Visual and microplate detection of aflatoxin B2 based on NaCl-induced aggregation of aptamer-modified gold nanoparticles

We describe a fast and sensitive method for the detection of aflatoxin B2 (AFB2) that is based on the addition of AFB2-sensitive aptamers to a colloidal solution of gold nanoparticles (AuNPs). Subsequent addition of AFB2 and NaCl to the solution causes a color change from wine-red to blue-purple. Best results are obtained at a pH value of 7.0, a 10 mM aptamer concentration, and a 2 M concentration of NaCl. The method has a linear dynamic range that extends from 0.025 to 10 nga (TM) mL(-1) of AFB2, and the detection limit is 25 pga (TM) mL(-1). The method is simple, fast, highly sensitive, and enables both visual and microplate readout.