Solubilisation and Release of Organic Compounds of Different Polarity by Interpolyelectrolyte Complexes Based on Block Copolymer Micelles

该项目的主要目的是开发明确的核-壳-电晕IPEC胶束，并研究它们的溶解和释放特性。为此，我们从聚（烷基丙烯酸酯）-b-聚（丙烯酸）（PAlkA-b-PAA）型两亲嵌段共聚物开始，它在水溶液中形成胶束，并将在本项目中合成。通过添加多阳离子，形成多电解质间复合物（IPEC）的壳层以产生共聚物IPEC胶束。作为一个有趣的变化，我们将采用具有中性嵌段的双亲水二嵌段共聚物作为聚阳离子。该壳的性质由多阳离子的选择来控制，而胶束核的疏水性则通过PAlkA的烷基链长度来控制。此外，核和壳的大小将分别由PAlkA块的长度和添加的多阳离子的量来控制。作为第一步，我们将详细描述这些IPEC胶束的结构，作为它们的分子构建块的功能，以确定它们之间的系统相关性。在这里，我们将主要采用散射技术和荧光测量。在第二步中，我们将确定不同极性的油对不同大小和结构的IPEC胶束的增溶能力。由增溶引起的IPEC胶束的结构变化以及增溶位点（核和/或壳）将被确定。从油、胶束核和IPEC壳的极性与溶解位点之间的系统相关性和由此产生的结构变化将被推断出来。在这里，我们也将使用药物分子作为极性增溶物，它们有望优先在IPEC外壳中被增溶。有了多室系统，我们期望能够在核和壳的不同区域形成具有不同极性的溶解物的聚集体，从而为能够同时携带非极性和极性活性剂的输送系统开辟了道路。当我们使用PAA稳定系统时，我们将研究这些负载的IPEC胶束在相关pH值范围5-8内的pH响应。重点将是发生的结构变化以及所含不同活性剂（有效载荷）的释放动力学。释放通常取决于IPEC胶束的结构和分子组成，以及pH值，这意味着它可以由pH值变化触发。这将主要通过荧光测量（高灵敏度）进行研究，并允许确定ipec胶束的多功能性，可以调整这种释放实验。总的来说，对这些复杂胶体的全面表征将对使用IPEC胶束进行选择性增溶和释放的科学理解产生实质性的进步，从而使这些系统更接近潜在的应用。

The main aim of this project is to develop well-defined core-shell-corona IPEC micelles and to investigate them with respect to their solubilisation and release properties. For that purpose we start from amphiphilic block copolymers of the poly(alkylacrylate)-b-poly(acrylic acid) (PAlkA-b-PAA) type, which form micelles in aqueous solution and will be synthesised in this project. By addition of a polycation a shell of an interpolyelectrolyte complex (IPEC) is formed to produce copolymer IPEC micelles. As an interesting variation we will employ double-hydrophilic diblock copolymers with a neutral block as polycations. The properties of this shell are controlled by the choice of polycation, and the hydrophobicity of the micellar core via the length of the alkyl chain of the PAlkA. In addition, the size of core and shell will be controlled by the length of the PAlkA block and the amount of the added polycation, respectively. As a first step we will characterise in detail the structure of these IPEC micelles as a function of their molecular building blocks in order to determine systematic correlations between them. Here we will mainly employ scattering techniques and fluorescence measurements. In the second step we will determine the solubilisation capacity for oils of different polarity for differently sized and structured IPEC micelles. Structural changes of the IPEC micelles induced by solubilisation as well as the solubilisation site (core and/or shell) will be determined. From that systematic correlations between the polarities of the oil, micelle core and IPEC shell and the solubilisation site and the resulting structural changes will be deduced. Here we will also use drug molecules as polar solubilisates, which are expected to become solubilized preferentially in the IPEC shell. Having a multi-compartment systems we expect to be able to form aggregates with solubilisates of different polarity in the different regions of core and shell, thereby opening the path to delivery systems that are able to carry both, unpolar and polar active agents at the same time. As we are working with PAA stabilized systems we will then study the pH response of these loaded IPEC micelles in the relevant pH range of 5-8. The focus will be on structural changes occurring as well as on the release kinetics for different active agents (payload) contained. The release will in general depend on structure and molecular composition of the IPEC micelles, as well as on pH, which means it can be triggered by a pH-change. This will mainly be studied by fluorescence measurements (high sensitivity) and allows to determine how versatile the IPEC-micelles can be tuned for such release experiments. In general, the comprehensive characterisation of these complex colloids will yield a substantial advancement of the scientific understanding for using IPEC micelles for selective solubilisation and release, thereby bringing such systems closer to potential applications.