A competitive strategy based on cucurbit[7]uril supramolecular interaction for simple and sensitive detection of dibucaine

•The fluorescence method was used for determination of dibucaine for the first time.•The competitive strategy was designed for determination of dibucaine.•The occupancy of the cucurbit[7]uril cavity was studied by spectroscopy and calculations.•The proposed method showed good sensitivity for detection of dibucaine in biological fluids.

In this work, the competitive interaction between dibucaine and three fluorescent probes (i.e., berberine, palmatine, and coptisine) for occupancy of the cucurbit[7]uril (CB[7]) cavity was studied by fluorescence spectra, UV–visible absorption spectra, 1H NMR spectra, and theoretical calculations in acidic aqueous solution. Based on the fluorescence enhancement of berberine, palmatine, and coptisine upon binding with CB[7], respectively, a series of fluorescence detection methods for dibucaine were proposed. At the optimized conditions, the fluorescence intensity of berberine-CB[7], palmatine-CB[7], and coptisine-CB[7] complexes showed negative correlation to the concentration of dibucaine, which led to a series of simple and sensitive fluorescence methods for the determination of dibucaine for the first time. Linear ranges obtained in the detection of the dibucaine were 0.018–3.34 μmol L−1, 0.032–4.47 μmol L−1, and 0.079–4.42 μmol L−1 with detection limits of 6.0 nmol L−1, 12.0 nmol L−1, and 25.0 nmol L−1, respectively. Moreover, the proposed method was successfully applied for the determination of the drug in biological fluids. The competitive mode based on CB[7] superstructure provided a promising assay strategy for fluorescence detection in various potential applications.

Graphical abstractThe competitive interaction between dibucaine (DC) and three fluorescent probes (i.e., berberine (BER), palmatine (PAL), and coptisine (COP)) for occupancy of the cucurbit[7]uril (CB[7]) cavity was observed and used for simple and sensitive detection of dibucaine.Figure optionsDownload full-size imageDownload as PowerPoint slide