Efficient Extraction of Sericin Protein from Mulberry and Non‐Mulberry Silk Fibers: Utilizing Aqueous Ionic Liquid Solutions as Green Solvents

Abstract Protein extraction from silk is a unique area of research and the foremost need is the efficient extraction of the silk proteins namely fibroin and sericin from the silk fibres, which is conventionally done using chemicals. In this work, we show that Ionic liquids (ILs) can be employed as a green and alternative method for degumming sericin from both mulberry ( B. mori ) and non‐mulberry ( A. assamensis and P. ricini ) silk. Six different ILs with varying tail lengths were studied for their degumming efficiencies. The interaction between silk proteins and IL ions involves a complex ionic disruption of hydrogen bonds, non‐polar interactions, and electrostatic effects. We have found that 1‐Butyl‐3‐methylimidazolium chloride (BMIM.Cl), 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIM.BF 4 ) and Tetraethylammonium bromide (TEAB) bring in higher weight loss % in silk fibres compared to other ILs, indicating that it can be used in better sericin removal without significant damage to the silk fibre. TEAB emerged as a potential candidate for sericin extraction due to its promotion of protein destabilization. Additionally, no drastic changes in the structure of the extracted silk protein sericin were observed, as evident from the FTIR spectra and SEM images. This work highlights for the first time, the use of ILs for extraction of non‐mulberry silk sericin and also proves that ILs can be a potential green solvent for sericin extraction.