The delicate balance of oral microbiota is frequently disrupted by exogenous discoloration and biofilm formation, thus requiring integrated antibacterial and whitening strategies. Conventional peroxide treatments often damage the integrity of tooth enamel, while nanocatalysts pose cytotoxicity risks. In this work, we designed a biocompatible polydopamine-engineered barium titanate nanocomposite (BTO@PDA_x). By optimizing polydopamine (PDA) shell thickness, BTO@PDA_0.5 exhibited superior excellent piezoelectric catalytic activity. Under ultrasound irradiation, PDA enhanced reactive oxygen species (ROS) generation by promoting charge carrier separation at the BTO interface, thereby accelerating chromogen degradation kinetics. Antibacterial assays and tooth whitening studies confirmed that BTO@PDA_0.5 could effectively inhibit microorganisms and degrade pigments with extremely low cytotoxicity. This study designed a highly biocompatible organic-inorganic composite piezoelectric material, providing a new strategy for oral health care.

Chronic bacterial infections are a key pathological factor hindering wound healing, significantly increasing the incidence of wound sepsis. Existing therapeutic strategies exhibit certain limitations, leading to a continuous decline in clinical efficacy. Therefore, there is an urgent need for the development of novel antibacterial materials to mitigate the risks associated with bacterial infections. In this study, a new antibacterial strategy is proposed, utilizing the flexoelectric polarization of manganese dioxide (MnO₂) nanoflowers (NFs) to generate reactive oxygen species (ROS) at the site of infected wounds, achieving in situ and broad-spectrum bacterial eradication. Upon external ultrasound (US) stimulation, the flexoelectric polarization induced in the MnO₂ NFs results in the generation of abundant ROS on the material surface, which disrupts the integrity of bacterial cell membranes, leading to their inactivation. Compared to conventional photodynamic therapy, this strategy achieves higher ROS generation efficiency (65.3% methylene blue (MB) degradation in 25 min) without light dependency. In vitro experiments confirmed the antibacterial efficacy, with the inactivation rates for Escherichia coli and Staphylococcus aureus reaching 66.22% and 70.67%, respectively. Furthermore, excellent antibacterial effects were observed at the site of infected wounds, promoting wound healing. The integration of the flexoelectric effect into material-based antibacterial strategies holds promise for expanding the range of novel antibacterial materials in the future.

Built-in electric field coupled piezoelectric polarization engineering is a promising method to adjust and boost the catalytic performance of photocatalysts. Herein, BiOIO₃-Bi₂Te₃ type-Ⅱ heterojunction piezo-photocatalyst was proposed and prepared by a sequential hydro-solvothermal method. Due to the co-drive of the heterojunction and photothermal-piezoelectric polarization effect certified by piezoelectric force microscopy, COMSOL simulations, and infrared thermography, the photocatalytic degradation performance of the as-prepared BiOIO₃-Bi₂Te₃ on rhodamine B was dramatically improved under the co-excitation of visible light and ultrasound compared with under the single light irradiation and the single ultrasonic conditions. Typically, the BiOIO₃-Bi₂Te₃ photocatalyst always showed significantly better catalytic degradation performance than the pure Bi₂Te₃, BiOIO₃, and BiOIO₃/Bi₂Te₃ mechanical mixtures. Impressively, based on the optimal conditions obtained by systematically studying the effects of temperatures, ultrasound intensities, and inorganic salts on the piezo-photocatalytic rhodamine B degradation, the optimum composite ratio BiOIO₃-Bi₂Te₃-20 piezo-photocatalyst can also effectively remove tetracycline and Cr(Ⅵ), and also achieve the purpose of simultaneously removing a mixture of these three pollutants with good recycling stability. Such enhanced catalytic performance was mainly attributed to the disruptions of the electrostatic equilibrium and saturation effects of the built-in electric field under successive ultrasonic and photoinduced co-disturbance, thus enhancing the driving force of separation and migration of photogenerated carriers as verified by electrochemical tests, energy band structure theory, and DFT calculations. Based on which and the sacrificial agent experiments, the photocatalytic degradation mechanism was proposed. This research showcased the significant potential for environmental remediation using solar energy and mechanical energy cooperatively.