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Abstract: The growth of giant vesicles (GVs) can be considered as a consecutive process of swelling/detachment/deformation, which is a response of lipid membranes on solid surfaces to the solvent and environmental factors such as temperature and ionic strength. The electroformation method allows to visualize the responses to such factors. The additive effect of the protein on the growth of GVs, composed of zwitterionic phospholipids, was herein investigated using the electroformation method. Proteins denatured by a pH-shift (to be in the Molten Globule state) perturbed the lipid membranes, resulting in the acceleration of GV growth. The GVs detached from the electrode showed deformation close to a stomatocyte. It was revealed that common factor for the response of lipid membranes was the variation of the apparent area elastic modulus associated with the interaction between proteins and lipid membranes. The present finding affords better understanding about the response of lipid membranes on solid surfaces under a variety of environment factors. [Copyright &y& Elsevier]

Abstract: Immobilization of model cell membranes (liposomes) on sensing devices is useful for the detection, evaluation, and analysis of interaction between cell membranes and proteins or other biological materials. The method to immobilize the liposomes on the solid surface was investigated by using the quartz crystal microbalance (QCM) method, focusing on the density of immobilized liposomes and their stability. The different liposomes were applied onto the planar surface of the QCM electrode by varying the immobilization method. The results showed that the immobilized liposomes depended not only on the immobilization method but also on the properties of the liposomes. The liposome with low membrane fluidity likely showed intact immobilization on a solid surface. An electrostatic interaction also affected the amount of immobilized liposomes on the functionalized quartz crystal. By using the amino-coupling method, intact liposomes could be immobilized on a solid surface and immobilized liposomes could stabilize for 10h with frequency changes less than 5%. [Copyright &y& Elsevier]