Calcium alginate films loaded with copper-molybdenum oxide nanoparticles for antimicrobial applications

Abstract

The rise in petroleum-based plastic waste, driven by increased consumption from delivery services and e-commerce, necessitates the search for sustainable alternatives like alginate-based materials to mitigate environmental risks. However, alginate, a biopolymer, has limited physico-chemical properties, lacks antibacterial capacity, and exhibits low antiviral activity. To address these issues, this study synthesized Cu3Mo2O9 semiconductor nanoparticles (CMO) and integrated them into alginate films crosslinked with Ca2+, producing advanced nanocomposite films with varying nanoparticle concentrations (0–10 wt%). CMO nanoparticles release Cu2+ and Mo6+ ions and generate reactive oxygen species (ROS), even in the dark. Results show that CMO weakly interacts with alginate blocks, causing slight structural changes but not significantly altering mechanical or thermal properties. CMO released Cu2+ (150–250 ppb at 24 h) and Mo6+ ions (5–8 ppm at 24 h), with Cu2+ undergoing cation exchange with Ca2+ crosslinking ions. Antibacterial tests demonstrated the composites' effectiveness against Gram-negative Pseudomonas aeruginosa (97.30 % and 91.36 % growth inhibition at 5 % and 10 % CMO), Gram-positive methicillin-resistant Staphylococcus aureus (87.26 % and 96.82 % inhibition at 5 % and 10 % CMO), and Mycobacterium smegmatis (99.83 % and 99.97 % inhibition at 5 % and 10 % CMO). These composites also showed antiviral activity against bacteriophage phi 6 (99.81 % and 92.66 % inactivation at 5 % and 10 % CMO) and bacteriophage MS2 (92.32 % and 92.93 % inactivation at 5 % and 10 % CMO). The primary mechanism is attributed to the release of Cu2+ cations and ROS generation. These nanocomposite films exhibit broad-spectrum antimicrobial activity, offering potential industrial applications in packaging and antimicrobial surfaces.