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

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 KF1 = 2548 ± 127 M-1 and KF2 = 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 (KF3 = 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.