中文摘要：

聚赖氨酸（poly lysine,PL）能使DNA发生电荷逆转及凝聚,而在溶液中加入两性物质增加溶液的介电常数后,DNA发生电荷逆转的临界浓度及DNA的凝聚状态都会发生改变。作者通过动态光散射与原子力显微镜技术,研究了不同介电常数及不同培育时间下,PL对DNA电荷逆转及DNA的粒径与形态的影响。结果表明,PL浓度在10 mg/L时,DNA的电泳迁移率为0.2×10^-4cm^2/V·S左右,然而,当在溶液里加入1 mol/L的两性物质6-羧基己酸后,DNA的电泳迁移率变为-0.4×10^-4cm^2/V·S左右,说明两性物质阻碍DNA发生电荷逆转。随着两性物质浓度的增加,DNA的粒径变大,且培育时间越长,变大的越多。最后,通过原子力显微镜观察两性物质对DNA凝聚形态的影响,发现PL本身会使DNA凝聚物的尺寸变小,加入两性物质后,DNA凝聚物的尺寸反而变大。说明两性物质对DNA的凝聚形态也有影响。

英文摘要：

Poly lysine （PL） can induce DNA charge inversion and condensation. As the dielectric constant of solution is increased by adding zwitterionic species into DNA solution, the critical concentration of DNA charge inversion and the morphologies of DNA condensation are varied. With different dielectric constants and incubation times, the effects of PL on DNA charge inversion, particle size and morphology were investigated by dynamic light scattering（DLS） and atomic force technology（AFM）. The experimental results showed that with the PL concentration of 10 mg/L, DNA electrophoresis mobility was about 0.2×10^-4cm^2N.S, while it was decreased to be -0.4 ×10^-4cm^2N.S as the zwitterionic species 6-aminocaproic acid of 1 mol/L was added. It indicates that the presence of zwitterionic species hinders DNA charge inversion. The particle size of DNA condensation was increased with the increase of the concentration of zwitterionic species, and was also affected by incubation time. Finally, the effects of zwitterionic species on the morphologies of DNA condensation were observed by AFM. It was found that PL could induce the DNA condensation to be smaller size, while the size of DNA condensation became larger instead with the addition of zwitterionic species. It shows that zwitterionic species have a hindrance effect on DNA condensation.