Potassium ferricyanide k3fe cn 6

The thiolated aptamer was synthesized by Synbio Technologies (Shanghai, China), the sequence of the aptamer was shown below: 5′-GATCGGGTGT GGGTGGCGTA AAGGGAGCAT CGGACA-3′, 5′-SH. OTA and OTB (analytical standard) used in this study was purchased from Pribolab Pte. Ltd. (Qingdao, China). Gold particles were synthesized from Chloroauric acid (HAuCl₄) and sodium citrate according to the literature [40 (link)].
Cysteamine (CA), Bovine serum protein (BSA), N-acetyl-l-phenylalanine (NAP), and Warfarin were purchased from Shanghai Yuanye Bio-technology Co. Ltd. (Shanghai, China). Potassium ferrocyanide (K₄[Fe(CN)₆]) and, potassium ferricyanide (K₃[Fe(CN)₆]), were purchased from Sinopharm Chemical Reagent Co. Ltd., Shanghai, China. The binding buffer (BB pH 7.4) was applied in all experiments containing 1 mM MgCl₂, 140 mM NaCl, 2.7 mM KCl, 0.1 mM Na₂HPO₄, and 1.8 mM KH₂PO₄ [28 (link)]. Ultra-pure water was obtained from a Milli-Q water-purification system (Millipore, Bedford, MA, USA).
An isolate H1 of Aspergillus niger isolated from the wine production region in Hexi Corridor, Gansu Province, which was provided by the College of Food Science and Engineering, Gansu Agricultural University, Lanzhou, China. The pathogen was grown on potato dextrose agar (PDA) medium for 7–10 days.

Approximately 2 kg samples of the aerial parts of ICM were freshly collected from Banma County (Qinghai, China) in August 2015 and were identified and authenticated by Professor Lijuan Mei (Northwest Institute of Plateau Biology, Chinese Academy of Science, Xining, China). The plant materials were shade-dried, ground into powder, sieved through a 0.8-mm metal sieve to achieve a standard size of particles and stored at 4 °C until use. DPPH, ABTS, BHT, VC, β-carotene, Tween 40, and linoleic acid were obtained from Aladdin Co. (Los Angeles, CA, USA). Ferric chloride (FeCl₃·6H₂O), potassium ferricyanide [K₃Fe(CN)₆] and other chemicals used were purchased from Sinopharm Chemical Reagent (Shanghai, China). The standards of gallic acid, rutin, and berberine were purchased from the National Institutes for Food and Drug Control (Beijing, China).

Pb(II) aptamer (5′-SH-GGGTGGGTGGGTGGGT-3′) was obtained from Sangon Biotechnology Co., Ltd. (Shanghai, China). Sodium tetrachloroaurate(III) (HAuCl₄) and GO was obtained from Sigma-Aldrich (Shanghai, China). Tris (2-carboxyethyl) phosphine (TCEP) and mercaptoethanol (MCH) was purchased from Aladdin Industrial Co. Ltd. (Shanghai, China). Pb (NO₃)₂ (Pb(II)), NaCl (Na(I)), KCl (K(I)), CaCl₂ (Ca(II)), MgCl₂ (Mg(II)), CdCl₂ (Cd(II)), CHO (25% in H₂O), EDTA, acetic acid, and potassium ferricyanide (K₃ Fe (CN)₆) were purchased from Sinopharm Reagent Co. Ltd. (Shanghai, China). Ultrapure water with a resistivity of 18.2 MΩ×cm was used in the whole experiment. Phosphate buffer (PBS) solution was acted as a supporting electrolyte (10 mM, contain 0.1 M NaCl, pH 7.4). Mantis shrimp samples were purchased from local seafood market (Shanghai, China).
Electrochemical experiments, such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV), were performed on a CHI 660 C workstation with a conventional three-electrode system. The working electrode was a glassy carbon electrode (GCE, Ф = 3 mm) or the prepared modified electrode; the auxiliary electrode was platinum wire electrode, and the reference electrode was saturated calomel electrode.