“…The properties and functions of the aptamers can be widely modulated and improved through chemical modifications and sequence variations. For example, the sequence mutation and extension of the yly12 aptamer lead to oligonucleotides showing improved binding affinities towards the sixth immunoglobulin-like domain of the L1CAM (L1 cell adhesion molecule), a protein highly relevant for human tumor formation, progression, and metastasis [3]. Similarly, the sequence of the most studied thrombin binding aptamer, named TBA, that adopts a two-layer G-quadruplex structure, was modified to produce threeand four-layer TBA analogues, which also contain non-natural alpha-deoxyguanosines at specific positions [4].…”