A Research Of Magnetic Molecularly Imprinted Polymers Nanoparticles Coupled SPR Sensor For The Determination Of Norfloxacin In Milk

In this paper,a highly sensitive approach is developed for detection of Norfloxacin(NOR)in dairy products based on surface plasmon resonance(SPR)sensor coupled with magnetic molecularly imprinted polymers nanoparticles(MMIPs NPs).The main research content and results were summarized as follows:(1)MMIPs NPs were prepared by simple self-polymerization of dopamine for effectively extracting NOR from milk.The characteristics of the obtained MMIPs NPs were investigated by transmission electron microscope,Fourier transform infrared spectrometry,vibrating sample magnetometer and X-ray diffraction.Results suggest that molecular imprinted layers are deposited onto the surface of magnetic particles,and the average size of MMIPs NPs is14.33 nm.MMIPs NPs are sensitive to magnetic fields and can be easily separated within 10s using an external magnet.(2)The adsorption experiment result indicates the maximum adsorption capacity of MMIPs NPs towards NOR is 14.17 mg/g,exhibiting remarkably adsorption ability than that of magnetic non-molecular imprinted polymers nanoparticles(6.41 mg/g).Further,the imprinted factor(2.03)and selectivity factor(2.27)were obtained through selective adsorption experiments.After six regeneration cycles,the adsorption efficiency of MMIPs NPs is lost only 9.0%.Subsequently,the MMIPs NPs were successfully applied as sorbents to extract NOR from milk samples with satisfying recoveries of 82.40?102.38%.(2)A highly selective and sensitive SPR method for detection of the NOR in milk samples was developed based on MMIPs NPs.The NOR-captured MMIPs NPs were flowed over the surface of the SPR chip that was modified with 3-Mercaptopropionic Acid.The SPR response exhibited a linear dependence on concentrations of NOR from 10 pg/m L to 250pg/m L,the linear regression equation is y=0.11051x+6.01831(R~2=0.9878)(R~2=0.9878),with a detection limit of 8.73 pg/m L.In the three different brands of milk samples,No NOR was detected using developed SPR method and High Performance Liquid Chromatography–tandem Mass Spectrometry(GB/T 21312-2007).Recovery experiments for the three different brands of milk samples were carried out by the established SPR method and Enzyme-linked Immunosorbent Assay(ELISA).The results showed that the recovery range of the established SPR method was 97.74%to 105.64%,with the standard relative deviation(RSD)ranged from 3.27%to 8.64%.The recovery range of ELISA was 81.10%to 99.04%,and the RSD was between 2.10%and 9.53%.These results show that the established SPR method has a satisfying reliability and accuracy,which can be used to detect NOR in milk samples.In summary,the established method perfectly combined sample pretreatment based on MMIPs NPs with SPR sensor detectiontechnology.It not only simplifies the steps of sample pretreatment,but also improves the accuracy and sensitivity of SPR sensor detection.Moreover,it has a good practical application.