Fluorescent Gold Nanocluster-based Sensor Array for Nitrophenol Isomer Discrimination via an Integration of Host-Guest Interaction and Inner Filter Effect
Analytical chemistry | 10 Oct 2018
H Yang, F Lu, Y Sun, Z Yuan and C Lu
The rapid discrimination of nitrophenol isomers has been a long-standing challenge because of the tiny structural differences among the isomers. In this study, a fluorescent sensor array based on three different-color emitting gold nanoclusters (Au NCs) that were functionalized with three different ligands and a co-capping ligand β-cyclodextrin (β-CD) has been constructed for the facile discrimination of three nitrophenol isomers via the linear discriminant analysis of isomer-induced fluorescence quenching patterns. The fluorescence quenching occurs in two steps: firstly, β-CDs adsorb nitrophenol isomers onto the surface of Au NCs via host-guest interaction; secondly, each nitrophenol isomer quenches the fluorescence of a specific type of Au NCs through an inner filter effect. The different binding affinities between β-CD and each nitrophenol isomer, as well as the distinct quenching efficiencies of the isomers on the fluorescence of each Au NCs, enable an excellent discrimination of the three isomers at a concentration of 5 µM, when linear discriminant and hierarchical cluster analyses were smartly combined. In addition, even a mixture of two isomers could be distinguished with the proposed sensor array. The practicability of this developed sensor array is validated by a high accuracy (98.0%) examination of 51 unknown samples containing a single isomer or a mixture of two isomers.
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