Analysis of the deep dyeing property and mechanism of reactive dyes in male silk fabrics

The male silkworm has a high silk yield and superior silk quality, making it a popular choice for producing high-quality raw silk. Additionally, it has also been reported that male silk fabrics have excellent dyeing depth properties. In this study, reactive dyes were employed to dye both male and female silk fabrics, with a comprehensive exploration of the underlying mechanisms contributing to the differences in dyeing properties. The results demonstrated that dyed male silk fabrics exhibit greater apparent depth and luster compared to female silk fabrics. Specifically, when reactive blue 19 dye was utilized, the K/S values of male silk fabrics were significantly higher than those of female silk fabrics, with the difference in dyeing effect approximately equivalent to a dye concentration of 50 mg/mL. Raman spectroscopy and phenolic color reaction analysis revealed that the tyrosine content in male silk fibers was higher and predominantly located in the surface layer of the fibers, a structural feature that enhances the binding of reactive dyes. Additionally, quantitative analysis using liquid chromatography-mass spectrometry (LC-MS) further corroborated this finding. Furthermore, molecular docking studies and molecular dynamics simulations revealed stable covalent bonds between tyrosine residues and reactive dyes. This distribution trend significantly improves the adsorption capacity of male silk to reactive dyes and makes its dye uptake higher. This study not only confirms that male silk possesses outstanding dye depth performance but also elucidates the mechanistic differences between female and male silks during reactive dyeing processes. The findings provide theoretical support for promoting and applying male silk in the future.