Colorimetric detection has been widely applied in daily life. However, on the other hand, the further development of colorimetric biosensors has been constrained by the lack of multiple detection capabilities. In this work, we proposed a pH-resolved colorimetric biosensor for the first time for the simultaneous detection of four targets, including ochratoxin A (OTA), aflatoxins B1 (AFB1), fumonisin B1 (FB1), and microcystin-LR (MC-LR). With allochroic dyes as the signal indicators, pH value was introduced as the new dimension to control the release of dyes. The concentrations of four targets can be obtained in order by adjusting the pH of the solution. Meanwhile, tedious and high-cost chemical modification processes in the fabrications of biosensors were also avoided by the combination of DNA-directed self-assembly of graphene oxide and magnetic separation. This biosensor provided a simple, rapid, accurate, and low-cost strategy for multiple target detection.
Keywords: aptamer; colorimetric biosensor; food safety; multiplex detection; mycotoxin.