Liposomes were prepared from phospholipid mixtures of dipalmitoylphosphatidylcholine (DPPC) and phosphatidylinositol (PI), encapsulating the enzymes glucose oxidase (GO) and GO in combination with horse radish peroxidase (HRP) by both extrusion (VET) and reverse-phase evaporation (REV). The optimum level of PI in DPPC/PI liposomes for targeting to biofilms of the oral bacterium Streptococcus gordonii has been established. The liposomes were characterised in terms of the content and activity of the encapsulated enzymes. The antibacterial activity of these 'reactive' liposomes arising from hydrogen peroxide and oxyacids in the presence of the substrates glucose and iodide ions, after targeting to the biofilms, were measured both as a function of liposome-biofilm incubation time and incubation time with the substrates. Bacterial inhibition increases with both liposome-biofilm and substrate-biofilm incubation time and with the extent of enzyme encapsulation. The reactive liposomes also display antibacterial activity in the presence of saliva. The reactive liposomes have potential value in the context of oral hygiene.
Phospholipid (dipalmitoylphosphatidylcholine (DPPC) plus phosphatidylinositol (PI)) proteoliposomes with surface bound lectins (succinylated concanavalin A (s con A) and wheat germ agglutinin (WGA)) have been prepared covering a range of size and surface density of lectin. Negatively charged phospholipid liposomes from DPPC-PI mixtures covering a range of PI mole % and positively charged liposomes from DPPC-cholesterol-stearylamine (SA) mixtures covering a range of SA mole % have been prepared. The targeting of the liposomes and proteoliposomes to a range of oral and skin-associated been prepared. The targeting of the liposomes and proteoliposomes to a range of oral and skin-associated bacterial biofilms has been investigated. The oral bacteria Streptococcus mutans and gordonii and the skin-associated bacterium Coryneform hofmanni can be targeted with s con A bearing proteoliposomes while the skin associated bacterium Staphylococcus epidermidis can be targeted with WGA bearing proteoliposomes. Both oral and skin-associated bacteria can be targeted with positively charged liposomes although the extents of adsorption to the biofilm are low except for Staphylococcus epidermidis. In the case of negatively charged liposomes targeting is critically dependent on the PI content of the liposomes and for all the bacteria studied optimum levels PI for targeting have been found. The adsorption of the oral bacterium Streptococcus gordonii to immobilised monolayers having the optimum PI level for adsorption has been studied by total internal reflection microscopy (TIRM). Both the phospholipid and proteoliposomes have been used to deliver the bactericide Triclosan to biofilms. All the systems studied inhibited bacterial growth to varying degrees.(ABSTRACT TRUNCATED AT 250 WORDS)
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