A biological heterojunction-based tooth bleaching material and a preparation method and application thereof

Abstract

The application provides a tooth bleaching material based on a biological heterojunction and a preparation method and application thereof, and belongs to the field of medical new materials. The tooth bleaching material is a BaTiO3@CeO2-GOx (BCG) biological heterojunction, and the preparation method comprises the following steps: preparing a BaTiO3@CeO2 heterojunction; fixing glucose oxidase GOx on the surface of the BaTiO3@CeO2 heterojunction through electrostatic adsorption to obtain a BaTiO3@CeO2-GOx (BCG) biological heterojunction material. Under the action of ultrasonic waves, the BCG produces active oxygen (ROS) through piezoelectric catalysis, realizes efficient oxidative decomposition of tooth pigments, and simultaneously, the CeO2 component in the BCG can effectively remove excessive free ROS, thereby protecting oral soft tissues from oxidative damage. The material has excellent non-damaging tooth whitening ability in in-vitro experiments, and provides a safe and efficient precise treatment method for oral aesthetic care.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oral medical materials, and more particularly to a tooth bleaching material based on a bioheterojunction and a preparation method and application thereof. BACKGROUND

[0002] Tooth discoloration is an important aesthetic problem affecting the quality of life of patients. Pigment deposition into dentin and chemical combination with tooth tissue form persistent discoloration, which seriously affects people's social self-confidence and mental health.

[0003] At present, the ROS-mediated tooth whitening method is the mainstream treatment. ROS is released by bleaching materials containing hydrogen peroxide or urea peroxide, and the conjugated double bond and aromatic ring structure of the pigment molecule are oxidized to decompose into colorless compounds, achieving the purpose of tooth whitening. However, traditional ROS treatment is prone to postoperative sensitivity and damage to oral soft and hard tissues. Free-state ROS diffuses indiscriminately in the oral environment and can cause oxidative damage to both tooth hard tissue and oral soft tissue, leading to increased tooth sensitivity, oral mucosa damage and other complications. SUMMARY

[0004] One of the purposes of the present application is to overcome the shortcomings of the prior art, and to provide a novel ultrasound-responsive bioheterojunction material capable of achieving precision and a preparation method and application thereof.

[0005] To achieve the above-mentioned purpose, one aspect of the present application provides a preparation method of a tooth bleaching material based on a bioheterojunction. The tooth bleaching material is a BaTiO3@CeO2-GOx (BCG) bioheterojunction. The preparation method comprises: preparing a BaTiO3@CeO2 heterojunction; fixing glucose oxidase GOx on the surface of the BaTiO3@CeO2 heterojunction by electrostatic adsorption to obtain a BaTiO3@CeO2-GOx (BCG) bioheterojunction material.

[0006] In an embodiment, the BaTiO3@CeO2 heterojunction can be synthesized by a hydrothermal method.

[0007] In an embodiment, the hydrothermal reaction temperature of the hydrothermal method can be controlled at 170-190°C.

[0008] In an embodiment, the weight ratio of BaTiO3 to CeO2 can be 2:1-4:1.

[0009] In an embodiment, the weight ratio of BaTiO3 to CeO2 can be 2.5:1-3.5:1.

[0010] In the embodiments, the concentration of glucose oxidase GOx can be 1-3 mg / mL, and it is fixed to the surface of the BaTiO3@CeO2 heterojunction by electrostatic adsorption for 22-26 hours.

[0011] Another aspect of the present invention provides a tooth bleaching material based on a bio-heterogeneous junction, the material being a BaTiO3@CeO2-GOx (BCG) bio-heterogeneous junction comprising BaTiO3, CeO2 and glucose oxidase (GOx).

[0012] In the embodiments, the BaTiO3@CeO2 heterojunction can be prepared by hydrothermal synthesis.

[0013] In this embodiment, the hydrothermal reaction temperature of the hydrothermal method can be controlled to be 170–190°C.

[0014] In the embodiments, the weight ratio of BaTiO3 to CeO2 can be 2:1 to 4:1.

[0015] In the embodiments, the weight ratio of BaTiO3 to CeO2 can be 2.5:1 to 3.5:1.

[0016] In the embodiments, the concentration of glucose oxidase GOx can be 1-3 mg / mL, and it is fixed to the surface of the BaTiO3@CeO2 heterojunction by electrostatic adsorption for 22-26 hours.

[0017] In the embodiments, the BaTiO3 has piezoelectric catalytic properties and can generate reactive oxygen species under ultrasonic activation; the CeO2 has the ability to scavenge reactive oxygen species and mimics the activities of superoxide dismutase and catalase; the GOx can decompose glucose to produce hydrogen peroxide.

[0018] In the embodiments, the weight ratio of BaTiO3 to CeO2 can be 2:1 to 4:1.

[0019] In this embodiment, the tooth bleaching material can be prepared by the preparation method described above.

[0020] Another aspect of the present invention provides the application of the tooth bleaching material prepared by the preparation method described above or the tooth bleaching material based on the bioheterogeneous junction described above in the preparation of a drug for non-destructive tooth whitening.

[0021] Another aspect of the present invention provides the use of a tooth bleaching material prepared by the preparation method described above or a tooth bleaching material based on a bioheterogeneous junction as described above in the preparation of a medicament for protecting oral soft tissues.

[0022] In one embodiment, the tooth whitening material can be formulated into a paste and applied to the tooth surface; the teeth are then irradiated with an ultrasonic device, causing the tooth whitening material to generate active oxygen under ultrasonic activation, thereby decomposing tooth pigments.

[0023] Compared with the prior art, the beneficial effects of the present invention include:

[0024] (1) Precise and controllable: BCG can only generate reactive oxygen species and exert a whitening effect when activated by ultrasound. It is safer and more controllable in clinical operation.

[0025] (2) Non-destructive whitening: While effectively decomposing tooth pigments, BCG does not cause significant damage to the microstructure and mechanical properties of tooth enamel, thus achieving safe and efficient teeth whitening.

[0026] (3) Soft tissue protection: The CeO2 component in BCG can effectively remove excess free ROS and significantly reduce the oxidative damage of ROS to oral soft tissues.

[0027] (4) Easy to operate: The preparation method is simple, the material has good stability, and it is easy to apply in clinical practice. Attached Figure Description

[0028] The accompanying drawings illustrate exemplary embodiments of the inventive concept and, together with the description, serve to explain the principles of the inventive concept. The drawings are included to provide a further understanding of the inventive concept and are incorporated in and form a part of this specification.

[0029] Figure 1 This is a characterization diagram of BCG material. Figure 1 A is a scanning electron microscope (SEM) image of BCG; Figure 1 B is the elemental mapping diagram of the energy dispersive spectrum (EDS) of BCG; Figure 1 C is a transmission electron microscope (TEM) image of BCG; Figure 1 D represents the full spectrum of X-ray photoelectron spectroscopy (XPS).

[0030] Figure 2 The graph shows the ROS release performance test results for BCG. Figure 2 The AC diagram is a schematic diagram of the principle of detecting ROS release performance using RhB, MB and DPBF; Figure 2 DF represents the consumption of RhB, MB, and DPBF by BCG under ultrasound irradiation; Figure 2 GI is produced by BCG-generated O2 - Electron spin resonance (ESR) spectra of ·OH and ¹O2.

[0031] Figure 3 This is a graph showing the ROS cleanup performance of BCG. Figure 3A represents the SOD activity measurement result; Figure 3 B represents the CAT activity analysis result; Figure 3 C represents the OH scavenging rate determination result; Figure 3 D and E are BCG pairs with O2 - ESR spectra of ·OH removal.

[0032] Figure 4 This is a test chart showing the teeth bleaching performance of BCG. Among them, Figure 4 A is a quantitative indicator of the color change of teeth after ultrasonic treatment. Figure 4 B is a SEM image of the enamel surface after bleaching. Figure 4 C represents the microhardness measurement result of tooth enamel after bleaching.

[0033] Figure 5 This is a biocompatibility assessment diagram for BCG. Among them, Figure 5 A represents the result of CCK-8 cell viability assay; Figure 5 Image B represents a cell morphology observation image; Figure 5 C represents the cell live / dead staining image. Detailed Implementation

[0034] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0035] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0036] In this document, the terms “containing” or “including” are open-ended expressions, meaning they include the contents specified in this invention but do not exclude other aspects.

[0037] In this document, the term “and / or” covers all combinations of items connected by the term and should be regarded as if each combination had been listed separately in this document. For example, “A and / or B” covers “A”, “A and B”, and “B”. For example, “A, B and / or C” covers “A”, “B”, “C”, “A and B”, “A and C”, “B and C”, and “A and B and C”.

[0038] The applicant discovered that barium titanate (BaTiO3), due to its unique piezoelectric properties and band structure, can efficiently generate ROS under ultrasonic activation, making it an excellent acoustic sensor. Cerium oxide (CeO2) through surface Ce 3+ / Ce 4+ Reversible oxidation, possessing the ability to mimic superoxide dismutase and catalase, can effectively remove various ROS. Constructing these two into a heterojunction holds promise for achieving controlled and precise release and timely removal of ROS, overcoming the limitations of traditional tooth bleaching methods.

[0039] One aspect of the present invention provides a method for preparing a tooth bleaching material based on a bio-heterojunction. In an embodiment, the tooth bleaching material is a BaTiO3@CeO2-GOx (BCG) bio-heterojunction. The preparation method includes: S100, preparing a BaTiO3@CeO2 heterojunction; and S200, fixing glucose oxidase GOx onto the surface of the BaTiO3@CeO2 heterojunction by electrostatic adsorption to obtain the BaTiO3@CeO2-GOx (BCG) bio-heterojunction material.

[0040] In S100, BaTiO3@CeO2 heterojunctions with high specific surface area can be synthesized via a hydrothermal method. The hydrothermal reaction temperature can be controlled between 170 and 190 °C. The weight ratio of BaTiO3 to CeO2 can be between 2:1 and 4:1. Optionally, the weight ratio of BaTiO3 to CeO2 can be between 2.5:1 and 3.5:1.

[0041] In S200, glucose oxidase (GOx) is immobilized: GOx can be immobilized on the surface of the heterojunction by electrostatic adsorption to form the final BCG composite material.

[0042] For example, the concentration of glucose oxidase GOx can be 1 to 3 mg / mL, and it can be fixed to the surface of BaTiO3@CeO2 heterojunction by electrostatic adsorption for 22 to 26 hours.

[0043] In an exemplary embodiment, the present invention provides a method for preparing a non-destructive tooth bleaching material activated by ultrasound, the method comprising:

[0044] 1. Preparation of BaTiO3@CeO2 heterojunction: BaTiO3@CeO2 heterojunction with high specific surface area was synthesized by hydrothermal method.

[0045] 2. Glucose oxidase (GOx) fixation: GOx is fixed to the surface of the heterojunction by electrostatic adsorption to form the final BCG composite material.

[0046] In an exemplary embodiment, the method for preparing the tooth bleaching material based on bioheterogeneous junctions of the present invention includes the following steps:

[0047] Step 1: Preparation of BaTiO3 nanoparticles

[0048] Dissolve 15 mL of tetrabutyl titanate (Ti(OC4H9)4) in 50 mL of anhydrous ethanol. Slowly add 5 mL of deionized water while stirring magnetically, and continue stirring for 30 min to form a white suspension. Dissolve 4.88 g of barium chloride (BaCl2·2H2O) in 30 mL of deionized water. Add the titanium precursor solution dropwise to the barium solution while stirring vigorously; a white precipitate immediately forms. After stirring for 1.5–2.5 h, transfer the mixture to a 100 mL stainless steel autoclave lined with polytetrafluoroethylene (PTFE) and hydrothermally react at 150–170 °C for 10–14 h. (The hydrothermal reaction temperature is a key factor determining the crystal phase and morphology of BaTiO3. Controlling the temperature between 150 and 170°C is beneficial for forming well-crystallized perovskite nanoparticles. Temperatures below 150°C result in incomplete reactions, potentially producing amorphous products or impurities; temperatures above 170°C exacerbate particle agglomeration, leading to increased particle size and decreased specific surface area, thus affecting its piezoelectric properties. A reaction time of 10–14 hours ensures sufficient crystal growth; too short a time leads to incomplete crystallization, while too long a time increases energy consumption and production costs without significantly improving product performance.) After the reaction, the precipitate is naturally cooled to room temperature and washed five times alternately with deionized water and anhydrous ethanol, centrifuged at 8000 rpm for 10 minutes after each wash. Finally, it is dried at 70–90°C for 10–14 hours, ground, and sieved to obtain BaTiO3 nanoparticles. Here, a drying temperature of 70–90°C effectively removes moisture while preventing hard agglomeration of particles; excessively high temperatures can cause particle sintering. A drying time of 10–14 hours ensures complete removal of moisture.

[0049] Step 2: Preparation of CeO2 nanoparticles

[0050] Dissolve 2.17 g of cerium nitrate (Ce(NO3)3·6H2O) in 40 mL of deionized water. Add 1.05 g of citric acid as a chelating agent while stirring magnetically, and stir until completely dissolved. Adjust the pH to 9–10 with ammonia; the solution will turn pale yellow. (pH is the key control parameter in this step; precise control within the range of 9–10 can promote the dissolution of Ce.) 3+ Oxidized to Ce 4+The precipitate is uniformly formed as CeO2. Below pH 9, oxidation is incomplete, resulting in low yield; above pH 10, Ce(OH)3 precipitate forms, introducing impurities. The solution is transferred to a 100mL stainless steel autoclave lined with polytetrafluoroethylene and hydrothermally reacted at 110–130℃ for 6–10 hours. After the reaction, the particles are washed with deionized water until neutral and dried at 80℃ to obtain CeO2 nanoparticles. (Hydrothermal temperature and time affect the particle size and crystallinity of CeO2. A temperature range of 110–130℃ helps form CeO2 with uniform particle size and good crystallinity. Too low a temperature results in incomplete reaction, while too high a temperature easily leads to particle growth and agglomeration. A reaction time of 6–10 hours is sufficient to ensure complete reaction. Washing to neutral is to remove residual nitrate ions and impurities such as citric acid.)

[0051] Step 3: Preparation of BaTiO3@CeO2 heterojunction

[0052] The prepared BaTiO3 nanoparticles and CeO2 nanoparticles were mixed at a weight ratio of 2.5:1 to 3.5:1 and added to 60 mL of deionized water. The mixture was ultrasonically dispersed for 30 min to ensure thorough mixing. 0.2 g of polyvinylpyrrolidone (PVP, molecular weight 40,000) was added as a dispersant under magnetic stirring, and stirring continued for 1 h. (The weight ratio of BaTiO3 to CeO2 is crucial for constructing a highly efficient heterojunction. A range of 2.5:1 to 3.5:1 ensures sufficient BaTiO3 as a piezoelectric core while providing a adequate amount of CeO2 as catalytic active sites and electron transport mediators. An imbalanced ratio will affect the overall performance of the material.)

[0053] The mixed suspension was transferred to a 100 mL stainless steel autoclave lined with polytetrafluoroethylene (PTFE) and hydrothermally treated at 170–190 °C for 10–14 h to allow BaTiO3 and CeO2 to form a tight heterojunction structure. After the reaction, the mixture was washed three times alternately with deionized water and anhydrous ethanol, and centrifuged at 6000 rpm for 15 min after each wash to remove unbound particles and organic matter. Finally, it was dried at 80 °C for 12 h, ground, and passed through a 200-mesh sieve to obtain BaTiO3@CeO2 heterojunction powder. Here, the purpose of the second hydrothermal treatment is to grow CeO2 in situ on the surface of BaTiO3, forming a tight heterojunction. The temperature of 170–190 °C is crucial for the formation of a high-quality heterojunction; too low a temperature results in weak interfacial bonding, affecting charge transfer efficiency; too high a temperature may damage the crystal structure of BaTiO3. The reaction time of 10–14 h ensures the full formation of the heterojunction.

[0054] Step 4: Immobilization of glucose oxidase (GOx)

[0055] 50 mL of phosphate-buffered saline (PBS, pH 7.2–7.6) was placed in a beaker, and 100 mg of glucose oxidase powder was added. The mixture was stirred at 4 °C for 2 h to completely dissolve the GOx, preparing a GOx solution with a concentration of 2 mg / mL. (The pH of PBS is crucial for the activity and stability of GOx; pH 7.2–7.6 is the optimal pH range for maintaining high GOx activity.) 1 g of BaTiO3@CeO2 heterojunction powder was weighed and dispersed in the above GOx solution. The mixture was stirred at 4 °C in the dark for 24 h, and samples were taken every 4 h to monitor the concentration change of GOx in the supernatant to ensure sufficient enzyme adsorption. After adsorption, the suspension was centrifuged at 4000–6000 rpm for 10 min, the supernatant was discarded, and the mixture was gently washed three times with PBS buffer to remove unbound GOx. Finally, the precipitate was redispersed in a small amount of PBS and freeze-dried at -20 °C for 48 h to obtain the BaTiO3@CeO2-GOx (BCG) composite material. (The purpose of centrifugation is to separate the solid BCG composite material from the unbound GOx in the liquid phase. The centrifugal force should not be too high; a speed of 4000–6000 rpm is sufficient to settle the material while avoiding excessive mechanical shear force on the immobilized enzyme.)

[0056] Step 5: Post-processing of BCG materials

[0057] The freeze-dried BCG material was gently ground in a mortar and passed through a 100-mesh sieve to obtain a powder with uniform particle size. The powder was then further dried in a vacuum drying oven at 40°C for 4 hours to remove residual moisture. Finally, the BCG material was sealed and stored at -20°C for later use.

[0058] Preparation points:

[0059] (1) Temperature control: The hydrothermal reaction temperature must be strictly controlled at 150-170℃ (BaTiO3 preparation), 110-130℃ (CeO2 preparation), and 170-190℃ (heterojunction preparation). Too high a temperature will cause particle agglomeration, growth or destruction of crystal structure, while too low a temperature will result in incomplete reaction, poor crystallinity or weak interfacial bonding.

[0060] (2) pH adjustment: The pH value must be controlled at 9-10 during the preparation of CeO2 to ensure that CeO2 is in a stable pH range. 3+ Oxidized to Ce 4+ It precipitates uniformly in the form of CeO2. If the pH value is below 9, oxidation is incomplete and the yield is low. If the pH value is above 10, Ce(OH)3 precipitate will form, introducing impurities.

[0061] (3) Washing process: Each washing step must be thorough to ensure the removal of unreacted precursors and byproducts. BaTiO3 needs to be washed to neutral to remove residual ions after preparation, CeO2 needs to be washed to neutral to remove nitrate ions and citric acid after preparation, and heterojunction needs to be washed to remove unbound particles and organic matter after preparation.

[0062] (4) Enzyme immobilization conditions: The pH of PBS must be controlled within the range of 7.2 to 7.6 to maintain high GOx activity and avoid enzyme inactivation.

[0063] (5) Centrifugation control: The centrifugal force should not be too large. A speed of 4000-6000 rpm is sufficient to settle the material, while avoiding excessive mechanical shearing force on the fixed enzyme.

[0064] (6) Weight ratio control: The weight ratio of BaTiO3 to CeO2 must be controlled between 2.5:1 and 3.5:1 to ensure that BaTiO3 is used as the piezoelectric core and that there is a sufficient amount of CeO2 as the catalytic active site and electron transfer medium. Imbalance in the ratio will affect the overall performance of the material.

[0065] Another aspect of the present invention provides a bio-heterogeneous tooth bleaching material, which is prepared by the preparation method described above.

[0066] In this embodiment, an ultrasonically activated, non-destructive tooth whitening material, namely a BaTiO3@CeO2-GOx(BCG) bioheterojunction, is utilized. This bioheterojunction is prepared via hydrothermal synthesis combined with electrostatic adsorption and immobilization of an enzyme. BaTiO3, as the main piezoelectric component, exhibits excellent piezoelectric catalytic performance; CeO2 endows the system with superior ROS scavenging ability; and the introduction of glucose oxidase (GOx) decomposes glucose to produce hydrogen peroxide, thereby enhancing whitening efficiency.

[0067] Another aspect of the present invention provides the application of the tooth bleaching material prepared by the preparation method described above or the tooth bleaching material based on the bioheterogeneous junction described above in the preparation of a drug for non-destructive tooth whitening.

[0068] Another aspect of the present invention provides the use of a tooth bleaching material prepared by the preparation method described above or a tooth bleaching material based on a bioheterogeneous junction as described above in the preparation of a medicament for protecting oral soft tissues.

[0069] In one embodiment, the tooth whitening material can be formulated into a paste and applied to the tooth surface; the teeth are then irradiated with an ultrasonic device, causing the tooth whitening material to generate active oxygen under ultrasonic activation, thereby decomposing tooth pigments.

[0070] Under ultrasound, BCG efficiently generates reactive oxygen species (ROS) through a piezoelectric catalytic mechanism, achieving the oxidative decomposition of tooth pigments. Simultaneously, the CeO2 component mimics the functions of superoxide dismutase (SOD) and catalase (CAT), effectively removing excess free ROS and protecting oral soft tissues from oxidative damage.

[0071] According to embodiments of the present invention, the limitations of non-selective oxidative damage in ROS-mediated whitening methods in the prior art are overcome, and a novel ultrasonic-responsive bioheterostructure material capable of achieving precise teeth whitening and protecting oral soft tissues is provided, along with its preparation method and application.

[0072] To better understand the exemplary embodiments of the present invention described above, further explanation is provided below with reference to specific examples.

[0073] Example 1

[0074] Step 1: Preparation of BaTiO3 nanoparticles

[0075] 15 mL of tetrabutyl titanate (Ti(OC4H9)4) was dissolved in 50 mL of anhydrous ethanol. 5 mL of deionized water was slowly added under magnetic stirring, and stirring continued for 30 min to form a white suspension. 4.88 g of barium chloride (BaCl2·2H2O) was dissolved in 30 mL of deionized water. The titanium precursor solution was added dropwise to the barium solution under vigorous stirring, immediately producing a white precipitate. After stirring for 2 h, the mixture was transferred to a 100 mL stainless steel autoclave lined with polytetrafluoroethylene and hydrothermally reacted at 160 °C for 12 h. After the reaction was complete, the mixture was allowed to cool naturally to room temperature. The precipitate was washed five times alternately with deionized water and anhydrous ethanol, centrifuged at 8000 rpm for 10 min after each wash. Finally, it was dried at 80 °C for 12 h, ground, and sieved to obtain BaTiO3 nanoparticles.

[0076] Step 2: Preparation of CeO2 nanoparticles

[0077] 2.17 g of cerium nitrate (Ce(NO3)3·6H2O) was dissolved in 40 mL of deionized water. 1.05 g of citric acid was added as a chelating agent under magnetic stirring until completely dissolved. The pH was adjusted to 9.5 with ammonia, turning the solution pale yellow. The solution was transferred to a 100 mL stainless steel autoclave lined with polytetrafluoroethylene and hydrothermally reacted at 120 °C for 8 h. After the reaction was complete, the solution was washed with deionized water until neutral and dried at 80 °C to obtain CeO2 nanoparticles.

[0078] Step 3: Preparation of BaTiO3@CeO2 heterojunction

[0079] BaTiO3 nanoparticles and CeO2 nanoparticles were mixed at a weight ratio of 3:1 and added to 60 mL of deionized water. The mixture was ultrasonically dispersed for 30 min to ensure thorough mixing. 0.2 g of polyvinylpyrrolidone (PVP, molecular weight 40000) was added as a dispersant under magnetic stirring, and stirring continued for 1 h. The mixed suspension was transferred to a 100 mL stainless steel autoclave lined with polytetrafluoroethylene and hydrothermally treated at 180 °C for 12 h. After the reaction was complete, the mixture was washed three times alternately with deionized water and anhydrous ethanol. After each wash, it was centrifuged at 6000 rpm for 15 min to remove unbound particles and organic matter. Finally, it was dried at 80 °C for 12 h, ground, and passed through a 200-mesh sieve to obtain BaTiO3@CeO2 heterojunction powder.

[0080] Step 4: Immobilization of glucose oxidase (GOx)

[0081] 50 mL of phosphate-buffered saline (PBS, pH 7.4) was placed in a beaker, and 100 mg of glucose oxidase powder was added. The mixture was stirred at 4 °C for 2 h to completely dissolve the GOx solution, preparing a GOx solution with a concentration of 2 mg / mL. 1 g of BaTiO3@CeO2 heterojunction powder was weighed and dispersed in the above GOx solution, and stirred at 4 °C in the dark for 24 h. After adsorption was complete, the suspension was centrifuged at 5000 rpm for 10 min, the supernatant was discarded, and the mixture was gently washed three times with PBS buffer. Finally, the precipitate was redispersed in a small amount of PBS and freeze-dried at -20 °C for 48 h to obtain the BaTiO3@CeO2-GOx (BCG) composite material.

[0082] Step 5: Post-processing of BCG materials

[0083] The freeze-dried BCG material was gently ground in a mortar and passed through a 100-mesh sieve to obtain a powder with uniform particle size. The powder was then further dried in a vacuum drying oven at 40°C for 4 hours to remove residual moisture. Finally, the BCG material was sealed and stored at -20°C for later use.

[0084] Results: The obtained BCG composite material was characterized and showed good piezoelectric-catalytic synergistic performance, and had a significant bleaching effect under ultrasonic activation.

[0085] Example 2

[0086] Step 1: Preparation of BaTiO3 nanoparticles

[0087] After stirring for another 1.5 hours, the mixture was transferred to a 100 mL stainless steel autoclave lined with polytetrafluoroethylene and hydrothermally reacted at 150 °C for 10 hours. Finally, it was dried at 70 °C for 10 hours.

[0088] Step 2: Preparation of CeO2 nanoparticles

[0089] Adjust the pH to 9.0 with ammonia water, and perform a hydrothermal reaction at 110℃ for 6 hours.

[0090] Step 3: Preparation of BaTiO3@CeO2 heterojunction

[0091] The prepared BaTiO3 nanoparticles and CeO2 nanoparticles were mixed at a weight ratio of 2.5:1 and hydrothermally treated at 170℃ for 10 h.

[0092] Step 4: Immobilization of glucose oxidase (GOx)

[0093] After the phosphate-buffered saline (PBS, pH 7.2) adsorption was complete, the suspension was centrifuged at 4000 rpm for 10 min...

[0094] Results: The obtained BCG composite material had slightly lower crystallinity but still maintained good piezoelectric response and catalytic activity. Under ultrasonic treatment, its whitening efficiency was slightly lower than that of Example 1, but still within an acceptable range, demonstrating the feasibility of the lower end of the parameter range.

[0095] Example 3

[0096] Step 1: Preparation of BaTiO3 nanoparticles

[0097] After stirring for another 2.5 hours, the mixture was transferred to a 100 mL stainless steel autoclave lined with polytetrafluoroethylene (PTFE) and subjected to hydrothermal reaction at 170 °C for 14 hours. Finally, it was dried at 90 °C for 14 hours.

[0098] Step 2: Preparation of CeO2 nanoparticles

[0099] Adjust the pH to 10.0 with ammonia water, and perform a hydrothermal reaction at 130℃ for 10 hours.

[0100] Step 3: Preparation of BaTiO3@CeO2 heterojunction

[0101] The prepared BaTiO3 nanoparticles and CeO2 nanoparticles were mixed at a weight ratio of 3.5:1 and hydrothermally treated at 190℃ for 14 h.

[0102] Step 4: Immobilization of glucose oxidase (GOx)

[0103] After the phosphate-buffered saline (PBS, pH 7.6) was fully adsorbed, the suspension was centrifuged at 6000 rpm for 10 min...

[0104] Results: The whitening efficiency of the obtained BCG composite material was slightly lower than that of Example 1, but still within an acceptable range, proving the feasibility of the high end of the parameter range.

[0105] Comparative Example 1: Hydrothermal temperature too low

[0106] Preparation process: Basically the same as Example 1, but in step 1, the hydrothermal reaction temperature of BaTiO3 is set to 140℃; in step 2, the hydrothermal reaction temperature of CeO2 is set to 100℃; in step 3, the hydrothermal treatment temperature of the heterojunction is set to 160℃.

[0107] Results: The final BaTiO3@CeO2 heterojunction interface was loosely bonded, resulting in low charge transfer efficiency. Under ultrasonic activation, its bleaching effect was significantly lower than that of Examples 1-3.

[0108] Comparative Example 2: Hydrothermal temperature too high

[0109] Preparation process: Basically the same as Example 1, but in step 1, the hydrothermal reaction temperature of BaTiO3 is set to 180℃; in step 3, the hydrothermal treatment temperature of the heterojunction is set to 200℃.

[0110] Results: In the heterojunction product, CeO2 particles were unevenly distributed on the BaTiO3 surface, with some areas exposed. Due to the excessively large particle size, the piezoelectric response was weakened. The whitening efficiency of the final material was much lower than that of Examples 1-3.

[0111] Comparative Example 3: Inappropriate pH value

[0112] Preparation process: basically the same as Example 1, but in step 2, the pH is adjusted to 8.5 with ammonia.

[0113] Result: During pH adjustment, the solution did not turn a distinct pale yellow, indicating that Ce... 3+ The oxidation was insufficient. After the hydrothermal reaction, the amount of product obtained was very small, and it contained a large amount of Ce(OH)3 impurities instead of pure CeO2. This prevented the formation of an effective BaTiO3@CeO2 heterojunction, resulting in the failure of the entire material system. Ultimately, the whitening efficiency of the material was far lower than that of Examples 1-3.

[0114] Test Example 1

[0115] Preparation and characterization of BCG materials

[0116] BCG materials were prepared according to the detailed preparation method described above, and then systematically characterized. For example... Figure 1 As shown in Figure A, scanning electron microscopy (SEM) observation revealed that BCG exhibits a granular morphology with a particle size distribution ranging from 50 to 200 nm. Energy-dispersive spectroscopy (EDS) elemental mapping... Figure 1 (B) clearly shows the uniform distribution of Ba, Ti, Ce, and O elements in BCG, confirming successful recombination. Transmission electron microscopy (TEM) analysis ( Figure 1The C) further confirmed the heterojunction structure of BC-HJs. X-ray photoelectron spectroscopy (XPS) analysis ( Figure 1 The D) confirmed the successful synthesis of BCG, and the BCG spectrum showed that the material contained key elements such as Ba, Ti, Ce and O.

[0117] Test Example 2

[0118] ROS Release Performance Test

[0119] Rhodamine B, methylene blue, and DPBF were used as ROS probes to evaluate the ROS generation capacity of BCG under ultrasonic activation. BCG (1 mg / mL) was mixed with RhB (10 μM), MB (10 μM), and DPBF (30 μM) solutions, respectively, and absorbance changes were measured every 10 minutes under 808 nm ultrasound (1.5 W / cm²). Specific ROS types were detected using ESR technology. Figure 2 As shown in DE, after 60 minutes of ultrasound irradiation, the degradation rate of RhB in the BCG group reached 78.6±3.2%, the degradation rate of MB reached 82.1±2.9%, and the degradation rate of DPBF reached 88.4±1.8%. Figure 2 As shown by GI, ESR detection further confirmed that BCG can generate ·OH and ·O2. - and 1 O2 contains various reactive oxygen species.

[0120] Test Example 3

[0121] ROS cleanup performance test

[0122] The antioxidant properties of BCG were evaluated, including SOD activity, CAT activity, and free radical scavenging ability. SOD and CAT activities of BCG were detected using commercial kits. Free radical scavenging rate was determined using the DPPH method. The effects of BCG on ·OH and ·O2 were validated using ESR technology. - The direct removal effect. For example... Figure 3 As shown in the AC results, BCG exhibited significant SOD and CAT activity, with a ·OH scavenging rate of 85.90 ± 2.80%. Figure 3 As shown in D and E, the ESR results confirm that BCG can directly absorb and neutralize free radicals.

[0123] Test Example 4

[0124] Teeth bleaching performance test

[0125] The whitening effect and safety of BCG were evaluated using artificially stained teeth. Extracted teeth were artificially stained with coffee solution, then coated with BCG paste and treated under ultrasonic irradiation for different time periods. Color changes were measured using a colorimeter, enamel surface morphology was observed using SEM, and mechanical properties were measured using a Vickers hardness tester. Figure 4 As shown in Figure A, after 6 hours of BCG treatment, the total color difference value ΔE reached 60.36±4.07, significantly better than the control group. Figure 4 B and Figure 4 As shown in Figure C, SEM images after bleaching showed that the enamel surface remained smooth and the Vickers hardness did not change significantly (2.16±0.07 GPa vs 2.19±0.15 GPa), proving that the whitening process was undamaged.

[0126] Test Example 5

[0127] Biocompatibility assessment

[0128] The cytotoxicity of BCG was assessed using human oral keratinocytes. HOK cells were co-cultured with different concentrations of BCG, and cell viability was detected using the CCK-8 assay. Cell morphology was observed using SEM, and cell status was assessed using live / dead staining. Figure 5 As shown, when the BCG concentration was 1 mg / mL, cell viability remained at 90.65 ± 2.18%. Figure 5 The cells shown in BC are morphologically intact, and most cells are viable, demonstrating that BCG has good biocompatibility.

[0129] Comparative Test Example 1: BaTiO3@CeO2 material without GOx

[0130] Preparation of GOx-free BaTiO3@CeO2 materials. Figure 4 As shown in Figure A, the whitening efficiency of this material is significantly lower than that of BCG, and the color difference value after 60 minutes of treatment is only 65% ​​of that of BCG.

[0131] Comparative Test Example 2: Traditional 10% Hydrogen Peroxide Teeth Whitening Agent

[0132] like Figure 4 As shown in BC, compared with 10% hydrogen peroxide whitening agent, BCG achieves similar whitening effect while causing less damage to tooth enamel, and no obvious surface roughening or decrease in hardness was observed.

[0133] This invention discloses a non-destructive tooth whitening material activated by ultrasound, its preparation method, and its applications. The material is a BaTiO3@CeO2-GOx (BCG) bioheterojunction, prepared by hydrothermal synthesis combined with electrostatic adsorption fixation of an enzyme. Under ultrasound, BCG generates reactive oxygen species (ROS) through piezoelectric catalysis, achieving efficient oxidative decomposition of tooth pigments. Simultaneously, the CeO2 component in BCG effectively removes excess free ROS, thereby protecting oral soft tissues from oxidative damage. The material of this invention exhibits excellent non-destructive tooth whitening capabilities in in vitro experiments, providing a safe, efficient, and precise treatment method for oral aesthetic care.

[0134] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a tooth bleaching material based on bio-heterogeneous junctions, characterized in that, The teeth whitening material is a BaTiO3@CeO2-GOx bioheterojunction, and the preparation method includes: BaTiO3@CeO2 heterojunctions were prepared by hydrothermal synthesis. The hydrothermal reaction temperature for BaTiO3 preparation was controlled at 150–170℃, the hydrothermal reaction temperature for CeO2 preparation was controlled at 110–130℃, the pH value for CeO2 preparation was controlled at 9–10, and the hydrothermal reaction temperature for BaTiO3@CeO2 heterojunction preparation was controlled at 170–190℃. The weight ratio of BaTiO3 to CeO2 was 2:1 to 4:

1. Glucose oxidase GOx was electrostatically adsorbed onto the surface of the BaTiO3@CeO2 heterojunction to obtain a BaTiO3@CeO2-GOx bio-heterojunction material. The concentration of glucose oxidase GOx was 1-3 mg / mL. The BaTiO3@CeO2-GOx exhibited a granular morphology with a particle size distribution in the range of 50-200 nm. The electrostatic adsorption of glucose oxidase GOx onto the surface of the BaTiO3@CeO2 heterojunction specifically included: adding glucose oxidase powder to a phosphate buffer solution to prepare a glucose oxidase GOx solution, wherein the pH value of the phosphate buffer solution was 7.2-7.

6.

2. The method for preparing the tooth whitening material based on bioheterogeneous junctions according to claim 1, characterized in that, BaTiO3 nanoparticles were prepared by hydrothermal reaction at 150–170 °C for 10–14 h.

3. The method for preparing the tooth whitening material based on bioheterogeneous junctions according to claim 1, characterized in that, Preparation of CeO2 nanoparticles: hydrothermal reaction at 110–130℃ for 6–10 h.

4. The method for preparing the tooth whitening material based on bioheterogeneous junctions according to claim 1, characterized in that, The weight ratio of BaTiO3 to CeO2 is 2.5:1 to 3.5:

1.

5. The method for preparing the tooth whitening material based on bioheterogeneous junctions according to claim 1, characterized in that, The material is fixed to the surface of the BaTiO3@CeO2 heterojunction by electrostatic adsorption for 22 to 26 hours.

6. The method for preparing the tooth whitening material based on bioheterogeneous junctions according to claim 1, characterized in that, After adsorption is complete, the suspension is centrifuged at 4000-6000 rpm. The purpose of the centrifugation step is to separate the solid phase BaTiO3@CeO2-GOx bioheterojunction material from the unbound GOx in the liquid phase.

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