Fluorescence mapping of redox activity in supported lipid bilayers

AYA SAKAYA; ANDRES. M. DURANTINI; TARA SVERKO; VINCENT WIECZNY; GONZALO COSA

Simposio; Quebéc Center for Advanced Materials Annual Student Symposium; 2019

Lipidmembranes have gained wide attention as assembly scaffolds, owing to theirability to self-assemble into well-defined fluid structures, allowing thecompartmentalization and direct assembly of components of interest in a fluidplatform. Model lipid membranes offer the opportunity to mimic and studyprocesses occurring across these fluid mosaics such as respiration, transportand signaling. Armed with aspectroelectrochemistry microscopy setup, in this study we have explored redoxreactions within lipid membranes, proof of concept experiments intended toaddress the response of membrane embedded redox systems. Experimentally, asupported lipid bilayer was formed on top on an indium tin oxide (ITO)-coatedglass. H4BPMHC, a redox sensitive fluorogenic probe bearing thechromanol moiety of α-tocopherol(Vitamin E), and a BODIPY tail segment was incorporated within the lipidmembrane. The electrochemical and optical properties were next studied usingour total internal reflection fluorescence (TIRF) microscopy basedspectro-electrochemical (SEC) setup, that enables monitoring emission whileminimizing background by virtue of sampling a small ~ 300 nm region above theglass water interface, while also controlling the redox potential at the basalleaflet of the lipid membrane. Our results are consistentwith oxidation of the chromanol moiety of the probe into a chromanone moietythrough an irreversible process that elicits fluorescence, and furtherthermally induced rearrangement of the newly formed chromanone into achromoquinone. We will discuss the general methodology, results, andimplications of the work in the context of electron transport through relayredox systems.