Green Physical Modification of Polypropylene Fabrics by Cross-Linking Chitosan with Tannic Acid and Postmodification by Quaternary Ammonium Grafting to Improve Antibacterial Activity

Abstract

A green cross-linking and straightforward method to physically trap inert fibers in a network of chitosan was implemented. The cross-linking reaction involved a biosourced and biocompatible cross-linker [tannic acid (TA)] and mild conditions in water (pH = 8.5, O 2 bubbling, 60 °C, 3 h). The steric hindrance of TA led to a low but effective cross-linking rate leaving parts of primary amines of chitosan available for postmodification such as the grafting of quaternary ammoniums for antibacterial purposes. Fabric's coatings were characterized by scanning electron microscopy coupled with energy-dispersive X-ray, infrared spectroscopy, and weight gain measurements. This allowed the optimization of process conditions. No significant antioxidant activity was observed on fabrics coated with chitosan cross-linked with TA, confirming the low cross-linking rate. This low cross-linking rate allowed grafting of quaternary ammoniums for antibacterial purposes, but it is possible to consider grafting other active molecules. Biological assays were conducted on this coating to assess its antibacterial properties. Reduction of bacterial colonization on both Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative), two of the major strains responsible for nosocomial infections, confirmed the potential of the coating for antibacterial purposes. This study displays a simple and ecofriendly process to coat inert fabrics with a chitosan network containing reactive functions (primary amines) available for grafting active molecules for various purposes.

Chemical Modification of Commercial Fabrics by Photoinduced Grafting Tannic Acid to Produce Antioxidant and Antibacterial Textiles

“…The process has been previously optimized in our group [42]. PP fabrics (1.5 × 1.5 cm) were coated with chitosan using an airbrush placed at 20 cm from the target.…”

“…Fabrics were coated by immersion in a solution of TA acr 10eq at 100 g.L 1 in ethanol for 3 h at room temperature under stirring. The two types of fabrics used were inert fibers (raw PP) and fibers coated with chitosan (PP fibers are coated with chitosan, which is physically immobilized around the fibers by cross-linking with tannic acid [42]). Before being washed, samples were weighed, and the weight gain associated with it was 42-43% for both fabrics.…”