Collaborative Research: Elucidating the Nanoscale Interaction between Invertible Micellar Assemblies (IMAs) and Biopolymer Cargos under Varied Environments

聚合物载体给药的研究仍处于起步阶段。这一领域的挑战是找到合适的载体结构和最佳的聚合物化学，以促进治疗剂（药物）对其目标的控制递送和释放。一种独特的载体是可逆聚合物胶束组合，它是由聚合物的快速自组织/组装形成的，这些聚合物具有交替和重复的疏水（憎水）和亲水（亲水）片段，呈棒状（数十纳米长）。可以将治疗各种疾病但不能直接进入人体的药物和多肽/核酸纳入到可逆胶束中。一旦环境条件发生变化（即，当组件从水“到达”细胞膜时），可逆胶束组件就会以一种智能的方式改变其尺寸和几何形状（形状），从而有效地将货物分子输送和释放到目标（生物膜），从而治疗相关疾病。虽然可逆胶束组合的结构和动力学已经在一定程度上得到了理解，但仍然需要回答的关键问题是(i)装载货物的可逆胶束组合的哪些特性使它们能够有效地治疗疾病（ii）独特的形状变化（在本项目中称为“反转”）对于有效的递送性能有多重要。回答这些问题需要在分子水平上深入了解不同环境下药物货物和可逆胶束组件之间的相互作用，这是一项具有挑战性的任务，因为大多数常见的技术没有足够高的分辨率来“穿透”这些组件并探测其中的生物聚合物货物。在这个项目中，来自北达科他州立大学的研究人员通过标记生物聚合物和使用一种称为电子顺磁共振波谱的独特技术研究标记位点的行为来弥合这一知识差距。获得的数据将提供有关可逆胶束组件如何与溶剂环境和生物聚合物货物相互作用以及货物如何在可逆胶束组件内部移动和/或聚集的详细信息。这些信息不仅回答了上述问题，而且有助于合理设计新的递送工具，更好地适应/递送生物聚合物和/或药物，扩大可逆性胶束组件作为一般药物载体的应用，以治疗各种疾病。该研究小组将为代表性不足的学生提供培训，包括美国土著学生和当地的本科生和高中生，学习纳米技术和化学。该团队还将通过北达科他州的“军事儿童行动”项目，为父母被部署为士兵的青少年提供科学教育机会。本项目旨在了解可逆胶束组件、货物和环境（溶剂）在纳米尺度上的相互作用，以揭示生物聚合物货物因环境极性变化而装载和释放时可逆胶束组件内部的机理细节。这一目标将通过三个步骤实现：(i)揭示在不同溶剂条件下可逆胶束组合的形态、拥挤和极性的变化，（ii）描述生物聚合物装载对水中可逆胶束组合的形态、拥挤和极性的影响，以及（iii）阐明在环境极性变化时可逆胶束组合中生物聚合物的运动和聚集状态（如果有的话）。获得这些知识的关键是将电子顺磁共振自旋探针/标签共价放置在可逆胶束组件和生物聚合物的特定位置/位置，然后进行（生物）聚合物结构和动力学的电子顺磁共振波谱研究。本研究将提供在不同溶剂条件下可逆胶束组合内的局部拥挤和极性的地图，并根据货物的局部拥挤和极性在可逆胶束组合中定位生物聚合物货物的各个部分（连接导致货物构象）。获得的知识提供了可逆胶束组件的微环境与货物结构/疏水性/极性之间的直接联系，以评估和合理可逆胶束组件与货物之间相互作用的相对强度。这项工作还将使用货物位置和货物运动的信息来描述货物与可逆胶束组件相互作用时的相对位置。最后，本研究将阐明由于可逆胶束组合与货物之间的相互作用而可能引起的货物结构变化。所有这些努力将导致对货物吸收/释放性能以及可逆胶束组件与货物之间相互作用的深入了解。该项目还将通过提供尖端纳米技术、生物聚合物工程和光谱学方面的实践研究经验，为不同教育水平（高中、本科）、不同背景的学生提供培训。从研究活动中获得的知识和实验方法将通过科学同行评审期刊出版物、国家/国际会议和地方科学博览会传播。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Research in drug delivery by polymeric carriers is still in its infancy. The demanding challenge in this field is to find the right carrier architecture and the optimum polymer chemistry that can facilitate controlled delivery and release of therapeutic agents (drugs) to their targets. A unique carrier is invertible polymer micellar assemblies, which are formed by the rapid self-organization/assembly of polymers with alternated and repeated hydrophobic (water-hating) and hydrophilic (water-loving) segments in a rod-like shape (tens of nanometers long). Drugs and polypeptides/nucleic acids which can treat various diseases but cannot be directly introduced to human body can be incorporated into invertible micellar assemblies. Once the environmental conditions are changed (i.e., when the assemblies from water “arrive” to the cellular membrane), the invertible micellar assemblies reverse their dimensions and geometry (shape) in a smart way to effectively deliver and release cargo molecules to the targets (biological membranes) and, thus, treat relevant diseases. Although the structure and dynamics of invertible micellar assemblies have been understood to a certain level, the key questions that still need to be answered are (i) what properties of cargo-loaded invertible micellar assemblies make them efficient in treating diseases (ii) how significant is a fact of unique change of shape (called “inversion” in this project) for efficient delivery performance. Answering these questions require an in-depth understanding on the interactions between drug cargos and invertible micellar assemblies under varied environments at the molecular level, which is a challenging task because most commonly seen techniques do not have a sufficiently high resolution to “penetrate” the assemblies and probe biopolymer cargos therein. In this project, researchers from the North Dakota State University bridge this knowledge gap by labelling biopolymers and studying the behavior of the labeled sites using a unique technique known as Electron Paramagnetic Resonance spectroscopy. The obtained data will provide details on how invertible micellar assemblies interact with the solvent environment and the biopolymer cargos as well as how the cargos move and/or aggregate within the interior of invertible micellar assemblies. This information not only answers aforementioned questions but also assists in the rational design of new delivery vehicles that better adapt/deliver biopolymers and/or drugs, broadening the application of invertible micellar assemblies as general drug carriers to treat various diseases. The research team will provide training to underrepresented students including Native American students and local undergraduate and high school students on nanotechnology and chemistry. The team will also offer scientific educational opportunities for youths whose parents are deployed as soldiers through the Operation Military Kids program in the state of North Dakota.This project aims to understand the interactions among the invertible micellar assemblies, cargo, and environment (solvent) at the nanoscale, in order to reveal the mechanistic details in the interior of invertible micellar assemblies when biopolymer cargos are loaded and released due to environment polarity changes. This goal will be achieved via three steps: (i) revealing the changes in the morphology, crowding, and polarity of invertible micellar assemblies under varied solvent conditions, (ii) depicting the impact of biopolymer cargo loading on the morphology, crowding, and polarity of invertible micellar assemblies in water, and (iii) elucidating the movement and aggregation state (if any) of the biopolymer within invertible micellar assemblies upon environment polarity change. The key to acquiring this knowledge is to covalently place an Electron Paramagnetic Resonance spin probe/tag at specific locations/positions within the invertible micellar assemblies and on biopolymers, followed by Electron Paramagnetic Resonance spectroscopy study of (bio)polymer structure and dynamics. This research will provide maps of the local crowding and polarity within the invertible micellar assemblies under various solvent conditions and locate various segments of biopolymer cargos (connecting which lead to cargo conformation) in the invertible micellar assemblies based on the local crowding and polarity of the cargo. The obtained knowledge offers a direct connection between the microenvironment of invertible micellar assemblies and cargo structure/hydrophobicity/polarity to assess and rationalize the relative strength of the interactions between invertible micellar assemblies and cargos. This work will also use the information of cargo location and cargo movement to depict the relative position of cargos upon interacting with the invertible micellar assemblies. Lastly, this research will elucidate the possible structural changes of cargos, if any, caused by the interactions between invertible micellar assemblies and cargos. All of these efforts will result in an in-depth understanding of the cargo uptake/release performance and the interactions between invertible micellar assemblies and cargos. This project will also provide training to students at various educational levels (high school, undergraduate) from diverse backgrounds by offering hands-on research experience in cutting-edge nanotechnology, biopolymer engineering, and spectroscopy. The obtained knowledge and experimental approaches from research activities will be disseminated through scientific peer-review journal publications, national/international conferences, and local science fairs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.