Visual and colorimetric detection of p-aminophenol in environmental water and human urine samples based on anisotropic growth of Ag nanoshells on Au nanorods

• p-AP in environmental water and human urine can be visual readout by the naked eyes.
• Anisotropic growth of Ag nanoshells on Au NRs causes a multicolor change.
• The samples can be tested without complicated pretreatment and sophisticated instruments.
• The colorimetric method is well-suited for on-site applications.
• The portable test kit provides a simple assay for non-professional end-users.

A simple, sensitive, selective and high-resolution colorimetric method has been developed for the detection of p-aminophenol in environmental water and human urine samples. In the presence of p-aminophenol, silver ions are reduced to silver atoms and subsequently Ag nanoshells anisotropically grow on the surface of Au nanorods to generate orange slice-like Au@Ag core–shell nanocrystals, thereby resulting in the blue-shift of longitudinal surface plasmon resonance band of Au nanorods accompanying a sharp-contrast multicolor change. Using Au@Ag core–shell nanocrystals as the transducer, sub-micromolar p-aminophenol can be detected by the colorimetric method and 10 μmol L−1 p-aminophenol can be visual readout by the naked eyes. Furthermore, a simple, cheap, portable test kit is constructed for the visual assay of urinary p-aminophenol without complicated sample pretreatment and sophisticated instruments. The proposed colorimetric method has the potential for the rapid and on-site analyses of p-aminophenol in environmental water and human urine samples.

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