Switchable DNA-Encoded Chemical Library: Interconversion between Double- and Single-Stranded DNA Formats.

DNA-encoded chemical libraries (DEL) have attracted substantial attention due to the infinite possibility for hit discovery in both pharmaceutical companies and academia. The encoding method is the initial step of DEL construction and one of the cornerstones of DEL applications. Classified by the DNA format, the existing DEL encoding strategies were categorized into single-stranded DNA-based strategies and double-stranded DNA-based strategies. The two DEL formats have their unique advantages but are usually incompatible with each other. To address this issue, we propose the concept of interconversion between double- and single-stranded DEL based on the "reversible covalent headpiece (RCHP)" design, which combines maximum robustness of synthesis with extraordinary flexibility of applications in distinct setups. Future opportunities in this field are also proposed to advance DEL technology to a comprehensive drug discovery platform.