Toxicity evaluation of dextran-spermine polycation as a tool for genetherapy in vitro.

Cationic polymers are a leading class of nonviral self-assembled nucleic acid delivery systems. Cationic polymers have been shown to condence the DNA so that the entrapped DNA is protected from contact with DNase. The objective of the present study is to evaluate the effect of cationic dextran on the proliferation rate, morphological changes and biosynthetic activities in vitro. Cationic dextran was prepared by means of reductive-amination between oxidized dextran and the natural oligoamine, spermine. Four kinds of biological evaluations including cell proliferation assay, ultrastructural changes of cells using transmission electron microscopy (TEM), acridine orange/Propidium Iodide and cell cycle were studied. Our results clearly indicated that the toxicity of cationic dextran is dose depended and it is not toxic at low concentration and tolerable by the cells, and it can be used as a tool for gene delivery

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