Effects of Chemical Post-treatments on Structural and Physicochemical Properties of Silk Fibroin Films Obtained From Silk Fibrous Waste

Abstract

Silk fibroin (SF) is a protein polymer claimed to have outstanding potential for medical applications. However, because of the manufacturing process, materials from regenerated SF exhibit a higher percentage of amorphous structures. The amorphous structures cause the material to be water soluble and can significantly limit its applications in wet biological environments. In order to increase the amount of crystalline structures and decrease the water solubility of SF materials, post-treatment with alcohols is usually employed. SF can be obtained from silk fibrous wastes (SFW), usually discarded in silk textile processes. This represents an opportunity to produce materials with high added value from low-cost natural sources. In this study, SF was obtained from SFW, and films were made thereof followed by a post-treatment by immersion or in a saturated atmosphere of methanol (MeOH) or ethanol (EtOH), using different exposure times. The resulting films were analyzed according to crystallinity, the percentage of crystalline and amorphous structures, and thermal stability. Also, water absorption and weight loss in aqueous media were determined. The results showed a significant increase in crystalline structures in all treated samples, varying according to the type and time of exposure to post-treatment conducted. The highest increase was shown in the case of the post-treatment by immersion in MeOH for 1 h, with a 23% increase over the untreated sample. This increase in crystallinity was reflected in an increase in the degradation temperature and a degradation rate of 5.3% on day 7. The possibility of tuning the degree of crystallinity, as well as thermal stability and aqueous integrity of thin films of SFW, can be applied to adjust these materials to the requirements of specific biomedical applications.

Enhancement of natural dyeing properties and UV resistance of silk fibers modified by phenylboronic acid/hydroxypropyl‐β‐cyclodextrin functionalized Fe3O4 particle

“…The X‐ray diffraction (XRD) curves of untreated and modified silk powder were determined by X'Pert3Powder diffractometer (Netherlands PANalytical) with Cu Kα radiation in a range (2 θ ) between 5° and 60°. The degree of crystallinity of silk sample can be calculated using the total diffracted X‐ray intensity assuming the signal comes from both the crystalline and amorphous regions, as shown in Equation () 46 where A c and A a are the areas of the crystalline and amorphous regions, respectively.…”

“…The degree of crystallinity of silk sample can be calculated using the total diffracted X-ray intensity assuming the signal comes from both the crystalline and amorphous regions, as shown in Equation ( 1). 46…”

Electrospun silk fibroin using aqueous and formic acid solutions

“…Silk fibrous wastes were provided by the Corporacion para el Desarrollo de la Sericultura del Cauca-Colombia (CORSEDA). These were used to obtain SFw following a procedure previously published in literature [3,[19][20][21]. Briefly, the silk fibrous wastes were degummed using Na 2 CO 3 (EMSURE) at boiling conditions for 60 min.…”

Silk Fibroin: A Promising Tool for Wound Healing and Skin Regeneration

“…Silk fibroin has also been utilised in the manufacturing of textiles and clinical sutures for generations [34]. Primary cells and cell lines can attach to, proliferate in, and differentiate in silk fibroin materials [35] and can be easily used to prepare mats [36], porous scaffolds [37], gels [38], and films [39].…”