Tungsten trioxide nanocomposite, preparation method and sensor
By modifying the tungsten trioxide nanocomplex of gold nanoclusters on tungsten trioxide nanosheets, combining targeting live bacterial metabolism pathways and nanomaterial signal amplification effect, the problem of time-consuming traditional detection methods is solved, and rapid and accurate detection of Listeria monocytogenes is achieved.
Patent Information
- Application Number
- CN202510531259.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-25
- Publication Date
- 2025-07-25
AI Technical Summary
The existing technology is difficult to quickly and accurately detect Listeria monocytic hyperplasia in food. The traditional methods take a long time, rely on professional equipment, and lack the ability to identify live bacteria, and cannot meet the rapid detection needs of the food industry.
Tungsten trioxide nanocomposite is used as a sensitive element to modify gold nanoclusters on tungsten trioxide nanosheets, and the 3-hydroxy-2-butanone in Listeria metabolic gases are detected by targeting live bacteria-specific metabolic pathways, and combined with the signal amplification effect of nanomaterials, to achieve rapid non-destructive detection.
It realizes rapid non-destructive testing of Listeria monocytogenes, which is portable and has high aging performance, can respond significantly at a concentration of 100 ppb, and improves the sensitivity and accuracy of the detection.
Smart Images
Figure CN120361893A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of biosensing technology, and specifically to a tungsten trioxide nanocomposite, a preparation method thereof, and a sensor. Background Art
[0002] Listeria monocytogenes ( L. monocytogenes ) is one of the most toxic foodborne pathogens, which can cause various diseases such as enteritis, meningitis, and systemic infection, with a fatality rate as high as 20%-30%. It shows strong reproductive ability in anaerobic, low-temperature, acidic, and high-salt environments. Therefore, accurate detection of Listeria monocytogenes in food is crucial for ensuring food safety.
[0003] Currently, the detection methods of Listeria monocytogenes mainly include traditional culture methods, molecular detection, and immunological detection, etc. However, these methods generally have problems such as poor detection timeliness (requiring 5-7 days), lack of viable bacteria discrimination ability, strong dependence on equipment, and the need for professional personnel for detection, etc., and it is difficult to meet the requirements of the food industry for rapid and accurate monitoring. Summary of the Invention
[0004] Aiming at the problems existing in the prior art, the present invention provides a tungsten trioxide nanocomposite, a preparation method thereof, and a sensor to achieve rapid and non-destructive detection of Listeria monocytogenes.
[0005] The present invention is realized through the following technical solutions: A tungsten trioxide nanocomposite, comprising tungsten trioxide nanosheets, and gold nanoclusters modified on the tungsten trioxide nanosheets; This tungsten trioxide nanocomposite is used to detect 3-hydroxy-2-butanone in the metabolic gas of Listeria monocytogenes.
[0006] A preparation method of a tungsten trioxide nanocomposite, comprising the following process: Deposit gold nanoclusters on tungsten trioxide nanosheets, and then calcine to remove the organic ligands on the surface of the gold nanoclusters to obtain the tungsten trioxide nanocomposite.
[0007] Preferably, the preparation method of the tungsten trioxide nanocomposite is as follows: Mix the tungsten trioxide nanosheet solution and gold nanoclusters evenly, and then calcine at 300 °C for 2 hours to obtain gold nanocluster-sensitized tungsten trioxide nanosheets, that is, the tungsten trioxide nanocomposite.
[0008] Preferably, the ratio of the tungsten trioxide nanosheets to the gold nanoclusters is (0.05 - 0.08 g): (0.2 - 1.0 mL), and the concentration of the gold nanoclusters is 1.6 mg / mL; The mixing ratio of tungsten trioxide nanosheets to deionized water in the tungsten trioxide nanosheet solution is (0.05 - 0.08 g):(8 - 12 mL).
[0009] Preferably, the preparation method of the tungsten trioxide nanosheets is as follows: Mix the Na2WO4·2H2O solution and L-lactic acid evenly to obtain a mixed solution. Adjust the mixed solution to be acidic, and then centrifuge, wash, and dry the acidic mixed solution. Calcinate at 500 °C for 2 hours to obtain tungsten trioxide nanosheets.
[0010] Preferably, the preparation method of the gold nanoclusters is as follows: Mix the glutathione aqueous solution and the HAuCl4·3H2O aqueous solution in deionized water to obtain a mixture, and then carry out a water bath reaction to obtain gold nanoclusters.
[0011] A sensor for detecting Listeria monocytogenes includes a housing, a sensitive element, and a main control module; A detection cavity is formed in the housing. The sensitive element is arranged in the detection cavity. The sensitive element is connected to the main control module. The tungsten trioxide nanocomposite as described in claim 1 is deposited on the sensitive element. The sensitive element can react with 3-hydroxy-2-butanone in the metabolic gas of Listeria monocytogenes, causing a change in the resistance of the sensitive element. The main control module detects Listeria monocytogenes according to the resistance change.
[0012] Preferably, the detection cavity is an air flow channel arranged in the housing. The sensitive element is arranged on the flow path of the air flow channel. The gas to be detected passes through the air flow channel under negative pressure drive and can react with the sensitive element.
[0013] Preferably, a fan module is arranged in the housing and is connected to the main control module. The fan module generates a negative pressure suction force on the detection cavity during operation to suck the gas to be detected into the detection cavity.
[0014] Preferably, a fan module is arranged in the housing. The sensitive element is connected to the main control module through a heating circuit. The heating circuit is used to preheat the sensitive element.
[0015] Compared with the prior art, the present invention has the following beneficial technical effects: A tungsten trioxide nanocomposite provided by the present application. Listeria monocytogenes releases 3-hydroxy-2-butanone during growth and metabolism. Taking it as a biomarker, gold nanoclusters are modified on the tungsten trioxide nanosheets. Through the targeted viable bacteria specific metabolic pathway (i.e., the α-acetolactate decarboxylase encoded by the alsD gene catalyzes the formation of 3-hydroxy-2-butanone), and combined with the signal amplification effect of the nanomaterial modified electrode, rapid and non-destructive detection of Listeria monocytogenes is achieved.
[0016] The preparation method of the tungsten trioxide nanocomposite of the present application, the gold nanocluster-sensitized tungsten trioxide nanosheets are synthesized by modifying gold nanoclusters (AuNCs) on the tungsten trioxide nanosheets. Acidify Na2WO4 by hydrothermal method, use L-lactic acid as a capping agent, and calcine at 500 °C to obtain tungsten trioxide nanosheets. Deposit AuNCs on the tungsten trioxide nanosheets, and then calcine at 300 °C to remove the organic ligands on the surface of AuNCs to obtain gold nanocluster-sensitized tungsten trioxide nanosheets.
[0017] For the sensor of the present application, deposit the tungsten trioxide nanocomposite on the gas-sensitive element. The gold nanocluster-sensitized tungsten trioxide nanosheets have a high specific surface area (22.98 m 2 / g), which can be in full contact with the target gas. This material can specifically recognize 3-hydroxy-2-butanone and react with it, thereby causing a decrease in its own resistance. The response can reach 23 at a 3-hydroxy-2-butanone gas concentration of 100 ppb. Description of the Drawings
[0018] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.
[0019] Figure 1 It is a schematic structural diagram of the sensor; Among them, (a) is the working logic block diagram of the sensor; (b) is the assembly relationship of each module of the sensor; (c) is the physical diagram and shell structure of the sensor.
[0020] Figure 2 It is the circuit schematic diagram of the main control module of the sensor.
[0021] Figure 3 It is the circuit schematic diagram of the display unit and switch of the sensor.
[0022] Figure 4 It is the relevant data for the sensor to detect actual samples.
[0023] Among them, (a) is the detection flow chart of the sensor for detecting Listeria monocytogenes-contaminated food; (b) is the actual sample detection process of the sensor for detecting Listeria monocytogenes-contaminated food; (c) is the original resistance change curve of the sensor for detecting actual samples of Listeria monocytogenes-contaminated food at different time intervals; (d) is the response value of the sensor for detecting actual samples of Listeria monocytogenes-contaminated food at different time intervals. Detailed implementation manners
[0024] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. The components of the embodiments of the present application described and illustrated herein generally may be arranged and designed in a variety of different configurations.
[0025] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but is merely representative of selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.
[0026] Regarding the problem of rapid and non-destructive detection of Listeria monocytogenes in the present application, since Listeria monocytogenes releases a large amount of microbial volatile organic compounds during its growth and metabolism, including 3-hydroxy-2-butanone, benzaldehyde, 2,5-dimethylpyrazine, 3-methylbutyraldehyde, etc. Among them, 3-hydroxy-2-butanone is the main biomarker, and there is a significant positive correlation between the bacterial concentration and the relative content of this 3-hydroxy-2-butanone. Taking it as the biomarker for detection, a tungsten trioxide nanocomposite was designed and used as a sensitive element. Based on this sensitive element, a corresponding sensor was developed. By targeting the specific metabolic pathway of live bacteria (i.e., the α-acetolactate decarboxylase encoded by the alsD gene catalyzes the generation of 3-hydroxy-2-butanone), and combining with the signal amplification effect of the nanomaterial-modified electrode, it is an effective strategy to achieve rapid and non-destructive detection of Listeria monocytogenes. Compared with the traditional detection methods for Listeria monocytogenes, this sensor has the advantages of portability, timeliness, low cost, etc., and is expected to play an important role in the fields of food non-destructive detection, exhaled breath diagnosis, etc. in the future.
[0027] A tungsten trioxide nanocomposite, comprising tungsten trioxide nanosheets and gold nanoclusters modified on the tungsten trioxide nanosheets.
[0028] The tungsten oxide nanosheets provide a stable carrier platform for the modification of gold nanoclusters. Their large specific surface area and specific structure enable the gold nanoclusters to be evenly dispersed on their surface, avoiding the aggregation of gold nanoclusters, ensuring the overall stability and dispersibility of the nanocomposite, and being conducive to the effective contact and reaction with the substance to be detected subsequently.
[0029] The mechanism of tungsten trioxide nanosheets during the sensing process depends on the interfacial redox reaction process between the target gas and the adsorbed oxygen. In air, oxygen molecules can be chemisorbed on the WO3 surface, capturing electrons from the conduction band and forming adsorbed oxygen clusters. At the same time, a relatively thick electron depletion layer is formed on the WO3 surface, increasing the barrier with a higher resistance. When 3-hydroxy-2-butanone molecules are exposed, the adsorbed oxygen species reacts with 3-hydroxy-2-butanone through a redox reaction. During this process, the captured electrons are released again and return to the material. The electron depletion layer narrows, and the resistance of Au-WO3 decreases. During the operation of the sensor, the electrical properties (resistance) of tungsten trioxide nanosheets change, and this change can be used as part of the detection signal, helping to convert the biorecognition event into a detectable electrical signal, thus achieving the detection of Listeria monocytogenes.
[0030] Gold nanoclusters can specifically recognize 3-hydroxy-2-butanone, the main biomarker released during the growth and metabolism of Listeria monocytogenes. This specific recognition is based on the chemical properties and structure of the gold nanocluster surface, enabling it to enhance the adsorption of 3-hydroxy-2-butanone and accelerate the charge transfer from Au nanocluster-modified WO3 to 3-hydroxy-2-butanone, thereby improving the sensing performance of the sensor for 3-hydroxy-2-butanone. In addition, gold nanoclusters can play a role in signal amplification during the sensor detection process. When gold nanoclusters bind to the target biomarker, it causes a significant change in their electrical properties. This change can be monitored through corresponding electrochemical detection, and due to the unique properties of gold nanoclusters, this change is amplified, thus improving the detection sensitivity, enabling the sensor to detect lower concentrations of Listeria monocytogenes metabolites, and further achieving rapid and non-destructive detection of Listeria monocytogenes.
[0031] Gold nanoclusters are modified on tungsten trioxide nanosheets, which can improve the performance of the entire nanocomposite. For example, the presence of gold nanoclusters can regulate the electronic structure of tungsten trioxide nanosheets, improving their electrical properties and catalytic activity. At the same time, the synergistic effect between gold nanoclusters and tungsten trioxide nanosheets can enhance the stability and anti-interference ability of the nanocomposite, enabling it to more accurately identify target molecules in a complex detection environment and improving the reliability and practicality of the sensor.
[0032] Correspondingly, the present application also provides a method for preparing a tungsten trioxide nanocomposite, including the following steps: Step 1, prepare tungsten trioxide nanosheets; Mix the Na2WO4·2H2O solution and L-lactic acid evenly to obtain a mixed solution, adjust the mixed solution to be acidic, then centrifuge, wash, dry, and calcine the acidic mixed solution to obtain tungsten trioxide nanosheets.
[0033] The mixing ratio of Na2WO4·2H2O to deionized water in the Na2WO4·2H2O solution is (0.8 - 1.2 g) : (45 - 55 mL).
[0034] The mixing ratio of the Na2WO4·2H2O solution and L-lactic acid is (0.8 - 1.2 g) : (2.0 - 3.5 mL), and the concentration of L-lactic acid is 50 wt%.
[0035] Optionally, hydrochloric acid is added to the mixture of the Na2WO4·2H2O solution and L-lactic acid to adjust the pH value of the mixed solution to 1.0. The concentration of hydrochloric acid is 50 wt%, and the mixing ratio of Na2WO4·2H2O to hydrochloric acid is (0.8 - 1.2 g) : (2.0 - 3.5 mL).
[0036] Optionally, the method of centrifugal washing and drying is as follows: Centrifuge (10000 rpm, 10 minutes), wash, and dry at 60 °C for 12 hours, then calcine at 500 °C for 2 hours to collect tungsten trioxide nanosheets.
[0037] Step 2: Prepare gold nanoclusters; Mix an aqueous glutathione solution and an aqueous HAuCl4·3H2O solution in deionized water to obtain a mixture, and then carry out a water bath reaction to obtain gold nanoclusters.
[0038] The mixing ratio of deionized water, the aqueous glutathione solution, and the aqueous HAuCl4·3H2O solution is (4 - 5 mL) : (0.12 - 0.18 mL) : (0.4 - 0.6 mL). The concentration of the aqueous glutathione solution is 3 wt%, and the concentration of the aqueous HAuCl4·3H2O solution is 0.8 wt%.
[0039] Optionally, the method of the water bath reaction of the mixture is as follows: Place the mixture in a water bath at 70 °C and heat it with gentle stirring for 24 hours. After the reaction is completed, cool the mixture to room temperature and filter it through a 0.22-μm filter membrane to obtain gold nanoclusters.
[0040] Step 3: Prepare tungsten trioxide nanocomposites After mixing the tungsten trioxide nanosheet solution and the gold nanoclusters evenly, calcine at 300 °C for 2 hours to obtain tungsten trioxide nanosheets sensitized by gold nanoclusters, that is, tungsten trioxide nanocomposites.
[0041] The mixing ratio of tungsten trioxide nanosheets to deionized water in the tungsten trioxide nanosheet solution is (0.05 - 0.08 g) : (8 - 12 mL). After mixing, ultrasonic stirring is carried out for 10 minutes to form a suspension.
[0042] Then, gold nanoclusters are added to the suspension and stirred evenly for 6 hours.
[0043] The ratio of tungsten trioxide nanosheets to gold nanoclusters is (0.05 - 0.08 g) : (0.2 - 1.0 mL), and the concentration of gold nanoclusters is 1.6 mg / mL.
[0044] Correspondingly, the present application also provides a sensitive element for detecting Listeria monocytogenes, including a MEMS chip and a tungsten trioxide nanocomposite loaded thereon.
[0045] Specifically, 1 - 3 mg of tungsten trioxide nanocomposite is placed into a 1.5 mL centrifuge tube, an appropriate amount of deionized water is added, and ultrasonic oscillation is carried out to disperse it evenly. The dispersed solution is dropped onto the MEMS chip and air-dried to obtain a sensitive element for detecting Listeria monocytogenes.
[0046] Example 1 A preparation method of a tungsten trioxide nanocomposite, comprising the following steps: Step 1: Dissolve Na2WO4·2H2O (1.0 g) in deionized water (50 mL), then add L-lactic acid (50 wt%, 0.9 mL) to the above solution, and continuously stir for 10 minutes to form a uniform solution. Then add hydrochloric acid (3.0 mL, 6M) to adjust the pH value of the solution to 1.0. Tungsten trioxide nanosheets are collected by centrifugation (10000 rpm, 10 minutes), washing, and drying at 60 °C for 12 hours, and then calcining at 500 °C for 2 hours.
[0047] Step 2: Add glutathione aqueous solution (0.15 mL, 100 mM) and HAuCl4·3H2O aqueous solution (0.5 mL, 20 mM) to deionized water (4.35 mL). Place the above mixture in a water bath at 70 °C and heat it under gentle stirring for 24 hours. After the reaction ends, cool the mixture to room temperature and filter it through a 0.22 μm filter membrane to obtain AuNCs.
[0048] Step 3: Mix 0.06 g of tungsten trioxide nanosheets with 10 mL of deionized water and sonicate for 10 minutes to form a homogeneous suspension. After adding 1.0 mL of gold nanoclusters (1.6 mg / mL), stir at room temperature for 6 hours. Dry at 50 °C for 12 hours and then calcine at 300 °C for 2 hours to remove the ligands, obtaining gold nanocluster-sensitized tungsten trioxide nanosheets.
[0049] Step 4: Place the tungsten trioxide nanocomposite in a 1.5 mL centrifuge tube, add an appropriate amount of deionized water, and sonicate to disperse it evenly. Drop the dispersed solution onto the MEMS chip and air-dry to obtain a sensitive element for detecting Listeria monocytogenes.
[0050] Example 2 A preparation method of a tungsten trioxide nanocomposite, comprising the following steps: Step 1: Dissolve Na2WO4·2H2O (0.8 g) in deionized water (45 mL), then add L-lactic acid (50 wt%, 1.0 mL) to the above solution and continuously stir for 10 minutes to form a homogeneous solution. Then add hydrochloric acid (3.5 mL, 6 M) to adjust the pH value of the solution to 1.0. Collect the obtained tungsten trioxide nanosheets by centrifugation (10000 rpm, 10 minutes), washing, and drying at 60 °C for 12 hours and calcining at 500 °C for 2 hours.
[0051] Step 2: Add glutathione aqueous solution (0.18 mL, 100 mM) and HAuCl4·3H2O aqueous solution (0.6 mL, 20 mM) to deionized water (5 mL). Place the above mixture in a water bath at 70 °C and heat under gentle stirring for 24 hours. After the reaction is completed, cool the mixture to room temperature and filter through a 0.22 μm filter membrane to obtain AuNCs.
[0052] Step 3: Mix 0.08 g of tungsten trioxide nanosheets with 12 mL of deionized water and sonicate for 10 minutes to form a homogeneous suspension. After adding 0.2 mL of gold nanoclusters (1.6 mg / mL), stir at room temperature for 6 hours. Dry at 50 °C for 12 hours and then calcine at 300 °C for 2 hours to remove the ligands, obtaining gold nanocluster-sensitized tungsten trioxide nanosheets.
[0053] Step 4: Place the tungsten trioxide nanocomposite in a 1.5 mL centrifuge tube, add an appropriate amount of deionized water, and sonicate to disperse it evenly. Drop the dispersed solution onto the MEMS chip and air-dry to obtain a sensitive element for detecting Listeria monocytogenes.
[0054] Example 3 A preparation method of a tungsten trioxide nanocomposite, comprising the following steps: Step 1: Dissolve Na2WO4·2H2O (1.2 g) in deionized water (55 mL), then add L-lactic acid (50 wt%, 0.8 mL) to the above solution, and continuously stir for 10 minutes to form a homogeneous solution. Then add hydrochloric acid (2.0 mL, 6 M) to adjust the pH value of the solution to 1.0. The obtained tungsten trioxide nanosheets are collected by centrifugation (10000 rpm, 10 minutes), washing, and drying at 60 °C for 12 hours.
[0055] Step 2: Add glutathione aqueous solution (0.12 mL, 100 mM) and HAuCl4·3H2O aqueous solution (0.4 mL, 20 mM) to deionized water (4 mL). Place the above mixture in a water bath at 70 °C and heat it under gentle stirring for 24 hours. After the reaction is completed, cool the mixture to room temperature and filter it through a 0.22-μm filter membrane to obtain AuNCs.
[0056] Step 3: Mix 0.05 g of tungsten trioxide nanosheets with 8 mL of deionized water and sonicate for 10 minutes to form a homogeneous suspension. After adding 0.6 mL of gold nanoclusters (1.6 mg / mL), stir at room temperature for 6 hours, dry at 50 °C for 12 hours, and then calcine at 300 °C for 2 hours to remove the ligands, obtaining gold nanocluster-sensitized tungsten trioxide nanosheets.
[0057] Step 4: Put the tungsten trioxide nanocomposite into a 1.5 mL centrifuge tube, add an appropriate amount of deionized water, and ultrasonically oscillate to disperse it evenly. Drop the dispersed solution on the MEMS chip and air-dry it to obtain a sensitive element for detecting Listeria monocytogenes.
[0058] Correspondingly, based on this sensitive element, the present application also provides a sensor for detecting Listeria monocytogenes. The sensor includes a housing, a sensitive element, and a main control module; A detection cavity is formed in the housing. The sensitive element is disposed in the detection cavity and is connected to the main control module. The sensitive element can identify the concentration of 3-hydroxy-2-butanone in the gas of Listeria monocytogenes in the detection cavity and react with the sensitive element, triggering a change in the resistance of the sensitive element. The main control module detects Listeria monocytogenes based on the resistance change.
[0059] Optionally, the detection cavity is an air flow channel provided in the housing, and the sensitive element is disposed on the flow path of the air flow channel. When the gas to be detected passes through the air flow channel under negative pressure drive, when the gas to be detected contains 3-hydroxy-2-butanone, 3-hydroxy-2-butanone reacts with the tungsten trioxide nanocomposite, resulting in a decrease in the resistance of the sensitive element, indicating that the gas to be detected is Listeria monocytogenes.
[0060] In another embodiment, a fan module is provided in the housing of the sensor and is connected to the main control module. The fan module generates a negative pressure suction force in the air flow channel during operation, sucking the gas to be detected into the air flow channel, and then detecting 3-hydroxy-2-butanone in the gas to be detected through the sensitive element.
[0061] In another embodiment, the sensitive element is connected to the main control module through a data acquisition module. The data acquisition module is used to sample the voltage and resistance of the sensitive element with high precision and send the sampling values to the main control module. The main control module compares the sampling values with the threshold value and determines the detection result of Listeria monocytogenes according to the comparison result.
[0062] In another embodiment, the sensitive element is further connected to a heating circuit. The heating circuit is used to preheat the sensitive element and is connected to the main control module to control the working state of the heating circuit.
[0063] In another embodiment, the main control module is connected to a mobile terminal through a wireless module, thereby realizing wireless transmission of detection data, realizing remote monitoring and storage of data, and facilitating pollution traceability and historical data analysis.
[0064] In another embodiment, the main control module is connected to an alarm module. The alarm module outputs an alarm signal according to the detection result. For example, alarm lights and alarm sounds.
[0065] Embodiment 4 A sensor includes a main control module, a charging module, a voltage stabilizing module, an adjustable voltage source module, a MEMS module, a data acquisition module, a fan module, a Bluetooth module, an OLED screen module, an acoustic-optic alarm module, and a 3D printed housing.
[0066] The main control module is used to centrally control the entire sensor system; the charging module is used to charge the lithium battery; the voltage stabilizing module steps down the high voltage provided by the battery or external power supply to meet the power supply requirements of STM32; the adjustable voltage source module is used to provide an adjustable working temperature for the tungsten trioxide nanosheets sensitized by gold nanoclusters; the MEMS module serves as a carrier (sensitive element) for the tungsten trioxide nanosheets sensitized by gold nanoclusters; the data acquisition module is used to collect the working voltage output by the adjustable voltage source and the partial pressure signal of the tungsten trioxide nanosheets sensitized by gold nanoclusters; the fan module sucks the target gas into the sensor to ensure sufficient contact between the gas and the tungsten trioxide nanosheets sensitized by gold nanoclusters; the Bluetooth module is used to remotely wirelessly transmit the data collected by STM32 to other devices; the OLED screen module is used to display the data information collected by STM32 in real time; and the acoustic-optic alarm module triggers an alarm when the concentration of 3-hydroxy-2-butanone reaches a preset threshold.
[0067] Refer to Figures 1-3, the main control module uses STM32F103C8T6 as the core control unit with a main frequency of 72 MHz and is equipped with multi-channel 12-bit ADCs to collect the resistance change signals of tungsten trioxide nanosheets sensitized by gold nanoclusters at different 3-hydroxy-2-butanone gas concentrations in real time.
[0068] The PC14-OSC32_IN and PC15-OSC32_OUT pins are connected to an external low-speed crystal oscillator with a frequency of 32.768 kHz to provide a real-time clock for the system; the PD0-OSC_IN and PD1-OSC_OUT pins are connected to a high-speed crystal oscillator of 8 MHz to provide the main frequency for the main system; the NRST pin is connected to a reset circuit for resetting STM32F103C8T6; the ADC12_IN1 and ADC12_IN5 channels are used to collect the working voltage of the adjustable voltage source module and the partial pressure signal of the tungsten trioxide nanosheets sensitized by gold nanoclusters respectively, the PC13-TAMPER-RTC pin is connected to an LED to indicate the system power-on, the BOOT0 and BOOT1 pins are connected to a 2*3 row of pins for serial port programming, and the PA13 and PA14 pins are connected to a 1*4 row of pins for programming.
[0069] The lithium-ion battery charging chip used in the charging module is of the model TP5400, and the external power supply is connected through the Type-C interface and the lithium-ion battery is charged through the TP5400 chip.
[0070] The low-dropout linear regulator chip used in the voltage regulation module is of the model AMS1117. AMS1117 reduces the 5V power supply provided by the Type-C interface or the lithium-ion battery to 3.3V for powering STM32F103C8T6.
[0071] The buck DC-DC regulator chip used in the adjustable voltage source module is of the model LGS5145, with an input voltage of 5 V and an adjustable output voltage range of 0.8 - 3.3 V. It controls the working temperature of the tungsten trioxide nanosheets sensitized by gold nanoclusters. The output voltage is precisely adjusted by controlling LGS5145 through a potentiometer to match the working voltage requirements of different sensing materials.
[0072] The MEMS module uses a MEMS chip as the carrier of the tungsten trioxide nanosheets sensitized by gold nanoclusters and is connected to a voltage-dividing resistor.
[0073] The data acquisition module uses the PA0 and PA5 pins of STM32F103C8T6 to connect to the voltage output terminal of the adjustable voltage source module and the tungsten trioxide nanosheets sensitized by gold nanoclusters. It uses ADC12_IN1 and ADC12_IN5 of STM32F103C8T6 to collect voltages, and configures an operational amplifier of model LM258APT as a voltage follower to reduce the error of voltage acquisition.
[0074] The data acquisition module realizes high-precision sampling of voltage and resistance changes based on the 12-bit ADC of STM32F103C8T6. The sampling frequency can reach up to 1 MHz at most, and it can capture the tiny signal fluctuations caused by the change in the concentration of 3-hydroxy-2-butanone in real time. Signal acquisition is configured as a voltage follower through the LM258APT operational amplifier to reduce signal distortion and improve the acquisition accuracy of data. ADC12_IN5 collects the output voltage of the adjustable voltage source module, and ADC12_IN1 collects the voltage-dividing resistor signal of the tungsten trioxide nanosheets sensitized by gold nanoclusters. High-speed data transmission is realized through the DMA module embedded in the main control chip to improve the data processing ability of the system.
[0075] The fan module uses a small DC fan with dimensions of 15*15*4 mm. After being powered on, it sucks external gas into the sensing channel through positive pressure, enabling the target gas to fully contact the tungsten trioxide nanosheets sensitized by gold nanoclusters, thereby improving the detection sensitivity and response speed.
[0076] The fan module is controlled by the PA1 pin of STM32F103C8T6. The fan switch state can be automatically switched according to the working mode, so as to realize the adaptive environmental detection of the sensor. The fan module uses the PA1 pin of STM32F103C8T6 to connect to a switch, and the other end of the switch is connected to a small fan of 15*15*4 mm.
[0077] The Bluetooth module adopts the HC-05 module, conducts data communication with STM32F103C8T6 through the UART interface, and realizes the remote wireless transmission of detection data. The default baud rate of the HC-05 module is 9600 bps, and it can be configured to 115200 bps according to application requirements to improve the data transmission rate. The Bluetooth module is connected to the main control chip through UART1 (TXD: PA9, RXD: PA10). The Bluetooth module is paired with a mobile phone and sends data to the mobile phone for display. After successful pairing with a mobile device, the detection data can be wirelessly transmitted to the mobile phone to realize remote monitoring and storage of data, which is convenient for pollution traceability and historical data analysis.
[0078] The OLED screen module uses a 0.96-inch OLED screen with the driving chip model SSD1306, and displays information such as the collected voltage, calculated resistance, and the concentration of 3-hydroxy-2-butanone calculated according to the pre-stored 3-hydroxy-2-butanone concentration-response curve.
[0079] The acoustic and optical alarm module uses an active buzzer and an LED lamp with the model YS-SBZ9650DYB05 to give an alarm according to the current concentration of 3-hydroxy-2-butanone. When the concentration of 3-hydroxy-2-butanone is higher than 100 ppb, the buzzer and the LED lamp are turned on for acoustic and optical alarm. When the concentration of 3-hydroxy-2-butanone is lower than 100 ppb, the buzzer and the LED are turned off.
[0080] The 3D housing is made of HPR9600 resin and has a size of 141.5 * 77.5 * 35 mm.
[0081] The OLED screen module uses a 0.96-inch OLED screen driven by SSD1306, communicates with the main control chip through the I2C interface (SCL: PB6, SDA: PB7), and realizes the local real-time display of detection data. The display content includes detection time, the resistance value of tungsten trioxide nanosheets sensitized by gold nanoclusters, the concentration of 3-hydroxy-2-butanone gas, and the system alarm status, etc. When the concentration of 3-hydroxy-2-butanone exceeds the preset threshold (100 ppb), the acoustic and optical alarm module automatically triggers an alarm. The acoustic and optical alarm module consists of an active buzzer and an LED lamp, which can realize double acoustic and optical alarms. The buzzer model is YS-SBZ9650DYB05, and the working frequency is 4 kHz; the LED lamp lights up synchronously with the buzzer to warn the operator.
[0082] The alarm logic is as follows: When the concentration ≥ 100 ppb, the buzzer and the LED lamp automatically trigger an alarm; When the concentration < 100 ppb, the buzzer and the LED lamp automatically turn off and return to the standby state.
[0083] Refer to Figure 4 , and the detection method of this sensor will be elaborated in detail below.
[0084] Detection operation process: (1) The user powers the device through the Type-C interface or the built-in lithium battery, and the system automatically performs a self-check to detect the working status of each module. The self-check includes: The system is initialized and enters the mode to be measured; Sensor preheating: Start the heating circuit of tungsten trioxide nanosheets sensitized by gold nanoclusters and preheat for 10 seconds; Working voltage detection: Detect the output voltage of the adjustable voltage source module to ensure that the voltage is the working voltage of the tungsten trioxide nanosheets sensitized with gold nanoclusters.
[0085] (2) After the fan module starts, the target gas is inhaled into the detection channel, enabling the 3-hydroxy-2-butanone gas to come into full contact with the tungsten trioxide nanosheets sensitized with gold nanoclusters. The resistance change signal is collected in real time through ADC12_IN1 and compared with the preset 3-hydroxy-2-butanone concentration-response curve. The detection data is locally displayed on the OLED screen and simultaneously transmitted to a mobile device through the HC-05 Bluetooth module for remote data monitoring.
[0086] (3) When the concentration of 3-hydroxy-2-butanone exceeds the set threshold (100 ppb), the buzzer and the LED light are triggered to alarm simultaneously, and the alarm status data is wirelessly uploaded to the mobile device through the HC-05 module for subsequent data analysis. When the concentration returns to the safe range, the buzzer and the LED light automatically turn off, and the system re-enters the mode to be measured.
[0087] The sensor for detecting Listeria monocytogenes. Compared with traditional 3-hydroxy-2-butanone detection equipment, it has lower cost, higher sampling frequency and accuracy, can meet the on-site real-time detection requirements, has higher circuit integration, and is simple and portable. The sensor has the following characteristics: 1) High-frequency and high-precision sampling, the ADC has a 12-bit resolution, and the highest frequency can reach 1 MHz; 2) It has an adjustable voltage source, and the output voltage range is 0.8 - 3.3 V, with higher material compatibility; 3) The alarm threshold can be flexibly set.
[0088] 4) The detection limit is as low as 10 1 CFU / mL.
[0089] From the perspective of the functional integration of the sensor, it has the following advantageous features: The layout of each functional module in the system is compact and has a high degree of integration. It can realize auxiliary functions such as working voltage monitoring and data calibration. At the same time, through the Bluetooth and OLED screen modules, it can realize the real-time transmission and display of data, thus greatly expanding the application prospects of the sensor in the fields of food non-destructive testing, exhaled breath diagnosis, etc.
[0090] Furthermore, based on the structural advantages of the above sensor system, from the perspective of the detection and alarm performance of the sensor, the sensor has the following advantageous features: The tungsten trioxide nanosheet material sensitized by gold nanoclusters used in the sensor has a high specific surface area and excellent gas-sensing characteristics, and can achieve a significant resistance response of up to 23 at a concentration as low as 100 ppb. At the same time, the high-precision data acquisition module in the system, supported by a 12-bit ADC and a sampling frequency of up to 1 MHz, can capture minute signal changes in real time, and cooperate with the acoustic-optic alarm module to quickly trigger an alarm when the concentration of 3-hydroxy-2-butanone exceeds 100 ppb, ensuring the accuracy and real-time nature of the detection results.
[0091] In summary, this application has developed a sensor for detecting Listeria monocytogenes, which has functions such as high sampling resolution, high sampling frequency, adjustable voltage source, remote data transmission, real-time data display, and acoustic-optic alarm. This sensor not only achieves a high degree of integration of multi-functional modules, but also significantly improves the detection sensitivity and real-time response ability. This sensor has rich performance and is expected to play an important role in the fields of food non-destructive testing, exhaled breath diagnosis, etc. in the future.
[0092] The above content is only to illustrate the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.
Claims
1. A tungsten trioxide nanocomposite, characterized in that, It includes tungsten trioxide nanosheets and gold nanoclusters modified on the tungsten trioxide nanosheets; This tungsten trioxide nanocomposite is used to detect 3-hydroxy-2-butanone in the metabolic gas of Listeria monocytogenes.
2. A method for preparing a tungsten trioxide nanocomposite, characterized in that, It includes the following process: Deposit gold nanoclusters on tungsten trioxide nanosheets, and then remove the organic ligands on the surface of the gold nanoclusters by calcination to obtain the tungsten trioxide nanocomposite.
3. The preparation method of a tungsten trioxide nanocomposite according to claim 2, characterized in that, The preparation method of the tungsten trioxide nanocomposite is as follows: After mixing the tungsten trioxide nanosheet solution and gold nanoclusters evenly, calcine at 300 °C for 2 hours to obtain gold nanocluster-sensitized tungsten trioxide nanosheets, that is, the tungsten trioxide nanocomposite.
4. The preparation method of a tungsten trioxide nanocomposite according to claim 3, characterized in that, The ratio of the tungsten trioxide nanosheets to the gold nanoclusters is (0.05 - 0.08 g):(0.2 - 1.0 mL), and the concentration of the gold nanoclusters is 1.6 mg / mL; The mixing ratio of the tungsten trioxide nanosheets to deionized water in the tungsten trioxide nanosheet solution is (0.05 - 0.08 g):(8 - 12 mL).
5. The preparation method of a tungsten trioxide nanocomposite according to claim 1, characterized in that, The preparation method of the tungsten trioxide nanosheets is as follows: Mix the Na2WO4·2H2O solution and L-lactic acid evenly to obtain a mixed solution, adjust the mixed solution to be acidic, and then centrifuge, wash and dry the acidic mixed solution, and calcine at 500 °C for 2 hours to obtain tungsten trioxide nanosheets.
6. The preparation method of a tungsten trioxide nanocomposite according to claim 1, characterized in that, The preparation method of the gold nanoclusters is as follows: Mix the glutathione aqueous solution and the HAuCl4·3H2O aqueous solution in deionized water to obtain a mixture, and then carry out a water bath reaction to obtain gold nanoclusters.
7. A sensor for detecting *Listeria monocytogenes*, characterized in that, It includes a housing, a sensitive element and a main control module; A detection chamber is formed in the housing, the sensitive element is arranged in the detection chamber, the sensitive element is connected to the main control module, the tungsten trioxide nanocomposite described in claim 1 is deposited on the sensitive element, and the sensitive element can react with 3-hydroxy-2-butanone in the metabolic gas of Listeria monocytogenes, causing a change in the resistance of the sensitive element, and the main control module detects Listeria monocytogenes according to the resistance change.
8. A sensor according to claim 7, characterized in that, The detection chamber is an air flow channel arranged in the housing, the sensitive element is arranged on the flow path of the air flow channel, and the gas to be detected passes through the air flow channel under negative pressure drive and can react with the sensitive element.
9. A sensor according to claim 7, characterized in that, A fan module is arranged in the housing and is connected to the main control module. The fan module generates a negative pressure suction force on the detection chamber during operation to suck the gas to be detected into the detection chamber.
10. A sensor according to claim 7, characterized in that, A fan module is arranged in the housing, and the sensitive element is connected to the main control module through a heating circuit, and the heating circuit is used to preheat the sensitive element.