Polymer micelles stabilization on demand through reversible photo-cross-linking
Polymer micelles stabilization on demand through reversible photo-cross-linking
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DOI：
10.1021/ma062493j
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发表时间：
2007-02-20
期刊：
影响因子：
5.5
通讯作者：
Zhao, Yue
中科院分区：
文献类型：
--
作者：
Jiang, Jinqiang;Qi, Bo;Zhao, Yue
聚合物胶束的稳定性影响客体分子的包封稳定性，可能是一些受控递送应用的关键条件。有可能聚合物胶束在体内给药后由于极度稀释至低于聚合物的临界胶束浓度而崩解。如果发生这种情况，被困的客体，如药物，可以迅速泄漏，这使得任何特定位置的胶束运输策略都无效。因此，人们提出了各种方法来稳定聚合物胶束，从而实现包封。其中，胶束核交联2或壳交联3由于化学交联胶束的结构完整性而特别有吸引力。然而，更稳定的客体封装可能使其在胶束到达目标后的较晚时间释放更加困难。片冈和他的同事展示了一种解决冲突效应问题的优雅方法。他们通过二硫键使核心交联，并随后用还原试剂裂解二硫键使胶束解离，从而成功地稳定了多离子复合物胶束。最近的一份报告显示了类似的方法，其中硫醇/二硫交换反应用于可逆交联和去交联热敏三嵌段共聚物胶束的壳层。5在本文中，作为我们正在进行的光可控聚合物胶束研究的一部分，6我们提出了一种新的全光策略来稳定聚合物胶束的需求，这与以前的化学方法不同。4,5我们的概念验证研究表明，通过在二嵌段共聚物中加入香豆素基团的可逆光控二聚化，胶束可以交联以稳定，随后通过两种不同波长的光照射去交联，并具有可调的交联密度。由于这种光学方法可以适用于显示可逆光反应的其他发色团和各种胶束聚集体，我们相信我们的研究为聚合物胶束提供了一种潜在的有用的新途径，通过光的使用，既可以提供稳定封装的结构稳定性，又可以提供在所需时间和地点控制释放的随后的不稳定性。
The stability of polymer micelles, which affects the stability of encapsulation of guest molecules, may be a crucial condition for some controlled delivery applications. It is possible that polymer micelles are disintegrated after being administrated in the body due to an extreme dilution to below the critical micelle concentration of the polymer. If this happens, the entrapped guest such as a drug can leak out quickly, which renders any strategy for site-specific transport of the micelles useless. 1 Therefore, various approaches have been proposed to stabilize polymer micelles and thus the encapsulation. Of them, micelle core cross-linking2 or shell cross-linking3 is particularly attractive owing to the structural integrity of chemically cross-linked micelles. However, a more stable encapsulation of a guest may render its release more difficult at a later time after micelles arrive at the target. Kataoka and co-workers have demonstrated an elegant method to resolve the problem of the conflicting effect. 4 They succeeded in stabilizing their polyion complex micelles by cross-linking the core through disulfide bonds and, subsequently, dissociating the micelles by cleaving the disulfide bond with a reducing reagent. A more recent report showed a similar approach in which the thiol/disulfide exchange reaction was used to reversibly cross-link and de-cross-link the shell of a thermosensitive triblock copolymer micelle. 5 In this paper, as part of our ongoing research on light-controllable polymer micelles, 6 we propose a new all-optical strategy for the stabilization on demand of polymer micelles, which differs from the previous chemical approaches. 4, 5 Our proof-of-concept study shows that, through the use of reversibly photocontrolled dimerization of coumarin moieties7 incorporated in a diblock copolymer, micelles can be cross-linked for stabilization and subsequently de-cross-linked by light illumination at two different wavelengths, with tunable cross-linking density. As this optical approach can be adapted to other chromophores displaying a reversible photoreaction8 and to various micellar aggregates, we believe our study suggests a potentially useful new route to polymer micelles that afford both structural stabilization for stable encapsulation and subsequent destabilization for controlled release at a required time and location, through the use of light.