posted on 2021-02-13, 16:13authored byEngin Er, Ana Sánchez-Iglesias, Alessandro Silvestri, Blanca Arnaiz, Luis M. Liz-Marzán, Maurizio Prato, Alejandro Criado
The detection of cancer biomarkers at an early stage of tumor development
is vital for effective diagnosis and treatment of cancer. Current
diagnostic tools can often detect cancer only when the biomarker levels
are already too high, so that the tumors have spread and treatments
are less effective. It is urgent therefore to develop highly sensitive
assays for the detection of such biomarkers at the lowest possible
concentration. In this context, we developed a sandwich immunoassay
based on surface-enhanced Raman scattering (SERS) for the ultrasensitive
detection of α-fetoprotein (AFP), which is typically present
in human serum as a biomarker indicative of early stages of hepatocellular
carcinoma. In the immunoassay design, molybdenum disulfide (MoS2) modified with a monoclonal antibody was used as a capture
probe for AFP. A secondary antibody linked to an SERS-encoded nanoparticle
was employed as the Raman signal reporter, that is, the transducer
for AFP detection. The sandwich immunocomplex “capture probe/target/SERS
tag” was deposited on a silicon wafer and decorated with silver-coated
gold nanocubes to increase the density of “hot spots”
on the surface of the immunosensor. The developed SERS immunosensor
exhibits a wide linear detection range (1 pg mL–1 to 10 ng mL–1) with a limit of detection as low
as 0.03 pg mL–1 toward AFP with good reproducibility
(RSD < 6%) and stability. These parameters demonstrate that the
proposed immunosensor has the potential to be used as an analytical
platform for the detection of early-stage cancer biomarkers in clinical
applications.