Biomedical Engineering Reference
In-Depth Information
methods were found to give similar results; however, the new approach
was less time consuming (30 min) compared to ELISA (2 h).
In 2007,
Yu a n
et al.
[67] presented a label-free amperometric immuno-
sensor for the determination of AFP by immobilizing TiO
2
colloids on a
PB-modii ed electrode. AFP responses showed two concentration ranges
from 3 to 30 ng mL
-1
and from 30 to 300 ng mL
-1
with a detection limit of 1
ng mL
-1
and exhibited high selectivity, good reproducibility, long-term sta-
bility (>2 months) and good repeatability. Finally, the author compared these
results, obtained for real serum samples, against chemiluminescence immu-
noassays (CLIA) and found good agreement between the two methods.
Lately,
Hong
et al.
[68] developed PBNPs and coated them with bovine
serum albumin (BSA) to improve their stability. h en gold colloids were
loaded on the BSA-coated PBNPs to construct a core-shell-shell nano-
structure. Finally, AFP antibody was attached to GNPs and PBNPs/BSA/
GNPs/anti-AFP was used to AFP detection. h e dynamic range of the
resulting immunosensor for the detection of AFP was from 0.02 to 200 ng
mL
-1
with a detection limit of 0.006 ng mL
-1
and displayed good selectivity,
stability and reproducibility.
In 2010,
Jiang
et al.
[69] reported an amperometric immunosensor
based on the sequential electrodeposition of PB and GNPs on a CNT/GCE
surface. Finally, anti-AFP was immobilized onto the GNP surface and BSA
employed to block possible remaining active sites of GNP monolayer and
avoid any nonspecii c adsorption. Under optimal experimental conditions,
the immunosensor showed an ultralow limit of detection of 3 pg mL
-1
and
a linear range from 0.01 to 300 ng mL
-1
. Moreover, the immunosensor, as
well as a commercially available kit, were both used in the determination of
AFP in real human serum and showed excellent correlation.
Finally, in 2011,
Dai
et al.
[70] developed a sandwich electrochemical
immunosensor for the sensitive determination of AFP based on PB-modii ed
hydroxyapatite (PB@HAP) modii ed with HRP and secondary anti-AFP
antibody (Ab
2
) to fabricate the electrochemical immunosensor label (PB@
HAP/HRP/Ab
2
). h e results indicated that the immunosensor fabricated
using PB@HAP/HRP/Ab
2
label had high sensitivity, much higher than other
labels such as PB@HAP/Ab
2
, PB/HRP/Ab
2
or HAP/HRP/Ab
2
.
Optimized
amperometric signals increased linearly with AFP concentration in the
range of 0.02 to 8 ng mL
-1
with a low detection limit of 9 pg mL
-1
.
12.5.2 CarcinoembryonicAntigen
Carcinoembryonic antigen (CEA) is a glycoprotein involved in cell adhe-
sion. It is normally produced during fetal development, but the production
