Toward Chromatography-Free Convergent Peptide Synthesis via Nanostar Sieving

Liquid-phase peptide synthesis (LPPS) has emerged as a versatile and efficient method for assembling peptides, offering significant advantages in purity and yield. In this study, we investigate the application of organic solvent nanofiltration (OSN) technology in LPPS for peptide fragment assembly by Nanostar Sieving. We report how a nanostar support decorated with solubilizing polymers can be used to achieve solubility at concentrations of up to 40 mM of a 39-mer peptide. This is assembled from eight peptide fragments on an 8-arm, 20 kDa nanostar support. OSN enables effective removal of reagents, byproducts, and unreacted fragments after each coupling cycle, enhancing synthesis efficiency. A photolabile linker was incorporated into the support before fragment assembly, enabling periodic analysis without full global deprotection. The Rink amide linker facilitated the final cleavage of the synthesized peptide using standard global deprotection protocols. Following synthesis, OSN was employed to isolate the peptide from the support. In contrast to previous OSN-assisted peptide fragment assembly methods, which required chromatographic purification to remove unreacted fragments at the end of synthesis, nanostar sieving enables their removal during synthesis. The potential to eliminate the need for chromatography could lead to more efficient and scalable therapeutic peptide production.