Marchetti S, Onori G, Cametti C
Dipartimento di Fisica, Universita di Perugia and CEMIN (Centro Eccellenza Materiali Innovativi Nanostrutturati), Via A. Pascoli, I-06123, Perugia (Italy).
J Phys Chem B. 2005 Mar 3;109(8):3676-80. doi: 10.1021/jp044867l.
The compaction of DNA induced by two simple amphiphiles, cetyltrimethylammonium bromide [CTAB] and dodecyldimethylamine oxide [DDAO], has been investigated by means of combined viscosity and dynamic light scattering measurements, to demonstrate the formation of soluble DNA/surfactant complexes, undergoing a coil-globule transition, upon the increase of the amphiphile concentration. In both of the two systems investigated, the complexation process reaches a maximum for a value of the surfactant to DNA phosphate groups molar ratio of about X = 1. Below this critical concentration, the coil and the globule state coexist in the solution, as clearly shown by the bimodal size distribution obtained from the light scattering intensity correlation functions. Some suggestions are given to support a molecular mechanism responsible for the complex formation, both in the case of a cationic surfactant (CTAB) and of a pH-dependent neutral or cationic amphiphile (DDAO), where the hydrophobic interactions play an important role.
通过结合粘度和动态光散射测量方法，研究了两种简单两亲分子十六烷基三甲基溴化铵[CTAB]和十二烷基二甲基氧化胺[DDAO]诱导的DNA压缩，以证明随着两亲分子浓度的增加，可形成经历线圈-小球转变的可溶性DNA/表面活性剂复合物。在所研究的两个系统中，当表面活性剂与DNA磷酸基团的摩尔比约为X = 1时，络合过程达到最大值。低于该临界浓度时，溶液中线圈态和小球态共存，这从光散射强度相关函数获得的双峰尺寸分布中可以清楚地看出。对于阳离子表面活性剂（CTAB）和pH依赖性中性或阳离子两亲分子（DDAO）的情况，给出了一些支持负责复合物形成的分子机制的建议，其中疏水相互作用起着重要作用。
