Environmental Engineering Reference
In-Depth Information
Fig. 11.1 Thiolation on
probes. Both antibody and
aptamer are shown as the
probe. Chemical structure
of 16-mercapto
hexadecanoic acid is shown
Fig. 11.2 Representation of SELEX cycle. SELEX process involves the following steps. (1) Incu-
bation of random oligonucleotide pool with the target molecule; (2) Separation of bound from
unbound nucleic acids; (3) Elution of the bound nucleic acids; (4) Amplification of the bound
nucleic acids; (5) ssDNA or RNA generation for next cycle
11.3.1.1 Colorimetric Assay
The main feature of this AuNP-based colorimetric biosensing is the differential
colour production in the presence or absence of the target. In the presence of the
target that affects the interparticle distance, well-dispersed AuNP particles harness
red colour while aggregated AuNP particles produce blue or purple colour
(Fig.
11.3
). Another advantage of AuNP is the ability of the Au atoms on the
AuNPs
surface to interact with the nitrogenous bases of ssDNA/RNA, enabling
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