Effect of Li-TiO₂ nanoparticles incorporation in LDPE polymer nanocomposites for biocidal activity

Large number of chronic infectious diseases caused by Staphylococcus aureus (S. aureus have become major health concern and therefore fabrication of polymer nanocomposites for S. aureus inactivation have attracted more attentions. Herein, Lithium-Titanate/low-density polyethylene (Li-TiO₂/LDPE) nanocomposites are fabricated via wet casting method by utilizing hydrothermally synthesized Li-TiO₂ photocatalyst and LDPE. The presence of Ti³⁺, oxygen vacancies and good interaction of Li–O–Ti have reduced the band gap energy of TiO₂, thus expand the visible light respond of photocatalyst embedded in the LDPE matrix. Besides, the incorporation of Li-TiO₂ has reduced the degree of crystallinity and improved the polarity and hygroscopic properties of the LDPE matrix, which demonstrating excellent water uptake for reactive oxygen species (ROS) and metal ion release for S. aureus inactivation. Furthermore, the scavenger test showed S.aureus inactivation are dominated by hydroxyl radicals (⋅OH) and superoxide radicals (⋅O₂ ⁻) instead of holes (h⁺) and Li⁺ ion. Nevertheless, the role of Li is more significant in altering the bandgap energy of TiO₂ for extending to visible region and reduce the electron–hole recombination for cell inactivation. The Li-TiO₂/LDPE nanocomposites with 1 wt% of Li-TiO₂ showed 94% reduction of S.aureus within 6 h and increased to 99% after 12 h. Enhance visible light activation of Li-TiO₂/LDPE nanocomposites with low Li-TiO₂ content shows great potential for biomedical application. A suitable microbial mechanism is determined and the correlation between structural properties and the antimicrobial efficacy is elucidated.