1 research outputs found
Near-Infrared Light-Excited Core–Core–Shell UCNP@Au@CdS Upconversion Nanospheres for Ultrasensitive Photoelectrochemical Enzyme Immunoassay
A novel
photoelectrochemical (PEC) enzyme immunoassay was designed
for the ultrasensitive detection of alpha-fetoprotein (AFP) based
on near-infrared (NIR) light-excited core–core–shell
UCNP@Au@CdS upconversion nanospheres. Plasmonic gold (Au) between
the sandwiched layers was not only utilized as an energy harvester
for the collection of the incident light but also acted as an energy
conveyor to transfer the energy from upconversion NaYF<sub>4</sub>:Yb<sup>3+</sup>,Er<sup>3+</sup> (UCNP) to semiconductor CdS, thus
exciting the efficient separation of electron–hole pairs by
the generated H<sub>2</sub>O<sub>2</sub> of enzyme immunoreaction
under the irradiation of a 980 nm laser. By virtue of high catalytic
activity of natural enzymes, gold nanoparticles heavily functionalized
with glucose oxidase (GOx) and polyclonal anti-AFP antibody were utilized
to generate H<sub>2</sub>O<sub>2</sub>. A sandwiched immunoreaction
was first carried out in a monoclonal anti-AFP antibody-coated microplate
by using an antibody-labeled gold nanoparticle as secondary antibody.
Accompanying the gold nanoparticle, the carried GOx oxidized glucose
in H<sub>2</sub>O<sub>2</sub>, thereby resulting in the enhanced photocurrent
via capturing holes on the valence band of CdS to promote the separation
of electron–hole pairs. Under optimum conditions, the NIR light-based
PEC immunosensing system exhibited good photocurrent responses toward
target AFP within the dynamic working range of 0.01–40 ng mL<sup>–1</sup> at a detection limit of 5.3 pg mL<sup>–1</sup>. Moreover, the NIR light-based sensing platform had good reproducibility
and high selectivity. Importantly, good well-matched results obtained
from NIR light-based PEC immunoassay were acquired for the analysis
of human serum specimens by using AFP ELISA kit as the reference