Functional DNA-Integrated Nanomaterials for Biosensing - DNA Nanotechnology: From Structure to Function - page 270

Fig. 13.1 ( a ) Target DNA-induced aggregation of DNA-modified AuNPs. ( b ) The colorimetric
response for DNA-modified AuNPs after adding target DNA (Reprinted with the permission
from Ref. [ 31 ]. Copyright 2003 American Chemical Society). ( c ) Secondary structure of the
Pb 2C -specific DNAzyme. ( d ) The substrate is cleaved into two pieces in the presence of Pb 2C .
Pb 2C -directed assembly of DNAzyme-linked AuNPs aligned in a head-to-tail ( e ) or a tail-to-tail
manner ( f ). ( g ) For head-to-tail aligned AuNP aggregates, the DNAzyme is inactive, and Pb 2C
cannot induce disassembly of the AuNPs. ( h ) For tail-to-tail aligned aggregates, Pb 2C can induce
DNAzyme cleavage and color change can be observed. In this case, adding invasive DNA can
significantly increase the rate of color change (Reprinted with the permission from Ref. [ 34 ].
Copyright 2005 American Chemical Society)
strand with a cleavage site in the middle (Fig. 13.1 c). Pb 2C can specifically induce
the enzyme to cleave the substrate into two pieces (Fig. 13.1 d). For the colorimetric
sensor design, the substrate strand was extended on both ends to allow it to hybridize
with DNA-modified AuNPs in a head-to-tail configuration (Fig. 13.1 e). The AuNPs
can be linked together by the substrate DNAs to form aggregates, which appeared
blue in color. When the system was heated to 50 ı C, the AuNPs disassembled