Abstract
Oligonucleotides are short, sequence-defined nucleic acid chains with major therapeutic and diagnostic potential. Their industrial production is currently dominated by solid-phase oligonucleotide synthesis (SPOS), which suffers from mass-transfer limitations, limited scalability, lack of real-time process monitoring, and high process mass intensity. Membrane-enhanced liquid-phase oligonucleotide synthesis (LPOS) has emerged as a scalable alternative, in which oligonucleotide chains are grown on soluble anchors and organic solvent nanofiltration is used (OSN) to remove excess reagents and by-products between each reaction steps. However, diafiltration also introduces a risk of large cumulative product loss over multiple addition cycles, which requires fine-tuning of design and operational strategies in practice. This paper presents the results of a comparative assessment of two LPOS variants with either a single- or dual-stage diafiltration against a state-of-the-art SPOS, within a unified dynamic modelling framework. A recent mechanistic kinetic model of SPOS is transferred to LPOS, including a description of OSN diafiltration dynamics and internal recycles. A feasibility analysis is conducted to identify operating regimes under which LPOS outperforms SPOS in terms of selected yield and impurity performance indicators and to expose the underlying trade-offs. Overall, the results establish LPOS with dual-stage diafiltration as a promising configuration towards more flexible and sustainable oligonucleotide manufacturing.