Skimmed milk powder

AFB₁–BSA, rabbit anti-AFB₁, goat anti-rabbit IgG horseradish peroxidase (HRP) conjugate, 3,3′,5,5′-tetramethylbenzidine (TMB) substrate, carbonate–bicarbonate buffer (capsule), multi-walled carbon nanotubes (MWCNTs), medium molecular weight chitosan (CS) and potassium ferricyanide, K₃[Fe(CN)₆], were purchased from Sigma-Aldrich Co. (St. Louis, MO, USA). Aflatoxin B₁ (AFB₁) standard solution was purchased from Supelco Analytical (Bellefonte, PA, USA). Skimmed milk powder was obtained from Nacalai Tesque (Kyoto, Japan). Other reagents were of analytical grade, and all aqueous solutions were prepared using deionized water. Phosphate buffer saline (PBS) was prepared at 10× stock concentration and diluted to 1×. Tween 20 (0.05%) was added to 1 L of 1× PBS to make PBST as a washing buffer in ELISA. For supporting electrolyte, 0.17 g of potassium ferricyanide, K₃[Fe(CN)₆], was added into 100 mL of 1× PBS to make a 5 mM solution, to study the reversible electrochemical behavior in cyclic voltammetry analysis.

AFB₁-BSA, rabbit anti-AFB₁, goat anti-rabbit IgG horseradish peroxidase (HRP) conjugate, 3,3′,5,5′-tetramethylbenzidine (TMB) substrate, carbonate-bicarbonate buffer (capsule), multi-walled carbon nanotubes (MWCNTs), medium molecular weight chitosan (CS) and potassium ferricyanide, K₃[Fe(CN)₆], were purchased from Sigma-Aldrich (St. Louis, MO, USA). Aflatoxin B₁ (AFB₁) standard solution (20 µg/mL in methanol) was purchased from Supelco Analytical (Bellefonte, PA, USA). Skimmed-milk powder was obtained from Nacalai Tesque (Kyoto, Japan). Other reagents were of analytical grade, and all aqueous solutions were prepared using deionized water. Phosphate buffer saline (PBS) was prepared at 10× stock concentration and diluted to 1×. Tween 20 (0.05%) was added to 1 L of 1× PBS to make PBST as a washing buffer in ELISA. For supporting electrolyte, 0.17 g K₃[Fe(CN)₆] was added into 100 mL of 1× PBS to make a 5 mM solution.