Tuning antibacterial properties of poly(vinyl alcohol)/TiO2 composite films by chemically grafting with 3,3′,4,4′-biphenyltetracarboxylic acid

Polyvinyl alcohol (PVA)/titanium dioxide nanoparticles (TiO2 NPs)/3,3',4,4'-Benzophenone tetracarboxylic acid (BPTA) antibacterial films were prepared by solvent casting and chemical grafting using PVA as the base material and TiO2 NPs and BPTA as antibacterial materials. Scanning electron microscopy results showed that the distribution of TiO2 NPs inside the polymer matrix was substantially uniform. X-ray diffraction (XRD) and FTIR-ATR spectroscopy were used to demonstrate the successful embedding of NPs and the formation of ester bonds in the grafting process, respectively. In the antibacterial experiment, the PVA/1%TiO2 NPs/BPTA film exhibited higher antibacterial activity than other films. Compared with the control group, the surviving population of S. aureus and E. coli decreased by 99.62 +/- 0.38% and 98.27 +/- 1.47%, respectively. The mechanism of reactive oxygen species (ROS) production was discussed, and the amount of ROS produced by the composite films under light and dark conditions was quantitatively measured. A cycling experiment after quenching ROS showed that the PVA/1%TiO2 NPs/BPTA composite film retained 81.01% and 66.12% of the original charging capacity of the OH center dot radical and H2O2 after seven cycles. In terms of biodegradability, the degradation performance of the PVA/TiO2 NPs/BPTA composite film was stronger than that of the pure PVA film. Thus, the PVA/TiO2 NPs/BPTA film is considered a promising antibacterial material with superior characteristics of structural stability, reusability, and functionality under both light and dark conditions.