Cambón Adriana, Figueroa-Ochoa Edgar, Juárez Josué, Villar-Álvarez Eva, Pardo Alberto, Barbosa Silvia, Soltero J F Armando, Taboada Pablo, Mosquera Víctor
Departamento de Física de la Materia Condensada, Grupo de Física de Coloides y Polímeros , 15782-Santiago de Compostela, Spain.
J Phys Chem B. 2014 May 15;118(19):5258-69. doi: 10.1021/jp500426k. Epub 2014 May 1.
Amphiphilic block copolymers have emerged during last years as a fascinating substrate material to develop micellar nanocontainers able to solubilize, protect, transport, and release under external or internal stimuli different classes of cargos to diseased cells or tissues. However, this class of materials can also induce biologically relevant actions, which complement the therapeutic activity of their cargo molecules through their mutual interactions with biologically relevant entities (cellular membranes, proteins, organelles...); these interactions at the same time, are regulated by the nature, conformation, and state of the copolymeric chains. For these reasons, in this paper we investigated the self-assembly process and physico-chemcial properties of two reverse triblock poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) block copolymers, BO14EO378BO14 and BO21EO385BO21, which have been recently found to be very useful as drug delivery nanovehicles and biological response modifiers under certain conditions (A. Cambón et al. Int. J. Pharm. 2013, 445, 47-57) in order to obtain a clear picture of the solution behavior of this class or block copolymers and to understand their biological activity. These block copolymers are characterized by possessing long BO blocks and extremely lengthy central EO ones, which provide them with a rich rheological behavior characterized by the formation of flowerlike micelles with sizes ranging from 20 to 40 nm in aqueous solution and the presence of intermicellar bridging even at low copolymers concentrations as denoted by atomic force microscopy. Bridging is also clearly observed by analyzing the rheological response of these block copolymers both storage and loss moduli upon changes on time, temperature, and or concentration. Strikingly, the relatively wide Poisson distribution of the polymeric chains make the present copolymers behave rather distinctly to conventional associative thickeners. The observed rich rheological behavior and their tunability also make these copolymers promising materials to configure drug gelling depots.
近年来，两亲性嵌段共聚物已成为一种引人入胜的基质材料，可用于开发胶束纳米容器，这种纳米容器能够在外部或内部刺激下将不同种类的货物溶解、保护、运输并释放到患病细胞或组织中。然而，这类材料也能引发与生物学相关的作用，通过它们与生物学相关实体（细胞膜、蛋白质、细胞器等）的相互作用，补充其负载分子的治疗活性；与此同时，这些相互作用受共聚链的性质、构象和状态的调节。基于这些原因，在本文中，我们研究了两种反向三嵌段聚（环氧丁烷）-聚（环氧乙烷）-聚（环氧丁烷）嵌段共聚物BO14EO378BO14和BO21EO385BO21的自组装过程和物理化学性质，最近发现它们在某些条件下作为药物递送纳米载体和生物反应调节剂非常有用（A. Cambón等人，《国际药学杂志》，2013年，445卷，47 - 57页），以便清晰了解这类嵌段共聚物的溶液行为并理解它们的生物活性。这些嵌段共聚物的特点是拥有长的BO链段和极长的中心EO链段，这赋予它们丰富的流变行为，其特征是在水溶液中形成尺寸范围为20至40纳米的花状胶束，并且即使在低共聚物浓度下也存在胶束间桥连，这由原子力显微镜观察到。通过分析这些嵌段共聚物在时间、温度和/或浓度变化时的储能模量和损耗模量的流变响应，也能清楚地观察到桥连现象。引人注目的是，聚合物链相对较宽的泊松分布使得本共聚物的行为与传统的缔合增稠剂有相当明显的不同。观察到的丰富流变行为及其可调性也使这些共聚物成为配置药物凝胶库的有前景的材料。
