Lateral organization of biomimetic cell membranes in varying pH conditions

Abstract

Many studies have been devoted to investigation of phase separation and formation of lipid domains, which play crucial role in many biological processes. Here we present a complex study on the formation, dynamics, and stability of the phase-separated supported lipid membranes under varying pH conditions. The size and distribution of liquid-ordered (Lo) phase domains were investigated in a wide range (1.7–9.0) of buffer pH values and a strong correlation was found between the size of the Lo domains and pH of the buffer hydrating the lipid bilayer. Interestingly, the dynamics of lipids composing both Lo and Ld phase are insensitive to the pH of the buffer. Our findings demonstrate that by varying pH of the environment one can induce formation of domains with a specific size and shape without any external modification of the solid support or altering the membrane composition. Finally, we show that the architecture of the lipid membrane is stable even upon replacement of the aqueous medium with the buffer of neutral pH. Consequently, this method of patterning of Lo phase domains in biomimetic membranes is applicable to the studies involving binding of proteins or incorporation of other pH-sensitive molecules.