A nylon membrane based amperometric biosensor for polyphenol determination

A nylon membrane based amperometric biosensor employing banana fruit polyphenol oxidase (PPO) is presented for polyphenol detection. Nylon membrane was first activated and then coupled with chitosan. PPO was covalently attached to this membrane through glutaraldehyde coupling. The membrane bioconjugate was characterized by scanning electron microscopy (SEM) and Fourier Transform Infrared (FTIR) study and then mounted onto Au electrode using parafilm to construct a working electrode. Once assembled along with Ag/AgCl as reference and Pt as auxiliary electrode, the biosensor gave optimum response within 15 s at pH 7.5 and 30 °C, when polarized at +0.4 V. The response (in mA) was directly proportional to polyphenol concentration in the range 0.2–400 μM. The lower detection limit of the biosensor was 0.2 μM. The biosensor was employed for determination of polyphenols in tea, beverages and water samples. The enzyme electrode showed 25% decrease in initial activity after 150 reuses over 6 months, when stored at 4 °C.

Graphical abstractAn amperometric biosensor employing nylon membrane bound banana polyphenol oxidase (PPO) is presented for polyphenol detection. Nylon membrane was first activated and then coupled with chitosan. Polyphenol oxidase was covalently attached to the membrane using glutaraldehyde coupling. The membrane bioconjugate was mounted onto Au wire to construct working electrode.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A nylon membrane based amperometric biosensor was constructed using banana polyphenol oxidase (PPO) for polyphenol detection. ► Biosensor gave optimum response within 15 s at pH 7.5 and 30 °C. ► Biosensor displayed lower detection limit of 0.2 μM. ► There was a linear relationship between sensor response and L-DOPA concentration (0.2 to 400 μM). ► The sensor measured successfully the polyphenolic level in tea leaves, alcoholic beverages and water samples.