Fusion of core-shell capsules serving as model nanoreactors

在自然界中，许多化学反应发生在空间受限的环境中。例如，在细胞内，这种反应可以在时间和空间上耦合。在一个反应室中进行的给定反应的产物通常是后续过程的反应物或催化剂。在多室系统中，也可以同时实现不相容反应。迄今为止，人工核/壳微胶囊和纳米胶囊主要通过两亲性嵌段共聚物作为聚合物囊泡（聚合物囊泡）的自组装或通过利用聚电解质在牺牲固体颗粒上的逐层沉积来制造。在FUSION-CAPS中，详细研究了一种通过相反电荷的胶囊的融合来实现纳米容器的新方法，该方法是基于通过在油滴周围组装具有梳状接枝结构的两亲性聚电解质形成的胶囊。FUSION-CAPS的目标特别是（1）了解分散在水中的充油核壳聚合物纳米胶囊的形成机制和性质，（2）揭示具有相反电荷的纳米胶囊融合形成纳米反应器的机制及其控制因素，以及（3）利用胶囊融合产生的受限疏水环境进行选定的化学反应。新的路线，纳米反应器在这里提出通过融合的充油纳米胶囊将提供重要的基本洞察力融合聚合物组件的形成动力学，并可能获得前所未有的控制稳定的疏水反应环境分散在水性介质中，这可能具有优势的绿色合成化学。在FUSION-CAPS中，我们解决了装载试剂并在融合后作为纳米反应器的胶囊的制造问题，其特性可以系统地针对所需的反应进行定制。对于选定的融合胶囊，模型过程，包括能量转移和碰撞淬灭，以及化学反应，如“点击”和狄尔斯-阿德勒反应，将详细研究荧光光谱和时间分辨荧光显微镜方法，等等。最后，由于这些反应的纳米反应器的尺寸和属性的限制的影响将被揭开。

In Nature, many chemical reactions take place in spatially confined environments. For instance within cells, such reactions can be coupled in time and space. Products of a given reaction executed in one reaction chamber are often the reactants or catalysts of a subsequent process. In multicompartment systems also incompatible reactions can be realized simultaneously. Artificial core/shell micro- and nanocapsules have thus far been mainly fabricated by self-assembly of amphiphilic block copolymers as polymeric vesicles (polymersomes), or by exploiting layer-by-layer deposition of polyelectrolytes on sacrificial solid particles. In FUSION-CAPS a new approach to realize nanocontainers via fusion of capsules of opposite charge is investigated in detail, which is based on capsules formed by the assembly of amphiphilic polyelectrolytes with comb-like graft architecture around oil droplets. The objectives of FUSION-CAPS are in particular (1) to understand the mechanism of formation and the properties of oil-filled core-shell polymer nanocapsules dispersed in water, (2) to unveil the mechanism of fusion of nanocapsules with opposite charges to form nanoreactors and the factors that govern it, and (3) to exploit the confined hydrophobic environments generated by capsule fusion for performing selected chemical reactions. The new route to nanoreactors proposed here via fusion of oil-filled nanocapsules will offer important fundamental insight into the formation dynamics of fused polymeric assemblies and may afford access to unprecedented control of stable hydrophobic reaction environments dispersed in aqueous media, which may possess advantages for green synthetic chemistry. In FUSION-CAPS we address the fabrication of capsules that are loaded with reagents and serve after fusion as nanoreactors, whose properties can be systematically tailored for the desired reactions. For selected fusing capsules, model processes, including energy transfer and collisional quenching, as well as chemical reactions, such as "click" and Diels-Adler reactions, will be studied in detail by fluorescence spectroscopy and time resolved fluorescence microscopy methods, among others. Finally, the impact of the confinement due to the dimensions and properties of the nanoreactors on these reactions will be unveiled.