▎ 摘　　要

In this study, we reported on a low detection limit penicillin biosensor with layer-by-layer (LbL) film containing single-graphene nanosheets (SGNs) preadsorbed with hematein, ionic liquids (ILs) and penicillinase. The penicillinase catalyzes the hydrolysis of penicillin to penicilloic acid, where H+ is liberated and monitored amperometrically with hematein as a pH indicator. The SGN-hemateinas/penicillinase biosensor exhibited excellent performance for penicillin in PBS with a wide range from 1.25 x 10(-13) to 7.5 x 10(-3) M, and a low detection limit of 10(-13) M (0.04 ppt, S/N >= 3). Furthermore, the detection of penicillin concentration in real sample (milk) had acceptable accuracy with the assay system. (C) 2014 Elsevier B.V. All rights reserved.