Electronic Supporting Information for Homogeneous Fluorescence Resonance Energy Transfer Immunoassay for the Determination of Zearalenone Taihua Li,1,+ Bo Bae Kim,2,+ Won-Bo Shim,1 Ju-Young Byun,1 Duck-Hwa Chung,3 YongBeom Shin,2 Min-Gon Kim1,4,* 1 School of Physics and Chemistry, Gwangju Institute of Science & Technology (GIST), 261 Cheomdan-gwagiro, Gwangju 500-712, Korea 2 Research Center of Integrative Cellulomics, Korea Research Institute of Bioscience & Biotechnology (KRIBB), 125 Gwahak-ro, Yuseong-gu, Daejeon 305-806, Korea 3 Division of Applied Life Science, Graduate School of Gyeongsang National University, Jinju 660-701, Republic of Korea 4 Advanced Photonics Research Institute, Gwangju Institute of Science & Technology (GIST), 261 Cheomdan-gwagiro, Gwangju 500-712, Korea *Corresponding author: FAX: +82-62-715-3419; E-mail address: [email protected] + These authors contributed equally to this work. A) B) C) Fig S1. (A) Chemical structure of zearalenone (ZEN); (B) Absorption spectrum of 10 μg mL-1 ZEN in methanol (red curve); (C) Fluorescence spectra of 5 μg mL-1 ZEN in methanol upon excitation at 280 and 320 nm. Fig S2. Fluorescence excitation spectra of ZEN (5 μg mL-1) in various pH conditions with 10 mM cetyltrimethylammonium bromide (CTAB) at emission wavelength of 450 nm. pH 4.0 and 5.0: 10 mM acetate buffer; pH 6.0, 7.0, and 8.0: 10 mM phosphate buffer; pH 9.0: 10 mM NaHCO3 buffer. A) B) C) D) E) F) Fig S3. Fluorescence spectra of ZEN, anti-ZEN antibody (anti-ZEN), and ZEN/anti-ZEN complex in pH 9.0 10 mM NaHCO3 buffer with various concentration of CTAB upon excitation at 280 nm: (A) 0 mM CTAB, (B) 0.5 mM CTAB, (C) 1 mM CTAB, (D) 2 mM CTAB, (E) 5 mM CTAB, (F) 10 mM CTAB. 100 ng mL-1 of ZEN and 20 μg mL-1 anti-ZEN were used in this analysis. A) B) Fig S4. (A) Fluorescence intensities of ZEN and ZEN/anti-ZEN complex at 430 nm from Fig S3; (B) Relative fluorescence intensities of ZEN/anti-ZEN complex (IZEN/anti-ZEN – IZEN) from (A) at 430 nm. A) B) Fig S5. Fluorescence excitation spectra of ZEN, anti-ZEN, and ZEN/anti-ZEN complex with 0 mM CTAB (A) and 0.5 mM CTAB (B) upon emission wavelength at 430 nm. 100 ng mL-1 of ZEN and 20 μg mL-1 anti-ZEN were used in this analysis. A) B) Fig S6. Plot of relative fluorescence intensities of I430 nm (A) and /I350 nm (B) from Fig 3A in the manuscript as a function of concentration of ZEN from 0 to 1000 ng mL-1. Inset figures: Linear portion of the plot A and B. Fluorescence spectra were recorded using excitation at 280 nm. Error bars denote standard deviation of 3 replicates each. Table S1. LOD determination Method LOD I430 nm/I350 nm 0.8 ng/mL I350 nm 2.3 ng/mL I430 nm 6.8 ng/mL A) C) B) D) Fig S7. Fluorescence spectra of 0, 20, and 100 ng mL-1 ZEN with anti-IFN - (A), anti-OTA (B), and anti-ZEN (C); 0, 20, and 100 ng mL-1 ZAN with 20 μg mL-1 anti-ZEN (D). (Excitation wavelength: 280 nm) A) B) C) D) Fig S8. Fluorescence spectra of solutions in final containing 0, 2, 10 ng mL-1 ZEN with unspiked wheat (A), with 20 μg mL-1 anti-ZEN (B), with spiked wheat (C) and 0, 2, 10 ng mL-1 ZEN spiked wheat samples with 20 μg mL-1 anti-ZEN (Excitation wavelength: 280 nm).