The interaction of phospholipid liposomes with bacteria and their use in the delivery of bactericides.

Liposomes have been prepared from dipalmitoylphosphatidylcholine (DPPC) incorporating the cationic lipids stearylamine (SA), dimethyldioctadecylammonium bromide (DDAB) and dimethylaminoethane carbamoyl cholesterol (DCchol) and the anionic lipids dipalmitoylphosphatidylglycerol (DPPG) and phosphatidylinositol (PI). Their adsorption to biofilms of skin-associated bacteria (Staphylococcus epidermidis and Proteus vulgaris) and oral bacteria (Streptococcus mutans and sanguis) has been investigated as a function of mole % cationic and anionic lipid. Targeting (adsorption) was most effective for the systems DPPC-chol-SA, DPPC-DPPG and DPPC-PI liposomes to S.

The targeting of phospholipid liposomes to bacteria.

Phospholipid liposomes have been prepared from phospholipid mixtures including dipalmitoylphosphatidylcholine/phosphatidylinositol (DPPC/PI) and DPPC/dipalmitoylphosphatidylglycerol (DPPC/DPPG) mixtures and targeted to adsorbed biofilms of the skin-associated bacteria Staphylococcus epidermidis and Proteus vulgaris and the oral bacterium Streptococcus sanguis. The effects of time, liposome concentration and density of bacteria in the biofilm have been studied in detail for Staphylococcus epidermidis. The targeting (as assessed by the apparent monolayer coverage of the biofilms by liposomes) to the biofilms was found to be sensitive to the mol% of PI and DPPG in the liposomes and optimum levels of PI were found for targeting to each bacterium.

EPR studies on the influence of chain length on the segmental motion of spin-labelled fatty acids in dimyristoylphosphatidylcholine bilayers.

The rotational dynamics of spin-labelled fatty acids of different chainlengths (9, 10, 12, 14, 16 and 18 C-atoms) and different positions of labelling (5-C, 6-C and 7-C) have been studied in dimyristoylphosphatidylcholine bilayers using EPR spectroscopy. The segmental flexibility at a given label position is found to vary considerably with the length of the lipid chain, when this is less than that of the dimyristoylphosphatidylcholine host lipid. For both the charged and protonated forms of labelled fatty acids with chainlengths of 9, 10, and 12 C-atoms, the spectral anisotropy decreases steadily with decreasing chainlength in fluid phase bilayers.

Activity coefficients of salts in highly concentrated protein solutions. II. Potassium salts in isoionic bovine serum albumin solutions.

Mean activity coefficients of different potassium salts KX (X = F-, Cl-, Br-, I-, NO3-, SCN-) have been measured in concentrated isoionic bovine serum albumin (BSA) solutions, by use of the EMF method with ion-exchange membrane electrodes. These solutions may be regarded as simple model systems for the cytoplasm of living cells as far as the influence of the macromolecular component on the activity coefficients of the salts is concerned. Two series of measurements have been carried out: (a) varying the amount of salt from 0.

Characterisation of phosphatidylcholine/phosphatidylinositol sonicated vesicles. Effects of phospholipid composition on vesicle size.

Phosphatidylinositol (PI), dipalmitoylphosphatidylcholine (DPPC) and mixed lipid (DPPC plus PI) sonicated vesicles have been prepared covering a range of composition. The vesicles were characterised by gel filtration, electron microscopy and photon correlation spectroscopy. The dimensions of the vesicles as measured by electron microscopy were in good accord with those obtained from photon correlation spectroscopy measurements.