Polyorganophosphazenes are water-soluble macromolecules with immunoadjuvant activity that self-assemble with proteins to enable biological functionality. Direct imaging by cryogenic electron microscopy uncovers the coil structure of those highly charged macromolecules. Here, we successfully visualize individual polymer chains within the vitrified state in the absence of additives for contrast enhancement which is attributed to the high mass contrast of the inorganic backbone. Upon assembly with proteins, multiple protein copies bind at the single polymer chain level resulting in structures reminiscent of compact spherical complexes or stiffened coils. The outcome depends on protein characteristics and cannot be deduced by commonly used characterization techniques, such as light scattering, thus revealing direct morphological insights crucial for understanding biological activity. Atomic force microscopy supports the morphology outcomes while advanced analytical techniques confirm protein-polymer binding. The chain visualization methodology provides tools for gaining insights into the processes of supramolecular assembly and mechanistic aspects of polymer-enabled vaccine delivery.

聚有机磷腈是具有免疫佐剂活性的水溶性大分子，可与蛋白质自组装以实现生物功能。低温电子显微镜的直接成像揭示了这些高电荷大分子的线圈结构。在这里，我们成功地在没有添加剂的情况下在玻璃化状态下可视化单个聚合物链以增强对比度，这归因于无机主链的高质量对比度。与蛋白质组装后，多个蛋白质拷贝在单聚合物链水平上结合，形成类似于紧凑球形复合物或硬化线圈的结构。结果取决于蛋白质特征，不能通过常用的表征技术（例如光散射）来推断，从而揭示对于理解生物活性至关重要的直接形态学见解。原子力显微镜支持形态学结果，而先进的分析技术证实蛋白质-聚合物结合。链可视化方法提供了深入了解超分子组装过程和聚合物疫苗输送机制方面的工具。