Fluorescent Janus emulsions for biosensing of Listeria monocytogenes

Abstract

Here we report a sensing method forListeria monocytogenesbased on the agglutination of all-liquid Janus emulsions. This two-dye assay enables the rapid detection of traceListeriain less than 2 h via an emissive signal produced in response toListeriabinding. 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 betweenListeriaand theListeriaantibody 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 inexpensiveListeriadetection 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.

Janus Emulsion Biosensors for Anti-SARS-CoV-2 Spike Antibody

“…Figure a illustrates the chemical structure of the block copolymer surfactant P-TCO, which contains an acrylic acid block partially amidated with transcyclooctene (TCO) block, for bioconjugation in a click reaction with tetrazine. ,− P-TCO (1 mg/mL) in dietheylbenzene (DEB) is mixed in a 1:1 ratio with fluorocarbon solvent (3-ethoxyperfluoro­(2-methylhexane), HFE7500). The mixture is heated above the upper consolute temperature (40 °C) and dispersed into an aqueous continuous phase containing PBS buffer and surfactants (0.5 wt % Zonyl/0.5 wt % Tween 20, 1:1 (v/v)).…”

“…Water dispersed droplets can be produced by a number of emulsification methods, and are important components of cosmetic, , medicine, − and food. − Janus droplets or double emulsions have found applications in the development of pharmaceuticals, , biosensing, − and in dynamic optics. , For example, complex emulsions behave as microlens systems that can be used to measure enzyme activity through catalytic processes modification of surfactants that cause changes in droplet morphology and hence the optical transmission . Changes in morphology can also produce sensing responses when measuring emissive signals from the interior of the droplets.…”

Janus particles and motors: unrivaled devices for mastering (bio)sensing

“…The principle of detection was based in the aggregation of the droplets after binding of the droplet-immobilized antibodies to Listeria. To perform detection, specific fluorescence dyes were added in solution and the subsequent changes of emission in the presence of Listeria were monitored [ 55 ]. Similarly, Janus emulsions have been used for biosensing of anti-SARS-CoV-2 spike antibodies (Fig.…”

Revisiting the Heck Reaction for Fluorous Materials Applications

“…We studied the fluorous partition behavior of these polymers with solvents diethylbenzene (DEB) and HFE-7500, which were chosen as a result of their low interfacial tension and low upper critical mixing temperature. 34,35 Both polymers showed good partition in HFE-7500 over DEB and were emissive in HFE-7500 solution (Scheme 5, right). Figure 3 summarizes the absorbance and fluorescence properties of the two polymers.…”