Evaluation of deep eutectic solvents as a potential non-aqueous medium for the efficient dissolution and biomaterial preparation of ε-poly-l-lysine

e-Poly-l-lysine (e-PLL) extracted from Streptomyces albulus was solubilized and analysed for its structural as well as chemical stability in several deep eutectic solvents (DESs). The DES synthesized was composed of urea (hydrogen-bond donor) and choline chloride (hydro­gen-bond acceptor) in the molar ratio 2 : 1. Furthermore, it formed a soft ionogel (gel strength: 177 g cm–2) in the presence of 20% w/v e-PLL at room temperature in about 10–15 days. However, such gelation was not observed at lower concentrations (5%, 10% and 15% w/v) of the homopolypeptide. Regenerated e-PLL from DES was examined, and it was found to maintain its structural and chemical stability during the dissolution process.