A DNA Aptamer for 2‐Aminopurine: Binding‐induced Fluorescence Quenching

2‐Aminopurine (2AP) is a fluorescent analog of adenine, and its unique properties make it valuable in various scientific and biotechnological applications. Its fluorescence property probes local dynamics in DNA and RNA because the surrounding bases quench its fluorescence. 2AP‐labeled probes that can bind to specific DNA or RNA sequences, enabling the detection of genetic mutations, viral RNA, or other nucleic acid‐based markers associated with diseases like cancer and infectious diseases. In this study, we isolated aptamers for 2AP using the library immobilization capture‐SELEX technique. Two major aptamer families were isolated after 15 rounds of screening. The Kd values for the 2AP1 aptamer from family 1 are 209 nM in a fluorescence assay and 72 nM in an isothermal titration calorimetry test. The 32 nM 2AP limit of detection was tested. Additionally, we conducted some mutation analysis. Furthermore, we tested the selectivity of our aptamer using various molecules with similar structures and discovered that it can bind adenine and adenosine as well.