Piezoelectric fluorescent composite material, preparation method and application thereof

Abstract

This invention belongs to the field of piezoelectric nanomaterials technology, and relates to a piezoelectric fluorescent composite material, its preparation method, and its application. The piezoelectric fluorescent composite material comprises amino-modified composite oxide nanoparticles and carboxyl-modified gold nanoparticles, which are linked by amide bonds formed by the dehydration condensation of amino and carboxyl groups; the chemical formula of the composite oxide nanoparticles is BaTiO3@mSiO2:Eu. 3+ The composite oxide nanoparticles include hollow mesoporous silica nanoparticles (SiO2) and europium-doped barium titanate nanoparticles (BaTiO3:Eu) loaded on the surface and inside of their mesoporous structures. 3+ The piezoelectric fluorescent composite material of the present invention emits orange light with a wavelength of 575-590 nm and red light with a wavelength of 590-620 nm when excited at 395 nm; it can be applied to photothermal and temperature-changing fields to achieve efficient thermotherapy and monitor temperature changes in real time.

Description

Technical Field

[0001] This invention belongs to the field of piezoelectric nanomaterials technology, specifically relating to a piezoelectric fluorescent composite material, its preparation method, and its application. Background Technology

[0002] The application of piezoelectric nanomaterials in temperature measurement stems from the general limitations of traditional temperature measurement technologies in terms of accuracy, size, response speed, and power supply. These limitations are becoming increasingly prominent, especially in current high-tech and extreme environment monitoring scenarios. Conventional temperature sensors, such as thermocouples and thermistors, are often limited by their large size, slow response, need for external power supply, and susceptibility to electromagnetic and environmental interference in applications such as real-time monitoring implanted in biological organisms, nanoscale hot spot detection in semiconductor devices, deep-sea exploration, or high-temperature industrial reaction environments. These limitations make it difficult to meet the stringent temperature measurement requirements of micro- and nanoelectronic devices for submicron-level spatial resolution and nanosecond-level temporal resolution.

[0003] In contrast, piezoelectric nanomaterials, such as PZT nanowires, ZnO nanofilaments, and BaTiO3-based composites, can directly convert temperature signals into electrical signals by leveraging the sensitive characteristics of their key physical properties, such as piezoelectric coefficient and dielectric constant, as they change with temperature. This mechanism endows them with comprehensive advantages, including self-powered operation, rapid response (detection sensitivity on the order of 0.1℃), and miniaturized structure. Furthermore, through modification methods such as material doping, compositing, and structural design, their temperature stability and operating temperature range can be effectively controlled, thereby better adapting to the precise temperature measurement needs of cutting-edge fields such as tumor hyperthermia monitoring in biomedicine, thermal management of new energy battery systems, and sensing and monitoring in extreme environments using the Internet of Things.

[0004] Although piezoelectric nanomaterials have shown significant potential in temperature measurement and have gradually penetrated into daily life and high-tech fields, several key issues still need to be addressed in their practical applications. First, the temperature and long-term stability of their core piezoelectric and dielectric properties remain insufficient, making them prone to performance degradation and signal drift during repeated temperature changes or prolonged use. Furthermore, the fabrication processes for some high-performance piezoelectric nanomaterials are complex and costly, and the effective temperature measurement range of existing materials is relatively limited. These factors all restrict their large-scale promotion and practical engineering applications. Summary of the Invention

[0005] The purpose of this invention is to provide a piezoelectric fluorescent composite material, its preparation method, and its application, thereby overcoming the shortcomings of the prior art, providing the preparation of small-particle-size, high-precision piezoelectric fluorescent materials and their application in temperature-dependent applications, and solving the problems of complex preparation process, high cost, and unstable piezoelectric and other core properties in the prior art.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a piezoelectric fluorescent composite material comprising amino-modified composite oxide nanoparticles and carboxyl-modified gold nanoparticles, wherein the amino-modified composite oxide nanoparticles and carboxyl-modified gold nanoparticles are connected by amide bonds formed by the dehydration condensation of amino and carboxyl groups.

[0008] The chemical formula of the composite oxide nanoparticles is BaTiO3@mSiO2:Eu 3+ The composite oxide nanoparticles include hollow mesoporous silica nanoparticles (SiO2) and europium-doped barium titanate nanoparticles (BaTiO3:Eu) loaded on the surface and inside of their mesoporous structures. 3+ .

[0009] The piezoelectric fluorescent composite material of this invention achieves efficient and stable conversion from mechanical force to fluorescence signal through the synergistic effect of its components. Among them, hollow mesoporous SiO2 serves as a multifunctional carrier, and its high specific surface area not only stably supports BaTiO3:Eu 3+ The functional units also ensure the effective transfer and distribution of stress within the structure. When the material is subjected to stress, the piezoelectric effect of BaTiO3 converts mechanical energy into a localized electric field, which directly modulates the adjacent Eu field. 3+ The luminescence behavior of ions completes the core process of force-to-light signal conversion. Simultaneously, carboxyl-based gold nanoparticles covalently linked by amide bonds can undergo temperature rise due to their surface plasmon resonance effect, thus possessing potential for photothermal therapy. Temperature detection can be achieved by detecting fluorescence changes during the photothermal process. Amino and carboxyl groups form strong amide bonds through dehydration condensation, tightly connecting the components. This ensures structural integrity and long-term stability, providing a reliable channel for efficient stress transfer and energy transfer.

[0010] In some other embodiments, the mass ratio of amino-modified composite oxide nanoparticles to carboxyl-modified gold nanoparticles is 2:(4-6). Specifically, the mass ratio of amino-modified composite oxide nanoparticles to carboxyl-modified gold nanoparticles is 2:4, 2:5, or 2:6, or any range thereof. This ratio enables a high-density and stable interconnection network, ensuring efficient stress transfer; simultaneously, it facilitates the achievement of optimal gold nanoparticle distribution density, effectively enhancing Eu through surface plasmon resonance. 3+ It can achieve an ideal balance between structural stability and enhanced optical performance by maintaining the fluorescence signal while avoiding fluorescence quenching caused by excessive aggregation.

[0011] In some other embodiments, the mass ratio of hollow mesoporous silica nanoparticles to europium-doped barium titanate nanoparticles is 1:(0.8-1.5);

[0012] Ba in europium-doped barium titanate nanoparticles 2+ With Eu 3+ The molar ratio is (7-9):(1-3).

[0013] Specifically, the mass ratio of hollow mesoporous silica nanoparticles to europium-doped barium titanate nanoparticles is 1:0.8, 1:1, 1:1.2, or 1:1.5, or any value within this range. This ratio allows the europium-doped barium titanate to fill the mesoporous space to the maximum extent, achieving a high-density, uniform distribution of the piezoelectric phase and fluorescent centers while avoiding nanoparticle aggregation or pore blockage.

[0014] Ba in europium-doped barium titanate nanoparticles 2+ With Eu 3+ The molar ratio is 7:3, 8:2, or 9:1, or any value within this range. At this ratio, barium ions ensure the stability of the perovskite lattice and maintain the material's excellent piezoelectric properties; europium ion doping is fully activated as a highly efficient fluorescence center, while avoiding the exacerbation of lattice distortion or fluorescence quenching caused by excessive doping. This allows the material to achieve both efficient electromechanical conversion and bright and stable fluorescence emission when excited by a piezoelectric field.

[0015] In some other embodiments, the amino-modified composite oxide nanoparticles are ellipsoidal with a particle size of 70-75 nm; the carboxyl-modified gold nanoparticles are spherical with a particle size of 60-65 nm.

[0016] Specifically, BaTiO3@mSiO2:Eu 3+ The nanoparticles are ellipsoidal in shape, with a diameter of approximately 72 nm; BaTiO3 nanoparticles are spherical, with a diameter of approximately 44 nm; and Au-COOH nanoparticles are spherical, with a diameter of approximately 61 nm. The ellipsoidal shape of the composite oxide particles provides a higher specific surface area and potential anisotropy, which is beneficial for stress bearing and functional units (such as Eu). 3+ The enrichment of gold nanoparticles with amide bonds and the similarly sized spherical gold nanoparticles ensure uniform dispersion and high surface activity. The particle size matching of the two not only promotes the formation of tight and ordered assembly through amide bonds, realizing efficient stress and energy transfer, but also enables the plasmon resonance peak of the gold nanoparticles to couple more effectively with the emission wavelength of the fluorescence center, thereby achieving synergistic optimization in terms of structural stability and optical signal enhancement.

[0017] In some other embodiments, the piezoelectric fluorescent composite material emits orange light with a wavelength of 575-590 nm and red light with a wavelength of 590-620 nm when excited at 395 nm.

[0018] The material exhibits three core advantages in its dual-band fluorescence emission (575-590 nm orange light and 590-620 nm red light): First, the strong emission peak in the red light region (originating from Eu) 3+ of 5 D0→ 7 The F2 transition, located in the optically transparent window of biological tissue, endows it with excellent in vivo penetration and bioimaging potential. Secondly, the emission of orange and red light can form a stable ratiometric fluorescence signal, which can be self-calibrated by intensity ratio rather than absolute intensity, significantly improving the reliability and anti-interference ability of mechanical stress sensing. Finally, this emission characteristic covering the long wavelength range of visible light can be effectively coupled with the surface plasmon resonance peak of gold nanoparticles, and further achieve selective enhancement of fluorescence signal on the stable interface constructed by amide bonds, thereby synergistically optimizing the comprehensive performance of this composite material in biosensing and high-precision mechanical detection.

[0019] In a second aspect, the present invention provides a method for preparing the piezoelectric fluorescent composite material of the first aspect, comprising the following steps:

[0020] The composite oxide nanoparticles BaTiO3@mSiO2:Eu 3+ After being treated with nitric acid and hydrogen peroxide in sequence, the nanoparticles were then reacted with 3-aminopropyltriethoxysilane, ammonia and anhydrous ethanol to obtain amino-modified composite oxide nanoparticles.

[0021] The composite oxide nanoparticles modified with amino groups and the gold nanoparticles modified with carboxyl groups are subjected to a dehydration condensation reaction between carboxyl and amino groups to obtain the final product.

[0022] This preparation method is the first to treat composite oxide nanoparticles sequentially with nitric acid and hydrogen peroxide to activate their surface and increase the density of silanol groups, which is beneficial for grafting amino functional groups. The composite oxide and gold nanoparticles are connected by covalent amide bonds, which ensures that each functional component (piezoelectric fluorescent oxide and plasma gold particles) maintains its excellent performance while achieving efficient and reliable force-to-light signal conversion.

[0023] In some other embodiments, the composite oxide nanoparticles BaTiO3@mSiO2:Eu 3+ The preparation method is as follows: mix barium source, europium source and alkaline solution, add oleic acid and oleylamine, heat and stir to dissolve, then add tetrabutyl titanate n-butanol solution and continue heating and stirring to dissolve, and then carry out hydrothermal reaction to obtain precipitate;

[0024] The precipitate was dissolved in an organic solvent, then an aqueous solution of hexadecyltrimethylammonium bromide was added, mixed well, and heated to remove the organic solvent. Then, 3-aminopropyltriethoxysilane, tetraethyl silicate, sodium hydroxide solution, and ethyl acetate were added and heated to react, thus obtaining the final product.

[0025] Specifically, the molar ratio of barium source to europium source is (7-9):(1-3); the mixed volume ratio of oleic acid and oleylamine is 2:(0.8-1.2); the concentration of tetrabutyl titanate in n-butanol solution is 0.08-0.12 mol / L; the europium salt is selected from europium chloride, europium nitrate, or europium acetate, and the barium source is selected from barium acetate, barium chloride, or barium nitrate. The alkaline solution is KOH, NaOH, or ammonia water; the heating and stirring temperature for dissolution is 55-65℃, and the hydrothermal reaction is carried out at 110-130℃ with sealing treatment for 15-20 h.

[0026] The organic solvent is chloroform, and the volume ratio of the organic solvent containing the precipitate to the aqueous solution of hexadecyltrimethylammonium bromide is 1:(4-5). The concentration of the aqueous solution of hexadecyltrimethylammonium bromide is 1-3 g / L. The temperature for removing the organic solvent by heating is 55-65℃, and after removing the organic solvent by heating, the solution is stabilized at 65-75℃ for 5-10 min.

[0027] The volume ratio of aminopropyltriethoxysilane, tetraethyl silicate, sodium hydroxide solution and ethyl acetate is 1:1:(0.6-0.8):(2-3); the reaction is carried out in an oil bath at 65-75℃ for 2-4 hours.

[0028] More specifically, the molar ratio of barium source to europium source is 8:2; the volume ratio of oleic acid to oleylamine is 2:1; the concentration of tetrabutyl titanate in n-butanol solution is 0.1 mol / L; the europium salt is europium acetate, and the barium source is barium nitrate. The alkaline solution is an aqueous solution of NaOH; the heating and stirring temperature for dissolution is 60℃, and the hydrothermal reaction is carried out at 120℃ under sealed conditions for 18 h.

[0029] The volume ratio of the organic solvent containing the precipitate to the aqueous solution of hexadecyltrimethylammonium bromide was 1:4.5, and the concentration of the aqueous solution of hexadecyltrimethylammonium bromide was 2 g / L. The organic solvent was removed by heating at 60℃, and the solution remained stable at 70℃ for 10 min after the organic solvent was removed by heating.

[0030] The volume ratio of aminopropyltriethoxysilane, tetraethyl silicate, sodium hydroxide solution, and ethyl acetate was 1:1:0.75:2.5; the reaction was carried out in an oil bath at 70°C for 3 hours.

[0031] In some other embodiments, the carboxyl-modified gold nanoparticles are prepared as follows: a hexadecyltrimethylammonium bromide solution, a chloroauric acid solution, and a sodium borohydride solution are mixed and stirred to obtain a gold nanocrystal seed solution;

[0032] The seed solution was then mixed with a growth solution consisting of hexadecyltrimethylammonium bromide solution, chloroauric acid solution and silver nitrate solution to carry out a growth reaction, thereby obtaining a carboxyl-modified gold nanoparticle solution.

[0033] Specifically, the volume ratio of hexadecyltrimethylammonium bromide solution, chloroauric acid solution, and sodium borohydride solution was 3:1:(10-20); the concentration of the hexadecyltrimethylammonium bromide solution was 0.1-0.15 mol / L, the concentration of the chloroauric acid solution was 0.01-0.1wt%, and the concentration of the sodium borohydride solution was 0.008-0.012 M. The growth reaction time was 20-30 h.

[0034] In some other embodiments, before the dehydration condensation reaction, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC), N-hydroxysuccinimide (NHS) and water are added to the carboxyl-modified gold nanoparticles to activate the carboxyl groups in the carboxyl-modified gold nanoparticles.

[0035] Specifically, the volume ratio of EDC to water is (3-5):1, the mass ratio of NHS to carboxyl-modified gold nanoparticles is 1:(18-22), and the activation time is 1-3 h.

[0036] Thirdly, the present invention provides the application of the piezoelectric fluorescent composite material of the first aspect in the preparation of temperature measuring products and photothermal therapy products. Specifically, the photothermal therapy product is a photothermal therapy drug.

[0037] The beneficial effects of this invention are:

[0038] (1) The piezoelectric fluorescent composite material of the present invention emits orange light with a wavelength of 575-590 nm and red light with a wavelength of 590-620 nm when excited at 395 nm.

[0039] (2) The preparation process of the present invention is clear, the conditions are mild, the raw materials used are inexpensive, and it is easy to scale up, laying a solid foundation for large-scale industrial production and application.

[0040] (3) The piezoelectric fluorescent composite material in this invention integrates luminescence and photothermal properties. By regulating its photothermal effect, it can not only be used for efficient photothermal therapy, but also use its fluorescence properties to perform real-time, in-situ optical monitoring of local temperature during the treatment process, thus realizing the synchronous integration of treatment and monitoring. Attached Figure Description

[0041] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0042] Figure 1 In Example 1 of this invention, BaTiO3@mSiO2:Eu 3+ X-ray diffraction pattern of nanoparticles;

[0043] Figure 2 The BaTiO3@mSiO2:Eu prepared in Example 1 of this invention 3+ Transmission electron microscopy (TEM) images of BaTiO3 and Au-COOH prepared in Example 3, where a represents BaTiO3@mSiO2:Eu 3+ Transmission electron microscopy (TEM) images of nanoparticles, scale bar 100 nm; b is a TEM image of BaTiO3 nanoparticles, scale bar 20 nm; c is a TEM image of Au-COOH, scale bar 200 nm.

[0044] Figure 3 In Example 1 of this invention, BaTiO3@mSiO2:Eu 3+ Emission spectrum of nanoparticles;

[0045] Figure 4 This is the absorption spectrum of Au-COOH in Example 3 of the present invention;

[0046] Figure 5 This is the Au-COOH absorption fitting curve in Example 3 of the present invention;

[0047] Figure 6 The Fourier transform infrared absorption spectrum of BT-NH2 in Example 2 of this invention;

[0048] Figure 7 This is the Fourier transform infrared absorption spectrum of Au-COOH in Example 3 of the present invention;

[0049] Figure 8 The Fourier transform infrared image of BT-Au in Embodiment 4 of the present invention;

[0050] Figure 9 In Example 1 of this invention, BaTiO3@mSiO2:Eu 3+ Typical temperature variation diagram of nanomaterials;

[0051] Figure 10 In Example 1 of this invention, BaTiO3@mSiO2:Eu 3+ Fluorescence intensity fitting curves of nanomaterials at ordinary temperature variations at wavelengths of 597 nm and 615 nm, where a is the fluorescence intensity fitting curve at wavelength of 597 nm and b is the fluorescence intensity fitting curve at wavelength of 615 nm.

[0052] Figure 11 This is a special temperature variation diagram of BT-Au in Embodiment 4 of the present invention;

[0053] Figure 12The following are fluorescence intensity fitting curves of BT-Au at wavelengths of 597 nm and 615 nm in Example 4 of the present invention, where a is the fluorescence intensity fitting curve at wavelength of 597 nm and b is the fluorescence intensity fitting curve at wavelength of 615 nm. Detailed Implementation

[0054] Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the invention. Specific conditions not specified in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Components whose manufacturers are not specified are all commercially available conventional products.

[0055] Existing single-temperature sensing materials suffer from complex preparation processes, high costs, low sensitivity, and are susceptible to environmental influences during use, leading to performance changes and poor stability. Therefore, there is an urgent need for a multifunctional material with a simple preparation process, easy identification, and resistance to counterfeiting.

[0056] Barium titanate (BaTiO3), as a typical perovskite ferroelectric material, exhibits unique application advantages in piezoelectric, photothermal, and temperature-dependent fields due to its intrinsic physicochemical properties. A barium carbonate-doped rare-earth particle piezoelectric-fluorescent composite material, prepared through amino modification and carboxyl dehydration condensation, demonstrates multi-dimensional performance advantages compared to single barium carbonate-doped rare-earth ion materials. The dehydration condensation reaction of amino and carboxyl groups constructs a covalently linked coating structure on the nanoparticle surface. This structure not only effectively inhibits nanoparticle aggregation, improving their dispersibility and compatibility in the matrix and avoiding performance degradation caused by particle aggregation in single materials, but also enhances the piezoelectric-fluorescence synergistic effect through the electronic regulation of functional groups, achieving intelligent "force-light" conversion and overcoming the limitation of single materials only exhibiting piezoelectric or fluorescence properties. Meanwhile, the amino and carboxyl groups retained on the surface of the material provide abundant sites for subsequent functional modification. Different functional molecules can be grafted to expand additional functions such as biological targeting and catalysis. Combined with the better mechanical properties and corrosion resistance of the composite material, its application scenarios have also been broadened from the single piezoelectric or fluorescent fields to complex scenarios such as flexible sensors, bioimaging, and intelligent monitoring.

[0057] Example 1

[0058] This embodiment provides a piezoelectric composite oxide nanofluorescent material BaTiO3@mSiO2:Eu 3+ The preparation method includes the following steps:

[0059] (1) Add 10 mL of an aqueous solution containing 2 mmol of 80% barium nitrate (9.6 mmol), 20% europium acetate and 10 mmol of NaOH to a beaker and stir to dissolve.

[0060] (2) Add 3.6 mL of oleic acid (OA) and 1.8 mL of oleylamine (OAm) to step (1) to form a large precipitate. Heat and stir at 60°C to prepare a mixed solution.

[0061] (3) Take 2 mmol Ti(Bu)4 and add it to 20 mL n-butanol solution. Add this solution to the mixed solution in step (2) above and heat and stir at 60 °C until the precipitate is completely dissolved.

[0062] (4) The solution in step (3) above was sealed and treated at 120 °C for 18 h. After cooling to room temperature, it was centrifuged. The solution was centrifuged once with water and once with ethanol. The precipitate was dispersed in 24 mL of chloroform.

[0063] (5) Take 6 mL of the solution from step (4) above and add it to 25 mL of aqueous solution containing 50 mg of hexadecyltrimethylammonium bromide. Sonicate for 30 min and remove chloroform by oil bath at 60 °C. After obtaining a clear and transparent material, stabilize at 70 °C for 10 min.

[0064] (6) Add 200 μL of 3-aminopropyltriethoxysilane (APTES) and sonicate for 5 min, then add 200 μL of LTEOS (tetraethyl silicate) and sonicate for 5 min. Add 150 μL of NaOH (2 mol / L) and 500 μL of ethyl acetate to the aqueous solution and incubate in an oil bath at 70°C for 3 h.

[0065] (7) Centrifuge the solution from step (6), wash twice with ethanol, and then dry to obtain BaTiO3@mSiO2. 2: Eu 3+ Nanoparticles.

[0066] BaTiO3@mSiO2:Eu 3+ X-ray diffraction pattern of nanoparticles as follows Figure 1 As shown, BaTiO3@mSiO2:Eu 3+ The XRD pattern of the nanoparticles is completely consistent with the standard card (PDF#05-0626), indicating that the prepared BaTiO3@mSiO3... 2: Eu 3+ Nanoparticles are pure phase and contain no impurities.

[0067] like Figure 3 As shown, a portion of the powder was taken to determine the BaTiO3@mSiO2:Eu ratio. 3+ The emission spectrum shows emission peaks at 594 nm and 615 nm, and the excitation source used is 395 nm.

[0068] Example 2

[0069] This embodiment provides BaTiO3@mSiO2:Eu 3+ The preparation of -NH2 involves the following steps:

[0070] 200 mg BaTiO3@mSiO2:Eu 3+ The sample was treated with 1M nitric acid for 2 h, followed by washing until the pH was neutral. It was then treated overnight with hydrogen peroxide (H₂O₂) and centrifuged (5000 r / m × 5 min) to obtain a hydroxyl radical-modified barium titanate complex, abbreviated as BT-OH. 140 μL of ATPES, 250 μL of ammonia (25%), and 36 mL of anhydrous ethanol were added, and the mixture was incubated in an oil bath at 70 °C for 8 h. After cooling, the sample was washed three times with ethanol, dried, and stored under vacuum to obtain an amino-modified barium titanate complex, abbreviated as BT-NH₂.

[0071] like Figure 6 As shown, the Fourier transform infrared absorption spectrum of BT-NH2 was determined from a portion of the powder: at 3424 cm⁻¹ -1 The stretching vibration of the NH bond in the amino group is at 1633 cm⁻¹. -1 The absorption peak at the point corresponds to the bending vibration of the NH bond in the amino group, proving the presence of amino groups on the particle surface.

[0072] Example 3

[0073] This embodiment provides the preparation of Au-COOH, and the steps are as follows:

[0074] (1) Preparation of the reaction raw material solution:

[0075] Preparation of HAuCl4 solution: Dissolve 1g of solid HAuCl4 in 100mL of deionized water to prepare a 1% concentrated solution. Store the solution in a brown reagent bottle at low temperature. Take 4mL of the 1% concentrated HAuCl4 solution and add deionized water to prepare a 100mL dilute solution for later use.

[0076] Preparation of NaBH4 solution: Take 9.5 mg of NaBH4 solid, dissolve it in 25 mL of deionized water, and store it in a brown volumetric flask for later use to obtain a 0.01 M NaBH4 solution. Prepare a fresh solution before each use.

[0077] Preparation of ascorbic acid (AA) solution: Dissolve 282 mg of AA solid in 25 mL of deionized water and store in a brown volumetric flask to obtain a 0.064 M AA solution for later use.

[0078] Preparation of AgNO3 solution: Dissolve 2.12 mg of AgNO3 solid in 50 mL of deionized water and store in a brown volumetric flask to obtain 2.5 × 10⁻⁶ mg / mL AgNO3 solution. -4 M's AgNO3 solution, for later use.

[0079] Preparation of seed solution: 7.5 mL of deionized water was placed in a beaker, and 364 mg of hexadecyltrimethylammonium bromide (CTAB) solid was added. The mixture was heated and stirred at 60 °C for 0.5 h until dissolved, and then cooled to room temperature. Next, 2.5 mL of dilute HAuCl4 solution was added to the solution, and stirring was continued until the solution turned light orange. 0.5 mL of freshly prepared NaBH4 solution was added to the beaker containing the mixture, and the stirring speed was increased (the time from the addition of the NaBH4 solution to the addition of the seed solution is the seed growth time). The solution turned yellowish-brown. Stirring was continued for 5 min, then stirring was stopped, and the mixture was allowed to stand for a period of time. The resulting solution is the seed solution.

[0080] (2) Preparation of growth solution:

[0081] Take 7.5 mL of deionized water in a beaker, add a certain mass of CTAB solid, heat and stir at 60℃ for half an hour until dissolved, then cool to room temperature. Next, add 2.5 mL of dilute HAuCl4 solution to the solution and continue stirring; the solution turns light orange. Then, add a certain volume of AgNO3 solution, and after stirring evenly, add a certain volume of AA solution and 20 mg of polyacrylic acid. Continue stirring, and the solution changes from light orange to colorless.

[0082] (3) Growth of gold nanorods:

[0083] After stopping the stirring of the growth solution, add 50 μL of seed solution to the solution, cover with plastic wrap, and let it stand for growth. The product obtained after 24 hours is the desired hydroxyl-modified gold nanorod, abbreviated as Au-COOH.

[0084] like Figure 7 As shown, the Fourier transform infrared absorption spectrum of Au-COOH was determined from a portion of the powder: at 3428 cm⁻¹ -1 The absorption peak at this location corresponds to the stretching vibration of the OH bond in the carboxyl group, proving the presence of carboxyl groups on the particle surface. For example... Figure 4 The absorption spectrum of Au-COOH shows that the absorbance increases with increasing concentration. Figure 5 The absorption curve of Au-COOH is fitted, and the fitting equation is y = 0.0115x + 1.2438 × 10⁻⁶. -4 R 2 The value is approximately 0.9999, indicating a good fit.

[0085] like Figure 2 As shown, the BaTiO3@mSiO2:Eu obtained in Example 1 was measured. 3+Transmission electron microscopy (TEM) images of nanoparticles with BaTiO3 and Au-COOH prepared in Example 3. It can be seen that BaTiO3@mSiO3... 2: Eu 3+ The nanoparticles are ellipsoidal in shape and approximately 72 nm in diameter. Figure 2 (a) The BaTiO3 nanoparticles are spherical with a diameter of approximately 44 nm. Figure 2 (b) Au-COOH is spherical with a diameter of approximately 61 nm. Figure 2 (c in the text)

[0086] Example 4

[0087] This embodiment provides BaTiO3@mSiO2:Eu 3+ The preparation of Au involves the following steps:

[0088] Take 40 mL of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC), 20 mg of N-hydroxysuccinimide (NHS), add 10 mL of water, and add 200 mg of Au-COOH and stir for 2 h (to activate the carboxyl group). Add 500 mg of BT-NH2 and stir overnight. Then centrifuge at high speed, wash once with water, and dry to obtain the gold-modified barium titanate complex, abbreviated as BT-Au.

[0089] like Figure 8 As shown, a portion of BT-Au powder was sampled and its Fourier transform infrared spectrum was measured: at 3432 cm⁻¹ -1 The absorption peak at 1630 cm⁻¹ corresponds to the stretching vibration of the NH bond in the amide; -1 The absorption peak at 1221 cm⁻¹ corresponds to the stretching vibration of the C=O double bond in the amide; -1 The absorption peak at the point corresponds to the in-plane bending vibration of the NH bond in the amide, proving that -NH2 and -COOH dehydrate and condense to form an amide bond.

[0090] Experimental Example 1

[0091] This experimental example conducts a photothermal experiment on Example 1, performing both general and special temperature-changing treatments, and plots the corresponding linear fitting curves.

[0092] like Figure 9 A portion of the composite oxide nanomaterial BaTiO3@mSiO2:Eu from Example 1 was taken. 3+ The temperature was increased every 10°C from 30°C to 100°C, and every 25°C from 100°C to 300°C. As shown in the figure, the emission intensity weakened with increasing temperature, and the emission peaks were mainly at 597 nm and 615 nm.

[0093] like Figure 10 Example 1: Composite oxide nanomaterial BaTiO3@mSiO2:Eu 3+ The fluorescence intensity fitting curves at ordinary temperature at wavelengths of 597 nm and 615 nm show good linearity. The fitting equation at 597 nm is y = -3158x + 567651, R0 2 The value is approximately 0.99403 ( Figure 10 (a) When the wavelength is 615 nm, the fitting equation is y = -5791x + 1086072, R0 2 The value is approximately 0.9934 ( Figure 10 (b) in the middle.

[0094] Experimental Example 2

[0095] This experimental example conducts a photothermal experiment on Example 4, performs special temperature variations, and plots corresponding linear fitting curves.

[0096] like Figure 11 A portion of the material was subjected to a special temperature-changing treatment, with measurements taken every 25 seconds during the temperature increase from 30 to 300℃. It can be seen that as the temperature increases, the emission intensity continuously increases, with the emission peaks mainly at 597nm and 615nm.

[0097] like Figure 12 The fluorescence intensity fitting curves of BT-Au with special temperature variation in Example 4 at wavelengths of 597 nm and 615 nm show good linear fitting. The fitting equation at 597 nm is y = 20.2x + 495994, R0 2 The value is approximately 0.99308 ( Figure 12 (a) When the wavelength is 615nm, the fitted equation is y=50.78x+1162706, R0 2 The value is approximately 0.99668 ( Figure 12 (b) in the middle.

[0098] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A piezoelectric fluorescent composite material, characterized in that, The invention includes amino-modified composite oxide nanoparticles and carboxyl-modified gold nanoparticles, wherein the amino-modified composite oxide nanoparticles and carboxyl-modified gold nanoparticles are linked by amide bonds formed by the dehydration condensation of amino and carboxyl groups. The chemical formula of the composite oxide nanoparticles is BaTiO3@mSiO2:Eu 3+ The composite oxide nanoparticles include hollow mesoporous silica nanoparticles (SiO2) and europium-doped barium titanate nanoparticles (BaTiO3:Eu) loaded on the surface and inside of their mesoporous structures. 3+ ; The mass ratio of the amino-modified composite oxide nanoparticles to the carboxyl-modified gold nanoparticles is 2:(4-6). During the heating process from 30 to 300°C, the emission intensity of the piezoelectric fluorescent composite material continuously increases with the increase of temperature. The preparation method of the piezoelectric fluorescent composite material includes the following steps: preparing composite oxide nanoparticles BaTiO3@mSiO2:Eu 3+ After treatment with nitric acid and hydrogen peroxide in sequence, the nanoparticles were reacted with 3-aminopropyltriethoxysilane, ammonia and anhydrous ethanol to obtain amino-modified composite oxide nanoparticles. The amino-modified composite oxide nanoparticles and carboxyl-modified gold nanoparticles were subjected to a dehydration condensation reaction of carboxyl and amino groups to obtain the final product. The composite oxide nanoparticles BaTiO3@mSiO2:Eu 3+ The preparation method is as follows: Barium source, europium source and alkaline solution are mixed, oleic acid and oleylamine are added and heated and stirred to dissolve, then tetrabutyl titanate in n-butanol solution is added and heated and stirred to dissolve, and then hydrothermal reaction is carried out to obtain precipitate; the precipitate is dissolved in organic solvent, then hexadecyltrimethylammonium bromide aqueous solution is added, mixed and heated to remove organic solvent, then 3-aminopropyltriethoxysilane, tetraethyl silicate, sodium hydroxide solution and ethyl acetate are added and heated to react, and the product is obtained; The method for preparing the carboxyl-modified gold nanoparticles is as follows: a hexadecyltrimethylammonium bromide solution, a chloroauric acid solution, and a sodium borohydride solution are mixed and stirred to obtain a gold nanoparticle seed solution; then the seed solution is mixed with a growth solution composed of a hexadecyltrimethylammonium bromide solution, a chloroauric acid solution, and a silver nitrate solution to carry out a growth reaction and obtain a carboxyl-modified gold nanoparticle solution.

2. The piezoelectric fluorescent composite material according to claim 1, characterized in that, The mass ratio of the hollow mesoporous silica nanoparticles to the europium-doped barium titanate nanoparticles is 1:(0.8-1.5); The europium-doped barium titanate nanoparticles contain Ba 2+ With Eu 3+ The molar ratio is (7-9):(1-3).

3. The piezoelectric fluorescent composite material according to claim 1, characterized in that, The amino-modified composite oxide nanoparticles are ellipsoidal with a particle size of 70-75 nm; the carboxyl-modified gold nanoparticles are spherical with a particle size of 60-65 nm.

4. The piezoelectric fluorescent composite material according to claim 1, characterized in that, The piezoelectric fluorescent composite material emits orange light with a wavelength of 575-590 nm and red light with a wavelength of 590-620 nm when excited at 395 nm.

5. The piezoelectric fluorescent composite material according to claim 1, characterized in that, Before the dehydration condensation reaction, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide and water are added to the carboxyl-modified gold nanoparticles to activate the carboxyl groups in the gold nanoparticles.

6. The use of the piezoelectric fluorescent composite material according to any one of claims 1-5 in the preparation of temperature measuring products and photothermal therapy products.

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