In-situ monitoring reversible redox reaction and circulating detection of nitrite via an ultrasensitive magnetic Au@Ag SERS substrate

Surface plasmon-assisted catalytic reaction of p–aminothiophenol (P-ATP) to p-nitrothiophenol (P-NTP) on ultrasensitive magnetic Au@Ag nanoparticles (Fe 3 O 4 /Au@Ag NPs) has been observed by surface-enhanced Raman scattering (SERS). The as-prepared magnetic nanoparticles integrate magnetic and desired plasmonic on the same nanostructure, show great potential for simultaneous magnetic separation and SERS-based catalytic analysis. In acid media, high concentration of nitrite ion triggered the P-ATP molecules quickly transform into P-NTP on Fe 3 O 4 /Au@Ag NPs. These unique attributes enable in-situ SERS monitoring nitrite-triggered oxidation reactions of P-ATP to P-NTP and the subsequent NaBH 4 -drived reduction reactions of P-NTP to P-ATP on Fe 3 O 4 /Au@Ag could achieve under optimized condition. Moreover, this circulated reversible redox process could provide a circular and efficient approach to detection of nitrite ion. Considering this method without sample pretreatment and can circulate many times, indicating that it is a promising method in-situ fast detection nitrite ion.