Biomedical Engineering Reference
In-Depth Information
Citrate-coated AgNPs have been used as SERS substrate to determine the
sequence of the DNA/RNA mononucleotides in the presence of MgSO
4
.
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The
AgNPs were directly added to the solution containing mononucleotides with-
out any modifications. Aggregation of the AgNPs was induced by the cation
Mg
2+
and mononucleotides existing at the gap between the AgNPs exhibited the
enhanced Raman signal that showed a detection limit at parts per million level
that resulted in in situ detection of biomacromolecules.
SERS has been used for detection of chemical and biological species at the
single-molecule level.
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AuNP and AgNP have optical properties that make
them useful as tags in a wide variety of measurement schemes including SERS
in glass-coated nanotags for a lateral flow immunoassay kit.
SERS-active platform to simultaneously detect multianalytes in a single bio-
assay had also been developed using Ag micropad on a silicon surface.
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The
silicon surface was functionalized with a mixture of three different aptamers
that specifically bound to the three proteins: human α-thrombin, platelet-derived
growth factor-BB, and immumoglobulin E. After each protein was specifically
captured by the respective aptamers bound on the silicon surface, three differ-
ent Raman reporter-labeled AgNPs were incubated in the aptamer-modified Ag
micropad forming the aptamer-Ag micropad/protein/Raman reporter-AgNP
sandwich architecture. The SERS sensor yielded a limit of detection of 100 pM.
4.7.1.6 Inductively Coupled Plasma Mass Spectrometry
Inductively coupled plasma mass spectroscopy (ICPMS) is one of the most
powerful methods for qualitative and quantitative trace element detection but
this technique has not been deeply explored for NMs. Merkoci explored ICPMS
to detect the NM tracer for DNA analysis.
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Not only can ICPMS be used for
detecting NMs in DNA analysis, it can also be used as a transducer for protein
analysis involving NM tracers.
The possibility of using the large diversity of available antibodies and their
many epitope sequences makes ONT-peptide conjugates good candidates for
the directed assembly of complex NMs. The DNA modification via peptide
method and consecutive antigen/antibody reaction can be even used for devel-
oping multiple genosensor platforms based on the same label. Moreover, this
approach can solve the problem of nonspecific adsorption coming from the lim-
ited available attachment mechanisms such as biotin-streptavidin or covalent
reactions used to label the DNA strands. The proposed method is a general one
with a broad range of application possibilities offered by metallic labels easily
to be detected by the ICPMS technique.
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4.7.2 Electronic Nanobiosensors
In this section, several nanobiosensors based on electronic properties of NMs
are presented. The electronic properties of NMs are based on their unique size
and atomic assembly that can be harnessed for nanobiosensors applications.
