This
work aims to develop universal sandwich-type electrochemiluminescence
(ECL) nanoimmunosensors for quantitative detection of biomarkers.
A series of low-toxic CdTe@ZnS QDs with different core sizes have
been synthesized via hydrothermal method and characterized by UV–vis
spectra, photoluminescence spectra, TEM, EDS, and XRD. Especially,
the ECL behaviors of CdTe@ZnS QDs have been investigated carefully.
The CdTe@ZnS QDs with the highest ECL quantum yields have been chosen
as ECL labels for conjugation with secondary antibodies. The QDs-labeled
antibodies have been characterized by agarose gel electrophoresis.
Meanwhile, Fe3O4@SiO2 magnetic nanoparticles
were utilized as nanocarriers for the immobilization of primary antibodies
due to magnetic separation ability, large specific surface area, and
ease of amination for biofunctionalization. Successful fabrication
of the nanoimmunosensor was confirmed by SEM and electrochemical impedance
spectroscopy. Carcinoembryonic antigen was detected as a model to
prove the feasibility of the above strategy. Under the optimal conditions,
the proposed nanoimmunosensor exhibited a wide linear range of 0.01
to 125 ng mL–1 for carcinoembryonic antigen determination
with a low detection limit of 3.0 pg mL–1 (S/N =
3). Moreover, the nanoimmunosensor also displayed excellent selectivity,
good stability, and acceptable reproducibility, indicating its potential
applications in clinical diagnostics and immune research.
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