Attaching targeting ligands on the surface of self-assembled drug delivery systems is the key request for a controlled transport of the drug to a desired location. Most commonly, the amphiphilic molecules (block-copolymers, lipids etc.) are therefore pre-functionalized before the self-assembly takes place. However, this strategy cannot be applied, if it interferes with the self-assembly process, if the introduced functional groups react with loaded cargo or if natural carriers like extracellular vesicles should be functionalized. Here, we present the site-specific coupling of antibodies to the surface of amino group-terminated liposomes via bio-orthogonal copper-free click chemistry after liposome formation. The present primary amino groups were functionalized with a linker carrying a strained alkyne group for a bio-orthogonal strain-promoted alkyne–azide cycloaddition (SPAAC) reaction where Cu(I) as a catalyst can be avoided. Antibodies were site-specifically functionalized with azide moieties along the Fc region to avoid interference with the antigen binding sites. The liposome surface functionalization reaction was optimized by precisely analyzing the number of available functional groups (both amine and alkyne), which often represents a challenge for self-assembled systems. By finally confirming the successful antibody coupling, we provide a facile and robust functionalization strategy, which can be applied to a wide range of self-assembled systems and desired targeting antibodies maintaining physiological conditions throughout the procedure.

中文翻译：

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自组装后在囊泡表面上特异性结合抗体的生物正交功能化策略†

将靶向配体附着在自组装药物递送系统的表面上是控制药物向所需位置的受控运输的关键要求。因此，最常见的是，两亲性分子（嵌段共聚物，脂质等）在自组装发生之前被预官能化。但是，如果该策略会干扰自组装过程，所引入的官能团与负载的货物发生反应，或者应将诸如细胞外囊泡之类的天然载体进行功能化，则无法应用此策略。在这里，我们提出抗体通过氨基末端脂质体表面的位点特异性偶联脂质体形成后的生物正交无铜点击化学。当前的伯氨基是通过带有应变炔基的连接子官能化的，用于生物正交应变促进的炔-叠氮化物环加成（SPAAC）反应，其中Cu（I）作为催化剂可以避免。沿Fc区使用叠氮基位点对抗体进行位点特异性功能化，以避免干扰抗原结合位点。通过精确分析可用官能团（胺和炔基）的数量来优化脂质体表面官能化反应，这对于自组装系统通常是一个挑战。通过最终确认成功的抗体偶联，我们提供了一种简便而强大的功能化策略，可将其应用于各种自组装系统和所需的靶向抗体，从而在整个过程中保持生理状况。