Amino acid functionalized barium titanate piezoelectric nano composite material as well as preparation method and application thereof

Abstract

The invention provides an amino acid functionalized barium titanate piezoelectric nano composite material as well as a preparation method and application thereof. According to the specific technical scheme, on the basis of glycine modified barium titanate (BTO) nanoparticles, the amino acid functionalized piezoelectric nanocomposite (BTG) is prepared through ultrasonic self-assembly. The material can generate strong piezoelectric polarization under ultrasonic stimulation, the ROS generation efficiency is remarkably improved, toxic organic dye is promoted to be rapidly degraded, and meanwhile the material has efficient broad-spectrum antibacterial activity and good biocompatibility. 92.08% of Congo red dye and 92.00% of rhodamine B dye can be degraded within 80 minutes, and the inactivation rate for gram-negative bacteria (escherichia coli) and / or gram-positive bacteria (enterococcus faecalis) is 97% or above. Therefore, the amino acid functionalized barium titanate piezoelectric nano composite material provided by the invention has the characteristics of high efficiency, low energy consumption and environmental friendliness, and can be widely applied to the technical field of antibiosis and / or organic dye degradation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of nano functional materials, and particularly relates to an amino acid functionalized barium titanate piezoelectric nanocomposite material, a preparation method and application thereof. BACKGROUND

[0002] In the current flourishing development of material science, traditional piezoelectric materials, photocatalytic materials and nanomaterials can all be used as antibacterial functional materials to achieve the effect of inhibiting or killing microorganisms such as bacteria. However, each of the three materials has obvious problems. Specifically:

[0003] (1) Traditional piezoelectric materials such as ZnO and BTO will cause lattice distortion when subjected to mechanical pressure, resulting in separation of positive and negative charge centers inside, and generating polarization charges. These polarization charges can interact with water molecules or oxygen molecules in the surrounding environment to produce reactive oxygen species (ROS) such as hydroxyl radicals (·OH), superoxide anion radicals (O2· - ), etc. ROS has strong oxidizing properties and can destroy the cell membranes, proteins and DNA of bacteria, thereby achieving bacterial inactivation and sterilization.

[0004] However, the existing traditional piezoelectric materials also have major problems. On the one hand, due to the limited separation efficiency of electron-hole pairs inside the piezoelectric material, and the recombination of some polarization charges inside the material, the number of effective charges participating in the generation of ROS is insufficient, and the ROS generation efficiency is low. On the other hand, due to the chemical composition and surface properties of the piezoelectric material, metal ions in the material are prone to leaching during use, which can potentially be toxic to living organisms. In addition, the roughness and charge distribution of the material surface are not conducive to cell adhesion and growth, and the biocompatibility is poor, which limits its wide application in the biomedical field.

[0005] (2) After absorbing light of a specific wavelength, the valence band electrons of the photocatalytic material are excited to the conduction band to form photo-generated electron-hole pairs. The photo-generated holes have strong oxidizing properties and can oxidize water molecules adsorbed on the surface of the material to generate ·OH. The photo-generated electrons can combine with oxygen molecules to generate O2· - , etc. These ROS can attack bacterial cells, causing damage to the cell wall and cell membrane of the bacteria, and leakage of cell contents, thereby achieving bacterial inactivation and sterilization.

[0006] However, photocatalytic materials rely on ultraviolet light for excitation, and ultraviolet light accounts for a small proportion of sunlight, and is even more scarce in indoor environments, which greatly limits its energy utilization rate and actual application scenarios. In addition, photocatalytic materials are prone to photo-corrosion during long-term use, which can cause a decline in material performance and affect the sterilization effect. At the same time, the recombination rate of photo-generated carriers of photocatalytic materials is high, which reduces the ROS generation efficiency.

[0007] (3) Nanomaterials include metal oxide nanoparticles (such as TiO2 nanoparticles), noble metal nanoparticles (such as Ag nanoparticles), etc., all of which have unique physical and chemical properties and can produce ROS to kill bacteria through various ways. Metal oxide nanoparticles can generate electron-hole pairs when exposed to light or interact with biomolecules, which in turn generate ROS. Ag nanoparticles can generate hot electrons through surface plasmon resonance, which react with the surrounding oxygen and water to generate ROS. In addition, the high specific surface area of nanomaterials allows them to adsorb more bacteria, increasing the probability of contact with bacteria and facilitating the attack of ROS on bacteria.

[0008] However, nanomaterials are prone to agglomeration due to their nanoscale size, which reduces the specific surface area and shields functional sites, reducing the contact area and reactivity with bacteria and affecting ROS generation and bactericidal effect. At the same time, the size, shape, and surface charge of nanomaterials have a significant impact on their bactericidal performance, making it difficult to precisely control the preparation process to achieve stable bactericidal performance. In addition, the safety of nanomaterials in biological systems needs further study, and some nanomaterials may have potential toxicity to biological systems.

[0009] In summary, the traditional piezoelectric materials, photocatalytic materials, and nanomaterials in the prior art have low ROS generation efficiency, low energy utilization rate, and reduced functional sites due to the inherent properties of the materials, which need to be addressed through innovation in material design and preparation technology. SUMMARY

[0010] The present application provides a kind of amino acid functionalization barium titanate piezoelectric nanocomposite and its preparation method and application to solve the problems of low ROS generation efficiency, low energy utilization rate and reduced functional sites of existing antibacterial functional materials. Specifically, barium titanate (BTO) nanoparticles are synthesized by solvothermal method, and then ultrasonic self-assembly with amino acid (glycine) is prepared. The material can produce strong piezoelectric polarization under ultrasonic stimulation, significantly improve the ROS generation efficiency, promote the rapid degradation of toxic organic dyes, and also have high-efficiency broad-spectrum antibacterial activity and good biocompatibility. In 80 minutes, 92.08% of Congo red dye and 92.00% of rhodamine B dye can be degraded, and the inactivation rate of gram-negative bacteria (Escherichia coli) and / or gram-positive bacteria (Enterococcus faecalis) is more than 97%. As can be seen, the amino acid functionalization barium titanate piezoelectric nanocomposite provided by the present application has high efficiency, low energy consumption and environmental friendly characteristics, and can be widely used in the field of antibacterial and / or organic dye degradation technology.

[0011] To achieve the above object, the present application provides a kind of amino acid functionalized barium titanate piezoelectric nanocomposite, the composite material is formed by barium titanate nanoparticles and amino acid by ultrasonic assisted self-assembly, wherein the mass ratio of barium titanate nanoparticles and amino acid is (6:4)-(8:2);Preferably, the mass ratio of barium titanate nanoparticles and amino acid is 7:3.

[0012] In a preferred embodiment, the amino acid is glycine.

[0013] In a preferred embodiment, the preparation method of the barium titanate nanoparticles comprises the following steps:

[0014] S1 BaCl2·2H2O is mixed with titanium tetrachloride, and stirred uniformly;

[0015] S2 after stirring uniformly, oxalic acid is added, and ammonia water is added to adjust the pH of the system to 9-11, and hydrothermal reaction is carried out;

[0016] S3 the reaction product is washed to neutral, calcined, ground, and the barium titanate nanoparticles with a particle size of 5-15 nm are obtained.

[0017] Preferably, in step S1, the molar ratio of barium chloride and titanium tetrachloride is (3:10)-(5:1);More preferably, the molar ratio of barium chloride and titanium tetrachloride is 50:91.

[0018] Preferably, in step S1, the stirring time is 0.5-1 hour.

[0019] Preferably, in step S2, the molar ratio of oxalic acid to BaCl2·2H2O is (0.5-2):1;More preferably, the molar ratio of oxalic acid to BaCl2·2H2O is 1:1.

[0020] Preferably, in step S2, the pH of the system is adjusted to 10 after adding ammonia water.

[0021] Preferably, in step S2, the hydrothermal reaction conditions include: 90-110 ℃ for 18-30 hours;More preferably, the hydrothermal reaction conditions include: 100 ℃ for 24 hours.

[0022] Preferably, in step S3, the washing method can adopt the conventional way mastered by those skilled in the art, such as repeatedly washing with deionized water 2-4 times until the washing liquid is neutral.

[0023] Preferably, in step S3, the calcination conditions include: calcination temperature 350-450 ℃, calcination time 1-3 hours;More preferably, the calcination conditions include: calcination temperature 400 ℃, calcination time 2 hours.

[0024] Preferably, in step S3, the barium titanate nanoparticles have a particle size of 8-10 nm.

[0025] In the present application, by limiting the element ratio of barium and titanium, limiting the pH of the system to 9-11, and the water reaction conditions, a barium titanate (BTO) nanocrystal with a particle size of only 5-15 nm is formed. The specific reaction mechanism is as follows: first, oxalic acid is added to control the size of the nanoparticles, laying the foundation for obtaining ultra-small size nanoparticles.

[0026] Further, as a typical perovskite structure (ABX3), barium titanate (BTO) nanocrystals require barium ions to occupy the A site, while titanium ions and oxygen ions are located at the B site and X site, respectively. The present application particularly adds ammonia to adjust the pH of the solution to 9-11, providing a high concentration of OH-, which on the one hand inhibits the Ostwald ripening of barium titanate small particles and the phagocytosis of large particles, and on the other hand promotes the rapid coordination polymerization of barium titanate precursors to form a large number of uniform crystal nuclei, inhibiting non-uniform growth. However, it was found through experiments that if the pH of the solution is greater than 12, the precipitate will dissolve, therefore, the present application limits the pH range as described above.

[0027] Further, the present application strictly limits the hydrothermal synthesis parameters, if the heating is excessive or the reaction time is prolonged, the crystal structure will be destroyed and the grain will abnormally grow, thereby weakening the piezoelectric performance, on the contrary, if the heating is insufficient or the reaction time is too short, impurity phase crystals that have not fully grown will be easily produced, therefore, the present application adopts a moderate condition of 90-110℃ hydrothermal reaction for 18-30 hours to ensure the uniform growth of nanocrystals and maintain the structural integrity.

[0028] Finally, the sintering temperature of the present application is 350-450℃, if the temperature is too high, the perovskite structure will be destroyed, and if it is too low, the impurities cannot be effectively removed, therefore, a slow and moderate sintering process is required to optimize the material performance.

[0029] In summary, the present application effectively controls the size of barium titanate (BTO) nanocrystals by limiting the above parameters, the obtained nanoparticles have a particle size of only 5-15 nm and excellent dispersibility. At the same time, the specific surface area, dielectric constant and other properties of the material are also improved, breaking through the bottleneck of traditional processes.

[0030] The present application also provides a preparation method of any one of the above amino acid functionalized barium titanate piezoelectric nanocomposites, which specifically comprises the following steps: weighing barium titanate nanoparticles and amino acid according to a mass ratio of (6:4)-(8:2), and respectively preparing a barium titanate solution and an amino acid solution, mixing the solutions and ultrasonic dispersing for a period of time, and drying to obtain the amino acid functionalized barium titanate piezoelectric nanocomposite.

[0031] In a preferred embodiment, the solvent in the barium titanate solution and / or the amino acid solution is deionized water; preferably, the solvent in the barium titanate solution and the amino acid solution is deionized water in equal volume.

[0032] In a preferred embodiment, the barium titanate solution and / or the amino acid solution is prepared by further including ultrasonic dispersion of the solute in the solvent, the ultrasonic dispersion condition including an ultrasonic frequency of 5-100 MHz, an ultrasonic power density of 0.1-5 W / cm 2 , and an ultrasonic time of 3-5 hours to improve the dispersion effect of the solute in the solution; more preferably, the ultrasonic frequency is 40 MHz, the ultrasonic power density is 1 W / cm 2 , and the ultrasonic time is 4 hours.

[0033] In a preferred embodiment, the ultrasonic dispersion condition of the mixed solution includes an ultrasonic frequency of 5-100 MHz, an ultrasonic power density of 0.1-5 W / cm 2 , and an ultrasonic time of 3-5 hours; more preferably, the ultrasonic dispersion condition of the mixed solution includes an ultrasonic frequency of 40 MHz, an ultrasonic power density of 1 W / cm 2 , and an ultrasonic time of 4 hours.

[0034] In a preferred embodiment, the drying condition can use a conventional method mastered by those skilled in the art, such as drying at 50-70°C for 1-2 hours.

[0035] In the prior art, glycine is only used as an initiator or a doping aid in a synthesis reaction, while in the present application, glycine is directly used for surface modification of barium titanate nanoparticles for the first time. The functions of glycine include: first, the hydrophilic group of glycine can improve the dispersibility of barium titanate in an aqueous system and avoid agglomeration; second, the amino group and the carboxyl group can act as active sites for self-assembly to guide the nanoparticles to arrange in a specific orientation; further, the natural amino acid property of glycine can improve the applicability of the composite material in the biomedical field; finally, the polar side chain of the amino acid can regulate the polarization direction of barium titanate to improve the electromechanical conversion efficiency and thus generate a better piezoelectric response. At the same time, the present application performs self-assembly through specific ultrasonic conditions (an ultrasonic frequency of 5-100 MHz, an ultrasonic power density of 0.1-5 W / cm 2 , and an ultrasonic time of 3-5 hours) to obtain an amino acid functionalized piezoelectric nanocomposite material, while also having the advantages of simple processing, easy operation, and low requirements for equipment and energy consumption.

[0036] The application also provides application of the amino acid functionalized barium titanate piezoelectric nanocomposite in ultrasonic-assisted ROS generation, and specifically includes: triggering a piezoelectric effect through ultrasonic stimulation, enhancing ROS generation, efficiently promoting degradation of toxic dyes (such as Congo red and rhodamine B) and / or being used for spectral bacterial inactivation (such as Escherichia coli and Enterococcus faecalis).

[0037] In a preferred embodiment, the ultrasonic stimulation has an ultrasonic frequency of 0.01-100 MHz and an ultrasonic power density of 0.01-20 W / cm 2 .

[0038] In a preferred embodiment, the inactivation rate of the composite material on gram-negative bacteria and / or gram-positive bacteria is 97.34% and 98.76%, respectively.

[0039] In a preferred embodiment, the dosage of the composite material is 1 mg / mL, and after 80 minutes of treatment, the degradation rate of Congo red is 92.08%, and the degradation efficiency of rhodamine B is 92.00%.

[0040] Compared with the prior art, the technical scheme of the application has the following advantages:

[0041] The technical scheme of the application is based on glycine-modified barium titanate (BTO) nanoparticles, and an amino acid functionalized piezoelectric nanocomposite (BTG) is prepared through ultrasonic self-assembly.

[0042] From the mechanism of action, the dispersion of the material can be improved and the synergistic effect of piezoelectric-catalysis can be enhanced through glycine functionalization of BTO; and the continuous generation of ROS can be promoted through ultrasonic stimulation to trigger piezoelectric polarization, without the need for external light excitation.

[0043] From the preparation method, the preparation process of the application is simple and efficient, has low energy consumption and low requirements for equipment, and is especially suitable for large-scale industrial production. At the same time, the application method of degradation and antibacterial is easy to operate and has low energy consumption, and has a broad application prospect.

[0044] From the product performance, the amino acid functionalized barium titanate piezoelectric nanocomposite prepared by the application has high efficient antioxidant capacity, can be used for enhancing reactive oxygen species (ROS) generation, promoting rapid degradation of toxic organic dyes, and has high efficient broad-spectrum antibacterial activity and good biocompatibility. Specifically, the prepared BTG has significant piezoelectric polarization under ultrasonic stimulation, and the ROS yield can be increased by more than 2 times compared with traditional piezoelectric materials. In terms of antioxidant capacity, the degradation efficiency of Congo red and rhodamine B within 80 minutes is 92.08% and 92.00% respectively. In terms of broad-spectrum antibacterial activity, the inactivation rate of gram-negative bacteria (Escherichia coli) and gram-positive bacteria (Enterococcus faecalis) is more than 97%. In terms of biological safety, the survival rate of normal cells (WI-38) is >95%, indicating that the material has good biocompatibility. BRIEF DESCRIPTION OF DRAWINGS

[0045] These and / or other aspects and advantages of the present application will become more apparent and more readily appreciated from the following detailed description of the embodiments of the present application, taken in conjunction with the accompanying drawings in which:

[0046] Figure 1 The characterization results of BTO prepared in Example 1 and BTG prepared in Example 2 of the present application include XRD (A), refined crystal structure (B), FT-IR spectrum (C), FESEM (D), TEM (E) and Zeta potential (F);

[0047] Figure 2 The piezoelectric property test results of BTG prepared in Example 2 of the present application include amplitude / phase hysteresis loop (A-B), optical band gap (C), COMSOL simulation piezoelectric polarization (D-E), polarization response under different pressures (F), ROS generation mechanism under ultrasonic stimulation (G) and EPR spectrum (H-I);

[0048] Figure 3 The organic dye degradation results of BTG prepared in Example 2 of the present application include degradation kinetics (A-B), efficiency (C), rate constant (D-E), cyclic stability (F) and ROS scavenging experiment (G-I);

[0049] Figure 4 The in vitro antibacterial experiment results of BTG prepared in Example 2 of the present application include antibacterial mechanism (A), cytotoxicity (B), bacterial SEM morphology (C), colony count (D-F) and ROS generation verification (G-H). DETAILED DESCRIPTION

[0050] In order to enable those skilled in the art to better understand the present application, the present application will be further described in detail below in conjunction with the drawings and specific embodiments, but it should be understood that the protection scope of the present application is not limited by the specific embodiments.

[0051] The technical solutions of the present application are described in detail below through specific examples.

[0052] If not specifically indicated, the technical means used in the present application are conventional means familiar to those skilled in the art, and various raw materials, reagents, instruments and equipment used in the present application can be purchased on the market or prepared by existing methods. The reagents used in the present application are analytical pure unless otherwise specified.

[0053] Example 1

[0054] The preparation method of barium titanate nanoparticles (BTO) comprises the following steps:

[0055] S1: 0.5M BaCl2·2H2O (60mL) is added dropwise to a TiCl4 (6mL) solution (molar ratio of the two is 50:91), and stirred for 1 hour;

[0056] S2: 0.5M oxalic acid (30mL) is added, and then ammonia water is added to adjust the pH of the system to 10, and hydrothermal reaction is carried out at 100℃ for 24 hours;

[0057] S3: The reaction product is washed with deionized water until neutral, calcined at 400℃ for 2 hours, and ground to obtain BTO powder with a particle size of 8-10nm.

[0058] Example 2

[0059] The preparation method of amino acid functionalized barium titanate piezoelectric nanocomposite (BTG) comprises the following steps:

[0060] (1) 0.3g glycine is dissolved in 30mL deionized water, and ultrasonic dispersion is carried out at 40MHz and 1W / cm 2 for 4 hours; the barium titanate nanoparticles (0.7g) prepared in Example 1 are dispersed in 30mL deionized water, and ultrasonic dispersion is carried out at 1W / cm 2 for 4 hours;

[0061] (2) The prepared glycine solution and BTO solution are mixed, and ultrasonic dispersion is carried out at 40MHz and 1W / cm 2 for 4 hours, and then dried at 60℃ for 2 hours to obtain the BTG composite material.

[0062] Application Example 1

[0063] The BTO prepared in Example 1 and the BTG prepared in Example 2 are subjected to characterization analysis, and the results are shown in Table 1. Figure 1

[0064] ​X-ray diffraction (D8-Advanced, Bruker, 35 kV / 35 mA, Cu-Ka radiation l = 1.5418 nm) was used to analyze the phase purity and crystal structure of barium titanate (BTO) and glycine-modified barium titanate (BTG) nanoparticles in the range of 10°–80° 2q with a scan rate of 0.5 s / step. The presence of 63.05% tetragonal BTO (space group P4mm, characteristic diffraction planes (100) / (110) / (111) / (211)) and 36.95% monoclinic Ba6Ti 17 O 40 :71-2110) confirmed the presence of 63.05% tetragonal BTO (space group P4mm, characteristic diffraction planes (100) / (110) / (111) / (211)) and 36.95% monoclinic Ba6Ti 17 O 40 (peak 2q = 28.21°, phase marker -531) in the sample, the latter originated from the formation of excess Ti02during calcination, which was confirmed by Rietveld refinement based on BTO / Ba6Ti 17 O 40 crystal information files (CIF) using MAUD software (refinement parameters are shown in Table 1, lattice structure visualization is shown in Figure 1B), while no new phase was formed in BTG nanoparticles, but the XRD peak intensity was significantly reduced due to the decrease in effective diffraction volume. Figure 1 B), while no new phase was formed in BTG nanoparticles, but the XRD peak intensity was significantly reduced due to the decrease in effective diffraction volume.

[0065] Table 1 Crystallographic parameters

[0066]

[0067] Further analysis of chemical bond vibration patterns was performed by Fourier transform infrared spectroscopy (FTIR, IR Affinity, 400–4000 cm -1 , ATR accessory). Characteristic vibrations of Ti–O bonds were observed at 427 / 474 / 530 / 849 / 1469 cm -1 in BTO (474 cm -1 assigned to Ti–O polar axis vibration, 530 cm -1 to Ti–O stretching vibration, and 1469 cm -1 corresponding to COO- bending vibration in the acidic ligand used for synthesis), while a new C=0 characteristic peak at 1700 cm -1 in the BTG spectrum confirmed the presence of -COOH in glycine, and doublet peaks at 3300–3500 cm -1 indicated -NH2functional groups.

[0068] Morphology was characterized by a combination of field emission scanning electron microscopy (FESEM, Inspect–F50, 10–20 kV) and transmission electron microscopy (TEM, JEM-2100Plus, 200 kV). The carbon-coated gold-plated pretreated samples showed that the BTG nanoparticles had a cubic morphology. Figure 1 D), TEM confirmed that its size distribution is 50–80 nm. Figure 1 E); Zeta potential analysis (Malvern Zetasizer) indicates ( Figure 1 F) The original BTO exhibits excellent stability due to its high positive charge, while the BTG nanocomposite has a slightly reduced surface positive charge, resulting in a slight decrease in stability. However, its positive charge still helps to target the negatively charged cell membrane of pathogenic bacteria through electrostatic potential and achieve efficient adsorption.

[0069] Application Example 2

[0070] The piezoelectric properties of the BTG prepared in Example 2 were tested, and the results are as follows: Figure 2 As shown.

[0071] Piezoelectric microscopy (PFM) characterization revealed significant piezoelectric and piezoelectric catalytic properties of the sample: ferroelectricity was verified by the typical butterfly-shaped amplitude hysteresis loop when the external electric field was reversed. Figure 2 A) The calculated piezoelectric coefficient d 33 ≈23.85pm·V -1 This indicates a significant improvement in piezoelectric modulus. This enhancement effect is attributed to glycine modification regulating the bandgap and widening the bandgap, promoting electron-hole separation. Doping-induced lattice distortion further strengthens piezoelectric polarization, with the phase diagram showing an approximately 180° reversal under ±8V DC bias. Figure 2 B) confirms the polarization reversal phenomenon inside the material.

[0072] Band structure analysis confirms the modification mechanism: Tauc curve ((αhν)) 2 -hν relation, Figure 2 C) shows that the band gap of BTG nanoparticles is reduced to 1.25 eV (BTO is 1.49 eV). This band gap reduction effect is due to the introduction of electronic states by the glycine -NH2 / -COOH group near the conduction / valence band of BaTiO3, and the presence of oxygen vacancies or Ti... 3+ Defect states form additional energy levels, and the narrow bandgap characteristics effectively improve charge separation efficiency and reactive oxygen species (ROS) yield under mechanical stimulation.

[0073] Finite element simulation (COMSOL Multiphysics) quantitatively elucidates the piezoelectric enhancement mechanism: applying a 100MPa / 1MHz periodic pressure to simulated nanosheets. Figure 2 DE can induce significant deformation and piezoelectric charge separation within a pressure range of 0.1–100 MPa. Figure 2F) The charge center separation along x, y, z axis is linearly related to the external force, which indicates its potential application in MRSA sterilization (enhancing ROS), bone tissue regeneration (activating MSCs calcium ion channel) and macrophage polarization regulation.

[0074] Electron paramagnetic resonance (EPR) confirmed the ROS generation mechanism: DMPO was used as a probe to detect ·OH (DMPO-OH adduct, quadruplet hyperfine splitting constant ≈ 14.9 G) and O2 - (DMPO-OOH adduct, doublet of triplets splitting constant ≈ 10-11 G) in water / DMSO solvent. The ROS signal intensity in aqueous phase was significantly higher than that in DMSO under ultrasonic conditions, confirming that hydroxyl radicals and superoxide anions were the key active species for degrading organic dyes and destroying bacterial cell walls.

[0075] Application Example 3

[0076] The BTG prepared in Example 2 was tested for organic dye degradation. The specific testing methods and results included:

[0077] Piezocatalytic degradation performance was studied by selecting acid-base dyes rhodamine B (RhB) and Congo red (CR) with an initial concentration of 10 ppm as model pollutants: Telesonic ultrasonic instrument (15 kHz) was used to treat dye solution (20 mL) containing BTG nanocatalyst (1 mg / mL), and ice bath was used to maintain a constant temperature of 25°C during the 80-minute degradation process; Perkin Elmer Lambda 25 ultraviolet-visible spectrophotometer (monitoring wavelength 554 nm) was used to determine the concentration change Figure 3 A-B), and the kinetic formula

[0078]

[0079] C = C0 exp(-kt)

[0080] The degradation rates of CR and RhB were calculated to be 92.08% and 92.00%, respectively, and the first-order reaction rate constant k was obtained from the slope of the -ln(C / C0)-t curve Figure 3 E shows that the degradation rate of CR is higher);

[0081] Circulation stability verification: after four repeated uses, the catalyst activity only decreased by about 2% Figure 3 F), which is due to the loss of surface active sites and the decrease in specific surface area caused by nanoparticle agglomeration during the washing and drying process; free radical capture experiments revealed the reaction mechanism: the addition of quenching agents such as DMSO, benzoquinone (BQ) and ethylenediaminetetraacetic acid (EDTA) Figure 3The results showed that DMSO significantly promoted the degradation of RhB (the linear relationship between C0 / Ct confirmed the first-order kinetic characteristics). Combined with the degradation rate variation, it was confirmed that the degradation process of organic dyes was mainly dominated by DMSO radicals.

[0082] Application Example 4

[0083] The BTG prepared in Example 2 was subjected to in vitro antibacterial experiments. The piezoelectric catalytic antibacterial mechanism was studied using Gram-negative Escherichia coli DH5α (E. coli) and Gram-positive Enterococcus faecalis (E. faecalis) as models. Figure 4 A):

[0084] Biocompatibility tests showed that BTG nanoparticles maintained a survival rate of >85% in WI-38 cells even at high doses. Figure 4 B) confirms its biosafety.

[0085] Standard piezoelectric dynamic therapy (PZDT) experiments were conducted at 37℃ / 120rpm. LB medium was supplemented with BTG (1 mg) followed by sonication (with 10-minute intervals) (ultrasound power density 1.5 W / cm²). 2 The colony counting method (ultrasound duty cycle 50%) showed that the ultrasound combined with BTG achieved a kill rate of 97.34% and 98.76% for Gram-negative and Gram-positive bacteria respectively within 30 minutes. Figure 4 The EF (effect of ultrasound) was significantly higher than that of the ultrasound-only group (weak thermal / mechanical effect) and the blank control group.

[0086] ROS generation mechanism analysis: DCFH-DA fluorescent probe (excitation 495nm / emission 600nm) confirms that ultrasonic activation of BTG generates a large amount of ROS. Figure 4 The intensity of GH increases over time and is positively correlated with the formation of the fluorescent product DCF.

[0087] The bactericidal mechanism of the BTG prepared in this invention includes: 1) electrostatic interaction: negatively charged BTG nanoparticles strongly bind to positively charged bacterial cell membranes; 2) oxidative stress: mechanical stress induces piezoelectric polarization to generate O2. - Free radicals such as OH and H2O2 induce lipid peroxidation, protein / DNA damage, and disruption of the electron transport chain; 3) Membrane structure collapse: FESEM directly observed perforation and shrinkage of bacterial membranes and cytoplasmic leakage in the ultrasound-BTG group. Figure 4 C and D), while the control group had an intact membrane structure. Furthermore, the BTG prepared in this invention also exhibits differences in bacterial species: Gram-positive bacteria, lacking an outer membrane lipopolysaccharide layer, are more susceptible to electrostatic effects, and the continuous mechanical stress induced by BTG enhances the piezoelectric response, synergistically promoting the explosive generation of free radicals, ultimately leading to the collapse of the cell defense system and irreversible death.

[0088] From the experimental results, it can be seen that the amino acid functionalized barium titanate piezoelectric nanocomposite prepared by the application has high efficient antioxidant capacity, has significant effect in promoting degradation of toxic organic dyes and spectral antibacterial, and has wide application prospect in the field of medical antibacterial due to its good biocompatibility.

[0089] The foregoing description of specific exemplary embodiments of the application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain the principles of the application and its practical application, to thereby enable others skilled in the art to implement and utilize the application in various embodiments and with various modifications as are suited to the particular use contemplated. The scope of the application is intended to be defined by the claims and their equivalents.

Claims

1. An amino acid functionalized barium titanate piezoelectric nanocomposite, characterized in that, The composite material is formed by ultrasonic-assisted self-assembly of barium titanate nanoparticles and amino acids, wherein the mass ratio of barium titanate nanoparticles to amino acids is (6:4)-(8:2).

2. The amino acid functionalized barium titanate piezoelectric nanocomposite of claim 1, wherein, The amino acid is glycine.

3. The amino acid functionalized barium titanate piezoelectric nanocomposite of claim 1, wherein, The preparation method of the barium titanate nanoparticles comprises the following steps: S1: mixing BaCl2.2H2O and titanium tetrachloride and stirring uniformly; S2: adding oxalic acid and stirring uniformly, then adding ammonia to adjust the pH of the system to 9-11, and performing hydrothermal reaction; S3: washing the reaction product to neutral, calcining, and grinding to obtain barium titanate nanoparticles with a particle size of 5-15 nm.

4. The amino acid functionalized barium titanate piezoelectric nanocomposite of claim 3, wherein, In step S1, the molar ratio of barium chloride to titanium tetrachloride is (3:10)-(5:1).

5. The amino acid-functionalized barium titanate piezoelectric nanocomposite material as described in claim 3, characterized in that, In step S2, the molar ratio of oxalic acid to BaCl2.2H2O is (0.5-2):1; In step S2, the hydrothermal reaction conditions include: 90-110℃ for 18-30 hours; In step S3, the calcination conditions include: calcination temperature 350-450℃, calcination time 1-3 hours.

6. The method for preparing the amino acid-functionalized barium titanate piezoelectric nanocomposite material according to any one of claims 1-5, characterized in that, The method comprises the following steps: Barium titanate nanoparticles and amino acids are weighed according to the mass ratio (6:4)-(8:2), and barium titanate solution and amino acid solution are prepared respectively, then the solutions are mixed and ultrasonically dispersed for a period of time, and then dried to obtain the amino acid functionalized barium titanate piezoelectric nanocomposite material.

7. The method for preparing the amino acid-functionalized barium titanate piezoelectric nanocomposite material as described in claim 6, characterized in that, The ultrasonic dispersion conditions of the mixed solution include: ultrasonic frequency of 5-100 MHz, ultrasonic power density of 0.1-5 W / cm 2 , and ultrasonic time of 3-5 hours.

8. Use of the amino acid functionalized barium titanate piezoelectric nanocomposites according to any one of claims 1-5 for the ultrasound-assisted generation of ROS, characterized in that, The application includes the application in antibacterial and / or organic dye degradation.

9. The application of the amino acid-functionalized barium titanate piezoelectric nanocomposite material as described in claim 8, characterized in that, The inactivation rate of the composite material on gram-negative bacteria and / or gram-positive bacteria is 97.34% and 98.76%, respectively.

10. Use of the amino acid functionalized barium titanate piezoelectric nanocomposite as claimed in claim 8, wherein, The degradation rate of Congo red is 92.08% and the degradation efficiency of rhodamine B is 92.00% after 80 minutes of treatment with the dosage of 1 mg / mL of the composite material.

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