Biology Reference
In-Depth Information
catalytic activities of Pt-NPs for chemical reactions, the sensitivity
was remarkably improved achieving a detection limit of 0.1 pM
of target DNA. The results showed that this DNA hybridization
biosensor responded more sensitively to target DNA than those
based on Pt-NPsorMWCNTs only.
5.3.2
Electrocatalytic Activity of Palladium
Nanoparticle Labels
Palladium belongs to the platinum group of metals, and, due to
its similar features in terms of electrocatalytic alctivity toward
numerous redox reactions, it has been used in electrode modifica-
tion processes in several electrochemical sensors [33]. Palladium
nanoparticles (Pd-NPs) were applied in several electrochemical
biosensors.Forinstance,aglucosebiosensorbasedoncodeposition
of Pd-NPs and glucose oxidase onto carbon electrodes [34],
encapsulated channels for protein biosensing and the reduction
of H
2
O
2
[35], and a DNA-template preparation of Pd-NPs onto
ITO for H
2
O
2
reduction and ascorbic acid oxidation, has been
reported [33].
IntheworkreportedbyChang
et al.
[36],Pd-NPsincombination
with MWCNTs were used to fabricate an electrochemical DNA
biosensor with enhanced sensitivity. Methylene blue (MB) was used
as hybridization indicator and a method with high sensitivity and
effective electrochemical discrimination against complementary
DNA, by coupling the large surface area and effective electron
transfer of MB redox from MWCNTs and the catalysis of the MB
redox reaction by Pd-NPs, was achieved. The Pd-NPs/MWCNTs
significantly increased the DNA hybridization signal to push down
the detection limits and facilitate potential manipulation of the
modified glassy carbon electrode. The LOD obtained was 0.12 pM
for target DNA. The catalytic activity of Pd-NPs employed in this
work is related to their ability to adsorb/release the involved
hydrogen atoms promoting the electronic transfer during the MB
redox reaction.
An ultrasensitive DNA sensor using the rapid enhancement
and electrocatalytic activity of DNA-conjugated Pd-NPs on NaBH
4
hydrolysis was reported by Yang's group [37]. After a previous
