Bacterially induced degradation of aqueous solutions of poly( l ‐lysine)‐ graft ‐poly(ethylene glycol) and poly( l ‐lysine)‐ graft ‐dextran: consequences for their lubrication properties

Experimental data are presented comparing the degradation in the lubrication behaviour of aqueous solutions of the brush copolymers poly( l ‐lysine)‐ graft ‐poly(ethylene glycol) (PLL‐ g ‐PEG) and poly( l ‐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 coefficient, 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. Copyright © 2009 John Wiley & Sons, Ltd.