Lipid Monolayer Formation and Lipid Exchange Monitored by a Graphene Field-Effect Transistor

Blaschke, Benno M.; Böhm, Philip; Drieschner, Simon; Nickel, Bert und Garrido, Jose A. (2018): Lipid Monolayer Formation and Lipid Exchange Monitored by a Graphene Field-Effect Transistor. In: Langmuir, Bd. 34, Nr. 14: S. 4224-4233

Abstract

Anionic and cationic lipids are key molecules involved in many cellular processes;their distribution in biomembranes is highly asymmetric, and their concentration is well-controlled. Graphene solution-gated field-effect transistors (SGFETs) exhibit high sensitivity toward the presence of surface charges. Here, we establish conditions that allow the observation of the formation of charged lipid layers on solution-gated field-effect transistors in real time. We quantify the electrostatic screening of electrolyte ions and derive a model that explains the influence of charged lipids on the ion sensitivity of graphene SGFETs. The electrostatic model is validated using structural information from X-ray reflectometry measurements, which show that the lipid monolayer forms on graphene. We demonstrate that SGFETs can be used to detect cationic lipids by self-exchange of lipids. Furthermore, SGFETs allow measuring the kinetics of layer formation induced by vesicle fusion or spreading from a reservoir. Because of the high transconductance and low noise of the electrical readout, we can observe characteristic conductance spikes that we attribute to bouncing-off events of lipid aggregates from the SGFET surface, suggesting a great potential of graphene SGFETs to measure the on-off kinetics of small aggregates interacting with supported layers.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Physik
• Themengebiete: 500 Naturwissenschaften und Mathematik > 530 Physik
• ISSN: 0743-7463
• Sprache: Englisch