A novel aflatoxin B1 biosensor based on a porous anodized alumina membrane modified with graphene oxide and an aflatoxin B1 aptamer

Abstract

A novel aflatoxin B1 biosensor is fabricated from a porous anodized alumina membrane modified with graphene oxide and an aptamer of aflatoxin B1. Briefly, the aptamer is immobilized on the surface of the porous anodized alumina nanochannels by covalent bonding. Graphene oxide is then added to the surface by π-π stacking with the aptamer. The negative charge of the nanochannels is increased by the introduction of the negatively charged graphene oxide and the aptamer, which also cause steric hindrance. On the addition of aflatoxin B1, graphene oxide is detached from the surface of the nanochannels due to the specific binding of aflatoxin B1 to the aptamer. The flux of Fe(CN)63− through the nanochannels is increased because the charge density and steric hindrance are reduced, resulting in an increased current response. The increase in current is proportional to the concentration of aflatoxin B1. The detection limit of the proposed biosensor is about 0.13 ng/mL and the linear range is 1–20 ng/mL. Furthermore, this sensor has excellent selectivity towards aflatoxin B1, offering the potential for a sensitive, simple and effective method for detecting mycotoxins.