Facile synthesis of FeO@Au core-shell nanocomposite as a recyclable magnetic surface enhanced Raman scattering substrate for thiram detection.

The FeO@Au core-shell nanocomposites, as the multifunctional magnetic surface enhanced Raman scattering (SERS) substrates, were fabricated successfully by the seeds growth method based on the FeO-Au core-satellite nanocomposites. The SERS properties of the FeO-Au core-satellite nanocomposites and the FeO@Au core-shell nanocomposites were compared using 4-aminothiophenol (4-ATP) as the probe molecule. It was found that FeO@Au core-shell nanocomposites showed better SERS performance than FeO-Au core-satellite nanocomposites. The Au shell provided an effectively large surface area for forming sufficient plasmonic hot spots and capturing target molecules. The integration of magnetic core and plasmonic Au nanocrystals endowed the FeO@Au core-shell nanocomposites with highly efficient magnetic separation and enrichment ability and abundant interparticle hot spots. The FeO@Au core-shell nanocomposites could be easily recycled because of the intrinsic magnetism of the FeO cores and had good reproducibility of the SERS signals. For practical application, the FeO@Au core-shell nanocomposites were also used to detect thiram. There was a good linear relationship between the SERS signal intensity and the concentration of thiram from 1 × 10 to 1 × 10 M and the limit of detection was 7.69 × 10 M. Moreover, residual thiram on apple peel was extracted and detected with a recovery rate range of 99.3%. The resulting substrate with high SERS activity, stability and strong magnetic responsivity makes the FeO@Au core-shell nanocomposites a perfect choice for practical SERS detection applications.