Sustainable biodegradation of cellulose fibers is critical for composting after the end of a product’s life. In this study, we aimed at investigating the effect of in situ synthesized CuO/Cu₂O nanoparticles (NPs) with biocidal concentration on the biodegradation behavior of cotton fibers pretreated with 1,2,3,4-butanetetracarboxylic acid (BTCA) and succinic acid (SUC). Biodegradation of the fibers was evaluated by soil burial tests in garden soil and in model compost after different soil burial times. The results showed that the application of BTCA, SUC, and CuO/Cu₂O NPs did not affect the hydrophilicity of the samples and allowed a smooth biodegradation process. The morphological and chemical changes during biodegradation, evaluated by FESEM and FTIR analyses, showed that the presence of CuO/Cu₂O NPs slightly hindered biodegradation of the fibers after 18 days in soil. However, biodegradation was much faster in the model compost, where all samples, regardless of their chemical modification, almost completely degraded after only 11 days. Intense microbial growth on the surface of all samples after nine days of burial in garden soil and model compost was confirmed by the presence of proteins produced by the microorganisms. The total number of microorganisms in the garden soil remained almost unchanged and increased in the model compost after the burial test. The only exception was the sample with the highest concentration of CuO/Cu₂O NPs, which caused a reduction in microbial growth but not complete growth inhibition. These results clearly showed that during material degradation, the cellulosic material supporting microbial growth prevailed over the suppression of microbial growth by CuO/Cu₂O NPs.

The syntheses of Ag-based nanoparticles (NPs) with the assistance of plant extracts have been shown to be environmentally benign and cost-effective alternatives to conventional chemical syntheses. This study discusses the application of Paliurus spina-christi, Juglans regia, Humulus lupulus, and Sambucus nigra leaf extracts for in situ synthesis of Ag-based NPs on cotton fabric modified with citric acid. The presence of NPs with an average size ranging from 57 to 99 nm on the fiber surface was confirmed by FESEM. XPS analysis indicated that metallic (Ag⁰) and/or ionic silver (Ag₂O and AgO) appeared on the surface of the modified cotton. The chemical composition, size, shape, and amounts of synthesized NPs were strongly dependent on the applied plant extract. All fabricated nanocomposites exhibited excellent antifungal activity against yeast Candida albicans. Antibacterial activity was significantly stronger against Gram-positive bacteria Staphylococcus aureus than Gram-negative bacteria Escherichia coli. In addition, 99% of silver was retained on the samples after 24 h of contact with physiological saline solution, implying a high stability of nanoparticles. Cytotoxic activity towards HaCaT and MRC5 cells was only observed for the sample synthetized in the presence of H. lupulus extract. Excellent antimicrobial activity and non-cytotoxicity make the developed composites efficient candidates for medicinal applications.