Polypropylene modified with Cu–N-doped titanium dioxide forantibacterial applications

Titanium dioxide (TiO₂) is an attractive biomaterial for its antibacterial properties. In this paper, TiO₂ nanoparticles were co-doped with copper and nitrogen and deposited onto polypropylene (PP) by the dip-coating technique. The nanoparticles were synthesised via the sol-gel technique and co-doped by the wet impregnation method. The physicochemical properties of the samples were characterised using scanning electron microscopy (SEM), wavelength-dispersive spectrometry (WDS), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and ultraviolet-visible (UV–vis) spectroscopy. The band gap energy was determined using a Tauc plot. The antibacterial activity was evaluated against gram-positive, gram-negative, and multi-resistant bacteria by measuring the number of colony-forming units (CFUs). All the tests were conducted in the presence of visible light. The results showed that the nanoparticles have a mean diameter of 20.40 ± 5.50 nm. The Cu–N-doped nanoparticles showed a 23% decrease of the band gap compared to their unmodified counterparts. The PP showed homogeneous coatings with a mean thickness of 33.00 ± 1.70 μm. The PP modified with Cu-N-doped TiO₂ exhibited strong antibacterial activity against E. coli (81%), S. aureus (98%) and methicillin-resistant S. aureus (MRSA) (97%) compared to unmodified PP. The results demonstrated the antibacterial activity of TiO₂–Cu–N nanoparticles against gram-negative and gram-positive bacteria and their potential use in biomedical applications. (paper)