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.

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