Fig. 2. (a) Magnetic hysteresis curves of Fe₃O₄, Fe₃O₄-20/3 nm Au seed, and Au@MNPs. (b) Magnetic separation behavior and (c) SERS intensity of Au@MNP-WGA tags in various food samples. (d) TEM and SEM images of Au@MNP-WGA-L. mono complexes (i), (iv), Au@MNP-WGA-C. jejuni complexes (ii), (v), and Au@MNP-WGA-S. aureus complexes (iii), (vi). (e) Photographs of the colonies on blood agar plates indicating the amounts of remaining L. mono, S. aureus, and C. jejuni in the supernatant after the magnetic enrichment of Au@MNP and Au@MNP-WGA tags. (f) Corresponding capture efficiencies of Au@MNP-WGA for L. mono, S. aureus, and C. jejuni.