ac051323m_si_001.pdf (90.92 kB)
Fluoroimmunoassay for Antigen Based on Fluorescence Quenching Signal of Gold Nanoparticles
journal contribution
posted on 2006-02-15, 00:00 authored by Limei Ao, Feng Gao, Bifeng Pan, Rong He, Daxiang CuiA unique, sensitive, and highly specific fluoroimmunoassay system for antigen detection using gold and magnetic
nanoparticles has been developed. The assay is based on
the fluorescence quenching of fluorescein isothiocyanate
caused by gold nanoparticles coated with monoclonal
antibody. To demonstrate its analytical capabilities, the
magnetic nanoparticles were coated with anti-α-fetoprotein
polyclonal antibodies, which specifically bound with α-fetoprotein. Gold nanoparticles coated with anti-α-fetoprotein monoclonal antibodies could sandwich the α-fetoprotein captured by the magnetic nanoparticle probes. The
sandwich-type immunocomplex was formed on the surface of magnetic nanoparticles and could be separated by
a magnetic field. The supernatant liquid, which contained
the unbound gold nanoparticle probes, was used to
quench the fluorescence, and the fluorescence intensity
of fluorescein isothiocyanate at 516 nm was proportional
to the α-fetoprotein concentration. The result showed that
the limit of detection of α-fetoprotein was 0.17 nM. This
new system can be extended to detect target molecules
with matched antibodies and has broad potential applications in immunoassay and disease diagnosis.