Multiplexed surface-enhanced Raman scattering detection of melamine and dicyandiamide in dairy food enabled by three-dimensional polystyrene@silver@graphene oxide hybrid substrate

Owing to its ultranarrow spectral line width, surface-enhanced Raman scattering (SERS) as a specific fingerprint identification technology has exhibited its distinctive talent in the multiplexed assay of illegal food additives. Herein, a three-dimensional (3D) hybrid SERS substrate was constructed by utilizing polystyrene (PS) nanospheres as template matrix, silver as active interlayer, and graphene oxide (GO) as coating surface to enable the effective monitoring of mixed melamine and dicyandiamide in dairy food without interference. Through amalgamating the significant electromagnetic effect triggered by the PS-mediated 3D architectures with the chemical enhancement and molecule-enrichment abilities of GO, the proposed substrate exhibited a highly sensitive detection characteristics with reliable reproducibility, facilitating a limit of detection low to 2.8 x 10(-8) M for 2-naphthalenethiol. After the further establishment of standard calibration lines, the feasibility of the proposed sensitive substrate in the multivariate monitoring of melamine and dicyandiamide was verified in milk as well as yogurt, achieving moderate recovery rates higher than 75%. This work proposed a facile strategy to construct 3D hybrid SERS substrate, which might show great promise to secure food security.