Covalent Immobilization of an Antimicrobial Peptide on Poly(ethylene) Film

An antimicrobial film was produced by covalently attaching synthetic peptide E14LKK to poly(ethylene) film. E14LKK is a 14 residue, magainin-class peptide with broad-spectrum antimicrobial activity. The poly(ethylene) surface was first oxidized with chromic/sulphuric acid, then PEGylated by using carbodiimide chemistry to attach omega-amino-alpha-carboxyl-poly(ethylene glycol) (PEG). The peptide was covalently coupled to the free terminus of the PEG, again using carbodiimide coupling. Surface contact angles for distilled water decreased from 101 degrees initially to 61 degrees following oxidation and 45 degrees following PEGylation. Film surface chemistry showed the expected changes during the modifications: dye adsorption assays indicated changes in the number of acidic and basic groups and X-ray photoemission spectroscopy showed increasing oxygen and nitrogen levels. Antimicrobial activity was demonstrated in broth cultures against E.coli: growth was reduced by atleast 3 log cycles compared to controls. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110: 2665-2670, 2008