Sensitive amperometric biosensor for phenolic compounds based on graphene–silk peptide/tyrosinase composite nanointerface

New graphene–silk peptide (Gr–SP) nanosheets were prepared and successfully fabricated with tyrosinase (Tyr) as a novel biosensor for the determination of phenolic compounds. The Gr–SP nanosheets were fully characterized with transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, UV/Vis and FTIR spectra. The developed biosensors were also characterized with scanning electronic microscopy and electrochemical impedance spectroscopy. Using bisphenol A (BPA) as a model substrate in the sensing system, a number of key factors including the volume of Gr–SP–Tyr solution, the applied potential, pH values, temperature, and the Tyr/Gr–SP ratio that influence the analytical performance of the biosensor were investigated. The biosensor gave a linear response on the concentration ranges of 0.001–16.91 μM for catechol with the sensitivity of 7634 mA M−1 cm−2, 0.0015–21.12 μM for phenol with the sensitivity of 4082 mA M−1 cm−2, and 0.002–5.48 μM for BPA with the sensitivity of 2511 mA M−1 cm−2. The low detection limits were estimated to be 0.23, 0.35 and 0.72 nM (S/N=3) for catechol, phenol and BPA, respectively. The biosensors also exhibit good repeatability and long-term stability. The practical application of the biosensor was also demonstrated by the determination of BPA leaching from commercial plastic drinking bottles.

► Silk peptide functionalized graphene nanosheets were synthesized and fully characterized;
► Graphene–silk peptide–tyrosinase/glassy carbon electrodes (Gr–SP–Tyr/GCE) were fabricated;
► Electrochemical behaviors of phenolic compounds at Gr–SP–Tyr/GCE were investigated;
► Sensitive amperometric method for phenolic compounds was developed;
► Practical application of the biosensor was demonstrated.