A colorimetric/SERS dual-mode sensor based on ferric ion-dopamine@Au-Ag-Au Janus NPs for acrylamide determination in baked goods.

This study successfully developed a colorimetric/SERS dual-mode sensor for determining acrylamide in baked goods based on the excellent peroxidase-like activity and Raman activity of Fe-PHS@Au-Ag-Au Janus NPs. In colorimetric mode, the thiol-ene Michael addition between acrylamide (AA) and glutathione (GSH) efficiently eliminates GSH-induced peroxidase-like activity inhibition. The peroxidase-like activity of Fe-PHS@Au-Ag-Au Janus NPs gradually recovered, and the blue color of the solution gradually deepened with the increase in AA dosage. In surface-enhanced Raman spectroscopy (SERS), Apt-Fe-PHS@Au-Ag-Au Janus NPs can selectively capture AA and bind specifically, leading to the dissociation of Apt and Fe-PHS@Au-Ag-Au Janus NPs. The Raman activity of Apt-Fe-PHS@Au-Ag-Au Janus NPs decreases due to the dissociation of Apt. The dual-mode sensor was utilized for the determination of acrylamide in the concentrations range from 0.05 to 20 µg·L with detection limits of 0.06 µg·L (SERS) and 0.01 µg·L (colorimetric). The recovery in baked samples was between 91.0 and 108.0%.