Berret Jean-François, Schonbeck Nicolas, Gazeau Florence, El Kharrat Delphine, Sandre Olivier, Vacher Annie, Airiau Marc
Matière et Systèmes Complexes, UMR 7057 CNRS Université Denis Diderot Paris-VII,140 rue de Lourmel, F-75015 Paris, France.
J Am Chem Soc. 2006 Feb 8;128(5):1755-61. doi: 10.1021/ja0562999.
When polyelectrolyte-neutral block copolymers are mixed in aqueous solutions with oppositely charged species, stable complexes are found to form spontaneously. The mechanism is based on electrostatics and on the compensation between the opposite charges. Electrostatic complexes exhibit a core-shell microstructure. In the core, the polyelectrolyte blocks and the oppositely charged species are tightly bound and form a dense coacervate microphase. The shell is made of the neutral chains and surrounds the core. In this paper, we report on the structural and magnetic properties of such complexes made from 6.3 nm diameter superparamagnetic nanoparticles (maghemite gamma-Fe(2)O(3)) and cationic-neutral copolymers. The copolymers investigated are poly(trimethylammonium ethylacrylate methyl sulfate)-b-poly(acrylamide), with molecular weights 5000-b-30000 g mol(-)(1) and 110000-b-30000 g mol(-)(1). The mixed copolymer-nanoparticle aggregates were characterized by a combination of light scattering and cryo-transmission electron microscopy. Their hydrodynamic diameters were found in the range 70-150 nm, and their aggregation numbers (number of nanoparticles per aggregate) from tens to hundreds. In addition, Magnetic Resonance Spin-Echo measurements show that the complexes have a better contrast in Magnetic Resonance Imaging than single nanoparticles and that these complexes could be used for biomedical applications.
当聚电解质-中性嵌段共聚物在水溶液中与带相反电荷的物质混合时，会发现稳定的复合物会自发形成。其机制基于静电作用以及相反电荷之间的补偿。静电复合物呈现出核壳微观结构。在核中，聚电解质嵌段和带相反电荷的物质紧密结合，形成致密的凝聚微相。壳由中性链构成并包围着核。在本文中，我们报道了由直径为6.3 nm的超顺磁性纳米颗粒（磁赤铁矿γ-Fe₂O₃）和阳离子-中性共聚物制成的此类复合物的结构和磁性特性。所研究的共聚物是聚（甲基硫酸乙酯丙烯酸三甲铵）-b-聚（丙烯酰胺），分子量分别为5000-b-30000 g mol⁻¹和110000-b-30000 g mol⁻¹。通过光散射和低温透射电子显微镜相结合的方法对混合的共聚物-纳米颗粒聚集体进行了表征。发现它们的流体动力学直径在70-150 nm范围内，其聚集数（每个聚集体中的纳米颗粒数）从几十到几百不等。此外，磁共振自旋回波测量表明，这些复合物在磁共振成像中的对比度比单个纳米颗粒更好，并且这些复合物可用于生物医学应用。
