Nonchromatographic Purification of Synthetic RNA

Abstract

Discoveries of the twenty-first century created a strong need for a robust solid phase synthesis of long DNA and RNA oligonucleotides. Solid phase synthesis has a number of advantages over biochemical methods for forming oligonucleotides. The chemical approach offers precise control over the sequence length and fidelity, which cannot be fully realized by in vitro transcription. Solid phase synthesis also offers an opportunity for site-specific incorporation of non-canonical nucleotides. However, long oligonucleotide constructs remain notoriously difficult to synthesize and purify. The limiting step of otherwise highly optimized process is HPLC purification. This review describes several innovative approaches aimed at non-chromatographic purification of synthetic oligonucleotides. These approaches utilize a number of innovative chemistries, such as methacrylamide polymerization, fluoride affinity, biotin-streptavidine conjugation, Staudinger ligation, and inverse electron demand Diels-Alder chemistry. Their ultimate goal is to achieve a fast and robust purification process that is independent of the oligonucleotide size.