Preparation Of Immunomagnetic Dextrin Microspheres And Study On Rapid Separation Of Listeria Monocytogenes

In this paper,we studied the optimal process of preparing magnetic dextrin microspheres and immunomagnetic dextrin microspheres,and used the prepared immunomagnetic dextrin microspheres to capture Listeria monocytogenes to achieve rapid separation of Listeria monocytogenes,To provide a theoretical basis for future research.In this study,dextrin was used as the raw material,n-hexane was used as the oil phase,span60 and tween60 as the surfactant,n-amyl alcohol as the cosolvent,sodium trimetaphosphate as the crosslinking agent,adding magnetic powder,Got magnetic dextrin microspheres.In the preparation process,the effects of dextrin concentration,water/oil ratio,magnetic powder dosage and n-pentanol content on the adsorption properties of magnetic dextrin microspheres were investigated.The factors affecting the preparation of magnetic dextrin microspheres were studied.The optimum scheme for the preparation of magnetic dextrin microspheres was obtained.With the increase of dextrin concentration and water/oil ratio,the adsorption rate of methylene blue was gradually decreased.With the increase of the amount of novolak and the amount of n-pentanol,the adsorption rate of methylene blue was increased first Reduced.At the same time,orthogonal experiments were carried out on these four factors.The results showed that dextrin concentration had the most significant effect on the adsorption properties of microspheres,and other factors had different effects on them.At the same time,the optimal conditions for the preparation of dextrin microspheres were dextrin concentration of 2%,water/oil ratio of 0.3,magnetic powder content of 0.010g,and n-amyl alcohol content of 18mL.Magnetic dextrin microspheres were activated by epichlorohydrin under alkaline conditions and reacted with the antibody to produce immunomagnetic starch microspheres.In this process,the optimum reaction conditions were as follows:the dosage of epichlorohydrin was 0.4 mL/g,the concentration of NaOH was 2.0 mol/L,and the optimum time was 5 h.On this basis,In the preparation process,the effects of antibody concentration,reaction temperature and reaction time on the preparation of immunomagnetic dextrin microspheres were investigated.With the increase of antibody concentration,the crosslinking rate of microspheres and antibody increased gradually.With the increase of reaction temperature and reaction time,the crosslinking rate of microspheres and the antibody increased first and then decreased.At the same time,the orthogonal test was designed for these three factors.The effect of three factors on the preparation of immunomagnetic dextrin microspheres was:antibody concentration>reaction temperature>reaction time.The optimal conditions for the preparation of immunomagnetic dextrin microspheres were as follows:the antibody concentration was 1.mg/mL,the reaction temperature was 28 ?,and the reaction time was 2.5h.100 ?L immunomagnetic dextrin microspheres were used for optimal dosage in the sample when captured with the prepared immunomagnetic dextrin microspheres,and 1 h was the best capture time.Under the action of external magnetic field,the immunomagnetic dextrin microspheres were enriched and the bacterial DNA was extracted.After PCR amplification,agarose gel electrophoresis was carried out.The results showed that the immunomagnetic dextrin microspheres could effectively and rapidly capture Listeria monocytogenes and could amplify specific products with the detection limit of 10 liters of Listeria monocytogenes per mL.