RCA120), with a detec-
tion sensitivity of 1 ppm [
54
]. In a fluorescent-based competition analyses, the
binding affinity of the protein (Lectin Con A) against lyconanoparticles (AuNPs
conjugated with underivatized mono-, oligo- and polysaccharides) was determined
[
50
]. A wide range of additional protein biomarkers have been detected besides
cancer biomarkers, including cholera toxin [
55
], inter-leukin [
56
] vascular endo-
thelial growth factors [
57
], Annexin II and MUC5AC antigens [
58
], antigens of
Schistosoma japonicum
[
59
],
Salmonella typhi
[
60
,
61
],
Escherichia coli
O157:H7
[
62
] and osteoprotegerin [
63
]. AuNP-based electrochemical sandwich
immunosensor was designed for the detection of fenolase (ENO1) antigen, a
potential diagnostic marker for lung cancer, with a detection limit of 11.9 fg [
64
].
11.5.2 Detection of DNA
Detection of DNA is very amenable with the AuNP-based sensor, as the formation
of duplex between the target and the probe DNA can also impart changes on the
degree of AuNP aggregation. Lee and colleagues have designed a single nucleotide
polymorphism (SNP)-based analysis for the genotyping of rs2131877 that is located
at human chromosome 3q29. In this study, oligonucleotide complementary to the
target DNA was hybridized to the PCR product from human DNA. Formation of the
complementary DNA sequence between the oligonucleotide and the PCR product
will not be absorbed onto the surface of AuNP. This causes the Na
+
to induce the
aggregation of the nanoparticles. However, if there is a single-mismatch nucleotide,
the formation of the complementary dsDNA will be prevented, causing the Na
+
to
be absorbed onto the surface of the AuNPs, stabilizing the nanoparticles against the
aggregation action Na
+
. In another approach, S1 nuclease was adopted and this
