“…Nucleic acid aptamers are single-stranded DNA or RNA molecules, generally 25 to 60 bases in length, identified from pools of random-sequence oligonucleotides (ONs) by an in vitro selection process called SELEX (Systematic Evolution of Ligands by EXponential enrichment) [1], introduced in the early 90s independently by the research groups of Gold and Szostak [2][3][4]. Thanks to their unique three-dimensional folding, aptamers can recognize a wide range of molecular targets including proteins, small molecules, ions, whole cells and even entire organisms, such as viruses or bacteria, with affinities, expressed in terms of dissociation constants (K d ), ranging from picomolar (pM) to micromolar (μM) [5][6][7]. Each ON aptamer can adopt a unique subset of 3D structures defined by the combination of base-pairing, π-π stacking, sugar puckering, as well as electrostatic, hydrogen bonding and noncanonical intra-molecular interactions.…”