Ellagic acid–borax fluorescence interaction: application for novel cyclodextrin-borax nanosensors for analyzing ellagic acid in food samples

Abstract

The food industry needs cheap, fast and sensitive methods to increase the number of analyses that are routinely carried out; for this reason, new methods are constantly being sought. This paper describes a novel fluorescent nanosensor based on cyclodextrin (CD) to determine ellagic acid (EA). The encapsulation of EA in the presence of borax was studied. Firstly, the complexation of EA–borax was tested. The stoichiometry of the EA–borax complex showed a 1 : 2 complex, with K_F1 = 2548 ± 127 M⁻¹ and K_F2 = 302 ± 15 M⁻¹. Different CDs were used to obtain a 1 : 1 : 1 CD–EA–borax complex with γ-CD providing the best complexation constant (K_F3 = 364 ± 18 M⁻¹). Furthermore, when the accuracy and sensitivity of the nanosensor were tested using a crude blueberry extract, the CD/borax mixture provided an 18 times stronger signal than with the crude extract alone and 7 times stronger than that obtained using borax alone.