Stationary photocurrent generation from bacteriorhodopsin-loaded lipo-polymersomes in polyelectrolyte multilayer assembly on polyethersulfone membrane

Agnieszka Mech-Dorosz*, Niada Bajraktari, Claus Hélix-Nielsen, Jenny Emnéus, Arto Heiskanen*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


Vesicles constructed of either synthetic polymers alone (polymersomes) or a combination of polymers and lipids (lipo-polymersomes) demonstrate excellent long-term stability and ability to integrate membrane proteins. Applications using lipo-polymersomes with integrated membrane proteins require suitable supports to maintain protein functionality. Using lipo-polymersomes loaded with the light-driven proton pump bacteriorhodopsin (BR), we demonstrate here how the photocurrent is influenced by a chosen support. In our study, we deposited BR-loaded lipo-polymersomes in a cross-linked polyelectrolyte multilayer assembly either directly physisorbed on gold electrode microchips or cross-linked on an intermediary polyethersulfone (PES) membrane covalently grafted using a hydrogel cushion. In both cases, electrochemical impedance spectroscopic characterization demonstrated successful polyelectrolyte assembly with BR-loaded lipo-polymersomes. Light-induced proton pumping by BR-loaded lipo-polymersomes in the different support constructs was characterized by amperometric recording of the generated photocurrent. Application of the hydrogel/PES membrane support together with the polyelectrolyte assembly decreased the transient current response upon light activation of BR, while enhancing the generated stationary current to over 700 nA/cm2. On the other hand, the current response from BR-loaded lipo-polymersomes in a polyelectrolyte assembly without the hydrogel/PES membrane support was primarily a transient peak combined with a low-nanoampere-level stationary photocurrent. Hence, the obtained results demonstrated that by using a hydrogel/PES support it was feasible to monitor continuously light-induced proton flux in biomimetic applications of lipo-polymersomes. Graphical abstract.
Original languageEnglish
JournalAnalytical and Bioanalytical Chemistry
Number of pages12
Publication statusAccepted/In press - 2020


  • Lipo-polymersome
  • Bacteriorhodopsin
  • Polyethersulfone membrane
  • Stationary photocurrent
  • . LbL assembly of polyelectrolytes
  • Amperometric recording

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