Antibacterial and cytotoxic performance of methenamine-based poly(lactic acid)/poly(ethylene glycol) (PLA/PEG) composite films

Abstract

In this study, antimicrobial plasticized poly(lactic acid) (PLA) films by incorporating poly(ethylene glycol) (PEG) and methenamine (MA) were prepared by solvent casting method. We investigated the effects of different concentrations of MA on the antimicrobial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) which were types of gram-negative and gram-positive bacteria in turn. It was determined that as the rate of MA in the PLA/PEG film enhanced, its antimicrobial activity against both bacteria also increased. As a result, the maximum inhibitory effect for E. coli was seen in MA5, MA8, and M10 films, and it reduced the bacterial population by 100%. In S. aureus, the high inhibition effect was seen in the MA8 film, and it reduced the bacterial population by 95%. Moreover, as the MA concentration increases, the thermal stability of PLA/PEG films increases and approaches the thermal decomposition temperature of neat PLA. The incorporation of 0.5% MA to this system caused a significant increase in elongation at break values. It is concluded that a minimum concentration of MA is sufficient for high flexibility compared with pure PLA. These MA containing PLA/PEG composite films have potential applications as biodegradable flexible packaging materials. Antimicrobial Activity Results against E. coli: Methenamine-based PLA/PEG Composite Films. image