Polydopamine-coated TiO₂ nanoparticles endow pectin films with desirable physical and antibacterial properties for...

Pectin-based biodegradable packaging materials are widely used in food packaging as sustainable alternatives to traditional petrochemical plastics. However, pure pectin films are constrained by poor mechanical properties, limited barrier performance, and a lack of antimicrobial functionality. Current modification approaches often fail to simultaneously enhance all these properties. In this study, titanium dioxide (TiO₂) nanoparticles were coated with a polydopamine (PDA) layer via dopamine self-polymerization to obtain TiO₂@PDA composites (∼400 nm), which were incorporated into a pectin polymer to prepare composite films. The TiO₂@PDA exhibits excellent compatibility with the pectin polymer, dispersing uniformly and filling the free volume to form a dense network structure. Consequently, the composite film shows enhanced tensile strength (28.64 MPa), elongation at break (13.41%), water contact angle (79.30°), and water vapor barrier property (1.40 × 10^-12 g·cm^-1·s^-1·Pa^-1). The PDA surface modification endows TiO₂ with a narrower bandgap (2.71 eV), extending its photodynamic antibacterial spectral response from the ultraviolet to the visible light region. As a result, the composite film simultaneously exhibits excellent UV shielding and visible-light-responsive antibacterial activity. Furthermore, the film is biocompatible and demonstrates potential in extending the post-harvest shelf life and maintaining the quality of packaged fruits. In summary, TiO₂@PDA effectively enhances the mechanical, barrier, and antibacterial properties of pectin films simultaneously, providing new insights for developing smart, responsive pectin-based packaging materials.