Biomedical Engineering Reference
In-Depth Information
a gold-silver-graphene hybrid nanosheet (AuAgGP)-functionalized
GCE. It was stated that the presence of AuAgGP nanosheets enhanced
the immobilized amount of biomolecules and also improved the elec-
trochemical properties of the immunosensor. Under optimal conditions,
the sensitivity and dynamic range of the immunosensor were evaluated
by using the labeled HRP on the AuTi as trace and H
2
O
2
as enzyme sub-
strate. As a result, a wide dynamic range of 0.001-200 ngmL
−1
with a
low detection limit of 0.5 pgmL
−1
was obtained. h e developed meth-
odology was evaluated for 8 positive serum specimens obtained from
hepatocarcinoma patients and 19 negative sera. h e validation of the
developed system was conducted with the commercially available Roche
2010 Electrochemiluminescent Automatic Analyzer. As it was reported,
no signii cant dif erences at the 95% coni dence level were encountered
between the two methods [89].
A microl uidic immunosensor was developed for the detection of
IgG antibodies specii c to Echinococcus granulosus in human serum
samples, which represents an alternative tool that can be used for the
immunodiagnosis of hydatidosis in an automated way. Hydatidosis is
a common disease of humans and animals, resulting from infection
with the larval stage or metacestode of Echinococcus granulosus. h e
developed device consists of a Plexiglas system with a central channel
and a gold electrode. For immobilization of the E. granulosus antigen,
the gold electrode was modii ed with AuNP. h e immunoassay reac-
tion was based on the reaction of immobilized antigen with IgGanti-E
granulosus antibodies in samples, where quantii cation was made by
HRP enzyme-labeled secondary antibodies specii c to human IgG
using catechol (Q) as enzymatic mediator. Horseradish peroxidase in
the presence of H
2
O
2
, catalyzes the oxidation of Q to o-benzoquinone.
Following this, the electrochemical reduction back to Q was detected
on the gold electrode at -0.15 V. h e obtained current was proportional
to the activity of the enzyme and to the concentration of antibodies of
interest. h e detection limit for electrochemical detection was 0.091 ng
ml
-1
, and the within- and between-assay coei cients of variation were
below 6.7% [90].
h e other HRP AuNP included immunosensor was constructed by
using AuNP/CNT hybrids platform with HRP-functionalized AuNP
label for the sensitive detection of human IgG. It was claimed that the
AuNP/CNT nanohybrids covered on the GCE provided an ef ective anti-
body immobilization matrix and allowed the immobilized biomolecules
to retain high stability and bioactivity. Besides a linear response range
