NBD-cholesterol (NBD-Ch)-modified liposome was immobilized on indium tin oxide (ITO) electrode via the covalent binding method. The transfer of NBD-Ch between the immobilized liposomes and the target liposomes was observed by using a fluorescent microscope. The addition of liposome suspension co-incubated with alpha-chymotrypsin or stimuli-responsive polymer to the surface of the above ITO electrode, enhanced the liposome-liposome interaction, resulting in the promotion of NBD-Ch transfer. The apparent transfer rate constant of NBD-Ch was found to be correlated with the index for the liposome-liposome interaction evaluated by an immobilized liposome chromatography. This suggests that the present method using the liposome-immobilized ITO electrode was effective to evaluate the liposome-liposome interaction induced by the protein or the stimuli-responsive polymer under stress conditions. (C) 2009, The Society for Biotechnology, Japan. All rights reserved.