Application Of SERS-ICA Based On Two Kinds Of Magnetic Nano-Tags In The Detection Of Multiple Veterinary Drug Residues

Veterinary drugs are often used to prevent and treat diseases,so they are widely used in the animal husbandry industry.However,the overuse or illegal use of veterinary drugs highlights the problem of veterinary drug residues,which will destroy the ecological environment and affect the quality and safety of the food.More importantly,entering the food chain will endanger human health(including allergies,carcinogens,or teratogenic reactions).The rapid detection of veterinary drug residues in environmental samples and animal food is an important way to avoid its harm to the ecological environment and human health,which is of great significance to effectively supervise food hygiene and safety and protect the health of consumers.The commonly used rapid detection techniques for veterinary drug residues,including chromatography,mass spectrometry,and so on,generally have some shortcomings such as long detection time,difficult operation,and so on.Therefore,from the perspective of environmental safety and food safety,there is an urgent need to develop a simple technology that can support direct and ultra-sensitive detection of a variety of drug residues.In this study,surface-enhanced Raman spectroscopy(SERS)and side-flow immunochromatography(ICA)were combined to introduce high-performance magnetic nanomaterials to establish a rapid,direct,and ultra-sensitive method for the detection of veterinary drug residues in complex environments and animal food samples.The specific research contents are as follows:(1)Preparation of Magnetic Nano-tags(Mag@Au)by PEI-mediated seed growth.A magnetic nano-label(Mag@Au)is designed,which consists of a large magnetic core Fe3O4(160nm),a rough Au nano-shell,surface-modified Raman reporter molecules,and specific antibodies.Transmission electron microscope(TEM),scanning electron microscope(SEM),zeta potentiometer,and other instruments were used to evaluate the morphology and SERS properties of Mag@Au tags.The results show that the magnetic nano-tags prepared by the PEI-mediated seed growth method have a uniform particle size,good dispersion,and SERS enhancement properties.(2)Establishment of SERS-ICA method based on Mag@Au and its application in the detection of two kinds of clenbuterol.Mag@Au-based SERS-ICA detection technique was used to detect two kinds of clenbuterol: clenbuterol hydrochloride(CLE)and ractopamine(RAC).As a dual-function tool for capture/detection,the Mag@Au tag can directly capture the target substance in the actual liquid sample and effectively enrich the target under the action of the magnetic field and can provide both colorimetric and SERS signals.Under the condition of optimal parameters,the detection limits of CLE and RAC based on the SERS signal are 7.8 and 3.5pg/m L,respectively.The detection limits of colorimetric signals are 1.0 and 0.33 ng/m L,respectively.In addition,by calculating the SERS intensity of the two detection lines to real food samples,a better recovery rate(89.63%-110.6%)was obtained.(3)Novel nano-labels(MDAu@Ag)were prepared by PEI-mediated layer-by-layer assembly method.A large amount of Au@Ag NPs was assembled on the core of Fe3O4 by electrostatic interaction.The results show that the prepared MDAu@Ag nanomaterials have excellent SERS activity,strong magnetic response,high repeatability,and good dispersion.By controlling the reaction time,controllable,sophisticated nano-interlayers(1 nm)can be formed between the MDAu@Ag nanoparticles to accommodate Raman dyes and create stable hot spots in the two layers of the Au@Ag satellite.Two kinds of MDAu@Ag tags with disjoint characteristic peaks were constructed by using two kinds of Raman reporter molecules DTNB and 4-MBA.(4)Establishment of SERS-ICA method based on MDAu@Ag and its application in the detection of four veterinary drug residues.The SERS-ICA based on MDAu@Ag detection technique is used to support the simultaneous and sensitive detection of four veterinary drugs(kanamycin,chloramphenicol,CLE,and RAC)in untreated complex samples.This method can quickly detect many kinds of drug residues in 35 min,and the detection limits are 0.52,2.5,0.87 and 6.2 pg/m L,respectively.In addition,the sensitivity of this method is more than 400 times higher than that of the traditional colorimetric ICA method.Compared with commercial ELISA kits,the sensitivity is increased by about 10-287 times.The above results show that the two SERS-ICA methods based on magnetic nanomaterials have the advantages of simple operation,flexible mode,short detection time,high sensitivity(pg/m L),good reproducibility,and strong specificity,and are expected to become powerful real-time detection techniques for detection of illegal food additives.