In this paper, an electrochemiluminescence (ECL) immunosensor
for
ultrasensitive detection of CA19-9 was constructed using ternary compound
CdSSe nanoparticles as ECL emitter. The immunosensor employs Cu2S and gold-doped diindium trioxide (Au–In2O3) nanocubes as coreaction accelerators to achieve a
double-amplification strategy. In general, a hexagonal maple leaf-shaped
Cu2S with a large surface area was selected as the template,
and the in situ growth of CdSSe on its surface was achieved using
a hydrothermal method. The presence of Cu2S not only inhibited
the aggregation of CdSSe nanoparticles to reduce their surface energy
but also acted as an ECL cathode coreaction promoter, facilitating
the generation of SO4•–. Consequently,
the ECL intensity of CdSSe was significantly enhanced, and the reduction
potential was significantly lower. In addition, the template method
was employed to synthesize Au–In2O3 nanocubes,
which offers the advantage of directly connecting materials with antibodies,
resulting in a more stable construction of the immunosensor. Furthermore,
In2O3 serves as a coreaction promoter, enabling
the amplification strategy for ECL intensity of CdSSe, thus contributing
to the enhanced sensitivity and performance of the immunosensor. The
constructed immunosensor exhibited a wide linear range (100 μU
mL–1 to 100 U mL–1) and a low
detection limit of 80 μU mL–1, demonstrating
its high potential and practical value for sensitive detection of
CA19-9.