Vibrational Study on the Structure, Bioactivity, and Silver Adsorption of Silk Fibroin Fibers Grafted with Methacrylonitrile

Abstract

Natural fibers have received increasing attention as starting materials for innovative applications in many research fields, from biomedicine to engineering. Bombyx mori silk fibroin has become a material of choice in the development of many biomedical devices. Grafting represents a good strategy to improve the material properties according to the desired function. In the present study, Bombyx mori silk fibroin fibers were grafted with methacrylonitrile (MAN) with different weight gains. The potential interest in biomedical applications of MAN functionalization relies on the presence of the nitrile group, which is an acceptor of H bonds and can bind metals. IR and Raman spectroscopy were used to characterize the grafted samples and the possible structural changes induced by grafting. Afterward, the same techniques were used to study the bioactivity (i.e., the calcium phosphate nucleation ability) of MAN-grafted silk fibroins after ageing in simulated body fluid (SBF) for possible application in bone tissue engineering, and their interaction with Ag+ ions, for the development of biomaterials with enhanced anti-microbial properties. MAN was found to efficiently polymerize on silk fibroin through polar amino acids (i.e., serine and tryptophan), inducing an enrichment in silk fibroin-ordered domains. IR spectroscopy allowed us to detect the nucleation of a thin calcium phosphate layer and the uptake of Ag+ ions through the nitrile group, which may foster the application of these grafted materials in biomedical applications.

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

“…Both degumming methods remove the existing sericin; however, SEM images show increased fibrillar damage in chemically degummed SW and DC. Previous studies have reported similar results when comparing these degumming methods, indicating that chemical degumming may cause hydrolytic degradation of proteins 21 , 22 .…”

“…Raw material comparisons showed differences in β-turn and side chains, corresponding to crystalline and amorphous secondary structures, respectively. This may be due to the DC having not undergone any prior SS removal process, shows an amorphous random form 21 , 22 . Although there were no significant differences between the chemical and autoclave degummed samples, a decrease in the β-turn structure was observed.…”

Progress in Research and Application of Modified Silk Fibroin Fibers

“…In conclusion, the modification of SF is necessary to improve its performance as well as be endowed with some above special functions. [7][8][9] The modified SF obtained by physical modification [10,11] and chemical modification [12,13] can effectively solve the above problems, and can be further spun into the modified SF fibers by dry spinning, wet spinning, electrospinning or microfluid spinning to be used in filtration, sensors, triboelectric nanogenerators, and tissue engineering, as shown in Figure 1.…”