聚电解质结构及盐浓度对基于DNA和聚阳离子的层层组装型大孔薄膜结构的影响

选择2种不同类型的聚阳离子强电解质型聚二烯丙基二甲基氯化铵(PDDA)和弱电解质型聚盐酸丙烯胺(PAH)], 分别和脱氧核糖核酸(DNA)分子通过静电吸附作用制备层层组装膜. 利用原子力显微镜和紫外-可见分光光度计研究了聚阳离子结构和组装分子溶液中盐(NaCl)浓度对大孔结构及薄膜生长规律的影响. 结果表明, 在DNA/PDDA体系中, 盐浓度对于大孔结构的形成起到关键性作用. 而对于DNA/PAH薄膜体系, 即使增加DNA或PAH溶液中盐的浓度, 也不会有大孔结构出现, 这主要是由PAH分子的弱电解质特性决定的.

Effect of Polyelectrolyte Structure and Salt Concentration on the Porous Architecture of Self-assembled DNA/Polycations Macroporous Multilayer Thin Films

Two different polycations, one is the strong polyelectrolyte of poly(diallyldimethylammonium chloride)(PDDA) and the other is the weak one of polyallylamine hydrochloride(PAH), were utilized to form multilayer thin films with deoxyribonucleic acid(DNA). Atomic force microscopy(AFM) and ultraviolet-visible spectroscopy(UV-Vis) were used to investigate the effects of polycation structure and salt concentration on the macroporous architecture and growing behaviors. The results demonstrate that in the case of DNA/PDDA multilayer thin films, salt concentration effect plays an important role on the formation of macroporous structure; however, in the case of DNA/PAH multilayer thin films, there is no porous structure even at higher salt concentration in the DNA or PAH solution. This is mainly due to the inherent weak electrolyte characteristics of PAH. Therefore, in addition to the effects of molecular weight mismatch and persistent length mismatch as-mentioned, the effects of salt concentration and polyelectrolyte structure are the key factors for controlling the formation of the macroporous architectures.