Silk Sericin–Dihydromyricetin Covalent Complexes: Interaction Mechanisms, Structural Characteristics, and Functional Properties

Dihydromyricetin (DMY) at varying concentrations (0-20%) was used to modify silk sericin (SS), thereby enhancing sericin's interfacial and functional properties. SS forms covalent complexes with DMY, as evidenced by the red shift of the ultraviolet absorption peak and fluorescence quenching, along with a decrease in free amino and sulfhydryl contents. Fourier transform infrared (FTIR) spectroscopy, ¹H NMR spectra, and molecular docking results further corroborated the predominant covalent binding. DMY altered sericin's amorphous state, disrupted its sheet-like structure, and exposed more hydrophobic sites to a hydrophilic microenvironment. Compared to native SS, complexation with DMY markedly increased the polyphenol binding equivalents, three-phase contact angle, radical scavenging activities, and thermal stability. The complex fabricated with 15% DMY exhibited the highest absolute ζ-potential, emulsifying activity index, emulsifying stability index, and surface hydrophobicity, while it exhibited the lowest particle size and polydispersity index (PDI), along with superior wettability. This study highlights the potential of SS-DMY complexes as novel functional biomaterials for various applications.