Preparation of bio-electrodes via Langmuir-Blodgett technique for pharmaceutical and waste industries and their biosensor application

[Display omitted] •PPO-ODA/ITO bio-electrodes were easily accomplished via the LB film technique.•In the biosensor applications, the NQCP detection limit was found as low as 0.644 μM.•The loss of catalytic activity at +4 °C for i-PPO was only 11.8% after one month.•The stability of the biosensor was found to be 94.83% after two weeks.•The bio-electrodes can be efficiently used for the determination of phenol in wastewater and for the production of l-DOPA. Langmuir films of cationic octadecylamine (ODA+) has been prepared by Langmuir-Blodgett (LB) film technique and is used as an immobilization matrix for polyphenol oxidase (PPO). The immobilization areas of PPO were demonstrated by an electrostatic surface potential map. PPO-ODA complexes were transferred onto ITO electrode which was then characterized for its catalytic and optical properties. Very high and maintained PPO activity of PPO-ODA/ITO bio-electrode was shown by UV–vis absorption studies. The highly sensitive and stability biosensor behavior of the bio-electrode was shown via cyclic voltammetry studies. The stability, sensitivity, LOD and, LOQ values of the prepared sensor were calculated as 94.83% (after two weeks), 1.839 μAmM−1 cm−2, 0.644 μM and, 0.214 μM, respectively for pyrocatechol in a wide linear range (10–100 mM). Successful prepare of the bio-electrode was confirmed from SEM and FT-IR techniques. This study revealed that the immobilization with LB film techniques contributes to the stability and recycling of PPO and its use in biological systems is superior to other film techniques mentioned in the literature. In this study, disadvantages that are observed in enzyme-based sensors were minimized. The first application of the bio-electrodes can be a promising tool towards enzymatic studies and opens a new path for industrial applications such as removing and transforming toxic compounds in industrial processes, decolorization, and drug industry such as biotechnological production of l-DOPA.