A Robust Strategy for Efficient Teeth Whitening and Oral Sterilization Leveraging the Synergistic Coupling of LSPR and Piezo-Phototronic Effects.

The development of safe, efficient, and convenient strategies for teeth whitening and oral hygiene remains a significant challenge in modern dentistry. In this work, we report a multifunctional composite hydrogel (CBA) that enables simultaneous teeth whitening and antibacterial activity through the synergistic coupling of localized surface plasmon resonance (LSPR) and piezo-phototropic effects. The CBA hydrogel, comprising BaTiO3 nanocubes decorated with Au nanoparticles and embedded in a biocompatible calcium alginate hydrogel matrix, can efficiently generate reactive oxygen species (ROS) under combined light and ultrasound stimulation. This dual activation greatly enhances pigment degradation on enamel surfaces and effectively inactivates pathogenic bacteria such as Fusobacterium nucleatum. Compared with the control group, the hydrogel exhibits three orders of magnitude reduction in bacteria inactivation and a six-fold increase in whitening efficiency, while maintaining excellent enamel integrity. Photoelectrochemical and photoluminescence analyses reveal that the synergistic interaction among the LSPR-induced hot electrons, piezoelectric polarization field, and semiconductor band modulation significantly improves charge separation and ROS generation efficiency. This work not only provides fundamental insights into the cooperative mechanism of LSPR and piezo-phototronic effects but also establishes a practical and safe approach for next-generation dental care materials.