Poly(adenine)-templated fluorescent Au nanoclusters for the rapid and sensitive detection of melamine.

A rapid and label-free fluorescence sensing strategy has been established for the sensitive determination of melamine (MA) on the basis of poly(adenine) (poly (A))-templated Au nanoclusters (AuNCs). The poly(A)-templated AuNCs possessed excellent luminescence and photo-stability. In the presence of Hg, the luminescence of AuNCs was quenched by Hg through the metallophilic interactions between Au and Hg. When melamine was introduced, the fluorescence intensity of sensing system could be recovered. There was a greater coordination interaction between Hg and melamine, which blocked the Hg-mediated fluorescence quenching of AuNCs. The assay allowed sensitive determination of melamine with a linear detection range from 50 nM to 100 μM. The limit of detection was as low as 16.6 nM. Furthermore, the label-free strategy was successfully employed for the detection of melamine concentration in real samples.