Fluorescent Janus emulsions for biosensing of <i>Listeria monocytogenes</i>.

Abstract

Here we report a sensing method for <i>Listeria monocytogenes</i> based on the agglutination of all-liquid Janus emulsions. This two-dye assay enables the rapid detection of trace <i>Listeria</i> in less than 2 h via an emissive signal produced in response to <i>Listeria</i> binding. The biorecognition interface between the Janus emulsions is assembled by attaching antibodies to a functional surfactant polymer with a tetrazine/transcyclooctene click reaction. The strong binding between <i>Listeria</i> and the <i>Listeria</i> antibody located at the hydrocarbon surface of the emulsions results in the tilting of the Janus structure from its equilibrium position to produce emission that would ordinarily be obscured by a blocking dye. This method provides rapid and inexpensive <i>Listeria</i> detection with high sensitivity (<100 CFU/mL in 2 h) that can be paired with many antibody or related recognition elements to create a new class of biosensors.