Bacterially induced degradation of aqueous solutions of poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) and poly(L-lysine)-graft-dextran (PLL-g-dex) and consequences for their lubrication properties

Experimental data are presented comparing the degradation in the lubrication behaviour of aqueous solutions of the brush copolymers poly(1-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) and poly(1-lysine)-graft- dextran (PLL-g-dex) when aged after exposure to bacterial contamination. While PLL-g-PEG solutions appear to be relatively unaffected by bacteria after a storage period of as much as 8 weeks, PLL-g-dex solutions exposed to bacteria during preparation lead to as much as a twofold increase in friction coeffi cient, when used as a lubricant in tribological tests, over an 8 week period when compared to reference data from freshly prepared and tested samples. Solutions prepared under sterile conditions and aged for up to 8 weeks do not appear to be degraded. Further experiments implementing the anti-bacterial agent sodium azide effectively prevented bacterial colonization and degradation in lubrication behaviour.