Antibacterial cotton from novel phytic acid-based multilayer nanocoating

In an effort to impart antimicrobial behavior to cotton using renewable and environmentally benign components, fabric was treated using layer-by-layer (LbL) assembly. Alternating layers of phytic acid (PA) and chitosan (CH) were deposited from water. Cotton coated with four and eight bilayers (BLs) of anionic PA and cationic CH, with and without adding copper (II) sulfate (CuSO₄) into the CH solution, was evaluated in accordance with the American Association of Textile Chemists and Colorists (AATCC) TM 100-2019 test method. Gram-positive Staphylococcus aureus and gram-negative Klebsiella pneumoniae were used to determine whether the addition of copper salt into a CH network improves antibacterial efficacy. The copper ions were successfully incorporated into the CH network formed using LbL assembly onto cotton fibers. The location of deposited copper ions was determined with electron microscopy. Just four BLs of PA/CH–copper (II) sulfate kill 100% of gram-positive and gram-negative bacteria and add only 5.2 wt% to the fabric. This nanocoating provides a unique opportunity to impart antibacterial behavior to textiles without harming the environment.