Biomedical Engineering Reference
In-Depth Information
12.5.7 Prostate Specii c Antigen
Prostate specii c antigen (PSA) is an androgen-regulated serine protease. PSA
is secreted by the epithelial cells of the prostate gland. PSA is produced for
the ejaculate, where it liquei es semen in the seminal coagulum and allows
sperm to swim freely. It is also believed to be instrumental in dissolving cer-
vical mucus, allowing the entry of sperm into the uterus. When PSA enters
in the circulatory system, it is rapidly bound by protease inhibitors, primarily
α
1
-antichymotrypsin (ACT), although a fraction is inactivated in the lumen
by proteolysis and circulates as free PSA (f-PSA). Total PSA (T-PSA) refers
to the sum of f-PSA and PSA/ACT complex in serum. T-PSA levels signii -
cantly increase in serum during prostate cancer and other prostatic diseases.
Han
et al.
[78]
described in 2012
a sandwich-type electrochemical
immunosensor for simultaneous sensitive detection of PSA and fPSA.
First, GNPs modii ed PB and nickel hexacyanoferrates nanoparticles were
prepared and used to decorate onion-like mesoporous graphene sheets
(O-GS/PBNPs/GNPs and O-GS/NiNPs/GNPs). h en, O-GS/PBNPs/
GNPs and O-GS/NiNPs/GNPs were modii ed with anti-fPSA and anti-
PSA respectively, and streptavidin and biotinylated alkaline phosphatase
(bio-AP) were employed to block active sites. h en dual catalysis amplii ca-
tion was achieved by catalysis of the ascorbic acid 2-phosphate to AA in the
presence of bio-AP, and then the enzyme-generated AA was further cata-
lytically oxidized by O-GS/PBNPs/GNPs and O-GS/NiNPs/GNPs nano-
hybrids at ~0.2 and ~0.4 V
vs
SCE, respectively. h e experiment results
showed that the linear range of the proposed immunosensor for simultane-
ous determination of fPSA was from 0.02 to 10 ng mL
−1
with a detection
limit of 7 pg mL
−1
and PSA was from 0.01 to 50 ng mL
−1
with a detection
limit of 3.4 pg mL
−1
. To evaluate the performance of the proposed immuno-
sensor, clinical analysis with serum samples were evaluated and compared
against ELISA. h e authors found good correlations between those results
that coni rm the viability of the developed method for real sample assay.
12.5.8
Hepatitis B Antigen
Hepatitis B (HB) is an infectious inl ammatory illness of the liver caused by
the hepatitis B virus (HBV). h e virus is transmitted by exposure to infec-
tious blood or body l uids such as semen and vaginal l uids, while viral
DNA has been detected in the saliva, tears, and urine of chronic carriers.
Perinatal infection is a major route of infection; other risk factors for devel-
oping HBV infection include working in a healthcare setting, transfusions,
dialysis, acupuncture, tattooing,
etc
.
