A green peptide-based functionalization platform for wash resistant textile finishing

Around 60 % of all textiles are made of polyester and polyamide due to their superior bulk properties. The wide use of polyester and polyamide in various textile applications with different and partly opposed requirements e.g. sportswear (moisture transfer) and outdoor clothing (water-repellency) is enabled by the application of functional coatings and finishes. Functionalization of polyester and polyamide is challenging due to their hydrophobic nature and finishes consist of often toxic compounds that can limit or prevent recycling. Current solutions include the application of synthetic polymers like polyacrylate, polyurethane, polyvinyl chloride and poly (ethylene-vinyl acetate). In a sustainable bioeconomy, as part of a climate neutral circular economy, biobased and energy-efficient textiles that enable green recycling processes are of importance. Anchor peptides like LCI enable at ambient temperature to cost-efficiently coat all kinds of polymers and their binding strength can be tailored to even withstand detergent formulations. In this work a validated screening system (WashResist) to engineer anchor peptides for efficient binding to polyester- and polyamide-based textiles is reported. Proof of concept was performed to improve binding strength to withstand full washing cycles (40 degrees C; 15 min; 3 cycles). Screening of 697 LCI variants yielded the variant LCI E42R which shows 2.0-fold improved binding strength to polyester and 3.6-fold improved binding strength to polyamide. Screening was performed in a 96-well microtiter plate-format that uses a customized 96-well textile puncher to process standardized polyester and polyamide fabrics. The improved LCI E42R variant withstands multiple standardized wash cycles and remains fully functional on the textile surface as visualized by peptide staining with Coomassie brilliant blue. The described peptide-based functionalization platform represents a sustainable and innovative way to achieve textile finishing and opens up new recycling routes.