Chitosan-templated enzymatic oxidative polymerization of phenolic pigments on bio-based polyamide 5,10

This study reports the first application of horseradish peroxidase (HRP)-mediated oxidative coloration to bio-based nylon 5,10 using natural phenolics, and clarifies the performance-enhancing role of chitosan as a dyeing template. Mass spectrometric analysis confirmed that the incorporation of chitosan significantly increases oligomer growth during pigment formation. Comparative process evaluation revealed that in-situ chitosan templating causes excessive surface polymerization, uneven coloration, and reduced K/S values, which is attributed to the formation of loosely bound pigment aggregates that are easily removed during washing, leading to significant pigment loss from the fiber surface, whereas ex-situ chitosan-templated bio-dyeing yields the highest color depth and superior shade uniformity. In addition, chitosan templating transforms the weak or selective antibacterial activity of pristine phenolics into strong broad-spectrum inhibition against both E. coli and S. aureus. Although washing and rubbing fastness were generally acceptable, light fastness remained insufficient. Overall, this study provides the first empirical demonstration that nylon 5,10 is a suitable substrate for enzymatic oxidative coloration, and establishes ex-situ chitosan-templated bio-dyeing as an optimal strategy to simultaneously achieve deep coloration, uniformity, and antibacterial functionality. The integration of a bio-based polyamide substrate with a bio-based enzymatic coloration system highlights a promising low-carbon and energy-efficient route toward industrially scalable sustainable textile production. Download: Download high-res image (181KB) Download: Download full-size image