**Preparation of Fluorescent Molecularly Imprinted Polymers via Pickering Emulsion Interfaces and the Application for Visual Sensing Analysis of** *Listeria Monocytogenes*

#### **Xiaolei Zhao 1,**†**, Yan Cui 1,**†**, Junping Wang 1,\* and Junying Wang 2,\***


Received: 2 April 2019; Accepted: 22 May 2019; Published: 4 June 2019

**Abstract:** In this work, a novel molecularly imprinted polymer (MIP) with water-soluble CdTe quantum dots (QDs) was synthesized by oil-in-water Pickering emulsion polymerization using whole *Listeria monocytogenes* as the template. *Listeria monocytogenes* was first treated by acryloyl-functionalized chitosan with QDs to form a bacteria–chitosan network as the water phase. This was then stabilized in an oil-in-water emulsion comprising a cross-linker, monomer, and initiator, causing recognition sites on the surface of microspheres embedded with CdTe QDs. The resulting MIP microspheres enabled selective capture of the target bacteria via recognition cavities. The target bacteria *Listeria monocytogenes* was detected. Scanning electron microscopy (SEM) characterization showed that the MIPs had a rough spherical shape. There was visual fluorescence detection via quenching in the presence of the target molecule, which offered qualitative detection of *Listeria monocytogenes* in milk and pork samples. The developed method simplified the analysis process and did not require any sample pretreatment. In addition, the fluorescence sensor provided an effective, fast, and convenient method for *Listeria monocytogenes* detection in food samples.

**Keywords:** pickering emulsion; quantum dots; *Listeria monocytogenes*
