pH-switchable vesicles from a serine-derived guanidiniocarbonyl pyrrole carboxylate zwitterion in DMSO.
pH-switchable vesicles from a serine-derived guanidiniocarbonyl pyrrole carboxylate zwitterion in DMSO.
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DOI：
10.1002/anie.201003405
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发表时间：
2010-11
影响因子：
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通讯作者：
Fabian Rodler;J. Linders;Tassilo Fenske;Thomas H. Rehm;C. Mayer;C. Schmuck
中科院分区：
文献类型：
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作者：
Fabian Rodler;J. Linders;Tassilo Fenske;Thomas H. Rehm;C. Mayer;C. Schmuck
这项工作描述了一种新型囊泡，它可以通过改变自组装两性离子的质子化状态来可逆地打开和关闭。囊泡是一种有趣的纳米材料，具有潜在的应用前景，如药物靶向递送系统。然而，为此目的，需要外部控制囊泡的形成。迄今为止，囊泡的形成通常是基于两亲性大分子（如脂类衍生物或嵌段共聚物）的自组装。[1,2]最近，其他类型的构建块，如形状持久的大环、环糊精或小肽也被报道形成囊泡这些分子大多数仍然是典型的两亲分子，它们的自组装主要由疏水或芳香相互作用驱动。我们最近介绍了一种新的囊泡形成分子，即从丙氨酸衍生的自互补胍羰基吡咯羧酸两性离子。我们已经通过NOESY NMR研究结合TEM和AFM实验表明，在DMSO中，两性阴离子形成离子配对二聚体，然后进一步聚集成直径约40-50纳米的空心囊泡我们还利用这种特殊类型的氢键辅助离子对在胍基羰基吡咯阳离子[5]和羧酸盐单元之间形成，用于构建其他类型的纳米结构，如二聚体、[6]环、[7]和超分子聚合物[8]由于胍基羰基吡咯部分的pKa值约为6-7，因此与羧酸盐（pKa约为3-5）的离子对形成仅发生在狭窄的pH范围内。这种限制提供了通过将pH值从中性改变为微酸性或碱性来有意地开启或关闭离子对形成的可能性因此，我们想探索是否也可以通过使用pH值作为外部信号来触发囊泡的形成为了验证这一假设，我们合成了一种丝氨酸衍生的胍基羰基吡咯羧酸两性离子3，并利用原子力显微镜研究了它在表面和溶液中的囊泡形成
This work describes a new type of vesicles that can be reversibly opened and closed by changing the protonation state of a self-assembling zwitterion. Vesicles are interesting nanomaterials with potential applications such as delivery systems for drug targeting. For this purpose, however, external control of vesicle formation is required. To date, vesicle formation has often been based on the self-assembly of amphiphilic macromolecules such as lipid derivatives or block copolymers.[1, 2] Recently, vesicle formation from other types of building blocks, such as shape-persistent macrocyles, cyclodextrins, or small peptides has also been reported.[3] Most of these molecules are still classical amphiphiles and their self-assembly is mainly driven by hydrophobic or aromatic interactions.We have recently introduced a new type of vesicle forming-molecule, namely a self-complementary guanidiniocarbonyl pyrrole carboxylate zwitterion derived from alanine. We have shown by NOESY NMR studies in combination with TEM and AFM experiments that, in DMSO, the zwitterion forms ion-paired dimers that then further aggregate into hollow vesicles of approximately 40–50 nm diameter.[4] We have also used this special type of hydrogen-bond-assisted ion-pair formation between the guanidiniocarbonyl pyrrole cation [5] and a carboxylate unit for the construction of other types of nanostructures such as dimers,[6] loops,[7] and supramolecular polymers.[8] As the guanidiniocarbonyl pyrrole moiety has an approximate pKa value of 6–7, ion-pair formation with a carboxylate (pKa ca. 3–5) only occurs within a narrow pH range. This restriction offers the possibility to deliberately turn the ion-pair formation on or off by changing the pH from neutral to slightly acidic or basic.[9] We therefore wanted to explore whether we can also trigger vesicle formation by using pH as an external signal.[10] To test this hypothesis, we have synthesized a serine-derived guanidiniocarbonyl pyrrole carboxylate zwitterion 3 and studied its vesicle formation on surface with AFM as well as in solution