Smartphone-assisted fluorescence sensor based on AuNCs/ZIF-8 for highly selective detection of Sb³⁺ ions

A novel smartphone-assisted fluorescence sensor was prepared for determination of antimony ions (Sb³⁺). It was synthesized by encapsulating glutathione (GSH)-decorated gold nanoclusters (AuNCs) into zeolitic imidazolate frameworks (ZIF-8) (denoted as AuNCs/ZIF-8). Based on the strong fluorescence quenching caused by the addition of Sb³⁺ ions, the AuNCs/ZIF-8 was designed for determination of  Sb³⁺ ions. The basic reason for fluorescence quenching of AuNCs caused by Sb³⁺ ions is the reduction of Au (I) to Au (0), which is proved by the XPS. Mercury ions (Hg²⁺) and copper ions (Cu²⁺), the common interfering ions that can cause the strong quenching of AuNCs, can be masked by sodium borohydride (NaBH₄) and diethylene triamine pentaacetic acid (DTPA), respectively. Therefore, the prepared fluorescent sensor of AuNCs/ZIF-8 has high selectivity to the Sb³⁺ ions. Under the optimal conditions, this proposed fluorescence sensor exhibited good linearity in the concentration range 1.25 × 10^-8 to 7.5 × 10^-4 M with a limit of detection of 3.13 × 10^-9 M. Furthermore, this portable smartphone-assisted sensing platform based on AuNCs/ZIF-8 has the advantages of significant simplification and speeds of the operation process, which provides a new analytical method for real-time determination analysis of Sb³⁺ ions in real samples.