Rapid and sensitive detection of Rhodamine B in food using the plasmonic silver nanocube-based sensor as SERS active substrate.

The use of dye in food is harmful to human health and is prohibited nowadays. However, it is still used because of the benefits, such as cheap prices and abundant resources. Rhodamine B is usually used as the colorant in food such as chili powder, chili oil, etc. It is colorless at very low concentration 10 M. The sensitive detection of RhB at ultra-low concentration help to prevent some risk for human. Surface-enhanced Raman scattering (SERS) is a great technique to detect the analytes at ultra-low concentration and provide the molecule's information as a fingerprint. In this study, silver nano-cube was facilely synthesized by reducing Ag in ethylene glycol and upgraded to thin-film as a SERS active substrate. RhB was detected at 10 M by a silver nano-cube sensor. The dynamic linear regression between the Raman intensity and RhB concentration over seven orders of magnitude (from 10 to 10 M) was excellent with high reliability (R = 0.99). Moreover, the substrate can be used after storing in a dark area for 60 days. This proposed nano-cube silver could serve as a potential substrate for detecting RhB in food at very low concentration.