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

•A layer-by-layer assembly amperometric penicillin biosensor was proposed.•Graphene nanosheets, hematein, ionic liquids and penicillinase are modified on GCE.•Single graphene nanosheets with the presence of carboxylic acid groups were prepared.•A wide range from 1.25 × 10− 13 to 7.5 × 10− 3 M and low detection limit of 10− 13 M•The electrochemical mechanism is discussed and it was used in the detection of milk samples.

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.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide