Sensitive detection of cyanide using bovine serum albumin-stabilized cerium/gold nanoclusters

Abstract

A simple, sensitive, and selective fluorescence assay for the detection of CN⁻ has been demonstrated using bovine serum albumin-stabilized cerium/gold nanoclusters (BSA–Ce/Au NCs). When excited at 325 nm, BSA–Ce/Au NCs have two fluorescence bands centered at 410 and 658 nm, which are assigned to BSA–Ce/Au complexes and Au NCs, respectively. Each BSA–Ce/Au NC contains 22 Au atoms and 8 Ce ions. Through etching of the Au core in BSA–Ce/Au NCs by CN⁻, the fluorescence at 658 nm is quenched, while that at 410 nm enhances during the formation of complexes among BSA, Ce⁴⁺, and [Au(CN)₂]⁻. The circular dichroism spectra reveal that relative to BSA–Au NCs, BSA–Ce/Au NCs have looser structures of the BSA templates. As a result, it is easier for CN⁻ to access the Au cores in BSA–Ce/Au NCs, allowing faster (within 15 min) etching of the Au cores by CN⁻. At pH 12.0, this assay allows the detection of CN⁻ down to 50 nM, with linearity over 0.1–15 μM. This assay has been applied to the determination of the concentrations of CN⁻ in spiked drinking water and pond water samples.

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