Biology Reference
In-Depth Information
Figure 5.3.
Schematic representation of the electrocatalytic effect of
Au-NPs on silver electrodeposition on ITO-based electrodes applied for the
DNA hybridization detection (adapted from Ref. 26 with permission). See
also ColorInsert.
low backgrounds, that is, possibility to achieve very low detection
limits. However, the conjugation of the electrocatalytic labels with
biomoleculesmaydecrease theirelectrocatalytic activity,andalong
distance between the electrode and the labels may also produce an
undesired slow electron tunneling between them, even if the label
exhibits a high electrocatalytic activity itself. To overcome these
problems, it is possible to enhance the electrocatalytic activity of
labels by electrochemical, thermal, or chemical treatment. Thermal
and electrochemical treatments may damage the sensing layers
during the detection process, since, respectively, high temperatures
and extreme applied potentials are often necessary. But mild
chemical treatments can bea desirable option [11].
When Au-NP labels are present near an electrode they can act
as (electro)catalytic agents. However if the electrocatalytic reaction
is not reproducible, which jeopardizes the achievement of low
detection limits, the electrocatalytic reaction should be minimized
and the electrochemical signal should arise only from the catalytic
reaction [7]. The latest can be done by limiting the electron
transfer between nanoparticles and the electrode through the use
of nonconductive spacers like other particles, organic monolayers,
etc. [11, 27, 28].
Selvaraju
et al.
[11]reportedtheuseofAu-NPsascatalyticlabels
to achieve ultrasensitive DNA detection via fast catalytic reactions
involved in p-nitrophenol reduction in presence of NaBH
4
.Inorder
