Genipin-directed assembly of zein-based colored nanostructures enabling one-step green multifunctionalization of wool

Multifunctional finishing of textiles often relies on various chemical auxiliaries to achieve modification, which involves complicated procedures and poses environmental and health risks. In this study, ε-polylysine (ε-PL) was introduced into zein molecules using genipin (GNP) as a crosslinking agent to prepare colored recombinant zein (ε-PL-zein). The structure of ε-PL-zein was characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared (FTIR) spectroscopy, circular dichroism (CD) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy and ¹H nuclear magnetic resonance (¹H NMR) spectroscopy. The results confirmed the successful grafting of ε-PL onto zein. After the grafting modification, the molecular weight of the protein increased significantly, its conformation was altered, and both the amino group content and the positive charge on the molecular surface were enhanced. Stable colored zein-based nanoparticles with an average particle size of approximately 200 nm were obtained via the antisolvent method and subsequently applied onto wool fabric in a single step, yielding multifunctional colored wool fabric with excellent antibacterial performance (>99% antibacterial rate against Escherichia coli and Staphylococcus aureus) and good anti-felting property (felting shrinkage rate of 4.00 ± 0.25%). Moreover, the treated fabrics maintained favorable color fastness and mechanical properties. The findings of this study provide an efficient and eco-friendly strategy for the development of multifunctional textile auxiliaries.