Photodynamic antifungal activity of curcumin-capped TiO₂ nanoparticles: A colorant-based photochemical approach for packaging applications.

The present study explores the development, characterization, and antifungal application of curcumin-capped titanium dioxide nanoparticles (cur-TiO₂ Nps) for photodynamic inactivation (PDI) of Aspergillus niger spores, particularly in food packaging contexts. Cur-TiO₂ Nps were synthesized via surface functionalization of anatase-phase TiO₂ with curcumin, and their physicochemical properties were evaluated using XRD, FTIR, UV-Vis spectroscopy, and dynamic light scattering. The structural analyses confirmed the preservation of TiO₂ crystallinity with effective curcumin capping, indicated by characteristic FTIR shifts and a modest increase in the band gap from 3.31 to 3.43 eV. Photoinactivation assays under blue LED irradiation (450 nm) demonstrated that cur-TiO₂ Nps achieved significantly higher antifungal activity (up to 80% inhibition) compared with either curcumin or TiO₂ Nps alone, highlighting a synergistic interaction that enhances reactive oxygen species (ROS) generation. Further evaluation of cur-TiO₂ Nps applied to A. niger-contaminated food packaging surfaces-including polyethylene terephthalate (PET), expanded polystyrene (EPS), and polyvinyl chloride (PVC)-showed material-dependent efficacy. PVC and EPS achieved superior inhibition rates (35% and 27%, respectively), while PET was less effective (~8%), likely due to differences in surface roughness, wettability, and nanoparticle adhesion. These results indicate that cur-TiO₂ Nps are promising candidates for use in light-activated antimicrobial systems, particularly as part of functional food packaging strategies aimed at controlling fungal contamination and extending product shelf life through non-thermal and residue-free methods.