The discovery that OmpF was related to the transportation of ruthenium complexes through cell membrane was achieved with proteomics technologies. An integral ruthenium complex exists inside the cell as identified by matrix-assisted laser desorption ionization (MALDI) mass spectrometry. An inhibition assay with Escherichia coli was used to demonstrate the relationship between the transportation of the polypyridyl ruthenium complexes and the presence of OmpF (outer membrane protein F). For instance, the amount of [Ru(tpy)(bpy)Cl](+) (tpy: teripyridine; bpy: bipyridine) that entered the cells was determined by inductively coupled plasma optical emission spectroscopy (ICP-OES) of cell extracts and was measured to be approximately 0.55 microM. In the presence of 10% sucrose solution which is known to reduce the OmpF concentration, the ruthenium complex concentration was reduced to approximately 0.28 microM, which is a 50% reduction. These data suggest that OmpF plays a key role in the transportation of positively charged polypyridyl chlororuthenium complexes into E. coli.