Silk wastes and autoclaved degumming as an alternative for a sustainable silk process

Abstract

Silk degumming is considered the first point in the preparation of silk-based materials since this process could modify the silk fiber and the properties of its related products. This study evaluated the differences in morphology, secondary structure, amino acid content, thermal stability, and mechanical properties of two types of raw materials, defective cocoons (DC) and silk fibrous waste (SW), degummed by chemical (C) and autoclaving (A) methods. Subsequently, silk fibroin films were prepared by dissolving each type of degummed fibers, and thermal and structural films properties were determined. The findings demonstrated that autoclaving is an efficient alternative to remove silk sericin, as the resulting fibers presented improved structural, thermal, and mechanical properties compared to those obtained by the chemical method. For films preparation, autoclave resulted in a good option, but dissolution parameters need to be adjusted for defective cocoons. Furthermore, similarities between the physicochemical properties of fibers and films from both fibrous wastes suggest that SW is a promising raw material for producing fibrous resources and regenerated silk fibroin materials. Overall, these findings suggest new recycling methods for fibrous waste and by-products generated in the silk textile production process.

Sustainable Silk-Based Particulate Systems for the Controlled Release of Pharmaceuticals and Bioactive Agents in Wound Healing and Skin Regeneration

“…SS structure includes random coil and β-sheet conformation, being mostly amorphous after dissolution (liquid) and more crystalline after cooling (gel-intrinsic properties). Changes from β-sheet to random coil occur as a response to mechanical stretching properties, moisture absorption, and temperature [ 22 , 50 , 51 , 52 ].…”

“…Boiling silkworm cocoons in a sodium carbonate solution is a widely adopted laboratory degumming method, demonstrating high SS extraction efficiency [ 18 , 47 , 49 ]. However, this process is energy-consuming, and partial hydrolysis can occur as a result of the harsh processing conditions [ 50 , 51 ]. The high-temperature and high-pressure method (HTHP) can be used since it dissolves SS in heated water at high pressure, removing the need for complex refining and purification processes.…”

Applications of Silk Fibroin in Human and Veterinary Medicine

“…For the medical applications in transplantology, sericin as a component of silk is unnecessary and can be even problematic, because its presence worsens the biocompatibility of grafts made using this material [1]. Therefore, it is crucial to remove residual sericin from silk that would be used for that purpose [6]. Such a process is called degumming, and it involves subjecting silk to thermal and chemical reactions that lead to the removal of sericin [5].…”

A Simplified Method for the Preparation of Highly Conductive and Flexible Silk Nanofibrils/MXene Membrane

“…Natural silk can be degummed in a variety of ways to obtain SF. Degumming can usually take place with the use of urea [26], neutral soaps [27], proteases [28][29][30], hightemperature and pressure treatments [31], autoclaving [32] and boiling in alkaline solutions [33]. Liu et al investigated the effect of several natural proteases on silk degumming and showed that the degumming rate of silk using natural proteases was much lower than the silk using Na 2 CO 3 [30].…”

“…Liu et al investigated the effect of several natural proteases on silk degumming and showed that the degumming rate of silk using natural proteases was much lower than the silk using Na 2 CO 3 [30]. Gaviria et al explored the differences in morphology, mechanical properties, amino acid content, etc., of SF degummed by the autoclaving method and the chemical method [32]. In addition, the use of different reagents had an effect on the rate of membrane degradation, with the degradation rate of membranes degraded by the acidic solvent being lower than that using the alkaline solvent [34].…”