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

In this paper,a new approach is developed for direct detection of tetracycline?TC?based on the two-channel surface plasmon resonance?SPR?sensor coupled with magnetic molecularly imprinted polymers nanoparticles?MMIPs NPs?.This approach is faster,more accurate and sensitive than previous methods.The specificity,reproducibility and accuracy of the SPR sensor were also investigated.The main research content and results were summarized as follows:?1?The carboxyl-modified Fe₃O₄ NPs was prepared using one-step chemical coprecipitation method with citric acid as carboxyl donor,and used as the carrier for molecularly imprinted polymers?MIPs?.When mole ratio of template molecule TC and functional monomer methylacrylic acid?MAA?was 1:8,the addition amount of carboxyl-modified Fe₃O₄ NPs was 0.5 g,and methanol-acetic acid solution?8:2,v/v?were selected as the eluent of template molecule TC,the MMIPs NPs with best adsorption effect and specific recognition to TC were successfully prepared.The prepared Fe₃O₄ NPs,carboxylated Fe₃O₄ NPs and MMIPs NPs were characterized in detail.The average particle sizes of MMIPs NPs were about 13 nm,which were slightly larger than that of carboxyl-modified Fe₃O₄ NPs.Additionly,MMIPs NPs maintained good magnetic properties.?2?The adsorption properties of MMIPs NPs prepared under optimal conditions were studied.The MMIPs NPs showed a high adsorption capacity?35.30 mg/g?,a relative fast adsorption equilibrium?about 60 min?,and significant selectivity?imprinting factor ? 2.55?.It is suitable for selective enrichment and separation of TC.The adsorption efficiency could reach 94.10% when the concentration of TC solution was 0.08 mg/mL?2 mL?,the addition of MMIPs NPs was 10 mg,and the reaction time was 40 min.At the same time,the MMIPs NPs can be reused for many times.After five cycles,the adsorption efficiency can still up to 84.88%.?3?SPR sensor coupled with MMIPs NPs for TC detection was achieved when TC-MMIPs NPs complex were directly flowed over the SPR sensor chip surface modified with mercaptoethylamine?MEA?after TC were enriched and separated using MMIPs NPs.The linear concentration range of this method was 5 pg/mL-100 pg/mL,the linear regression equation was Y=0.33X+2.80?R²=0.9955?,and the range of relative standard deviation?RSD?was 1.57%-13.33%.The minimum detection concentration was 5 pg/mL,and the limit of detection?LOD?was 0.98 pg/mL?S/N=3?.In the three different brands of milk samples,No TC was detected using developed SPR method and liquid chromatography-tandem mass spectrometry?LC-MS/MS??GB/T 21317-2007?.Compared with enzyme linked immuno sorbent assay?ELISA?,the recovery range of developed SPR method was 95.70%-104.56%,96.26%-105.69%,94.79%-100.24%,and the RSD range was 2.13%-9.22%,2.67%-6.28%,4.58%-12.01%.The recovery range of ELISA was 104%-117.33%,96.67%-107.20%,99.63%-109.20%,and the RSD range was 1.13%-4.29%,2.08%-5.32%,2.33%-6.50%.In conclusion,the developed method of SPR sensor coupled with MMIPs NPs for TC detection is a perfect combination of sample pretreatment and sensor detection technology.It not only simplifies the operation steps,effectively shortens the detection time,improves the detection accuracy and sensitivity,but also has good specificity,reproducibility and reproducibility.Meanwhile,the developed SPR method has good practical application value.