| Gene vector had very important effect on gene therapy system. Infection between cationic polymer and plasmid DNA included various item: such as electrostatic, hydrophobic etc. The role of hydrophobic interaction in plasmid DAN condensation had paid more interests in the research of gene therapy.In current paper, (polyamidoamine) dendrimers having phenylalanine and tryptamine residues in the periphery were synthesized. NMR spectra exhibited that new cationic polymers have many amino residues. Thus, novel cationic polymers had charge and hydrophobic group in the periphery.Plasmid DNA extraction kit in the combination with ion-exchange chromatography was used to obtain plasmid with high purity and no pyrogen. Electrophoresis and UV-VIS spectroscopy were used to check its purity and concentration. The plasmid was used in the following experiments.Agarose gel electrophoresis, ethidium bromide displacement assay, multi-angle laser light scattering, transmission electron microscopy were used to examine self-assembling between polymer and plasmid from various aspects.Toxicity experiment and transfection efficiency assay indicated biological characteristics of new polymer. The polymer having phenylalanine or tryptamine on its surface had low cell toxicity in low dosage and high transfection efficiency in Africa green monkey kidney cell line when R+/-=5.At last, PAMAM, which have Phe and Trp as its graft, could effect plasmid condensation and enhance transfection efficiency. As Phe and Trp have phenyl and indole, the experiments proved that hydrophobic had an important effect on gene delivery system. It gave a direction to cationic polymer gene vector's development. |
