| Malachite green(MG)is a kind of toxic and carcinogenic fishery drug,which exists in aquatic products and aquaculture water and is likely to arouse problems of food safety and environment at the same time.Recent years,there have been many approaches for MG detection in order to supervise the illegal use of MG.As a novel trace detection technology,surface-enhanced Raman scattering(SERS)has been more and more researched and applied in the detection of MG owing to the outstanding advantages such as simple operation,high sensitivity and rapid detection.However,the non-targeted substances in the actual sample interfere with the SERS spectra of MG,leading to the difficulty of quantitative determination in the complex matrix using SERS.Thus,the purpose of the research was to synthesize a multifunctional SERS sensor(molecular selectivity,molecular enrichment,Raman signal amplification and recovery)based on plasma nanomaterials,metal organic frameworks and magnetic materials,and to achieve accurate,sensitive and convenient detection of trace amounts of MG fishery drug residues in a relatively complex matrix.In addition,the approach requied very small amount of sample and simple pre-processing procedures,which was beneficial to the monitoring and analysis of MG in real samples.The research content and results of this paper are as follows:(1)The synthesis methods of MNP@Au@MIL-100(Fe)composite nanostructure were explored,and the magnetic core(MNP),satellite layer(gold nanoparticle)and the outer layer structure(MIL-100(Fe))were optimized layer by layer through a series of characterization methods.And the results showed that the magnetic core was a regular sphere with relatively smooth surface,the gold nanoparticles formed an ideal satellite structure outside the magnetic core,and the surface of MNP@Austructure was successfully coated with the MIL-100(Fe)shell(thickness of which was about 25 nm).Furtheremore,the main pore sizes of nanostructure were 17.656 and 27.691(?)and the superficial area was 140.141 m2/g.(2)The SERS activity and detection conditions of the MNP@Au@MIL-100(Fe)SERS sensor were optimized.In addition,the sensitivity and stability of the SERS sensor were determined.The results showed that the SERS activity of MNP@Ausubstrate achieved the highest when the mixing ratio of magnetic nanoparticles to gold nanoseed solution was 1:5 and the amount of HAuCl4 solution(5 mM)was 4 mL.When MNP@Au@MIL-100(Fe)multifunctional SERS sensor was applied in MG detection,a relatively strong SERS signal could be obtained after incubation of 40 minutes.In addition,the structure of the MNP@Au@MIL-100(Fe)composite material could still remain stable after repeated ultrasonic treatments in a liquid environment.The relative standard deviation(RSD)of 40 SERS spectra of 4-nitrobenzenethiol obtained by the multifunctional SERS sensor was 5.52%,and the limit of detection(LOD)was 3.45×10-10 M,illustrating the good reproducibility and sensitivity of such SERS sensor.(3)The molecular selectivity,sensitivity and stability in mixed sample systems(shrimp protein extract and aquaculture water system)of multifunctional SERS sensor were explored.The results indicated that:MNP@Au@MIL-100(Fe)“filtered”more than 92%of the R6G signal,demonstrating that such multifunctional SERS sensor was capable to recognize the analyte selectively.MNP@Au@MIL-100(Fe)multifunctional SERS sensor had good reproducibility(RSD is 9.68%)when detecting MG molecules.Additionly,the multifunctional SERS sensor successfully sensed the MG in shrimp protein extract system,with a LOD of1.32×10-10 M.Moreover,the recovery rate of MG spiked in aquaculture water samples was between 94.45%and 109.00%with a LOD of 1.29×10-10 M.The SERS intensity of MG obtained by the multifunctional SERS sensor stored for seven weeks was above 98%of that stored for one week,indicating the excellent stability of the SERS sensor. |
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