First studies on thrombin-inhibiting DNA aptamers were reported in 1992, and since then a large number of anticoagulant aptamers has been discovered. TBA – also named HD1, a 15-mer G-quadruplex (G4)-forming oligonucleotide – is the best characterized thrombin binding aptamer, able to specifically recognize the protein exosite I, thus inhibiting the conversion of soluble fibrinogen into insoluble fibrin strands. Unmodified nucleic acid-based aptamers, in general, and TBA in particular, exhibit limited pharmacokinetic properties and are rapidly degraded in vivo by nucleases. In order to improve the biological performance of aptamers, a widely investigated strategy is the introduction of chemical modifications in their backbone at the level of the nucleobases, sugar moieties or phosphodiester linkages. Besides TBA, also other thrombin binding aptamers, able to adopt a well-defined G4 structure, e.g. mixed duplex/quadruplex sequences, as well as homo- and hetero-bivalent constructs, have been identified and optimized.

Considering the growing need of new efficient anticoagulant agents associated with the strong therapeutic potential of these thrombin inhibitors, the research on thrombin binding aptamers is still a very hot and intriguing field. Herein, we comprehensively described the state-of-the-art knowledge on the DNA-based aptamers targeting thrombin, especially focusing on the optimized analogues obtained by chemically modifying the oligonucleotide backbone, and their biological performances in therapeutic applications.

1992 年首次报道了对凝血酶抑制 DNA 适体的研究，此后发现了大量抗凝适体。TBA - 也称为 HD1，一种 15 聚体 G-四链体 (G4) 形成寡核苷酸 - 是表征最好的凝血酶结合适体，能够特异性识别蛋白质外位点 I，从而抑制可溶性纤维蛋白原转化为不溶性纤维蛋白链。未修饰的基于核酸的适体，尤其是 TBA，通常表现出有限的药代动力学特性，并在体内迅速降解通过核酸酶。为了提高适体的生物学性能，一个广泛研究的策略是在核碱基、糖部分或磷酸二酯键的水平上在其骨架中引入化学修饰。除了TBA，还鉴定和优化了能够采用明确定义的G4结构的其他凝血酶结合适体，例如混合双链体/四链体序列，以及同源和异源二价构建体。

考虑到对与这些凝血酶抑制剂的强大治疗潜力相关的新型高效抗凝剂的需求不断增长，对凝血酶结合适体的研究仍然是一个非常热门和有趣的领域。在此，我们全面描述了靶向凝血酶的基于 DNA 的适配体的最新知识，特别是通过化学修饰寡核苷酸骨架获得的优化类似物，以及它们在治疗应用中的生物学性能。