Colorimetric detection of benzoyl peroxide based on the etching of silver nanoshells of Au@Ag nanorods

A fast, sensitive and high-resolution colorimetric method for sensing benzoyl peroxide (BPO) was proposed by using orange sheath-like Au@Ag nanorods (NRs) as the signal transducer. BPO can oxidize Ag nanoshells on the surface of Au@Ag NRs; the etching of Ag nanoshells changes the aspect ratio of Au nanostructures and causes a red-shift of longitudinal local surface Plasmon resonance (LSPR) peak, resulting in a sharp-contrast multicolor change within 2 min. Under the optimal conditions, the red-shift of longitudinal LSPR peak was in linear with the BPO concentration over the range of 0-100 μmol L−1 with a limit of detection of 0.75 μmol L−1. Furthermore, a simple, inexpensive and portable test kit was designed for the visual detection of BPO. A color variation can be distinguished by naked eyes at a concentration of BPO as low as 20 mg kg−1 in flour samples. The colorimetric sensor shows a great potential application for the rapid and on-site assay of BPO in flour samples.