Solid-supported polymer–lipid hybrid membrane for bioelectrochemistry of a membrane redox enzyme†

Hybrid membranes, consisting of phospholipids and amphiphilic block polymers, offer enhanced stability compared to liposomes and greater biocompatibility than polymersomes. These qualities make them a versatile platform for a wide range of applications across various fields. In this study, we have investigated the ability of solid-supported polymer–lipid hybrid membranes (SSHM) to act as a platform for bioelectrochemistry of membrane proteins. The redox enzyme, cytochrome bo₃ (cyt bo₃), a terminal oxidase in Escherichia coli, was reconstituted into hybrid vesicles (HVs), which were subsequently tested for their ability to form SSHMs on different self-assembled monolayers (SAMs) on gold electrodes. SSHM formation was monitored with electrochemical impedance spectroscopy (EIS), quartz crystal microbalance with dissipation (QCM-D), and atomic force microscopy (AFM). SSHMs were successfully formed on gold electrodes with mixed SAMs of 6-mercapto-1-hexanol and 1-hexanethiol at a 1 : 1 ratio. The activity of cyt bo₃ was confirmed using cyclic voltammetry (CV), with electron transfer to cyt bo₃ mediated by a lipophilic substrate-analogue decylubiquinone (DQ). SSHMs formed with HVs-cyt bo₃ samples, stored for more than one year before use, remain bioelectrocatalytically active, confirming our previously established longevity and stability of HV systems.