Investigation of membrane condensation induced by CaCO3 nanoparticles and its effect on membrane protein function

Abstract

The membrane dynamics both across the lipid bilayer and in the lateral lipid domains play an important role in a number of key cellular processes including the normal functions of membrane proteins. Herein, we report an electrical method to monitor the changes in membrane dynamics with respect to the interactions between the lipid bilayer and CaCO₃ nanoparticles (nano CaCO₃). Through transmembrane capacitance measurements, the electrostatic interaction between lipid molecules and Ca²⁺ ions dissolved from nano CaCO₃ turned out to be responsible for the membrane condensation, whereas nano CaCO₃ itself didn't show any notable interaction with the lipid bilayer. Moreover, the activities of gramicidin represented by the channel forming rate and lifetime of the channel were shown to be greatly influenced by nano CaCO₃. These findings demonstrate that a potential cytotoxicity of nano CaCO₃ could be derived from the dissolved Ca²⁺ ions, but not from nano CaCO₃ itself, affecting cellular membrane dynamics by lipid condensation.