Biomedical Engineering Reference
In-Depth Information
between 0.125 and 80 ng/mL, a detection limit of 40 pg/mL was obtained
with this system [91].
Another immunosensor was constructed by modii ying gold electrode
with a passivating organic layer, 4-thiophenol, where AuNPs were attached
on it. h en a biotin derivative as a model epitope was immobilized onto
nanoparticles in order to detect anti-biotin IgG. h e measurement of the
developed system was based on analyzing of Fe(CN)
6
4−/3−
redox couple
as a probe by cyclic voltammetry (CV) and electrochemical impedance
spectroscopy (EIS). h e impedance change, due to the specii c immuno-
interaction at the immunosensor surface, was utilized to detect anti-biotin
IgG. As a result, a linear range of 5-500 ngmL
−1
with a detection limit of 5
ngmL
−1
was obtained [92].
Human chorionic gonadotrophin (hCG) is an important diagnostic
marker of pregnancy and many diseases. It is a secretion of the placenta
during pregnancy and gestational trophoblastic diseases and increases as
a consequence of abnormal placental invasion and placental immaturity.
A novel amperometric immunosensor for determination of hCG was
constructed by immobilizing hCG antibody on the Pt-Au alloy nano-
tube array. In this study the “usual” AuNP has not been used. Instead
Pt-Au alloy nanotube array was produced by electrodepositing these
nanometals on a nanopore polycarbonate membrane at −0.35 V. h e ver-
tically aligned Pt-Au alloy nanotube was accepted as a nanoelectrode.
h e measurement principle was based on following the electrocatalytic
reduction of H
2
O
2
by Pt-Au alloys at er the hCG antigen was bound on
the surface of the electrode through immunoreactions. Under the opti-
mal condition, the current response of the immunosensor is in linear
relationship with concentration of hCG ranging from 25 to 400 mLU/
ml with a detection limit of 12 mLU/mL. h is method was applied for
the determination of hCG in serum samples and satisfactory results were
obtained [93].
Glassy carbon electrode was modii ed by nanoporous gold i lm and
label-free electrochemical immunosensor for ultrasensitive detection of
cancer biomarker prostate-specii c antigen (PSA) was obtained. h en the
adsorption of anti-PSA antibody on the electrode surface was made and
amperometric measurements of K
3
Fe(CN)
6
were conducted. At er the
optimization of experimental conditions, the analytical characteristics
were done. h e linear range was found to be between 0.05-26 ng/mL PSA
concentration with a limit of detection of 3 pg/mL. h is system was also
applied for PSA detection in human serum samples and very promising
results were obtained [94].
