Evaluation of antibacterial activity of branched quaternary ammonium grafted green polymers

This study describes the antibacterial activity evaluation of film-shaped polymers based on biodegradable chains of polylactic acid (PLA), polycaprolactone (PCL) and polyhydroxybutyrate (PHB) in branched structures with quaternary ammonium pendant groups. The materials were tested against both Gram-negative (Escherichia coli and Salmonella Typhimurium) and Gram-positive (Listeria monocytogenes) bacteria. Minimal inhibitory and maximal tolerated concentrations of the quaternary ammonium monomers were first determined. Films of pure quaternary ammonium functionalized polymers (QAFPs) and of blends of QAFPs with commercial matrices were studied to determine their inhibition effects and their bactericidal activity. A high antibacterial activity was found, up to 5.6 log, 4.4 log, and 4.2 log CFU.mL(-1) reduction for respectively Escherichia coli (Salmonella Typhimurium and Listeria monocytogenes after only one hour of bactericidal tests, 6.7 log, 5.2 log and 4.9 log CFU.mL(-1) reduction was observed for the respectively cited bacteria after 24 h, making these materials potentially applicable in many fields. (C) 2017 Elsevier Ltd. All rights reserved.