Fluorescence modulation sensing of positively and negatively charged proteins on lipid bilayers

Detecting ligand-receptor binding on cell membrane surfaces is required to understand their function and behavior. Detection platforms can also provide an avenue for the development of medical devices and sensor biotechnology. The use of fluorescence techniques for such purposes is highly desirable as they provide high sensitivity. Herein, we describe a technique that utilizes the sensitivity of fluorescence without directly tagging the analyte of interest to monitor ligand-receptor interactions on supported lipid bilayers. The fluorescence signal is modulated according to the charge state of the target analyte. The binding event elicits protonation or deprotonation of pH-responsive reporter dyes embedded in the lipid bilayer.