Département de Chimie, Université de Sherbrooke , Blvd Universite, Sherbrooke, Québec J1K 2R1, Canada.
Langmuir. 2014 Jan 14;30(1):410-7. doi: 10.1021/la404493n. Epub 2013 Dec 20.
The design, synthesis, and study of a new dual-stimuli-responsible ABC-type triblock copolymer are reported. Using ATRP and click coupling reaction, the prepared copolymer is composed of poly(ethylene oxide) (PEO), polystyrene (PS), and poly[2-(dimethylamino)ethylmethacrylate] (PDMAEMA) and features a redox-cleavable disulfide junction between the PEO and PS blocks as well as a photocleavable o-nitrobenzyl linkage between the PS and PDMAEMA blocks. This design allows the triblock copolymer to respond to both a reducing agent like dithiothreitol (DTT) and UV light, while having the minimum number of stimuli-reactive moieties in the copolymer structure (two per chain). The disruption of the triblock copolymer micelles in aqueous solution was examined under the action of either UV light or DTT alone or combined use of the two stimuli. It was found that the removal of one type of hydrophilic polymer chains from the water-soluble corona of the micelles with a hydrophobic PS core, that is, either redox-cleaved PEO or photocleaved PDMAEMA, could only result in a limited destabilization effect on the dispersion of the micelles. Severe aggregation of the polymer was observed only by applying the two stimuli converting the triblock copolymer onto three homopolymers. By monitoring the quenching by aqueous medium of the fluorescence of a hydrophobic dye (Nile Red) loaded in the triblock copolymer micelles, the effect on the payload release was also investigated of the different ways in which the micelles can be disrupted by the stimuli.
本文报道了一种新型双刺激响应型 ABC 三嵌段共聚物的设计、合成与研究。通过 ATRP 和点击偶联反应，制备的共聚物由聚环氧乙烷（PEO）、聚苯乙烯（PS）和聚[2-（二甲氨基）乙基甲基丙烯酸酯]（PDMAEMA）组成，其特点是 PEO 和 PS 嵌段之间存在可还原的二硫键连接，PS 和 PDMAEMA 嵌段之间存在可光解的邻硝基苄基连接。这种设计使三嵌段共聚物能够同时响应还原剂如二硫苏糖醇（DTT）和紫外光，同时在共聚物结构中具有最少数量的刺激响应性基团（每个链两个）。在单独使用紫外光或 DTT 或联合使用两种刺激的情况下，研究了在水溶液中三嵌段共聚物胶束的破坏情况。结果发现，从具有疏水性 PS 核的水溶性胶束的亲水性聚合物链中去除一种，即 either 氧化还原断裂的 PEO 或光解的 PDMAEMA，只能对胶束的分散产生有限的不稳定化作用。只有施加两种刺激将三嵌段共聚物转化为三种均聚物时，才能观察到聚合物的严重聚集。通过监测疏水染料（尼罗红）负载在三嵌段共聚物胶束中的荧光在水介质中的猝灭，可以研究不同的刺激方式对载药释放的影响。
