Cotton Fabric Modified with a PAMAM Dendrimer with Encapsulated Copper Nanoparticles: Antimicrobial Activity

A new methodology for modifying textile materials with dendrimers containing nanoparticles was developed. This involved a combination of eosin Y and N-methyldiethanolamine (MDEA) for reducing the copper ions in the dendrimer complex by enabling a photochemical reaction under visible light and ambient conditions. The conversion of copper ions into nanoparticles was monitored using scanning electron microscopy (SEM) and by performing colorimetric, fluorescence, and electron paramagnetic resonance (EPR) studies. Regardless of the concentration of the photoinitiator eosin Y, it discolored completely upon illumination. Three types of cotton fabrics were compared as antimicrobial materials against Bacillus cereus. One of the fabrics was dyed with a first-generation PAMAM dendrimer which had been functionalized with eight 1,8-naphthalimide fluorophores. Another fabric was dyed with a dendrimer-copper complex, and the third was treated by conversion of the complex into copper nanoparticles encapsulated into the dendrimer. An enhancement in the antimicrobial activity of the textiles was achieved at higher dendrimer concentrations, under illumination with visible light. The fabric modified with the copper nanoparticles encapsulated inside the dendrimer exhibited the best antibacterial activity because it had two photosensitizers (PS), as both 1,8-naphthalimide fluorophores and copper nanoparticles were contained in the dendrimer molecules. The presence of oxygen and suitable illumination activated the photosensitizers to generate the reactive oxygen species (singlet oxygen (¹O₂) and other oxygenated products, e.g., anion radicals, hydroxyl radicals, and hydrogen peroxide) responsible for destroying the bacteria.