Abstract

Supramolecular Interaction of Benzalkonium Bromide with Cucurbit[7]uril and Its Analytical Application

Author(s): Jian HX, Shi L, Li-Ming D

Benzalkonium bromide (BKB) shows weak fluorescence in aqueous solutions, which makes it difficult to determine its concentration directly using fluorescence methods. In the present study, a competitive reaction between BKB and palmatine for occupation of the cucurbit[7]uril (CB[7]) cavity was studied by spectrofluorometry. Palmatine reacted with CB[7] to form a probe with strong fluorescence. However, the presence of BKB quenched the fluorescence of the probe. The rate of fluorescence quenching was proportional to the concentration of BKB. Formation of a supramolecular complex with CB[7] provides a simple, accurate, and highly sensitive fluorescent probe for the determination of BKB in commercially available injection solutions and plasma samples. The linear range of the method was 0.004 μg mL-1 to 1.768 μg mL-1, with a detection limit of 0.002 μg mL-1. Molecular modeling of the interaction between BKB and CB[7] was established, and the results were confirmed by 1H NMR. The mechanism of fluorescence for the probe is discussed. The proposed method has potential for therapeutic monitoring, pharmacokinetics, and clinical applications.