Polyplexes of Poly(methylaminophosphazene): Energetics of DNA Melting

详细信息    查看全文

• 作者：Tatiana V. Burova ; Natalia V. Grinberg ; Dzidra R. Tur ; Vladimir S. Papkov ; Alexander S. Dubovik ; Valerij Y. Grinberg ; Alexei R. Khokhlov
• 刊名：Langmuir
• 出版年：2011
• 出版时间：September 20, 2011
• 年：2011
• 卷：27
• 期：18
• 页码：11582-11590
• 全文大小：884K
• 年卷期：v.27,no.18(September 20, 2011)
• ISSN：1520-5827

文摘

The interaction of DNA with a synthetic biocompatible and biodegradable cationic polymer, poly(methylaminophosphazene) hydrochloride (PMAP路HCl), was investigated by high-sensitivity differential scanning calorimetry under conditions of strong and weak electrostatic interactions of the macroions. Thermodynamic parameters of the DNA double-helix melting were determined as a function of pH and the PMAP路HCl/DNA weight ratio. PMAP路HCL was shown to reveal two functions with respect to DNA: the polyelectrolyte function and the donor鈥揳cceptor one. The first function stabilizes the helical conformation of DNA, and the second one destabilizes it. The stabilizing effect of PMAP路HCl is of entropic origin, related to a displacement of mobile counterions from the DNA鈥檚 nearest surroundings by the poly(methylaminophosphazene) charged groups. The donor鈥揳cceptor function of poly(methylaminophosphazene) dominates when its electrostatic interaction with DNA is either saturated (in the complex coacervate phase at high poly(methylaminophosphazene) concentrations) or completely suppressed (in a salt medium when the polycation carries a small charge). Under these conditions, poly(methylaminophosphazene) destabilizes DNA. It preferentially binds to the DNA coil form likely via the formation of multiple labile hydrogen bonds with the donor鈥揳cceptor groups of DNA.