Oligonucleotides: Current trends and innovative applications in the synthesis, characterization and purification.

Oligonucleotides (ONs) are gaining increasing importance as a promising novel class of biopharmaceuticals. Thanks to their fundamental role in gene regulation, they can be used to develop custom-made drugs (also called N-to-1) able to act on the gene expression at pre-translational level. With recent approvals of ON-based therapeutics by FDA, a growing demand for high-quality chemically-modified ONs is emerging and their market is expected to impressively prosper in the very next future. To satisfy this growing market demand, a scalable and economically sustainable ON production is needed. In this paper, the state of the art of the whole ON production process is illustrated with the aim of highlighting the most promising routes towards the auspicated market-size production. In particular, the most recent advancements in both the upstream stage, mainly based on solid-phase synthesis and recombinant technology, and the downstream one, focusing on chromatographic techniques, are reviewed. Since ON production is projected to expand to the large scale, automatized multi-column countercurrent technologies will reasonably be required soon to replace the current ones based on batch single-column operations. Cutting edge purification solutions, based on continuous chromatography, will be thus presented in the last part of this review. This article is protected by copyright. All rights reserved.