Potassium ferrocyanide trihydrate

Potassium ferricyanide (K₃FeC₆N₆, ≥99.0%), potassium ferrocyanide trihydrate (K₄FeC₆N₆·3H₂O, ≥99.0%), and acetone (≥99.5%) was obtained from Sinopharm Chemical Reagent Co., Ltd. (Beijing, China). DIF, bromadiolone (BRD), coumafuryl (CF), and brodifacoum (BRF) were purchased from J and K Scientific (Beijing, China). Phosphate buffered saline (PBS, 0.01 M, pH 7.4) was obtained from Transgen Biotech (Beijing, China). Tetramethylenedisulfotetramine (TETS) and human serum samples were supplied by the Beijing Center for Disease Prevention and Control (Beijing, China) and stored at −20 °C [15 (link)]. Nb AR-H2-1 was produced by our lab and will be described elsewhere. Deionized water applied for preparing all the solutions was obtained by Milli-Q^® Integral from Millipore (Billerica, MA, USA). In this work, the electrochemical measurements were conducted using CHI760E electrochemical workstations that was purchased by CH Instruments, Inc. (Shanghai, China).

AChE (from electric eel), ATCl, AgNWs and DDVP were from Sigma-Aldrich. CS (viscosity > 400 mPa s) and Gra (stripped by 1-methyl-2-pyrrolidinone (NMP)) were from Aladdin Bio-Chem Technology (Shanghai, China). Glucose was from Sangon Biotech (Shanghai, China), ethanol absolute, glacial acetic acid, tetra-n-butyl titanate, hydrochloric acid, N,N-dimethylformamide (DMF), isopropanol, potassium ferricyanide, potassium ferrocyanide trihydrate, potassium chloride, sodium chloride, sodium dihydrogen phosphate, disodium hydrogen phosphate were from Sinopharm Chemical Reagent Co., Ltd (Shanghai, China). All chemical reagents used are of analytical grade. Nitrogen with a purity of 99.9% comes from Air Liquide (China) Holding Co., Ltd. The deionized water (DI water) used in the whole experiment was obtained by ion exchange method. Vegetable juice is a supernatant obtained by washing, grinding, filtering, and centrifuging fresh lettuce purchased from a nearby vegetable market (ESI†).

All chemicals used in the experiments were reagent grade or higher without further purification. Lead nitrate (Pb (NO₃)₂), Nitric acid (HNO₃), Sodium fluoride (NaF), Ammonium fluoride (NH₄F), ethylene glycol ((CH₂OH)₂), and sodium sulphate (Na₂SO₄) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Sulphuric acid (H₂SO₄), Sodium hydroxide (NaOH), Isopropanol (C₃H₈O), Potassium ferricyanide (K₃Fe(CN)₆), Potassium ferrocyanide trihydrate (K₄Fe(CN)₆ · 3H₂O), Humic acid (HA), and Bisphenol A (BPA) were purchased from Sinopharm group. Porous titanium (Ti) substrate with a diameter of 30 mm and thickness of 2 mm was obtained from Bairong Co., Baoji, China; the purity was greater than 99%. Ultrapure water was obtained from Milli-Q^® EQ 7000.