title: The effects of pH and surfactants on the absorption and fluorescence properties of ochratoxin A and zearalenone.
abstract: The pH and surfactant dependencies of the absorption and fluorescence properties of ochratoxin A (OTA) and zearalenone (ZEN), the main mycotoxins found as contaminants in foods and feeds, were evaluated. Three surfactants with different ionic properties were investigated, namely sodium dodecyl sulfate (SDS, anionic), Tween 20 (nonionic) and hexadecyltrimethylammonium bromide (CTAB, cationic). The results show that the effects of pH on the absorption wavelength maxima and fluorescence efficiencies of the mycotoxins, which are a consequence of the presence of acidic phenol and/or carboxyl containing fluorophores, are dependent on the ionic nature of the added surfactants. Specifically, the fluorescence responses to pH changes of OTA and ZEN are similar in the presence or absence of Tween 20 and SDS. By contrast, the pH-dependent fluorescence properties of these mycotoxins are altered when CTAB is present in the solutions. Moreover, unlike OTA, ZEN in aqueous solution displays almost no fluorescence. However, fluorescence enhancement takes place when surfactants are present in aqueous solutions of this mycotoxin. The results of this study demonstrate that the different microenvironments, present in the organized micellar systems created by the individual surfactants, can be potentially employed to modulate the sensitivities and selectivities of the fluorescence detection of OTA or ZEN.
authors.affiliation: Department of School of Physics and Chemistry, Gwangju Institute of Science & Technology (GIST), 261 Cheomdan-gwagiro, Gwangju, 500-712, Republic of Korea.
authors.forename: Taihua
authors.initials: T
authors.lastname: Li
authors.affiliation: Biomedical Translational Research Center, Korea Research Institute of Bioscience & Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon, 305-806, Republic of Korea.
authors.forename: Bo Bae
authors.initials: BB
authors.lastname: Kim
authors.affiliation: Biomedical Translational Research Center, Korea Research Institute of Bioscience & Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon, 305-806, Republic of Korea.
authors.forename: Tae Hwan
authors.initials: TH
authors.lastname: Ha
authors.affiliation: Biomedical Translational Research Center, Korea Research Institute of Bioscience & Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon, 305-806, Republic of Korea.
authors.forename: Yong-Beom
authors.initials: YB
authors.lastname: Shin
authors.affiliation: Department of School of Physics and Chemistry, Gwangju Institute of Science & Technology (GIST), 261 Cheomdan-gwagiro, Gwangju, 500-712, Republic of Korea.|Advanced Photonics Research Institute, Gwangju Institute of Science & Technology (GIST), 261 Cheomdan-gwagiro, Gwangju, 500-712, Republic of Korea.
authors.forename: Min-Gon
authors.initials: MG
authors.lastname: Kim
mesh_terms: D005453:Fluorescence; D006863:Hydrogen-Ion Concentration; D008823:Micelles; D015394:Molecular Structure; D009793:Ochratoxins / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013501:Surface-Active Agents / Q000737:chemistry*; D015025:Zearalenone / Q000737:chemistry*
chemical_list: D008823:Micelles; D009793:Ochratoxins; D013501:Surface-Active Agents; C025589:ochratoxin A; D015025:Zearalenone
keywords: fluorescence; mycotoxin; ochratoxin A; pH; surfactant; zearalenone