Analysis of the photophysical properties of zearalenone using density functional theory

Authors: Appell, Michael; Wang, Lijuan; BOSMA, WAYNE - Bradley University

Submitted to: Luminescence
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2017
Publication Date: 6/12/2017
Citation: Appell, M., Wang, L.C., Bosma, W.B. 2017. Analysis of the photophysical properties of zearalenone using density functional theory. Luminescence. 188:551-557.

Interpretive Summary: Zearalenone is a toxin that is produced by fungi that occasionally contaminate agricultural commodities and can negatively impact food safety and value. Researchers in Peoria, Illinois, determined key factors of water’s influence on the fluorescence detection of zearalenone using computational and experimental methods. Computational quantum chemical methods indicated the interaction of water with the oxygen containing functional groups influences the fluorescence detection properties. The results of this study support the validation of analytical methods to detect zearalenone and this phenomenon can be applied to develop more selective methods of detection. These research findings will be of interest to food safety scientists, analytical scientists, and chemists.

Technical Abstract: The intrinsic photophysical properties of the resorcylic acid moiety of zearalenone offer a convenient label free method to determine zearalenone levels in contaminated agricultural products. Density functional theory and steady-state fluorescence methods were applied to investigate the role of structural chemistry on zearalenone detection. Geometry optimization calculations using the B3LYP density functional identified a tautomeric form of zearalenone. Excited state geometries for zearalenone and a tautomeric form were obtained by MNDO semi-empirical optimizations. Steady-state fluorescence studies suggest that fluorescence quenching at neutral pH is associated with water interactions. Time-dependent density functional and ground state calculations indicate that the anionic and dianionic forms of zearalenone possess lower band gaps, excitation energies, and the lowest unoccupied molecular orbitals are positioned over the non-fluorophoric portion of zearalenone. These results suggest that deprotonation of one or more of the phenolic hydroxyls diminishes the intensity of the fluorescence emission of zearalenone.