Establishment Of A Method For Synthesis Fluorescent Molecularly Imprinted Material To Detect Listeria Monocytogenes

It is widely acknowledge that Listeria monocytogenes is a common foodborne pathogens, which has an effect on food safety and cause bacterial food poisoning by milk,meat and other. It is a real public health problem all over the world. The traditional bacterial detection method is the culturing and colony counting as a basic detection, which is time-consuming and laborious. Thus, it is very important to establish a sensitive, rapid, convenient,low-cost detection method.Quantum dots (QDs) have attracted attention owing to unique optical properties over conventional organic and inorganic fluorophores in recent years. In this study, we report the formation of the Molecular Imprinting polymer (MIP) beads based on water soluble CdTe QDs via a pickering emulsion polymerization, and its application for the detection of Listeria monocytogenes. Firstly, synthesis of water soluble CdTe quantum dots by one-step method.Besides, synthesis of N-acrylchitosan (NAC) pre-polymer, which modified acrylation of the amino groups on chitosan. Then N-acrylchitosan-CdTe QDs (NAC-QDs) formed catalyzed by EDC. The molecular imprinting polymerization initiated by Benzoyl peroxide (BPO),which included Listeria monocytogenes as the template molecule, NAC-QDs as a functional monomer, trimethylolpropane trimethacrylate (TRIM) and Divinylbenzene (DVB) as cross-linking agent. The experiment optimized and analyzed the conditions of polymerization. The application capability of the developed molecularly imprinted microspheres were evaluated in a series of experiments, and the possible mechanism was discussed. The synthesis of polymeric material do characterization by SEM, FT-IR and other. Adsorption equilibrium,adsorption kinetics and specificity measured. The results showed that: The resulting MIP microsphere enable to selectively capture the target bacteria via the recognition cavities. It can be reach adsorption equilibrium until 2 hours, and the adsorption capacity of 1644.45CFU/mg.Establishment of a method for synthesis fluorescent molecularly imprinted material to Detect Listeria monocytogenes. The results were analyzed by fluorescence visualization and direct counting. Based on the mechanism of fluorescence quenching, the MIP microspheres were used for the direct fluorescence degree of Listeria monocytogenes, and the lower limits of detection adsorption quantity could reach 10~3 CFU/mL. The lower limits of detection adsorption quantity could reach 75 CFU/mL by direct counting.In order to evaluate the practicality of this method, the MIP beads were used for the quick determination of Listeria monocytogenes in milk and raw pork samples, which spiked with dilution series different concentrations of Listeria monocytogenes. The proposed method was successfully applied for the determination of Listeria monocytogenes in spiked milk and pork samples, with lower limits of detection of 1.6 × 103 CFU/g and 6.5 × 10~2 CFU/g by fluorescence detection. The lower limits of detection 120 CFU/g and 76 CFU/g in spiked milk and pork samples by direct counting. It was consistent with this method was feasible for the sensitive and visual detect foodborne pathogenic.