Fluorescent Janus emulsions for biosensing of .

Here we report a sensing method for based on the agglutination of all-liquid Janus emulsions. This two-dye assay enables the rapid detection of trace in less than 2 h via an emissive signal produced in response to 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 and the 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 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.