The binding of ionic organic compounds, anionic diamine blue 3R (DAB) and cationic rhodamine B (RB) to in vitro single phospholipids membrane (SPM) and Escherichia coli (E. coli) strains was investigated. The interactions correspond to the Langmuir and Temkin adsorption isotherm in only monolayers. The influence of ionic strength, pH and temperature on the adsorption were examined and analyzed. The binding force, type and interaction sites of DAB and RB were determined and identified. The interaction of DAB and RB with SPM and the cells are exothermal and idiopathic, which contained the union of non-covalent bonds, such as electrostatic bond, hydrogen bond and van der Waals force. Moreover, most of DAB and RB were accumulated on the excellular membrane and walls, to hardly enter the cytoplasm. Besides, the adsorption competition was found when both DAB and RB existed simultaneously.

Key words: ionic organic compound, single phospholipid membrane, cellular membrane, E. coli, chemical adsorption