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 g/mL, and Gram-negative, that is, Escherichia coli at 320 g/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

Polyethyleneimine nanoparticles incorporated into resin composite cause cell death and trigger biofilm stress in vivo

Incorporation of cross-linked quaternary ammonium polyethylenimine (QPEI) nanoparticles in dental resin composite has a long-lasting and wide antimicrobial effect with no measured impact on biocompatibility in vitro. We hypothesized that QPEI nanoparticles incorporated into a resin composite have a potent antibacterial effect in vivo and that this stress condition triggers a suicide module in the bacterial biofilm. Ten volunteers wore a removable acrylic appliance, in which two control resin composite specimens and two resin composite specimens incorporating 1% wt/wt QPEI nanoparticles were inserted to allow the buildup of intraoral biofilms. After 4 h, the specimens were removed and tested for bacterial vitality and biofilm thickness, using confocal laser scanning microscopy. The vitality rate in specimens incorporating QPEI was reduced by > 50% (p < 0.00001), whereas biofilm thickness was increased (p < 0.05). The ability of the biofilm supernatant to restore bacterial death was tested in vitro. The in vitro tests showed a 70% decrease in viable bacteria (p < 0.05). Biofilm morphological differences were also observed in the scanning electron microscope micrographs of the resin composite versus the resin composite incorporating QPEI. These results strongly suggest that QPEI nanoparticles incorporated at a low concentration in resin composite exert a significant in vivo antibiofilm activity and exhibit a potent broad spectrum antibacterial activity against salivary bacteria

Comb-shaped copolymers composed of hydroxypropyl cellulose backbones and cationic poly((2-dimethyl amino)ethyl methacrylate) side chains for gene delivery

10.1021/bc900044hBioconjugate Chemistry2081449-1458BCCH