A method for preparing a WO3-based limonene-sensitive material and its application

Abstract

A method for preparing a WO3-based limonene-sensitive material and its application are disclosed. This invention addresses the problem that existing WO3-sensitive materials cannot resist interference from endogenous gases in exhaled breath. The method includes: 1. Preparation of a polyhedral precursor; 2. Heat treatment. The application involves the preparation of limonene gas-sensitive elements.

Description

Technical Field

[0001] This invention relates to the preparation and application of limonene-sensitive materials. Background Technology

[0002] Chronic liver disease remains a major threat to human health, and respiratory monitoring is one of the most promising technologies for liver monitoring. Limonene is a natural monoterpene compound abundant in citrus peel, characterized by its unique aroma. It is detected in the liver by cytochrome P45 enzymes (primarily CYP2C9 and CYP2C). 19 Limonene is metabolized into metabolites such as perillyl alcohol, trans-carvone, and trans-isoprenol. When liver function is severely impaired, the ability to metabolize limonene decreases significantly, leading to the accumulation of unmetabolized limonene in the body, which is then expelled in exhaled breath. Therefore, elevated concentrations of exhaled limonene have become a potential biomarker for detecting liver metabolic dysfunction. The detection of limonene in exhaled breath has been achieved using various techniques, such as soft chemical ionization mass spectrometry and gas chromatography-mass spectrometry (GC-MS). However, although these techniques have shown promise in exploratory studies, their high equipment cost and large size limit their widespread use in routine clinical settings. In contrast, metal oxide-based gas sensors offer advantages such as low cost, small size, high selectivity, and high sensitivity, thus showing great promise in applications such as early screening and real-time monitoring of liver diseases. For example, existing WO3-based limonene gas-sensitive materials are synthesized by flame spraying, where 10 mol% Si-doped WO3 nanoparticles are directly deposited onto interdigitated platinum electrodes on an Al2O3 substrate to construct a gas-sensitive element. However, the front end of this gas-sensitive element is connected to a Tenax separation column that operates at room temperature to pre-screen and separate other interfering components in the exhaled gas, thereby realizing the detection of limonene content in the exhaled gas.

[0003] Therefore, existing methods for synthesizing WO3-sensitive materials cannot resist interference from humidity and endogenous gases such as CO2, acetone, and hydrogen sulfide in exhaled gas. Pretreatment of exhaled gas using a Tenax separation column is necessary for effective detection of limonene, which undoubtedly increases the construction cost of the gas-sensitive element. Furthermore, the composition of exhaled gas varies greatly from individual to individual, making it impossible to guarantee that the separation column can screen for all interfering gases, thus compromising detection accuracy. Summary of the Invention

[0004] This invention aims to solve the problem that existing WO3-sensitive materials cannot resist interference from endogenous gases in exhaled air, and thus provides a method for preparing WO3-based limonene-sensitive materials and their applications.

[0005] A method for preparing a WO3-based limonene-sensitive material, comprising the following steps:

[0006] I. Preparation of polyhedral precursors:

[0007] 1-Benzyl-3-methylimidazolium hexafluorophosphate was dissolved in deionized water by ultrasonication, and then ammonium metatungstate was added and ultrasonically treated to obtain a white emulsion. The white emulsion was placed in a hydrothermal reactor and heated at high temperature. Finally, it was washed and dried to obtain a polyhedral precursor.

[0008] II. Heat Treatment:

[0009] The polyhedral precursor was heat-treated in an air atmosphere to obtain a WO3-based limonene-sensitive material.

[0010] An application of a WO3-based limonene-sensitive material, used to prepare limonene gas-sensitive elements.

[0011] The beneficial effects of this invention are:

[0012] (1) The present invention provides a method for preparing polyhedral WO3 using 1-benzyl-3-methylimidazolium hexafluorophosphate ([Bzmim][PF6]) as a surfactant.

[0013] (2) The WO3-based sensitive material prepared by the present invention can resist the interference of endogenous gases in exhaled gas and can directly detect the exhaled gas of patients with liver disease without filtering the exhaled gas sample. Therefore, it saves time and effort and is easier to mass-produce.

[0014] (3) Compared with existing reports on the detection of limonene using gas-sensitive elements, the preparation process of this invention is simple and the cost is low. Attached Figure Description

[0015] Figure 1 This is a scanning electron microscope image of the polyhedral precursor prepared in step one of Example 1;

[0016] Figure 2 This is a scanning electron microscope image of the WO3-based limonene-sensitive material prepared in step two of Example 2;

[0017] Figure 3 The XRD patterns of the WO3-based limonene-sensitive materials prepared in step two of Examples 1 to 3 are shown below.

[0018] Figure 4The following are the gas-sensing performance test results of the WO3-based limonene gas-sensitive element prepared in Example 2 for limonene gas under the condition of operating temperature of 100℃. a is the dynamic response-recovery curve of limonene gas with a concentration range of 0.01ppm~10ppm under 25% RH humidity; b is the linear fitting result of response values ​​for different concentrations under 25% RH humidity; c is the single dynamic response-recovery curve of 10ppm limonene under 25% RH humidity; d is the repeatability response curve of 0.05ppm limonene under 25% RH and 52% RH humidity; e is the five consecutive response-recovery curves of 10ppm limonene under 25% RH humidity; f is the response value of 10ppm limonene and the response value of water under 23% RH~97% RH during 60 days of continuous testing under 25% RH humidity.

[0019] Figure 5 The bar chart shows the gas-sensing performance response values ​​of the WO3-based limonene gas-sensing element prepared in Example 2 to 14 interfering gases under the condition of operating temperature of 100℃.

[0020] Figure 6 The results of the WO3-based limonene gas-sensitive element prepared in Example 2 on the detection of respiratory samples and gas mixtures under the condition of operating temperature of 100℃ are shown in Figures a and b. These are the response-recovery curves of five tests on the exhaled gas of two liver disease volunteers. Figure c is a scatter plot of the distribution of response values ​​of multiple measurements of exhaled gas from two liver disease volunteers and two healthy volunteers. Figures d and e are the response-recovery curves of five tests on the exhaled gas of two healthy volunteers. Figure f is a bar chart of the response values ​​when 0.05 ppm limonene is mixed with different concentrations of interfering gas. Detailed Implementation

[0021] Specific Implementation Method 1: This implementation method is a preparation method of a WO3-based limonene sensitive material, which is carried out according to the following steps:

[0022] I. Preparation of polyhedral precursors:

[0023] 1-Benzyl-3-methylimidazolium hexafluorophosphate was dissolved in deionized water by ultrasonication, and then ammonium metatungstate was added and ultrasonically treated to obtain a white emulsion. The white emulsion was placed in a hydrothermal reactor and heated at high temperature. Finally, it was washed and dried to obtain a polyhedral precursor.

[0024] II. Heat Treatment:

[0025] The polyhedral precursor was heat-treated in an air atmosphere to obtain a WO3-based limonene-sensitive material.

[0026] This embodiment provides a method for preparing a WO3-based limonene-sensitive material. Specifically, it uses (NH4)6H2W... 12 O 40 Using tungsten as the source and 1-benzyl-3-methylimidazolium hexafluorophosphate ([Bzmim][PF6]) as the surfactant, a WO3-based sensitive material with a polyhedral morphology was prepared. Due to the presence of W in WO3... 6+ The acidic sites conjugate with the π-electron cloud of the C=C double bond in limonene, enhancing the selective adsorption capacity of WO3 for limonene. This WO3-based limonene-sensitive material can directly detect the exhaled gases of patients with liver disease and healthy volunteers without any pretreatment of the breath samples, showing a significant difference in response values, thus enabling non-invasive screening for liver disease. This gas-sensitive element is inexpensive to construct and highly accurate, therefore it has broad application prospects in respiratory diagnosis and treatment, health monitoring, and other fields.

[0027] The beneficial effects of this embodiment are:

[0028] (1) This embodiment is a method for preparing polyhedral WO3 using 1-benzyl-3-methylimidazolium hexafluorophosphate ([Bzmim][PF6]) as a surfactant.

[0029] (2) The WO3-based sensitive material prepared in this embodiment can resist the interference of endogenous gases in exhaled gas and can directly detect the exhaled gas of patients with liver disease without filtering the exhaled gas sample. Therefore, it saves time and effort and is easier to mass-produce.

[0030] (3) Compared with existing reports on the detection of limonene using gas-sensitive elements, this embodiment has a simple preparation process and low cost.

[0031] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: the molar ratio of 1-benzyl-3-methylimidazolium hexafluorophosphate to deionized water in step one is 1 mmol:(125~175) mL; the molar ratio of 1-benzyl-3-methylimidazolium hexafluorophosphate to ammonium metatungstate in step one is 1:(1~2.5). Everything else is the same as in Specific Implementation Method One.

[0032] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: in step one, 1-benzyl-3-methylimidazolium hexafluorophosphate is added to deionized water and sonicated for 30-45 minutes at an ultrasonic power of 50-60W and an ultrasonic frequency of 40-50kHz. Then, ammonium metatungstate is added, and the mixture is sonicated for 1-2 hours at an ultrasonic power of 50-60W and an ultrasonic frequency of 40-50kHz to obtain a white emulsion. The rest is the same as in Specific Implementation Method One or Two.

[0033] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the high-temperature heating mentioned in step one is specifically carried out at a temperature of 180℃~210℃ for 8 to 12 hours. Everything else is the same as in Specific Implementation Methods One to Three.

[0034] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the washing and drying in step one are specifically performed by washing with anhydrous ethanol and ultrapure water respectively, followed by vacuum drying at a temperature of 60℃~80℃ for 8h~10h. Everything else is the same as in Specific Implementation Methods One to Four.

[0035] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: in step two, the polyhedral morphology precursor is heated to 550℃~750℃ in an air atmosphere at a heating rate of 5℃ / min~10℃ / min, and then heat-treated for 1h~1.5h in an air atmosphere at a temperature of 550℃~750℃. Everything else is the same as in Specific Implementation Methods One to Five.

[0036] Specific Implementation Method Seven: This implementation method describes the application of a WO3-based limonene sensitive material, which is used to prepare limonene gas-sensitive elements.

[0037] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Seven in that the limonene gas-sensitive element is used to detect limonene in human exhaled breath. Everything else is the same as in Specific Implementation Method Seven.

[0038] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Seven or Eight in that the limonene gas-sensitive element is specifically prepared according to the following steps:

[0039] The WO3-based limonene sensitive material is ground, and then terpineol is added dropwise to continue grinding to obtain a slurry. The slurry is coated onto a ceramic tube, and then calcined at 300℃~350℃ for 0.5h~1h. Finally, it is heat-aged at 90℃~120℃ for 8h~12h to obtain the WO3-based limonene gas-sensitive element. Other aspects are the same as in specific embodiments seven or eight.

[0040] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods Seven to Nine in that the mass ratio of the WO3-based limonene sensitive material to the volume ratio of terpineol is 1 g:(0.3~0.4) mL. Everything else is the same as in Specific Implementation Methods Seven to Nine.

[0041] The beneficial effects of the present invention are verified using the following embodiments:

[0042] Example 1:

[0043] A method for preparing a WO3-based limonene-sensitive material, comprising the following steps:

[0044] I. Preparation of polyhedral precursors:

[0045] 0.2 mmol of 1-benzyl-3-methylimidazolium hexafluorophosphate ([Bzmim][PF6]) was added to 30 mL of deionized water and sonicated for 35 min at an ultrasonic power of 50 W and an ultrasonic frequency of 50 kHz. Then, 0.2 mmol of ammonium metatungstate (NH4)6H2W was added. 12 O 40 Under ultrasonic power of 50W and ultrasonic frequency of 50kHz, the mixture was ultrasonically treated for 1 hour to obtain a white emulsion. The white emulsion was placed in a hydrothermal reactor and heated at 210℃ for 12 hours. Then, it was washed with anhydrous ethanol and ultrapure water, respectively. Finally, it was vacuum dried at 70℃ for 8 hours to obtain H2W3O with a polyhedral morphology. 11 • 2H2O precursor, i.e., polyhedral precursor;

[0046] II. Heat Treatment:

[0047] In an air atmosphere, the polyhedral precursor was heated to 550°C at a heating rate of 5°C / min, and then heat-treated for 1 hour in an air atmosphere at 550°C to obtain WO3 polyhedral material, namely WO3-based limonene sensitive material, named WO3-550.

[0048] A limonene gas-sensitive element was prepared using the WO3-based limonene-sensitive material prepared in Example 1. The limonene gas-sensitive element was specifically prepared according to the following steps:

[0049] The WO3-based limonene sensitive material was ground, and then terpineol was added dropwise and the grinding continued to obtain a slurry. The slurry was coated onto a ceramic tube, and then calcined at 300℃ for 1 hour. Finally, it was heat-aged at 120℃ for 8 hours to obtain the WO3-based limonene gas-sensitive element. The mass ratio of the WO3-based limonene sensitive material to the volume ratio of terpineol was 1 g: 0.3 mL.

[0050] Example 2: This example differs from Example 1 in that, in step 2, the material is heat-treated for 1 hour in an air atmosphere at a temperature of 650°C to obtain a WO3 polyhedral material, namely a WO3-based limonene-sensitive material, named WO3-650. Everything else is the same as in Example 1.

[0051] Example 3: This example differs from Example 1 in that, in step 2, the material is heat-treated for 1 hour in an air atmosphere at a temperature of 750°C to obtain a WO3 polyhedral material, namely a WO3-based limonene-sensitive material, named WO3-750. Everything else is the same as in Example 1.

[0052] Figure 1 The image shows a scanning electron microscope (SEM) image of the polyhedral precursor prepared in step one of Example 1. As can be seen from the image, the product is a polyhedron with a particle size of about 10 to 15 micrometers.

[0053] Figure 2 The image shows a scanning electron microscope (SEM) image of the WO3-based limonene-sensitive material prepared in step two of Example 2. As can be seen from the image, the calcined product has a polyhedral morphology composed of nanoparticles with a particle size of about 200-300 nanometers, and the particle size is about 10-15 micrometers.

[0054] Figure 3 The XRD patterns of the WO3-based limonene sensitive materials prepared in step two of Examples 1 to 3 are shown in the figure. As can be seen from the figure, the XRD diffraction peaks of all calcined products coincide with the characteristic diffraction peaks of tetragonal WO3 (standard card JCPDS: 05-0388), proving that the products are pure phase WO3.

[0055] Figure 4The following are the gas-sensing performance test results of the WO3-based limonene gas-sensitive element prepared in Example 2 for limonene gas under an operating temperature of 100℃. a) is the dynamic response-recovery curve for limonene gas concentrations ranging from 0.01ppm to 10ppm under 25% RH humidity; b) is the linear fitting result for different concentrations of response value under 25% RH humidity; c) is the single dynamic response-recovery curve for 10ppm limonene under 25% RH humidity; d) is the repeatability response curve for 0.05ppm limonene under 25% RH and 52% RH humidity; e) is the five consecutive response-recovery curves for 10ppm limonene under 25% RH humidity; f) is the response value for 10ppm limonene during 60 days of continuous testing under 25% RH humidity and under 23% RH to 97% RH humidity. The response value of the gas-sensitive element to water at RH; as shown in Figure a, the resistance change of the gas-sensitive element increases significantly with the increase of limonene concentration, indicating that the response value is positively correlated with the target gas concentration. The resistance of the gas-sensitive element decreases rapidly after each contact with limonene gas, and returns to the initial level after contact with air, reflecting the reversible adsorption-desorption characteristics of the gas-sensitive element for limonene. As shown in Figure b, within the concentration range of 0.01ppm to 10ppm, the response value of the gas-sensitive element (R... a / R g The correlation between limonene concentration and limonene concentration was highly linear, with a fitting R0. 2 The value is 0.993, and the linear relationship remains stable in the low concentration range of 0.01ppm to 0.7ppm (R0). 2 =0.998), this result indicates that the WO3 gas sensor can reliably quantitatively detect limonene gas across different concentration ranges. As shown in Figure c, for 10 ppm limonene, the response time of the gas sensor is 23 s, while the recovery time is 2509 s. This is attributed to the strong interaction between limonene and the WO3 material surface, which triggers rapid adsorption of limonene but also leads to a relatively slow desorption process, thus exhibiting a fast response speed and a slow recovery speed. Figure d shows that the gas sensor maintains good repeatability for detecting low concentrations of limonene under different humidity conditions; Figure e shows that the gas sensor exhibits excellent reproducibility in limonene detection. As shown in Figure f, during the continuous testing over a period of 60 days, the standard deviation of the response value of the gas-sensitive element to 10 ppm limonene was less than 8.6%, indicating that the WO3 sensitive material has excellent structural stability and long-term operational reliability. Meanwhile, when the gas-sensitive element was placed in a humidity bottle with a relative humidity range of 23% to 97%, the response value was less than 1.5, further confirming its good resistance to humidity interference.

[0056] Figure 5The bar chart shows the response values ​​of the WO3-based limonene gas sensor prepared in Example 2 to 14 interfering gases under an operating temperature of 100℃. The interfering gases included common endogenous interfering components in respiration detection, such as carbon dioxide, ethanol, acetone, ammonia, and hydrogen sulfide, and all interfering gas concentrations were 100 ppm. As shown in the figure, the response values ​​of all these interfering gases were in the range of 1.0–2.6, significantly lower than the response value of the gas sensor to 10 ppm limonene (268.21).

[0057] Under an operating temperature of 100℃, the WO3-based limonene gas-sensitive element prepared in Example 2 was tested using breath samples: First, the gas-sensitive element was placed in air to obtain a stable resistance. Then, the gas-sensitive element was placed in a test sample of exhaled gas from a liver disease patient or a test sample of exhaled gas from a healthy volunteer, and a stable resistance was obtained before removing it. The ratio of the resistance value in air to the resistance value in the breath sample was defined as the response value. Figure 6 The results of the WO3-based limonene gas sensor prepared in Example 2 on the detection of respiratory samples and gas mixtures under an operating temperature of 100℃ are shown in Figures a and b. Figures a and b are the response-recovery curves of five tests on the exhaled gases of two liver disease volunteers. Figure c is a scatter plot of the distribution of response values ​​from multiple measurements of the exhaled gases of two liver disease volunteers and two healthy volunteers. Figures d and e are the response-recovery curves of five tests on the exhaled gases of two healthy volunteers. Figure f is a bar chart of the response values ​​when 0.05 ppm limonene is mixed with different concentrations of interfering gases. As shown in the figures, when the WO3 polyhedral-based gas sensor was used to detect exhaled gas samples from liver disease patients and healthy volunteers, the response values ​​for the exhaled samples from healthy volunteers were all around 1, while the response values ​​for the exhaled samples from the two liver disease patients were greater than 2.6. This effectively distinguishes between liver disease patients and healthy volunteers. As shown in Figure f, when 0.05 ppm limonene (target gas) is mixed with three different concentrations (0.5 ppm, 2 ppm, and 5 ppm) of interfering gases (carbon dioxide, acetone, and ethanol), the fluctuation of the gas-sensitive element response value is less than 5%, indicating that the gas-sensitive element can still have a high selective response capability to limonene in complex gas mixtures.

Claims

1. A method for preparing a WO3-based limonene-sensitive material, characterized by It is done in the following steps: I. Preparation of polyhedral precursors: 1-Benzyl-3-methylimidazolium hexafluorophosphate was dissolved in deionized water by ultrasonication, and then ammonium metatungstate was added and ultrasonically treated to obtain a white emulsion. The white emulsion was placed in a hydrothermal reactor and heated at high temperature. Finally, it was washed and dried to obtain a polyhedral precursor. II. Heat Treatment: The polyhedral precursor was heat-treated in an air atmosphere to obtain a WO3-based limonene-sensitive material.

2. The method for preparing a WO3-based limonene-sensitive material according to claim 1, characterized in that... The molar ratio of 1-benzyl-3-methylimidazolium hexafluorophosphate to deionized water in step one is 1 mmol:(125~175) mL; the molar ratio of 1-benzyl-3-methylimidazolium hexafluorophosphate to ammonium metatungstate in step one is 1:(1~2.5).

3. The method for preparing a WO3-based limonene-sensitive material according to claim 1, characterized in that... In step one, 1-benzyl-3-methylimidazolium hexafluorophosphate was added to deionized water and sonicated for 30-45 minutes under ultrasonic power of 50-60W and ultrasonic frequency of 40-50kHz. Then, ammonium metatungstate was added and sonicated for 1-2 hours under ultrasonic power of 50-60W and ultrasonic frequency of 40-50kHz to obtain a white emulsion.

4. The method for preparing a WO3-based limonene-sensitive material according to claim 1, characterized in that... The high-temperature heating mentioned in step one specifically refers to heating at a temperature of 180℃~210℃ for 8h~12h.

5. The method for preparing a WO3-based limonene-sensitive material according to claim 1, characterized in that... The washing and drying process described in step one specifically involves washing with anhydrous ethanol and ultrapure water, respectively, followed by vacuum drying at a temperature of 60℃~80℃ for 8h~10h.

6. The method for preparing a WO3-based limonene-sensitive material according to claim 1, characterized in that... In step two, the polyhedral morphology precursor is heated to 550℃~750℃ in an air atmosphere at a heating rate of 5℃ / min~10℃ / min, and then heat-treated for 1h~1.5h in an air atmosphere at a temperature of 550℃~750℃.

7. The application of a WO3-based limonene-sensitive material prepared according to claim 1, characterized in that... It is used to prepare limonene gas-sensitive elements.

8. The application of a WO3-based limonene-sensitive material according to claim 7, characterized in that... The limonene gas-sensitive element is used to detect limonene in human exhaled gas.

9. The application of a WO3-based limonene-sensitive material according to claim 7, characterized in that... The limonene gas-sensitive element is specifically prepared according to the following steps: The WO3-based limonene sensitive material was ground, and then terpineol was added dropwise to continue grinding to obtain a slurry. The slurry was coated onto a ceramic tube, and then calcined at a temperature of 300℃~350℃ for 0.5h~1h. Finally, it was heated and aged at a temperature of 90℃~120℃ for 8h~12h to obtain the WO3-based limonene gas sensitive element.

10. The application of a WO3-based limonene-sensitive material according to claim 9, characterized in that... The mass ratio of the WO3-based limonene sensitive material to the volume ratio of terpineol is 1 g:(0.3~0.4) mL.

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