Bimetallic MOF-derived Ni nanocluster composites for fluorescence sensing of 5-nitroimidazole antibiotics.

Abstract

The non-noble fluorescent nickel nanoclusters (Ni NCs) have promising application in the fluorescence sensing field, but their controllable synthesis remains a challenge. In this study, a straightforward and controllable synthesis strategy for Ni NCs was presented by in situ etching of Ni-based metal-organic frameworks (Ni-MOFs). Specifically, the bimetallic Ni/Zn-MOFs as precursors were etched and transformed into a nanocomposite, denoted as Ni NCs/Zn-MOFs. Due to different redox properties of bimetals, the Zn-MOFs retained their framework structures during the formation of Ni NCs, thus effectively enhancing fluorescence performance of the Ni NCs. Notably, the fluorescence of the Ni NCs/Zn-MOFs was quenched more efficiently by 5-nitroimidazole (5-NDZ) antibiotics than that of Ni NCs derived from Ni-MOFs. This likely originates from the synergistic effects of the Zn-MOFs, namely their capacity for enriching the analyte and promoting fluorescence quenching. Thus, a fluorescence sensor for ornidazole (ODZ) was constructed based on the Ni NCs/Zn-MOFs with two linear ranges of 0.005-1.0 and 1.0-80 µM and a low detection limit of 0.005 µM. It was also successfully applied to detect other 5-NDZs and real samples with satisfactory results, further validating its practical applicability. This study provides a new strategy for preparing Ni NCs and demonstrates their potential in fluorescence sensing.

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