Acetylcholinesterase type 6 s

Acetylcholinesterase (Type VI-S, EC 3.1.1.7, from Electrophorus electricus, lyophilized powder, 217 U/mg) and choline oxidase (EC 1.1.3.17, from Alcaligenes sp., lyophilized powder, 15 U/mg), acetylcholine chloride (ACh), bovine serum albumin (BSA) and hydrogen peroxide (H₂O₂) were purchased from Sigma-Aldrich. Certified reference pesticide standards were all purchased from Dr. Ehrensdorfer (Augsburg, Germany). Water-soluble CdSe/ZnS core/shell quantum dots (QDs) were obtained from Ocean Nanotech (Springdale, AR, USA). Phosphate buffer solution (PBS) (pH 8.0, 10 mM) and Milli-Q ultrapure water (Millipore, ≥18 MΩ·cm) were used throughout. All chemicals were used without further purification. Individual stock solutions of the pesticides were prepared in acetonitrile and stored at 4 °C. A series of working solutions were prepared daily by an appropriate dilution by PBS (pH 8.0, 10 mM) which contains 0.5 mg/mL of BSA.

Lactic acid (99% purity), Folin–Ciocalteu reagent, sucrose (98% purity), aluminum chloride (AlCl₃ > 97% purity), and potassium persulfate (K₂S₂O₈ > 99.99% purity) were purchased from Biochem-Chemopharma (Montreal, QC, Canada). Sodium carbonate (Na₂CO₃), sodium phosphate mono (NaH₂PO), and dibasic (Na₂HPO), as well as ascorbic acid (C₆H₈O₆ > 99.53 purity) were obtained from Biochem-Chemopharma (Georgia, USA). Quercetin was procured from Panpharma (Shanghai, China). Ferric chloride (FeCl₃) was from Panreac (Barcelona, Spain). The DPPH (2-2-diphenyl-1-picrylhydrazyl), ABTS (2,2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid), and TPTZ (2,4,6-Tris (2-pyridyl)-1,3,5-triazine) were purchased from Sigma Chemical (Sigma-Aldrich, GmbH, Sternheim, Germany). Gallic acid was obtained from Prolabo (Montreuil, France). The DTNB (5,5′ dithiobis 2-nitrobenzoic acid) (>98% purity), acetylcholinesterase (Type VIS; EC 3.1.1.7), acetylthiocholine iodide, and porcine pancreatic α-amylase (EC 3.2.1.1, type VI) were from Sigma Chemical (Sigma-Aldrich, GmbH, St Louis, MO, USA).