An organic-inorganic hybrid copper nanocluster for ratiometric fluorescence of tobramycin.

Antibiotics, as widely used therapeutic agents, have attracted considerable attention in pharmaceutical analysis. Copper nanoclusters (CuNCs) are powerful signal converters in fluorescence assays, but are still challenged by their photoluminescence efficiency and the capability of precise detection on single-signal strategy. Herein, a novel ratiometric fluorescence sensor based on an organic-inorganic hybrid nanoprobe (CuCoNCs@PVP/Flu Na) was constructed for tobramycin (TOB) detection, which demonstrates a blue fluorescence emission of metal-doped copper clusters at 417 nm and a green fluorescence emission of fluorescein sodium (Flu Na) at 513 nm. In the presence of TOB, the hydrogen bonding between TOB and CuCoNCs@PVP/Flu Na causes the aggregation of nanocluster and improves absorption capacity of Flu Na moiety, resulting in a decrease in fluorescence at 417 nm and an increase in emission at 513 nm. The ratiometric fluorescence assay has realized sensitive and robust analysis of TOB with a detection limit (LOD) of 4.79 nM and a relative standard deviation (R.S.D) of 1.64 % within one week, as well as high accuracy in eye drops and human urines with recoveries of 94-113 %. The proposed methodology provides a new thought for the detection of tobramycin and other antibiotics, and holds great prospects in field applications.