重链仅抗体的可变区域（VHH），也称纳米抗体（Nbs），是源自骆驼重链仅抗体的单体抗原结合区域。Nbs 的特点是尺寸小、靶点选择性高、溶解度和稳定性显著，这些共同促进了高质量药物的开发。此外，Nbs 可以从各种表达系统中轻松表达，包括大肠杆菌和酵母细胞。出于这些原因，Nbs 已成为蛋白质工程，疾病诊断和治疗的首选抗体片段。截至目前，已有两种基于 Nb 的治疗药物获得美国食品和药品管理局（FDA）的批准。数百个候选药物涵盖了癌症、免疫障碍、传染病和神经退行性疾病等广泛的疾病谱，正在进行临床前和临床研究。在这里，我们讨论了 Nbs 的结构特点，这些特点允许特定，多功能和强大的靶点结合。我们还总结了用于 Nbs 的识别，结构分析和人源化的新兴技术。我们的主要重点是回顾使用 Nbs 作为模块化支架促进多价聚合物工程的最新进展。最后，我们讨论了 Nb 发展尚存的挑战，并展望了 Nb 研究的新机会。版权所有©2023 Elsevier B.V.。

Variable domains of heavy chain-only antibodies (VHH), also known as nanobodies (Nbs), are monomeric antigen-binding domains derived from the camelid heavy chain-only antibodies. Nbs are characterized by small size, high target selectivity, and marked solubility and stability, which collectively facilitate high-quality drug development. In addition, Nbs are readily expressed from various expression systems, including E. coli and yeast cells. For these reasons, Nbs have emerged as preferred antibody fragments for protein engineering, disease diagnosis, and treatment. To date, two Nb-based therapies have been approved by the U.S. Food and Drug Administration (FDA). Numerous candidates spanning a wide spectrum of diseases such as cancer, immune disorders, infectious diseases, and neurodegenerative disorders are under preclinical and clinical investigation. Here, we discuss the structural features of Nbs that allow for specific, versatile, and strong target binding. We also summarize emerging technologies for identification, structural analysis, and humanization of Nbs. Our main focus is to review recent advances in using Nbs as a modular scaffold to facilitate the engineering of multivalent polymers for cutting-edge applications. Finally, we discuss remaining challenges for Nb development and envision new opportunities in Nb-based research.Copyright © 2023 Elsevier B.V. All rights reserved.