Green Strategy for Sustainable Silk Lipopeptide Production using Mechanochemistry

Abstract

A mechanochemical approach to peptide N-acylation was used for silk sericin lipopeptide production. A one-pot, two-step method with 1,1′-carbonyldiimidazole (CDI) fatty acid activation, followed by acylation, was implemented. First, the procedure was optimized on model amino acids such as leucine, glycine, serine, and aspartic acid using two different types of ball mill equipment: a vibrational ball mill and a planetary ball mill. High conversion rates of 99% were observed for amino acid acylation under optimal conditions with both types. Then, grafting hydrophobic chains on to two different silk sericin hydrolysates was studied. The peptide acylation rate of 48–51% was obtained with three fatty acids with chain lengths of 10, 12, and 14. Lipopeptides obtained using the mechanochemical methodology showed good surface activity and reduced surface tension of up to 26 mN/m. The advantage of the proposed approach compared to conventional Schotten–Baumann N-acylation was confirmed with green metrics calculation.