1：Experimental Design and Method Selection:

The design utilizes the intrinsic G-quadruplex structure of aptamers and the specific binding of ThT to this structure. A FRET-based ratiometric approach is employed, with FAM-labeled aptamer as the acceptor and ThT as the donor. The method involves homogeneous analysis in solution at room temperature.

2：Sample Selection and Data Sources:

OTA toxin, other toxins (aflatoxins B1, B2, M1, zearalenone), amino acids (tyrosine, leucine, histidine, arginine), and real samples (coffee and oat) were used. OTA aptamer with specific sequence was synthesized and labeled.

3：List of Experimental Equipment and Materials:

Reagents include ochratoxin A, aflatoxins, zearalenone, amino acids, thioflavin T, coffee, oat, Tris-HCl buffer, NaCl, CaCl2, KCl. Equipment includes fluorescence microplate reader Synergy H1, F-7000 fluorophotometer, Evolution 201 UV-Visible Spectrophotometer.

4：Experimental Procedures and Operational Workflow:

For OTA detection, FAM-labeled aptamer and ThT are mixed with reaction buffer, then OTA is added and incubated for 30 s. Fluorescence spectra are measured at excitation wavelengths of 425 nm and 485 nm. Real-time fluorescence and UV-Vis spectra are also recorded. Sample preparation for coffee and oat involves filtration, dilution, extraction, and centrifugation.

5：Data Analysis Methods:

Fluorescence intensity ratios (485Ex/425Ex) are calculated for ratiometric detection. Calibration curves are plotted, and limit of detection is determined based on standard deviations. Specificity is tested by comparing responses to different analytes.