Ethylenediaminetetraacetic acid disodiumsalt edta

Methanol and potassium chloride (KCl) were purchased from the Aladdin company (Shanghai, China), potassium ferrocyanide (K₄[Fe(CN)₆]), potassium ferricyanide (K₃[Fe(CN)₆]), disodium hydrogen phosphate dodecahydrate (Na₂HPO₄-12H₂O), disodium hydrogen phosphate dehydrate (NaH₂PO₄-2H₂O), sodium hydroxide (NaOH), and glucose (C₆H₁₂O₆), were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Chloroauric acid (HAuCl₄·4H₂O), graphene oxide nanosheets (GO, XF002-1, 500 nm–5 μm; ~99%, Hummers) were purchased from Nanjing XFNANO Materials Tech. Co., Ltd (Nanjing, China). Tris(2-carboxyethyl) phosphine (TCEP) was obtained from Sigma-Aldric. Ochratoxin A (OTA), ochratoxin B (OTB), deoxynivalenol (DON), and zearalenone (ZEA) were purchased from Sigma-Aldrich (Shanghai, China). Tris(hydroxymethyl)aminomethane hydrochloride (tris-HCl) and ethylenediaminetetraacetic acid disodiumsalt (EDTA) were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Bovine serum albumin (BSA) was purchased from Sigma-Aldrich. OTA binding-aptamer with a sequence (5′-GAT CGG GTGTGG GTG GCG TAA AGG GAG CAT CGG ACA-(CH₂)₆-SH-3′) was purchased from Sangon Biotech. (Shanghai, China). All reagents and chemicals were of the highest analytical grade. Millipore-Q water (18.2 MΩ cm⁻¹) was used to prepare all aqueous solutions.

Fluorescence spectra were taken on a FL3C-111 TCSPC luminescence spectrometer equipped with a 20-kW xenon discharge lamp as a light source (Horiba, Kyoto, Japan). X-ray powder diffraction (XRD) spectra were taken on a Rigaku D/MAX2500V X-ray diffractometer (Rigaku, Tokyo, Japan). The microstructural features of the samples were characterized by a F200X (Semerfeld, Seattle, WA, USA) transmission electron microscope (TEM).
Thioglycolic acid (TGA), NaBH₄, CdCl₂·2.5H₂O, Na₂S·9H₂O, and ethylenediaminetetraacetic acid disodium salt (EDTA) in analytical grade and various standard solution of metal ions (K⁺, Na⁺, Mg²⁺, Ba²⁺, Al³⁺, Mn²⁺, Fe³⁺, Ca²⁺, Hg²⁺, Pb²⁺, Cu²⁺, Ag⁺, Ni⁺, Zn²⁺, Cd²⁺) were purchased from Sinopharm Chemical Reagent Co., Ltd. Analytically pure tris (hydroxymethyl) methyl aminomethane (Tris) was purchased from Aladdin company. Ultra-pure water was used in the whole experiment except for particular notations in text, and the resistivity of ultra-pure water is above 18 MΩ·cm (25 °C).