Quaternary Ammonium Polyethyleneimine: Antibacterial Activity

Quaternary ammonium polyethyleneimine‐ (QA‐PEI‐) based nanoparticles were synthesized using two synthetic methods, reductive amination and N‐alkylation. According to the first method, QA‐PEI nanoparticles were synthesized by cross‐linking with glutaraldehyde followed by reductive amination with octanal and further N‐methylation with methyl iodide. The second method is based on crosslinking with dialkyl halide followed by N‐alkylation with octyl halide and further N‐methylation with methyl iodide. QA‐PEI nanoparticles completely inhibited bacterial growth (>106 bacteria), including both Gram‐positive, that is, Staphylococcus aureus at 80 μg/mL, and Gram‐negative, that is, Escherichia coli at 320 μg/mL. Activity analysis revealed that the degree of alkylation and N‐methylation of the QA‐PEI nanoparticles plays a significant role in antibacterial activity of the reagent. The most potent compound was octyl alkylated QA‐PEI alkylated at 1 : 1 mole ratio (primary amine of PEI monomer units/alkylating agent). Also, cytotoxicity studies on MAT‐LyLu and MBT cell lines were performed with QA‐PEI nanoparticles. These findings confirm previous reports that polycations bearing quaternary ammonium moieties inhibit bacterial growth in vitro and have a potential use as additives in medical devices which need antibacterial properties.