A bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction, a preparation method and use thereof

Abstract

The application provides a bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction and a preparation method and application thereof. The bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction comprises the following raw material components in moles: 3-5 moles of bismuth-doped sodium niobate; and 1 mole of oxygen vacancy ceria. The bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction has strong piezoelectric properties and acoustic power properties, and has enzyme-like activity. Under the driving of ultrasonic waves, the piezoelectric effect of the material not only promotes the proliferation of osteoblasts, but also enhances the acoustic power and enzyme-like activity of the material, generates various ROS, cooperatively kills bacteria and removes biofilms, and has potential application prospects in the treatment of infected bone tissues.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of medical biological materials, in particular to a bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction as well as a preparation method and application thereof. BACKGROUND

[0002] The treatment of infected bone defects is tortuous and long, and the control of bone infection and the repair of bone defects have always been a thorny problem in orthopedics. The infected bone defects caused by bacteria are often hidden and difficult to treat. The formation of bacterial reproduction and biofilm can reduce the activity of osteoblasts and hinder the repair of bone defects, so the treatment of bacterial infection and the promotion of bone tissue regeneration are crucial for the repair of infected bone defects. Although some materials (such as antibiotic slow-release materials) are used for local antibiosis, their antibacterial effect is limited, and long-term use may lead to bacterial drug resistance. An ideal bone repair material should have osteoinduction, which can promote the proliferation of bone cells and new bone formation. However, many materials (such as artificially synthesized inorganic materials) lack bone induction function and are only used as fillers, which cannot effectively promote bone regeneration.

[0003] At present, it is urgent to develop new treatment materials to combat bacterial infection in bone defect repair, and ideal materials must have safety, biocompatibility, bioactivity and biological stability. Light energy, electrical energy, ultrasound and thermal energy have great potential in promoting bone regeneration and antibiosis. Sonodynamic therapy is a non-invasive treatment strategy, which can produce various ROS under the excitation of ultrasound, causing bacterial oxidative damage and death. In addition, piezoelectric materials can generate electrical signals through piezoelectric effect, stimulate cell response and promote bone regeneration. At the same time, they can act as sonosensitizers to form an internal electric field under the trigger of ultrasound, promote the rapid separation and migration of electric charges, and enhance the rate of oxidation-reduction reaction, thereby increasing the ROS yield and enhancing the sonodynamic therapy. It has also received widespread attention in the field of bone repair; however, how to select suitable piezoelectric materials and modify them to obtain suitable bone repair materials with biocompatibility is still a problem. SUMMARY

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present application is to provide a bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction as well as a preparation method and application thereof, which is used to solve the problems of insufficient antibacterial ability and poor osteoinduction of the bone repair materials in the prior art, and cannot simultaneously control infection and promote bone repair.

[0005] To achieve the above-mentioned objects and other related objects, the present application provides a bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction as well as a preparation method and application thereof.

[0006] The present application provides a bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction in the first aspect; the heterojunction comprises the following molar amounts of raw material components:

[0007] Bismuth-doped sodium niobate 3-5 moles

[0008] Oxygen vacancy ceria 1 mole.

[0009] Further preferably, the molar ratio of the bismuth-doped sodium niobate and the oxygen vacancy ceria includes but is not limited to 3:1, 4:1 or 5:1.

[0010] In some preferred embodiments of the present application, the molar ratio of the bismuth-doped sodium niobate and the oxygen vacancy ceria is 4:1.

[0011] Preferably, the preparation method of the bismuth-doped sodium niobate includes: adding bismuth nitrate and niobium pentoxide in a molar ratio of (0.01-0.1):1 into an alkaline solution, obtaining a powder after reacting at 120-200℃ for 10-15h, and calcining the powder at 350-450℃ for 0.5-5h.

[0012] Further preferably, the molar ratio of the bismuth nitrate and the niobium pentoxide is (0.02-0.05):1; for example, it can be 0.02:1, 0.03:1, 0.04:1 or 0.05:1.

[0013] Further preferably, the alkaline solution is a sodium hydroxide solution with a concentration of (1-5) mol / L; for example, it can be 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L.

[0014] Further preferably, the amount of the alkaline solution added is 10-100ml based on the amount of the niobium pentoxide added, which is 1g; for example, it can be 10ml, 20ml, 30ml, 40ml, 50ml, 60ml, 70ml, 80ml, 90ml or 100ml.

[0015] Further preferably, the reaction temperature is 140-180℃; for example, it can be 140℃, 150℃, 160℃, 170℃ or 180℃.

[0016] Further preferably, the reaction time is 11-14h; for example, it can be 11h, 12h, 13h or 14h.

[0017] Further preferably, the preparation method further includes washing and drying the powder after the reaction.

[0018] More preferably, the washing is performed using water and / or ethanol.

[0019] Further preferably, the calcination temperature is 360~430℃; for example, it can be 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃ or 430℃.

[0020] Further preferably, the calcination time is 0.5~3h; for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h or 3h.

[0021] Preferably, the preparation method of the oxygen vacancy ceria comprises: mixing ceria powder and sodium borohydride powder in a molar ratio of (0.3~3):1, and calcining the mixed powder under an inert gas atmosphere at 300~500℃ for 0.5~5h.

[0022] Further preferably, the molar ratio of the ceria and sodium borohydride is (0.5~2):1; for example, it can be 0.5:1, 1:1, 1.5:1 or 2:1.

[0023] Further preferably, the inert gas atmosphere is an argon or nitrogen atmosphere.

[0024] Further preferably, the calcination temperature is 350~450℃; for example, it can be 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, 430℃, 440℃ or 450℃.

[0025] Further preferably, the calcination time is 0.5~3h; for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h.

[0026] Further preferably, the preparation method further comprises washing and drying the calcined powder.

[0027] More preferably, the washing is performed using water and / or ethanol.

[0028] Preferably, the particle size of the heterojunction is 500~1200nm; including but not limited to 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, 1100nm or 1200nm.

[0029] Preferably, the content of oxygen vacancies in the ceria is 10%~50%; for example, it can be 10%~20%, 20%~30%, 30%~40% or 40%~50%.

[0030] The second aspect of the present application provides a preparation method of the above-mentioned bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction, which comprises: mixing raw material components, grinding in anhydrous ethanol, and calcining at 300~500℃ under an inert gas atmosphere for 0.5~5h after grinding.

[0031] Preferably, the amount of the absolute ethyl alcohol added is 20-50 mL, based on 1 g of the mixed powder; including but not limited to 1 mol / L, 2 mol / L or 1 mol / L.

[0032] Preferably, the grinding time is 1-5 h; including but not limited to 1 h, 2 h, 3 h, 4 h or 5 h.

[0033] Preferably, the inert gas atmosphere is an argon atmosphere.

[0034] Preferably, the calcination temperature is 350-450℃; including but not limited to 350℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, 430℃, 440℃ or 450℃.

[0035] Preferably, the calcination time is 0.5-3 h; including but not limited to 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h or 3 h.

[0036] The third aspect of the present application provides a composite material, which comprises bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction and polyether ketone ketone two raw material components, and the volume ratio of the heterojunction and the polyether ketone ketone is (0.2-0.5):0.6.

[0037] Preferably, the volume ratio of the heterojunction and the polyether ketone ketone includes but is not limited to 0.2:0.6, 0.3:0.6, 0.4:0.6 or 0.5:0.6.

[0038] The polyether ketone ketone in the present application is medical grade, and preferably, the density of the polyether ketone ketone is 1.28-1.31 g / cm 3 .

[0039] Preferably, the mesh number of the polyether ketone ketone is 300-800 mesh.

[0040] Preferably, the weight average molecular weight of the polyether ketone ketone is 80000-150000 g / mol; including but not limited to 80000 g / mol, 90000 g / mol, 100000 g / mol, 110000 g / mol, 120000 g / mol, 130000 g / mol, 140000 g / mol or 150000 g / mol.

[0041] The fourth aspect of the present application provides an application of bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction and bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction / polyether ketone ketone composite material in bone repair bodies.

[0042] Preferably, the application comprises at least one of the following 1) - 8):

[0043] 1) application in preparing products with POD-like enzyme activity;

[0044] 2) application in preparing products with CAT-like enzyme activity;

[0045] 3) application in preparing products with piezoelectric properties;

[0046] 4) application in preparing products with sonodynamic properties;

[0047] 5) application in preparing products to promote the proliferation of bone cells;

[0048] 6) application in preparing products to promote the osteogenic differentiation of bone cells;

[0049] 7) application in preparing antibacterial products;

[0050] 8) application in preparing anti-inflammatory products.

[0051] As described above, the bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction of the present application has the following beneficial effects:

[0052] 1. The bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction of the present application has strong piezoelectric properties and sonodynamic properties, and has enzyme-like activity. Under the drive of ultrasonic waves, the piezoelectric effect of the material not only promotes the proliferation of osteoblasts, but also enhances the sonodynamic and enzyme-like activity of the material. In a bacterial infection microenvironment, a variety of ROS are generated, which synergistically kill bacteria and remove biofilms, and have potential application prospects in the treatment of infected bone tissue.

[0053] 2. The bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction of the present application can exert CAT-like enzyme activity in a normal physiological environment, effectively scavenge ROS, has excellent antioxidant properties, significantly reduces the oxidative stress of cells, and effectively controls inflammation.

[0054] 3. The preparation method of the bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction of the present application is simple, low in cost, and suitable for large-scale industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 The scanning electron microscope diagram of CeO, CeO-1, CeO-2 and CeO-3 in Example 2 of the present application is shown.

[0056] Figure 2 a The X-ray diffraction pattern of CeO, CeO-1, CeO-2 and CeO-3 in Example 2 of the present application is shown. Figure 2 b to Figure 2e X-ray photoelectron spectroscopy of CeO, CeO-1, CeO-2 and CeO-3 in Example 2 of the present application.

[0057] Figure 3 shows the degradation effect of CeO, CeO-1, CeO-2 and CeO-3 on Rhodamine B (RhB) under US irradiation in Example 2 of the present application.

[0058] Figure 4 shows the degradation effect of BNbC on Rhodamine B (RhB) in Example 3 of the present application.

[0059] Figure 5 shows the scanning electron microscope images of BNO and 4BNbC in Example 3 of the present application.

[0060] Figure 6 shows the energy dispersive spectroscopy images of BNO and 4BNbC in Example 3 of the present application.

[0061] Figure 7 a shows the XRD patterns of BNO, CeO-2 and 4BNbC in Example 3 of the present application; Figure 7 b to Figure 7 c are the XPS spectra of BNO and 4BNbC in Example 3 of the present application, respectively.

[0062] Figure 8 a shows the PFM amplitude images of BNO and 4BNbC in Example 3 of the present application; Figure 8 b are the phase images of BNO and 4BNbC in Example 3 of the present application; Figure 8 c are the butterfly loops of BNO and 4BNbC in Example 3 of the present application; Figure 8 d are the phase hysteresis loops of BNO and 4BNbC in Example 3 of the present application.

[0063] Figure 9 a shows the band gap of CeO, CeO-1, CeO-2 and CeO-3 in Example 3 of the present application; Figure 9 b shows the band gap of BNO in Example 3 of the present application; Figure 9 c and Figure 9 d are the XPS valence band spectra of BNO and CeO-2 in Example 3 of the present application, respectively; Figure 9 e shows the electrochemical impedance spectroscopy of different samples in Example 3 of the present application.

[0064] Figure 10 shows the mechanism of 4BNbC improving piezoelectric / acoustic power in Example 3 of the present application.

[0065] Figure 11a shows the degradation effect of methylene blue (MB) by different samples in Example 3 of the present application; Figure 11 b shows the degradation effect of methylene blue (MB) by 4BNbC under different pH conditions in Example 3 of the present application; Figure 11 c shows the degradation effect of methylene blue (MB) by 4BNbC under different US conditions in Example 3 of the present application.

[0066] Figure 12 a shows the change trend of the amount of oxygen generated by the decomposition of H2O2 by different samples in Example 3 of the present application over time; Figure 12 b shows the change trend of the amount of oxygen generated by the decomposition of H2O2 by 4BNbC under different pH conditions in Example 3 of the present application over time; Figure 12 c shows the change trend of the amount of oxygen generated by the decomposition of H2O2 by 4BNbC under different US conditions in Example 3 of the present application over time.

[0067] Figure 13 shows the proliferation of cells after 1 d, 3 d and 7 d of incubation of cells with samples in Example 4 of the present application.

[0068] Figure 14 a and Figure 14 b are respectively the colony photos of S. aureus and E. coli after incubation under different samples and different conditions in Example 4 of the present application; Figure 14 c and Figure 14 d are respectively the antibacterial rates of different samples on S. aureus and E. coli in Example 4 of the present application.

[0069] Figure 15 a and Figure 15 b are respectively the crystal violet staining photos of S. aureus and E. coli after incubation under different samples and different conditions in Example 4 of the present application; Figure 15 c and Figure 15 d are respectively the biofilm residual photos of S. aureus and E. coli in Example 4 of the present application. DETAILED DESCRIPTION

[0070] The present application is described herein with reference to specific specific examples. A person skilled in the art can easily understand other advantages and effects of the present application from the disclosure of the present specification. The present application can also be implemented or applied by other different specific embodiments, and the details in the present specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present application.

[0071] Before particular embodiments of the present application are further described, it is to be understood that the application is not limited to the particular specific embodiments described below; it is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application; and that unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It must be noted that as used herein and in the appended claims, the singular forms "a", "an", and "the" include plural reference unless the context clearly dictates otherwise. As used herein and in the appended claims, the term "comprising" includes the instances in which the term "consisting of is used.

[0072] When numerical ranges are given, it should be understood that every numerical range encompasses any number falling within the range, unless the context clearly indicates otherwise. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Any methods, devices and materials similar or equivalent to those described herein can be used in the practice of the present application, unless expressly defined otherwise in the specification. The present application illustratively described in terms of particular embodiments does not limit the scope of the present application to these particular embodiments.

[0073] Unless otherwise indicated, the experimental methods, detection methods, preparation methods disclosed in the present application all employ conventional techniques in the fields of molecular biology, biochemistry, chromatin structure and analysis, analytical chemistry, cell culture, recombinant DNA technology and related fields. These techniques are well described in the existing literature and can be found in Sambrook et al. MOLECULAR CLONING: A LABORATORY MANUAL, Second edition, Cold Spring Harbor Laboratory Press, 1989 and Third edition, 2001; Ausubel et al. CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, John Wiley & Sons, New York, 1987 and periodic updates; the series METHODS IN ENZYMOLOGY, Academic Press, San Diego; Wolffe, CHROMATIN STRUCTURE AND FUNCTION, Third edition, Academic Press, San Diego, 1998; METHODS IN ENZYMOLOGY, Vol. 304, Chromatin (P. M. Wassarman and A. P. Wolffe, eds.), Academic Press, San Diego, 1999; and METHODS IN MOLECULAR BIOLOGY, Vol. 119, Chromatin Protocols (P. B. Becker, ed.) Humana Press, Totowa, 1999, etc.

[0074] In view of the problems of insufficient antibacterial ability, poor osteoinduction ability and inability to simultaneously control infection and promote bone repair of the bone repair materials in the prior art, the present application selects sodium niobate (NaNbO3) and cerium dioxide (CeO2) as base materials to prepare a composite material, Bi-doped sodium niobate is prepared by doping bismuth elements in sodium niobate, so that the lattice defects of sodium niobate are generated, and the piezoelectric performance is enhanced; oxygen vacancies are generated in cerium dioxide, so that the lattice distortion of cerium dioxide is caused, and the band gap is reduced; the oxygen vacancies can act as charge trapping centers and adsorption sites, promote the separation of electrons and holes, and make them more easily excited by ultrasonic waves (US) to generate acoustic power, and can improve the POD and CAT enzyme activities of cerium dioxide, therefore, the heterojunction formed by Bi-doped sodium niobate and oxygen vacancy cerium dioxide has enhanced piezoelectric performance, acoustic power performance and enzyme-like activity, can promote the proliferation and differentiation of osteoblasts, and enhance the antibacterial performance. In use, the heterojunction is injected into a bone infection site and an ultrasonic wave treatment is additionally applied, so that the antibacterial effect can be achieved at the bone infection site, and the bone repair is promoted, in addition, the heterojunction can be doped into a polyarylether high polymer to prepare a scaffold implant into the body by a 3D printing technology.

[0075] Example 1

[0076] The present embodiment provides a preparation method of a Bi-doped sodium niobate / oxygen vacancy cerium dioxide heterojunction, comprising the following steps:

[0077] Step one: preparation of Bi-doped sodium niobate

[0078] 1g of di-niobium pentoxide is added into 50ml (2mol / L) of sodium hydroxide solution, 4% of bismuth nitrate in molar ratio is added, the mixture is stirred uniformly, then poured into an autoclave, the autoclave is placed into an oven to react at 160℃ for 12h, the obtained powder is washed by water and ethanol, dried, calcined at 400℃ in a muffle furnace for 1h to remove crystal water, and then Bi-doped sodium niobate powder (denoted as BNO) is obtained.

[0079] Step two: preparation of oxygen vacancy cerium dioxide by a thermal reduction method

[0080] 1g of CeO2 is blended with NaBH4 in different molar ratios (1:0, 2:1, 1:1, 1:2), calcined at 400℃ in an argon atmosphere in a tube furnace for 1h, the obtained powder is washed by water and ethanol, dried, and then oxygen vacancy CeO2 (denoted as bCeO) is obtained, and the specific sample groups are shown in Table 1.

[0081] Table 1. Sample groups of oxygen vacancy cerium dioxide

[0082] CeO2: NaBH4 Abbreviations 1:0 CeO 2:1 CeO-1 1:1 CeO-2 1:2 CeO-3

[0083] Step three: preparation of Bi-doped sodium niobate / oxygen vacancy cerium dioxide heterojunction

[0084] The bismuth-doped sodium niobate (BNO) prepared in step one and the oxygen vacancy ceria (bCeO) prepared in step two were mixed in different molar ratios (3:1, 4:1, 5:1), 0.5 g of the mixed powder was taken into a mortar, 10 mL of anhydrous ethanol was added to uniformly mix the powder, grinding for 2 h, and calcination in a tube furnace at 400 DEG C under argon atmosphere for 1 h to obtain a bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction (denoted as BNbC). The specific sample grouping is shown in Table 2.

[0085] Table 2. Sample grouping of bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction

[0086] BNO: CeO2 Abbreviations 3:1 3BNbC 4:1 4BNbC 5:1 5BNbC

[0087] Example 2

[0088] The micro-morphology, oxygen vacancy content and sonodynamic performance of the oxygen vacancy ceria prepared in Example 1 of the present application were detected and analyzed.

[0089] Firstly, the micro-morphology of the CeO, CeO-1, CeO-2 and CeO-3 prepared in Example 1 above was characterized by scanning electron microscopy (SEM), and the results are shown in Figure 1 .

[0090] The reducing agent NaBH4 can produce hydrogen gas under thermal decomposition, and capture the lattice oxygen in CeO2 to produce oxygen vacancies. It can be known from Figure 1 that the oxygen vacancies do not change the size of CeO2 particles, and the size of all samples is about 50 nm.

[0091] Further, the crystal structure of the CeO, CeO-1, CeO-2 and CeO-3 prepared in Example 1 above was characterized by X-ray diffraction (XRD), and the specific results are shown in Figure 2 a, from which it can be known that there is no obvious difference in the diffraction peaks of each sample, indicating that the thermal reduction does not significantly change the crystal structure of CeO2.

[0092] Further, the oxygen vacancy content of the CeO, CeO-1, CeO-2 and CeO-3 prepared in Example 1 above was analyzed by X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) technology, and the XPS spectrum results are shown in Figure 2 b- Figure 2 e.

[0093] In the O1s high-resolution XPS spectrum, O1, O2 and O3 correspond to lattice oxygen, oxygen defects and surface adsorbed oxygen, respectively. The oxygen vacancy content in the oxygen vacancy ceria was calculated according to the formula Vo / O (%) = oxygen vacancy content / (oxygen vacancy content + lattice oxygen content + adsorbed oxygen content) x 100%, and the results are shown in Figure 2 b-Figure 2 The results of e show that the oxygen vacancy content gradually increases with the increase of the content of NaBH4, indicating that the oxygen vacancy content in the oxygen vacancy ceria can be regulated by adjusting the proportion of NaBH4.

[0094] Further research on the sonodynamic performance of CeO, CeO-1, CeO-2 and CeO-3 prepared in the above embodiment 1 was carried out, and the samples were irradiated by ultrasonic waves (US), and the specific test conditions were as follows: the US parameters were 1 MHz, 1.5 W / cm 2 ; the concentration of RhB was 10 mg / L. After US irradiation for 5 min, the supernatant was obtained by centrifugation, and the absorbance of the supernatant at 550 nm was measured by ultraviolet spectrophotometer. The specific detection results are shown in Figure 3 .

[0095] According to the results of Figure 3 , the appropriate oxygen vacancy can act as a charge trapping center and an adsorption site to promote the separation of electrons and holes, thereby improving the sonodynamic performance, and too many oxygen vacancies are easy to cause charge recombination, which will reduce the sonodynamic performance. Therefore, only CeO-2 (V O / O = 31.79%) with appropriate oxygen vacancies has the best sonodynamic performance.

[0096] Embodiment 3

[0097] The sonodynamic performance, micro-morphology, element distribution, crystal structure, piezoelectric performance and enzyme activity of the bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction prepared in the above embodiment 1 were analyzed.

[0098] The sonodynamic performance of BNbC prepared in the above embodiment 1 was studied by detecting the degradation effect of rhodamine B (RhB), and the specific detection process was consistent with that of embodiment 2. The detection results are shown in Figure 4 , and the results show that 4BNbC has the best sonodynamic performance, because the appropriate proportion of heterojunction (molar ratio of BNO and CeO-2 is 4:1) promotes the separation of electrons and holes.

[0099] The micro-morphology of BNO and 4BNbC prepared in the above embodiment 1 was characterized by scanning electron microscope (SEM), and the results are shown in Figure 5 .

[0100] According to the results of Figure 5 , it can be seen that after the formation of heterojunction, the surface of 4BNbC is uniformly distributed with CeO2 particles containing oxygen vacancies, and the particle size of 4BNbC is between 500-1200 nm.

[0101] Further, the element distribution of BNO and 4BNbC prepared in the above embodiment 1 was characterized by energy dispersive spectroscopy (EDS), and the results are shown inFigure 6 As shown, the results indicate that Bi elements are distributed on the surfaces of both BNO and 4BNbC, but Ce elements are distributed only on the surface of 4BNbC.

[0102] Furthermore, the crystal structures of BNO, CeO₂⁻, and 4BNbC were investigated using X-ray diffraction (XRD), and the specific results are as follows: Figure 7 As shown in Figure a, the results show that the diffraction peaks of CeO-2 and BNO both appear in the diffraction peaks of 4BNbC.

[0103] Further X-ray photoelectron spectroscopy (XPS) Figure 7 (b-7c) Elemental analysis of BNO and 4BNbC showed that characteristic peaks of Bi4f and Ce3d were detected in 4BNbC, proving the successful formation of the heterojunction.

[0104] The piezoelectric properties of BNO and 4BNbC were investigated using piezoelectric microscopy (PFM). Specific amplitude images, phase images, butterfly loops, and phase hysteresis curves are shown below. Figure 8 As shown in a-8d. (By...) Figure 8 a and Figure 8 The amplitude and phase images of the piezoelectric response induced by PFM in b show that both BNO and 4BNbC are piezoelectric. (The image is derived from the butterfly hysteresis loop.) Figure 8 c) It can be seen that, compared with BNO, 4BNbC exhibits a higher amplitude variation, indicating that 4BNbC produces a larger strain under the influence of an electric field, suggesting that 4BNbC has superior piezoelectric properties. Phase hysteresis curve ( Figure 8 d) indicates that the phase hysteresis curve of 4BNbC is significantly narrower than that of BNO, suggesting that 4BNbC is easier to polarize and has better piezoelectric properties. Figure 7 The results of a-7c demonstrate that the piezoelectric performance of 4BNbC is improved. This is because the formation of the heterojunction enhances the macroscopic polarization field. The larger polarization field provides a higher driving force for carrier migration, improves carrier separation and migration, and thus improves the overall piezoelectric performance.

[0105] The band gap of the sample was further analyzed and calculated using ultraviolet-visible-near-infrared spectroscopy (UV-Vis-NIR); the results are as follows. Figure 9 a and Figure 9 As shown in b, the results indicate that compared to CeO, the band gaps of CeO, CeO-1, CeO-2, and CeO-3 with oxygen vacancies are significantly reduced, while the band gap of BNO is 2.89 eV. A smaller band gap indicates higher material activity; the presence of oxygen vacancies enhances the activity of cerium dioxide. (XPS valence band diagram) Figure 9c-9d) shows: the valence band of BNO and CeO-2 is 1.97 eV and 1.36 eV, respectively. The electrochemical impedance diagram (9e) shows: oxygen vacancies reduce the impedance of CeO-2, Bi doping reduces the impedance of BNO, and the impedance of BNO and CeO-2 after forming a heterojunction is further reduced, and the reduction of impedance indicates that it is easier to promote the separation of electrons and holes.

[0106] Figure 10 To improve the 4BNbC piezoelectric / acoustic dynamic mechanism diagram of the heterojunction, according to E VB =E CB +E g (E CB =conduction band value, E VB = valence band value, E g = band gap width), the conduction band of BNO and CeO-2 is -0.92 eV and -1.49 eV, respectively. The heterojunction formed by BNO and CeO-2 enhances the macroscopic polarization electric field, improves the piezoelectric performance, generates an internal electric field under the trigger of US, and the piezoelectric promotes the band bending, promotes the separation of electrons and holes, and accelerates the charge transfer rate, so that the valence band potential is more positive and the conduction band potential is more negative, reaching the redox potential of ·OH and O2 - , thereby improving the efficiency of the redox reaction, catalyzing the conversion of H2O and O2 in the surrounding environment into ROS (·OH and ·O2 - ), and enhancing the acoustic dynamic performance.

[0107] The enzyme activity of the bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction prepared in Example 1 of the present application was analyzed. Specifically, 10 g of the sample was immersed in a 10 mL methylene blue (MB) solution containing 10 mM H2O2, the solution pH was 5.5, after 10 min of reaction, the supernatant was centrifuged and the absorbance of the supernatant at 663 nm was measured using a UV spectrophotometer, and the results are shown in Figure 11 a. The effect of different pH conditions on the enzyme activity of 4BNbC was further investigated, and the absorbance of the supernatant at 663 nm was measured under different pH conditions (4.5, 5.5, 6.5, 7.4) after 10 min of reaction, and the results are shown in Figure 11 b. The effect of different US conditions on the enzyme activity of 4BNbC was further investigated, and the absorbance of the supernatant at 663 nm was measured under different US conditions (1 MHz, 0, 0.3, 0.5, 0.8, 1, 1.5 W / cm2) after 5 min of reaction, and the results are shown in Figure 11The results show that, compared with CeO, the POD-like enzyme activity of oxygen vacancy CeO-2 is enhanced, and the POD-like enzyme activity of the heterojunction 4BNbC is optimal; with the increase of pH, the POD-like enzyme activity of 4BNbC is weakened, indicating that the POD-like enzyme activity is better under acidic conditions; with the increase of US power, the POD-like enzyme activity of 4BNbC gradually increases, which is because the US triggered piezoelectric response promotes the redox cycle of Ce ion valence transformation, and when US>0.5 W / cm 2 , sonodynamic excitation, the US triggered piezoelectric response enhances the sonodynamic and POD-like enzyme activity at the same time, degrades MB, and generates a large amount of ROS, proving that both oxygen vacancies and bismuth doping can improve the POD-like enzyme activity of the material.

[0108] The CAT enzyme activity of the sample was characterized by detecting the dissolved oxygen content in the solution by a dissolved oxygen meter. 50 mg of the sample was immersed in 50 mL of PBS solution containing 10 mM H2O2, and the solution pH was 7.4. The Control group was PBS solution with pH adjusted to 7.4 by NaOH. The dissolved oxygen content (mg / L) was detected by a dissolved oxygen meter, and the results are shown in Figure 12 a. Under different pH conditions (4.5, 5.5, 6.5, 7.4), the dissolved oxygen content of 4BNbC was detected, and the results are shown in Figure 12 b. Under different US conditions (1 MHz, 0, 0.3, 0.5, 0.8, 1, 1.5 W / cm 2 ), the dissolved oxygen content of 4BNbC was detected, and the results are shown in Figure 12 c. The results show that, compared with other samples, 4BNbC has the best CAT-like enzyme activity and can decompose H2O2 to generate a large amount of oxygen; with the increase of pH, the CAT-like enzyme activity of 4BNbC increases, indicating that the CAT-like enzyme activity is better under neutral conditions; under US conditions, when US≤0.5 W / cm 2 , the sonodynamic is weak, and US only triggers piezoelectric response to enhance the CAT-like enzyme activity, and when US>0.5 W / cm 2 , sonodynamic excitation, the oxygen generated by the CAT-like enzyme activity is consumed as an oxygen source by the sonodynamic, so the dissolved oxygen content decreases.

[0109] Example 4

[0110] The cell proliferation ability and antibacterial performance of the bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction prepared in Example 1 of the present application were studied.

[0111] The cells used in this example are rat bone marrow mesenchymal stem cells (rBMSC).

[0112] The samples were divided into four groups: (1) Control group; (2) BNO group; (3) 4BNbC group; (4) US group; (5) BNO+US group; (6) 4BNbC+US group; the Control and US groups were pure rBMSCs without samples. After sterilization by ultraviolet irradiation, the proliferation of cells on the samples was evaluated using CCK-8 assay. The sample concentration was 500 ug / mL. rBMSCs (density 2×10⁻⁶) 4 The samples (in each well) were cultured in 96-well plates for different times (1 day, 3 days, 7 days). After 24 hours of culture, the samples were treated daily with 1 MHz, 0.5 W / cm² solution. 2 rBMSCs in the US treatment group were irradiated (twice daily, 10 s each time). Subsequently, CCK-8 solution (100 μL) was added to the culture medium. After incubation for 1 h, the absorbance (OD value) of the culture medium was measured at 450 nm using a microplate reader.

[0113] The results are as follows Figure 13 As shown, the results indicate that cell proliferation increased with increasing cell culture time, demonstrating that both BNO and 4BNbC exhibit excellent biocompatibility and are non-cytotoxic. Furthermore, 4BNbC showed higher cell proliferation than BNO, likely due to the osteogenic effect of the CeO-2 component in 4BNbC, which promotes cell proliferation. Under US treatment, cell proliferation of both BNO and 4BNbC further increased, indicating that US treatment stimulated cell proliferation through piezoelectric charge generation, with 4BNbC demonstrating superior piezoelectric properties compared to BNO, thus exhibiting optimal cell proliferation.

[0114] The in vitro antibacterial properties of BNO and 4BNbC prepared in Example 1 of this invention were further investigated.

[0115] The bacteria were divided into 9 groups: (1) Control group; (2) H2O2 group; (3) US group; (4) BNO group; (5) 4BNbC group; (6) BNO+US group; (7) 4BNbC +H2O2 group; (8) 4BNbC +US group; (9) 4BNbC +US+H2O2 group. The Control group, H2O2 group, and US group were pure rBMSC cells without samples. The samples were co-cultured with Staphylococcus aureus and Escherichia coli, respectively, and treated under US and H2O2 conditions; the US power was 1.5 W / cm². 2 The H2O2 concentration was 2 mM, and the treatment time was 20 min. The specific procedure was as follows: the inhibition ratio was determined by colony counting, and the sample was disinfected with ultraviolet irradiation for 12 h. A concentration of 1×10⁻⁶ H₂O₂ was used. 6The bacterial suspension (1 mL) with CFU / mL was co-cultured with the sample (500 ug / mL) in a 24-well plate at 37°C in a shaking incubator for 6 h. The bacterial suspension after culture was diluted 10 times, and the bacterial suspension (20 μL) was spread on a nutrient agar plate, which was incubated at 37°C for 24 h, photographed, and the colonies were counted. The antibacterial ratio calculation formula: Antibacterial ratio (%) = (C-S) / S, where C and S are the number of colonies in the Control group and the sample group, respectively. 100 μL of bacterial suspension (1×10 8 CFU / mL) was mixed with 900 μL of bacterial culture medium (TSB for S. aureus and LB for E. coli) in a 24-well plate at 37°C for 48 h. The sample (500 ug / mL) was added to the well plate after different experimental grouping conditions, and incubated at 37°C for 12 h. Then the well plate was washed with PBS for 2 times, and 500 μL of glutaraldehyde was added for fixation at 4°C for 15 min. Then, in each well, 300 μL of 1% crystal violet dye was added, and incubated for 30 min. After washing with PBS for 3 times, the bacterial biofilm image in each well was recorded by a digital camera.

[0116] Figure 14 a and Figure 14 b is the antibacterial effect of the sample under different conditions (S. aureus and E. coli). The results show that BNO and 4BNbC alone have no antibacterial ability. Under the action of US, the antibacterial effect of 4BNbC is better than that of BNO, which is due to the heterojunction that improves the piezoelectric properties of 4BNbC, thereby correspondingly enhancing the sonodynamic performance. In the presence of H2O2, the antibacterial performance of 4BNbC is improved, which is due to the POD-like enzyme activity of 4BNb in the acidic environment of bacteria, producing ROS antibacterial. Further calculation of the antibacterial rate of different samples, the results are shown in Figure 14 c and Figure 14 d, the results show that in the presence of US and H2O2, 4BNbC has the best antibacterial performance, and the antibacterial rates are 98.3%±1.1% (S. aureus) and 98.7%±1.3% (E. coli), respectively, which is due to the piezoelectric response triggered by US to enhance the sonodynamic and POD-like enzyme activity, and the combination of the two produces multiple ROS, which synergistically kills a large number of bacteria.

[0117] The biofilm removal ability of the sample was detected, and after the bacteria were co-cultured with the sample, crystal violet dye was added, and the biofilm state of the bacteria in the well was photographed; and the absorbance was detected at 590 nm, and the residual rate of the biofilm was calculated. Figure 15a-15d is the evaluation of the ability of the samples to remove biofilm (S. aureus and E. coli) under different conditions. The results show that BNO alone and 4BNbC are difficult to remove bacterial biofilm. Under US irradiation, 4BNbC is significantly better than BNO in removing biofilm. In the presence of H2O2, 4BNbC improves the ability to remove biofilm due to its POD-like enzyme activity. In the presence of US and H2O2, 4BNbC has the strongest ability to remove biofilm, and the residual rate of biofilm is 5.4% ± 1.7% (S. aureus) and 3.7% ± 1.3% (E. coli), respectively.

[0118] In summary, the present application prepares cerium dioxide piezoelectric material with appropriate oxygen vacancies by thermal reduction method. The appropriate oxygen vacancies cause lattice distortion, reducing the band gap; oxygen vacancies can act as charge trapping centers and adsorption sites, promoting the separation of electrons and holes, making it easier to be excited by US to produce sonodynamic effect, and improving its POD and CAT-like enzyme activity. Then bismuth-doped sodium niobate (BNO) is prepared by hydrothermal method, and BNO is combined with CeO-2 to form heterojunction 4BNbC. The heterojunction structure enhances the piezoelectric properties of 4BNbC compared with BNO, so that 4BNbC can generate an internal electric field through the enhanced piezoelectric effect under the trigger of US, promoting the separation and migration of electrons and holes, improving the charge transfer rate, and enhancing the sonodynamic effect together with the CeO-2 component. In addition, the piezoelectric effect also promotes the 4+ valence change of Ce 3+ and oxygen vacancies to improve the POD and CAT-like enzyme activity of 4BNbC. Therefore, the heterojunction 4BNbC formed by bismuth-doped BNO and oxygen vacancy CeO-2 has enhanced piezoelectric properties, sonodynamic properties and enzyme-like activity. The antibacterial experiment shows that 4BNbC generates a large amount of ROS due to the enhanced piezoelectric response, sonodynamic effect and POD-like enzyme activity, which synergistically kills S. aureus and E. coli. The present application proposes a new strategy of piezoelectric effect and enhanced nanoscale enzyme activity and sonodynamic effect to synergistically promote cell proliferation and antibacterial effect. It can be used as an antibacterial bone repair material and has great application prospect in the field of bacterial infection and tissue healing.

[0119] The above merely describes preferred embodiments of the present application, and is not intended to limit the present application in any form or in essence. It should be noted that those skilled in the art can make some improvements and supplements without departing from the method of the present application, and these improvements and supplements should also be considered as the protection scope of the present application. For those skilled in the art, some slight changes, modifications and equivalent changes made by using the disclosed technical content without departing from the spirit and scope of the present application are equivalent embodiments of the present application; meanwhile, any equivalent changes, modifications and evolution made according to the essential technology of the present application to the above embodiments are still within the scope of the technical solutions of the present application.

Claims

1. A bismuth-doped sodium niobate / oxygen-vacancy ceria heterojunction, characterized in that, The heterojunction comprises the following raw material components by mole: Bismuth-doped sodium niobate 3-5 moles Oxygen vacancy ceria 1 mole The preparation method of the bismuth-doped sodium niobate comprises: adding bismuth nitrate and niobium pentoxide in a molar ratio of (0.01-0.1):1 into an alkaline solution, obtaining a powder after reacting at 120-200°C for 10-15h, and calcining the powder at 350-450°C for 0.5-5h; The preparation method of the oxygen vacancy ceria comprises: mixing ceria powder and sodium borohydride powder in a molar ratio of (0.3-3):1, and calcining the mixed powder at 300-500°C for 0.5-5h in an inert gas atmosphere; The preparation method of the heterojunction comprises: mixing the raw material components, grinding in anhydrous ethanol, and calcining at 300-500°C for 0.5-5h in an inert gas atmosphere after grinding.

2. The heterojunction according to claim 1, characterized in that The alkaline solution is a sodium hydroxide solution with a concentration of (1-5) mol / L; and / or, the addition amount of the alkaline solution is 10-100ml based on the addition amount of 1g niobium pentoxide; and / or, the method further comprises washing and drying the powder after reaction. The washing is performed by using water and / or ethanol.

3. The heterojunction according to any one of claims 1 to 2, wherein The particle size of the heterojunction is 500-1200nm; and / or, the content of oxygen vacancies in the ceria is 10%-50%.

4. A method of producing a heterojunction as claimed in any one of claims 1 to 3, characterised in that, The method comprises: mixing the raw material components, grinding in anhydrous ethanol, and calcining at 300-500°C for 0.5-5h in an inert gas atmosphere after grinding.

5. The preparation method according to claim 4, characterized in that, The addition amount of the anhydrous ethanol is 20-50mL based on 1g of the mixed powder; and / or, the inert gas atmosphere is an argon or nitrogen atmosphere; and / or, the grinding time is 1-5h.

6. A composite material, characterized by, The composite material comprises the bismuth-doped sodium niobate / oxygen vacancy ceria heterojunction of any one of claims 1-3 and polyether ketone ketone as two raw material components, and the volume ratio of the heterojunction and polyether ketone ketone is (0.2-0.5):0.

6.

7. Use of the heterojunction of any one of claims 1-3 or the composite material of claim 6 as a bone repair material.

8. Use according to claim 7, characterized in that, The use comprises at least one of the following 1)-8): 1) use in preparing a product with POD-type enzyme activity; 2) use in preparing a product with CAT-type enzyme activity; 3) use in preparing a product with piezoelectric properties; 4) use in preparing a product with sonodynamic properties; 5) use in preparing a product for promoting the proliferation of bone cells; 6) use in preparing a product for promoting the osteogenic differentiation of bone cells; 7) use in preparing an antibacterial product; 8) use in preparing an anti-inflammatory product.

Images