A low detection limit penicillin biosensor based on single graphene nanosheets preadsorbed with hematein/ionic liquids/penicillinase

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-hematein/ILs/penicillinase biosensor exhibited excellent performance for penicillin in PBS with a wide range from 1.25 × 10− 13 to 7.5 × 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.