Fluoroimmunoassay for antigen based on fluorescence quenching signal of gold nanoparticles.
A 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-alpha-fetoprotein polyclonal antibodies, which specifically bound with alpha-fetoprotein. Gold nanoparticles coated with anti-alpha-fetoprotein monoclonal antibodies could sandwich the alpha-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 alpha-fetoprotein concentration. The result showed that the limit of detection of alpha-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.
Department of Bio-Nano Science and Engineering, National Key Laboratory of Nano/Micro Fabrication Technology, Institute of Micro and Nano Science and Technology, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai 200030, China.
Limei
L
Ao
Feng
F
Gao
Bifeng
B
Pan
Rong
R
He
Daxiang
D
Cui
D005453:Fluorescence; D005455:Fluorescent Antibody Technique / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles; D011863:Radioimmunoassay
D006046:Gold