Enhanced Photocatalytic and Biological Properties of Cellulose Cotton Fabric Coated with Carboxyethyl Chitosan/Zinc Oxide Bio-nanocomposite

Abstract

This study developed a CECS/ZnO-functionalized cotton fiber sheets as a single-use filter layer for face masks, with enhanced antibacterial and photocatalytic properties. Cotton fiber sheets were modified with zinc oxide nanoparticles (ZnO NPs) using a dip-coating method, with and without carboxyethyl chitosan (CECS) as a binder and stabilizing agent. The fiber sheets were treated with 0.1, 0.3, and 0.5 M Zn(NO₃)₂ solutions, followed by hydrothermal synthesis in NH₄OH (Zn:NH₄OH = 1:2) at 100 °C for 1 h. The study successfully demonstrated ZnO NPs formation on cotton sheets, producing ZnO-immobilized cotton sheets (Cf/Zn). Higher Zn²⁺ concentrations promoted greater nucleation of ZnO nanoparticles. However, they also caused particle agglomeration, which reduced the surface area and weakened ZnO adhesion to the cotton fibers. This presents a significant challenge in achieving a uniform nanoparticle distribution. However, the introduction of carboxyethyl chitosan (CECS) (Cf/CECS/Zn) as a binder and stabilizer represents a novel approach that showed a superior ZnO adhesion, better particle distribution, and higher Zn content than untreated Cf/Zn. Among the samples, Cf/CECS/Zn0.1 exhibited the highest Zn content (154 ppm), the highest antibacterial zone diameter (29.39 mm), and the most effective photocatalytic activity (65.66%). While both Cf/Zn and Cf/CECS/Zn demonstrated antibacterial activity against S. aureus, Cf/CECS/Zn0.1 showed superior performance, with low cytotoxicity confirmed by Vero cell viability tests. The treated fibers also displayed enhanced hydrophobic and photocatalytic properties. These results demonstrate the potential of CECS-modified ZnO-immobilized cotton sheets for advanced healthcare filtration applications, offering enhanced antibacterial, photocatalytic, and non-toxic properties.