Cells and Materials


An antibiotic delivery system has been developed using ciprotloxacin (CIPRO) encapsulated within sonicated unilamellar vesicles (SUV) of different lipid compositions composed of dipalmitoylphospatidylcholine (DPPC), L-aphosphatidylcholine (PC), phosphatidylethanolamine (PEA) and cholesterol (CHOL). The interaction of SUV (i.e. liposomes) with Pseudomonas aeruginosa (Tl 2977) cells was studied and the effect of the liposome encapsulated antibiotic was tested. Encapsulation of CIPRO apparently increased the amount of antibiotic resident in the vicinity of bacteria in aqueous solution at neutral pH.

Electrophoretic mobility measurements showed that P. aeruginosa cells were negatively charged. The zeta potential of P. aeruginosa was -11.4 ± 2.9 m V in phosphate buffered saline at pH 7 .0, and the corresponding surface charge density was -14.7 ± 3.9 mC/m2. DPPC liposomes and PC liposomes had mean diameters of 103 ± 35 nm and 80 ± 25nm, respectively. They were electrically neutral or had a small positive charge of +S.0 ± 3.0 mC/m2 when prepared with PC:CHOL:PEA=S: 1: 1. The interaction and attachment of neutral or positively charged SUV to negatively charged bacterial cells was studied in an effort to increase the residency of the liposomes and CIPRO, in the vicinity of the bacterial cells. Key