A label-free, rapid, sensitive and selective technique for detection of Fe2+ using SERRS with 2,2′-bipyridine as a probe

Abstract We have developed a label-free, concise, time-efficient, ultrasensitive, and selective strategy for the determination of Fe2+ ion based on surface-enhanced resonance Raman scattering (SERRS) spectroscopy. There was no Raman signal because of the weak adsorption of 2,2′-bipyridine (Bpy) on silver nanoparticles (AgNPs). Upon the addition of Fe2+, Bpy quickly formed [Fe(Bpy)3]2+ complexes with Fe2+ and produced an intense Raman signal through inducing the aggregation of AgNPs, which provided a theoretical foundation for quantitative analysis of Fe2+. The proposed SERRS platform displayed a wide linear range from 10–11 to 10–7 M with an unprecedented detection limit of 5.73 pM. The whole process can be completed in 3 min and provided a new universal route for practical detection in various water samples.