AUTHOR=Chen Zefeng , Luo Hang , Gubu Amu , Yu Sifan , Zhang Huarui , Dai Hong , Zhang Yihao , Zhang Baoting , Ma Yuan , Lu Aiping , Zhang Ge TITLE=Chemically modified aptamers for improving binding affinity to the target proteins via enhanced non-covalent bonding JOURNAL=Frontiers in Cell and Developmental Biology VOLUME=11 YEAR=2023 URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2023.1091809 DOI=10.3389/fcell.2023.1091809 ISSN=2296-634X ABSTRACT=

Nucleic acid aptamers are ssDNA or ssRNA fragments that specifically recognize targets. However, the pharmacodynamic properties of natural aptamers consisting of 4 naturally occurring nucleosides (A, G, C, T/U) are generally restricted for inferior binding affinity than the cognate antibodies. The development of high-affinity modification strategies has attracted extensive attention in aptamer applications. Chemically modified aptamers with stable three-dimensional shapes can tightly interact with the target proteins via enhanced non-covalent bonding, possibly resulting in hundreds of affinity enhancements. This review overviewed high-affinity modification strategies used in aptamers, including nucleobase modifications, fluorine modifications (2′-fluoro nucleic acid, 2′-fluoro arabino nucleic acid, 2′,2′-difluoro nucleic acid), structural alteration modifications (locked nucleic acid, unlocked nucleic acid), phosphate modifications (phosphorothioates, phosphorodithioates), and extended alphabets. The review emphasized how these high-affinity modifications function in effect as the interactions with target proteins, thereby refining the pharmacodynamic properties of aptamers.