Biology Reference
In-Depth Information
during immobilization or electrochemical measurement, giving less
reliability. To avoid this problem, DNA biosensors using a thin
gold film sputtered on capacitive anodic nanoporous niobium
oxide were proposed [18]. The nanoporous niobium oxide offers
a good adhesion as well as an enhancement of redox signals by
accumulation of charges in between the gold film and the niobium
oxide. The mechanism of enhancing the signal by the thin gold film
on nanoporous niobium oxide is in part attributed to capacitive
niobium oxide and is in part ascribed to the bridged thin gold
film.
4.2.3
Carbon Nanotube-Gold Nanoparticle Hybrids
Carbonnanotubes(CNTs)arewidelyrecognizedasanidealsupport
for fabricating electrochemical sensors with a high sensitivity
and selectivity [19]. Due to the ability of carbon nanotubes
to promote electron-transfer reactions, and the high catalytic
activity and biocompatibility of gold nanoparticles, the developed
genosensors showed excellent reproducibility and stability under
the DNA hybridization conditions [20]. A novel DNA biosensor
was constructed by layer-by-layer (LBL) covalent assembly of
gold nanoparticles and multiwalled carbon nanotubes (MWCNTs).
Cysteamine molecules acted as a glue to connect activated MWCNTs
and Au-NPs into a three-dimensional hybrid network on a gold
electrode.Then,NH
2
-ssDNAwasimmobilizedonmultilayerfilmsvia
amino linkat the 5'-end.
4.2.4
Polymer-Gold Nanoparticle Hybrids
Because electrochemical polymerization allows the control of film
thickness, permeation, and charge-transport characteristics by
adjusting the electrochemical parameters, this methodology has
demonstrated to be a promising approach to immobilize DNA
probes. Among other electronconducting polymers, polyaniline
(PANI) has attracted a special attention in the field of conducting
macromolecules. Due to its homogeneity, unique redox properties,
high electrical conductivity and strong adherence to electrode sur-
face, PANI has been extensively applied to develop electrochemical
