Venturoni, Francesco and Haber, Julien (2025) Fully liquid phase oligonucleotide synthesis. Organic process research & development.

Abstract

Representative oligonucleotides (oligos; a 21-mer siRNA strand and a 16-mer ASOlike
gapmer) were synthesized by Nanostar Sieving, a membrane-assisted liquid phase oligo
synthesis (LPOS) method, at 10 mmol scale and 20 mM concentration in a single solvent. This
process is the first total LPOS, i.e., the reagents and intermediates remain in the liquid phase from
the very first reaction to isolation. At all times during the synthesis of the full-length product (FLP),
the concentration of oligo within the Nanostar-10 reactor remained roughly constant. Both
sequences were synthesized four times, twice using membranes sheets clamped flat in circular cells, and twice using scalable spiral wound modules (SWMs). Cleavage and deprotection
continued to maintain the oligo in the liquid phase until the final lyophilization, when yields were
calculated by mass, adjusting for chromatographic and mass spectral purity. Process mass
intensities equal to or better than solid phase oligo synthesis (SPOS) were achieved.

Item Type:	Article
Date Deposited:	26 Dec 2025 00:45
Last Modified:	26 Dec 2025 00:45
URI:	https://oak.novartis.com/id/eprint/58204