The growing application of quantum dots (QDs) in biomedical research necessitates, in turn, continuous development of surface functionalizing ligands to optimize their performance for ever more challenging and diverse biological applications. Here, we demonstrate the novel multifunctional polypeptide ligands for compact and biocompatible QDs. The target ligand preparation exploits the efficient, activating agent-free Ugi reaction of four functional components to incorporate lipoic acid, pyridine, zwitterion motifs, and reactive functionalities in a one-pot procedure under mild conditions. Cap exchange with these multifunctional polypeptide ligands generates hydrophilic QD dispersions, which are colloidally stable for prolonged periods of time. The zwitterionic ligation delivers compact and small QDs, and the existence of reactive functionalities enables coupling of the QDs to biologics through bio-orthogonal coupling chemistry, such as ligation of azide-modified QDs to DNA. Therefore, this QD functionalization strategy via Ugi reaction is believed to be a viable approach for compact and biocompatible QDs with efficient bioconjugation.

中文翻译：

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通过尿素反应的多功能多肽，具有高效生物共轭的紧凑和生物相容性量子点

量子点（QD）在生物医学研究中的日益增长的应用反过来又需要不断开发表面功能化配体，以优化其性能，以应对更具挑战性和多样化的生物应用。在这里，我们演示了紧凑和生物相容性量子点的新型多功能多肽配体。目标配体制剂利用温和条件下的一锅法，有效地，无活化剂地将四个功能成分进行Ugi反应，以整合硫辛酸，吡啶，两性离子基序和反应性功能。与这些多功能多肽配体的帽交换产生亲水的QD分散体，其在长时间内是胶体稳定的。两性离子连接可提供紧凑而小巧的QD，反应功能的存在使QD通过生物正交偶联化学（例如叠氮化物修饰的QD与DNA的连接）与生物制剂偶联。因此，通过Ugi反应的这种QD功能化策略被认为是具有有效生物缀合的紧凑和生物相容性QD的可行方法。