Rosa Heloísa, Petri Denise F S, Carmona-Ribeiro Ana M
Departamento de Bioquímica, Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, P.O. Box 26077, São Paulo, SP 05513-970, Brazil.
J Phys Chem B. 2008 Dec 25;112(51):16422-30. doi: 10.1021/jp806992f.
The interaction between giant bacteriophage DNA and cationic biomimetic particles was characterized from sizing by dynamic light-scattering, zeta-potential analysis, turbidimetry, determination of colloid stability, visualization from atomic force microscopy (AFM), and determination of cytotoxicity against E. coli from colony forming unities counting. First, polystyrene sulfate (PSS) particles with different sizes were covered by a dioctadecyldimethylammonium bromide (DODAB) bilayer yielding the so-called cationic biomimetic particles (PSS/DODAB). These cationic particles are highly organized, present a narrow size distribution and were obtained over a range of particle sizes. Thereafter, upon adding lambda, T5 or T2-DNA to PSS/DODAB particles, supramolecular assemblies PSS/DODAB/DNA were obtained and characterized over a range of DNA concentrations and particle sizes (80-700 nm). Over the low DNA concentration range, PSS/DODAB/ DNA assemblies were cationic, colloidally stable with moderate polydispersity and highly cytotoxic against E. coli. From DNA concentration corresponding to charge neutralization, neutral or anionic supramolecular assemblies PSS/DODAB/DNA exhibited low colloid stability, high polydispersity and moderate cytotoxicity. Some nucleosome mimetic assemblies were observed by AFM at charge neutralization (zeta-potential equal to zero).
通过动态光散射法测定粒径、ζ电位分析、比浊法、胶体稳定性测定、原子力显微镜（AFM）观察以及通过菌落形成单位计数测定对大肠杆菌的细胞毒性，对巨型噬菌体DNA与阳离子仿生颗粒之间的相互作用进行了表征。首先，用二辛基二甲基溴化铵（DODAB）双层覆盖不同尺寸的聚苯乙烯磺酸盐（PSS）颗粒，得到所谓的阳离子仿生颗粒（PSS/DODAB）。这些阳离子颗粒高度有序，尺寸分布窄，且在一系列粒径范围内均可获得。此后，将λ、T5或T2-DNA添加到PSS/DODAB颗粒中，得到超分子组装体PSS/DODAB/DNA，并在一系列DNA浓度和粒径（80-700nm）范围内对其进行表征。在低DNA浓度范围内，PSS/DODAB/DNA组装体呈阳离子性，胶体稳定，多分散性适中，对大肠杆菌具有高度细胞毒性。从电荷中和对应的DNA浓度开始，中性或阴离子超分子组装体PSS/DODAB/DNA表现出低胶体稳定性、高多分散性和中等细胞毒性。在电荷中和（ζ电位等于零）时，通过AFM观察到了一些核小体模拟组装体。
