Nanoassembly-enabled aqueous solid-phase peptide synthesis (ASPPS): a practical DMF-free approach based on the Fmoc strategy

-dimethylformamide (DMF)-based solid-phase peptide synthesis (SPPS) with greener alternatives. Here, we present a practical SPPS protocol that uses water as the reaction medium and eliminates hazardous organic solvents. The method leverages nanoassemblies formed from Fmoc-protected amino acids, coupling reagents, and bases, which create reactive interfacial microenvironments that enhance local concentration and promote efficient peptide bond formation under aqueous conditions. These nanoassemblies are readily prepared without specialized equipment and are compatible with microwave-assisted coupling, enabling scalability and semi-automation using existing SPPS platforms. Using this approach, we synthesized various peptides, including β-endorphin (31 residues), with yields and purities comparable to those obtained using conventional DMF-based SPPS. By integrating DMF-free chemistry with nanoassembly-driven reactivity, this work introduces a reaction-field-based strategy for peptide synthesis and provides a simple and eco-friendly platform aligned with the principles of green chemistry.