| Foodborne illness is a disease caused by the toxic and harmful substances(including biological pathogens) which enter the human body through ingestion. Foodborne diseases can be divided into infectious and toxic generally. In recent years, the incidence of foodborne diseases ranks among the forefront of the total incidence of various diseases and it is the most prominent health problem in the world.In recent years, nanotechnology has developed rapidly. Due to the unique physical and chemical properties of nano-materials, nanotechnology is widely used in the various fields, including targeted drug delivery, separation and enrichment of biological molecules, clinical treatment and diagnosis of diseases, detection of various biological molecules and biological sensors.Listeria monocytogenesas is an important foodborne pathogen in both human beings and animals, which has already aroused great concern in several countries. L. monocytogenesas exists widely in various dairy products, vegetables, meat and other food, especially in ready-to-eat(RTE) foods. It has caused great threat to people’s health and safety. L. monocytogenesas causes meningitis, neonatal listeriosis, septicemia and abortion on infected humans.In this paper, we demonstrate a rapid method of detecting L. monocytogenesin food which is based on the combination of biofunctional magnetic nanoparticles and low-field magnetic resonance technology(LF-NMR). We also explore the effect of LFNMR of different nano-materials on the rapid detection of L. monocytogenesin. The first part successfully synthesized biological functionalization Fe/Fe3O4 NPs and Fe3O4 NPs. NPs were synthesized by the pyrolysis method. The Fe/Fe3O4 NPs obtained averaged a diameter of 12.22 nm and Fe3O4 NPs was 11.29 nm. Through reverse microemulsion method, NPs was coated by silicon dioxide, and modified with amino. These particles had a high dispersibility and broad compatibility to biomacromolecules. EDC·HCL and NHS activated antibody. Activated antibody immunized amination Fe/Fe3O4 NPs and Fe3O4 NPs, which formed immunized NPs. In the second part, the influence of different nano-materials on the LF-NMR detection method of L. monocytogenesin was explored. We studied the optimum medium of L. monocytogenesin. Through the growth curve drawing, it was concluded that the optimal culture medium was listeria richment broth. A rapid and sensitive detection method of L. monocytogenesin was successfully constructed by using different nano-materials. We found that dispersed nanoparticles in solution self-assemble on the surface of a bacterial target accompanied by the increase of the T2 value of water protons. We can determine the presence of L. monocytogeneson the basis of the change of T2 value(ΔT2) using NMR. Different nano-materials had a strong specificity for L. monocytogeneson. Through the comparative experiment, the biological function of Fe/Fe3O4 NPs and Fe3O4 NPs for magnetic resonance experiment for optimal stabilizer was low fat(2%) milk. The optimal concentration of Fe/Fe3O4 NPs was 0.16 mg/m L and Fe3O4 NPs was 0.2mg/m L. The optimal incubation time of Fe/Fe3O4 NPs was 30 min, while Fe3O4 NPs was 40 min, which was slightly shorter in the former. The linear detection range of different nano-materials in the rapid detection of L. monocytogeneson was 1-103CFU/mL. The detection range was consistent. It showed that the sensitivity of the method was not related to the nano-material itself.In conclusion, we have demonstrated the development of a highly specific, sensitive and fast method for the detection of L. monocytogenesis using LF-NMR. We also explore the effect of LF-NMR of different nano-materials on the rapid detection of L. monocytogenesin. The experiments were used to increase the stability of this method, which had important significance for the rapid detection of foodborne pathogens in the future. |
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