Interaction of aminoglycoside antibiotics with phospholipid liposomes studies by microelectrophoresis

Microelectrophoresis was found to be a rapid method for studying the interaction between aminoglycoside antibiotics and liposomes prepared from acid phospholipids. The ability to cause charge reversal of liposomes prepared from phosphatidyl inositol was ranked in the order neomycin greater than gentamicin greater than tobramycin greater than amikacin greater than kanamycin greater than ribostamycin greater than streptomycin greater than dihydrostreptomycin greater than Ca2+. Similar results were obtained with liposomes prepared from a mixture (8: 2) of phosphatidyl choline and phosphatidic acid, but no effect was detectable with neutral liposomes made from phosphatidyl choline only. The results support the view that the attraction between positively charged nitrogen groups on the antibiotics and the negatively charged groups of acidic phospholipids are predominantly responsible for the interaction. Extension of the studies to ionic strengths and calcium concentrations similar to those found in vivo showed a reduction, but not elimination, of the observed effects.