Engineered chromogenic proteins with carbohydrate binding modules for advanced textile dyeing

To address the environmental burden associated with conventional synthetic textile dyes, this work introduces a sustainable protein-based coloration strategy that combines marine-derived chromoproteins fused to the carbohydrate-binding module CBM_N1. Three recombinant fusion proteins-Lime-CBM, Purple-CBM, and Red-CBM-were designed to enable direct binding to textile fibers, in particular cotton, without harsh chemical pre-treatments. Structural characterization and molecular dynamics simulations confirmed that the fusion proteins retain their native β-barrel architecture and chromogenic properties at temperatures up to 80 °C, with irreversible denaturation occurring only at 90 °C. Coloration experiments demonstrated that Lime-CBM and Purple-CBM imparted homogeneous and durable color to cotton, polyamide, and polyester substrates, maintaining color fastness over ten washing cycles without any process optimization. In vitro cytotoxicity assays using human skin keratinocytes revealed low cellular toxicity, supporting the suitability of these protein-based colorants for textiles and consumer-facing applications. These findings highlight the potential of chromoprotein-CBM _N1 fusion proteins as versatile, high-performance, and eco-friendly sustainable platforms for textile functionalization.