Biology Reference
In-Depth Information
the DNA backbone, giving a clear hybridization detection signal by
differential pulse voltammetry.
Electrochemical DNA biosensors were also prepared using
carbon nanotube-polymer hybrids in combination with gold
nanoparticles. Composite materials based on integration of CNTs
and polymers have gained growing interest because they possess
the properties of each component with a synergistic effect. In a
recent report [23],
p
-aminobenzoic acid (PABA), which contains
electron-rich N atom and high electron density of carbonyl group,
was electrodeposited by cyclic voltammetry on the surface of a
multiwalled carbon nanotube-modified glassy carbon electrode.
Gold nanoparticles were subsequently electrodeposited onto the
surfaceofthePABA/MWNTscompositefilm,andtheprobeDNAwas
immobilizedon the surface ofAu-NPsthrough an Au-S bond.
4.2.5
Avidin-Biotin A
nity Reactions
Electrochemical detection of bioa
nity interactions with a gold
nanoparticles sensing platform was accomplished by using
thrombin-thrombin binding aptamer couple as a model [24]. The
aptamer was immobilized on a screen-printed electrode modified
with gold nanoparticles by avidin-biotin technology. The cathodic
peak area resulting from the reduction of previously formed gold
oxide was found to be proportional to the thrombin quantity
specifically adsorbed onto the modified electrode surface.
Dendritic polymers (dendrimers) belong to a new class of
synthetic macromolecules possessing a regularly branched tree-
like structure. A great attention has been paid to the potential
applications of polyamidoamine (PAMAM) dendrimers for the
development of biosensors, because of the dendrimer high geo-
metric symmetry, chemical stability, controllable size, and surface
functionality.Dendrimer-Au-NPsnanocompositeshavebeenshown
to combine the physical and chemical properties of Au-NPs with
the surface reactivity of dendrimers. A recent report describes an
electrochemicalapproachforsequence-specificDNAdetectionusing
PAMAMandgoldnanoparticles[25].Thebiosensordesignconsisted
of a gold electrode modified with 3-mercaptopropionic acid, which
was reacted with an amino-terminated polyamidoamine (PAMAM,
