Targeting and delivery of bactericide to adsorbed oral bacteria by use of proteoliposomes

Abstract

Proteoliposomes having surface-bound succinylated concanavalin A (s-conA) have been prepared from a range of phospholipid mixtures by sonication (SUV) and reverse phase evaporation (REV) covering a range of size ( weight-average diameter ( d w ) ) from approx. 35 to 310 nm and weight-average number of protein molecules per liposomes ( P w ) from approx. 50 to 3000. The targeting of the proteoliposomes to adsorbed biofilms of the bacteria Streptococcus sanguis and Streptococcus mutans has been assessed from the extent of inhibition of an enzyme-linked immunosorbent assay (ELISA) for bacterial cell surface antigens. The surface-bound lectin enhances targeting relative to ‘naked’ liposomes of comparable concentration by factors of 2–50 depending on the liposomal lipid composition and P w . The effect of the bactericide Triclosan® on the thermal properties and permeability characteristics of liposomes has been studied. At and above a molar ratio of Triclosan® to lipid of 0.6, Triclosan® eliminates the gel to liquid-crystalline phase transition in dipalmitoylphosphatidylcholine (DPPC) containing liposomes and increases the bilayer permeability of both liposomes and proteoliposomes to d-glucose. The proteoliposomes have been used to deliver Triclosan® to S. sanguis biofilms and the inhibition of growth of the bacteria after treatment with liposomally delivered Triclosan® has been determined using a microtitre plate re-growth assay and compared with growth inhibition by ‘free’ Triclosan®. It is shown that for short exposure times (1 to 2 min) proteoliposomally delivered Triclosan® is a more effective growth inhibitor than free Triclosan®. The results are discussed in terms of the targeting, retention and subsequent release of Triclosan® into the bacterial biofilms.