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A homogeneous assay for protein analysis in droplets by fluorescence polarization

Authors

  • Haakan N. Joensson,

    Corresponding author
    1. Division of Nanobiotechnology, Royal Institute of Technology (KTH), Albanova University Center, Stockholm, Sweden
    • Division of Nanobiotechnology, Royal Institute of Technology (KTH), Albanova University Center, SE-10691 Stockholm, Sweden Fax: +46-8-5537-8481
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    • These authors contributed equally to this work.

  • Chi Zhang,

    1. Division of Nanobiotechnology, Royal Institute of Technology (KTH), Albanova University Center, Stockholm, Sweden
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    • These authors contributed equally to this work.

  • Mathias Uhlén,

    1. Division of Proteomics, Royal Institute of Technology (KTH), Albanova University Center, Stockholm, Sweden
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  • Helene Andersson-Svahn

    1. Division of Nanobiotechnology, Royal Institute of Technology (KTH), Albanova University Center, Stockholm, Sweden
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  • Colour Online: See the article online to view Figs. 1–3 in colour.

Abstract

We present a novel homogeneous (“mix-incubate-read”) droplet microfluidic assay for specific protein detection in picoliter volumes by fluorescence polarization (FP), for the first time demonstrating the use of FP in a droplet microfluidic assay. Using an FP-based assay we detect streptavidin concentrations as low as 500 nM and demonstrate that an FP assay allows us to distinguish droplets containing 5 μM rabbit IgG from droplets without IgG with an accuracy of 95%, levels relevant for hybridoma screening. This adds to the repertoire of droplet assay techniques a direct protein detection method which can be performed entirely inside droplets without the need for labeling of the analyte molecules.

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