• KSBB Journal
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• v.22 no.6
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• pp.426-432
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• 2007

We have developed a sensitive, one-step, homogeneous open sandwich fluoroimmunoassay (OsFIA) based on fluorescence resonance energy transfer (FRET) and luminescent semiconductor quantum dots (QDs). In this FRET assay, estrogen receptor-$\beta$ (ER-$\beta$) antigen was incubated with QD-labeled anti-ER-$\beta$ monoclonal antibody and AF (Alexa Fluoro)-labeled anti-ER polyclonal antibody for 30 minutes, followed by FRET measurement. The dye separation distance was estimated to be between $80\sim90\;{\AA}$. The present method is rapid, simple and highly sensitive, and did not require the bound/free reagent separation steps and solid-phase carriers. A concentration as low as 0.05 nM (2.65 ng/ml) receptor was detected with linearity ($R^2$ > 0.990). In addition, the assay was performed with commercial antibodies. This assay provides a convenient alternative to conventional, laborious sandwich immunoassays.