Quantum dot-based phenol gas sensor and preparation method thereof

Abstract

The invention belongs to the field of electrochemical gas sensors, and particularly relates to a phenol gas sensor based on quantum dots and a preparation method of the phenol gas sensor. The gas sensor comprises a quantum dot sensing film, polyphenol oxidase on the surface of the quantum dot sensing film and an enzyme stabilizing composite reagent covering the polyphenol oxidase, benzoquinone is formed on the basis that phenol is oxidized through molecular oxygen on the basis of the polyphenol oxidase, the enzyme-substrate efficient specific catalysis effect is achieved, and the content of the polyphenol oxidase in the gas sensor is increased. The polyphenol oxidase-based quantum dot phenol gas sensor is designed. The sensor is high in phenol gas detection specificity and sensitivity.

Description

Technical Field

[0001] The present application belongs to the field of electrochemical gas sensors, and more specifically, to a quantum dot-based phenol gas sensing detection and a preparation method thereof. Background Art

[0002] Phenol, also known as carbolic acid and hydroxybenzene, is a colorless needle-shaped crystal with a special smell. It is the simplest phenolic organic compound and a weak acid. It is a colorless crystal at room temperature and is toxic. The hydroxyl group replaces the hydrogen on the benzene ring, making phenol have a strong chemical reaction ability. It is an important raw material for the production of certain resins, fungicides, preservatives and drugs (such as aspirin). Phenol pollution in the environment comes from human activities such as industry, phenol leakage accidents, and interior decoration.

[0003] Phenol has a strong corrosive effect on the skin and mucous membranes, and can inhibit the central nervous system or damage liver and kidney function. Acute poisoning: Inhalation of high concentrations of vapor can cause headaches, dizziness, fatigue, blurred vision, pulmonary edema, etc. Ingestion can cause digestive tract burns, burning pain, phenol smell in exhaled breath, blood in vomitus or stool, and possible gastrointestinal perforation. Shock, pulmonary edema, liver or kidney damage, acute renal failure, and death from respiratory failure can occur. Eye contact can cause burns. It can be absorbed through the burned skin and cause acute renal failure after a certain incubation period. Chronic poisoning: It can cause headaches, dizziness, cough, loss of appetite, nausea, vomiting, and proteinuria in severe cases. It can cause dermatitis. In addition, studies have shown that although teratogenic effects are not related to exposure to phenol through inhalation or oral routes, high doses of phenol are fetotoxic.

[0004] Therefore, it is urgent to develop a fast and accurate phenol detection method. At present, the main detection methods of phenol gas are chromatography, spectroscopy and immunoassay, but these detection methods have the disadvantages of high detection cost, large and inconvenient equipment, cumbersome detection and professional operation, and long detection time. Therefore, it is very necessary to design a phenol gas sensor with simple preparation, low cost and good selectivity. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of this application is to provide a quantum dot-based phenol gas sensor and a preparation method thereof, prepare a phenol gas sensor by labeling quantum dots with a polyphenol oxidase preparation, and construct a quantum gas sensor with three electrodes or high-mobility field-effect transistors as transducers, aiming to solve the technical problems of the prior art phenol gas sensors, such as high detection cost, non-portable equipment, complicated detection steps, and poor selectivity.

[0006] To achieve the above objectives, in a first aspect, the present application provides a quantum dot-based phenol gas sensor, comprising a quantum dot sensing film, polyphenol oxidase on the surface of the quantum dot sensing film, and an enzyme-stabilizing composite reagent covering the polyphenol oxidase; The quantum dot sensing film is a film formed by transferring a quantum dot solution to a working electrode of a planar electrochemical three-electrode, or to a gate surface of a high electron mobility transistor chip; the polyphenol oxidase forms an enzyme-quantum dot binding interface with the quantum dot sensing film; The enzyme-stabilizing complex reagent covers the quantum dot binding interface to ensure the normal activity of the enzyme, wherein the enzyme-stabilizing complex reagent is a mixed solution of chloride, glycerol and phosphate buffer; When the sensor is working, the specific catalytic effect of the polyphenol oxidase on the phenol in the gas to be detected is utilized to cause an oxidation reaction of the phenol gas to generate a current signal, thereby realizing the specific detection of the phenol in the gas to be detected.

[0007] Preferably, the quantum dots are sulfide colloidal quantum dots.

[0008] Further preferably, the volume ratio of phosphate buffer to glycerol in the enzyme-stabilizing complex reagent is 1:1 to 10:1.

[0009] Preferably, the molar concentration of the chloride in the enzyme-stabilizing complex reagent is 1-10 mM.

[0010] According to another aspect of the present invention, a method for preparing a quantum dot-based phenol gas sensor is provided, comprising the following steps: (1) Transferring the quantum dot solution to the working electrode of the planar electrochemical three-electrode, or to the gate surface of the high electron mobility transistor chip, to form a quantum dot sensing film; (2) dissolving the polyphenol oxidase preparation in PBS buffer reagent to obtain an enzyme solution, transferring it to the quantum dot sensor film, and incubating to form an enzyme-quantum dot binding interface; (3) Covering the quantum dot binding interface with an enzyme-stabilizing composite reagent, the enzyme-stabilizing composite reagent is used to ensure the normal activity of the enzyme, thereby obtaining a quantum dot-based phenol gas sensor; wherein the enzyme-stabilizing composite reagent is a mixed solution of chloride, glycerol and phosphate buffer; When the sensor is working, the specific catalytic effect of the polyphenol oxidase on the phenol in the gas to be detected is utilized to cause an oxidation reaction of the phenol gas to generate a current signal, thereby realizing the specific detection of the phenol in the gas to be detected.

[0011] Preferably, the concentration of sulfide colloidal quantum dots in the quantum dot solution is 5 to 15 mg / mL.

[0012] Preferably, the polyphenol oxidase preparation in step (2) is polyphenol oxidase lyophilized powder.

[0013] Preferably, the volume ratio of the quantum dot solution used to form the quantum dot sensor film in step (1) to the enzyme solution transferred to the quantum dot sensor film in step (2) is 1:(0.5-1.5), and the concentration of the enzyme in the enzyme solution is 0.5-3 mg / mL.

[0014] Preferably, the incubation in step (3) is performed at 25-37° C. for 0.5-1 h.

[0015] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art: (1) The present invention provides a quantum dot-based phenol gas sensor, comprising a quantum dot sensing film, polyphenol oxidase on the surface of the quantum dot sensing film, and an enzyme-stabilizing composite reagent covering the polyphenol oxidase. The polyphenol oxidase-based quantum dot phenol gas sensor is designed based on the "enzyme-substrate" efficient and specific catalytic action that polyphenol oxidase oxidizes phenol to form benzoquinone by molecular oxygen. The sensor has strong specificity and high sensitivity for phenol gas detection.

[0016] (2) When preparing other gas sensors based on quantum dots in the present invention, a solid phase one-step labeling method is used to achieve efficient loading of polyphenol oxidase on the surface of quantum dots. The labeling method is simple and efficient.

[0017] (3) The present invention is based on the principle of biomimetic and uses an electrochemical planar three-electrode / HEMT chip as an electrical signal transduction device to achieve efficient electron transduction during enzyme-catalyzed substrate reactions.

[0018] (4) The enzyme-based quantum dot gas sensor of the present invention has a simple preparation method, low detection cost, high specificity for phenol gas, high detection sensitivity, and can realize qualitative and quantitative detection of phenol.

[0019] (5) When the phenol gas sensor proposed in the present invention is used for detection, the enzyme-quantum dot binding interface is covered with an enzyme-stabilizing composite reagent comprising chloride, glycerol and PBS buffer reagent, which can ensure the activity of the enzyme and the normal detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a gas-sensitive cyclic voltammetry test curve of the quantum dot gas sensor provided in Example 1 of the present application in phenol gas with different concentrations; Figure 2 It is a dynamic response curve diagram of the quantum dot phenol gas sensor corresponding to the charge transfer interface regulated by enzymes labeled with quantum dots of different sizes in Examples 1, 2, 3, and 4, tested 5 ppm phenol four times continuously at room temperature; Figure 3The selectivity test results of the quantum dot gas sensor prepared in Example 1 for 100 ppm ethanol, 5 ppm phenol, 100 ppm ammonia, 100 ppm hydrogen sulfide, 100 ppm benzene, 50 ppm nitric oxide, 100 ppm acetone, 100 ppm p-xylene, and 50 ppm nitrogen dioxide at room temperature; Figure 4 The response recovery curve of the quantum dot gas sensor prepared in Example 1 under the concentration of phenol (100 ppb-20 ppm); Figure 5 The phenol gas-sensing performance test result curve of the sensor prepared in Comparative Example 2; Figure 6 This is a curve showing the phenol gas-sensing performance test results for the sensor prepared in Comparative Example 4. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0022] The embodiments of the present invention are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and processes are given, but the protection scope of the present invention is not limited to the following embodiments. The process parameters of the following embodiments that do not specify specific conditions are usually based on conventional conditions.

[0023] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0024] In the present invention, unless otherwise specified and / or described, all numerical values ​​involving the amounts of components are "parts by weight" from beginning to end. The process parameters in the following examples without specifying specific conditions are usually based on conventional conditions.

[0025] Polyphenol oxidase (PPO) is a metalloproteinase widely distributed in nature and is commonly found in the plastids of plants, fungi, and insects. The common feature of polyphenol oxidase is that it can oxidize phenol or polyphenols by molecular oxygen to form corresponding quinones. Based on the specific catalytic effect of polyphenol oxidase on phenol, the present invention fixes polyphenol oxidase on colloidal quantum dots to achieve specific detection of phenol gas in complex atmospheres. The present invention provides a quantum dot phenol gas sensor based on polyphenol oxidase (PPO). Polyphenol oxidase (PPO) oxidizes phenol to benzoquinone by molecular oxygen, thereby achieving specific detection of phenol gas. The technical problem to be solved by the present invention is to construct a quantum dot gas sensor that is specific to phenol gas and can avoid interference from other gases.

[0026] The present invention provides a quantum dot-based phenol gas sensor, comprising a quantum dot sensing film, polyphenol oxidase on the surface of the quantum dot sensing film, and an enzyme-stabilizing composite reagent covering the polyphenol oxidase; The quantum dot sensing film is a film formed by transferring a quantum dot solution to a working electrode of a planar electrochemical three-electrode, or to a gate surface of a high electron mobility transistor chip; the polyphenol oxidase forms an enzyme-quantum dot binding interface with the quantum dot sensing film; The enzyme-stabilizing complex reagent covers the quantum dot binding interface to ensure the normal activity of the enzyme, wherein the enzyme-stabilizing complex reagent is a mixed solution of chloride, glycerol and phosphate buffer; When the sensor is working, the specific catalytic effect of the enzyme on phenol in the gas to be detected is used to cause an oxidation reaction of the phenol gas to generate a current signal, thereby achieving specific detection of phenol in the gas to be detected. Correspondingly, the present invention also provides a method for preparing the quantum dot-based phenol gas sensor, comprising the following steps: (1) Transferring the quantum dot solution to the working electrode of the planar electrochemical three-electrode, or to the gate surface of the high electron mobility transistor chip, to form a quantum dot sensing film; (2) dissolving the polyphenol oxidase preparation in PBS buffer reagent to obtain an enzyme solution, transferring it to the quantum dot sensor film, and incubating to form an enzyme-quantum dot binding interface; (3) Covering the quantum dot binding interface with an enzyme-stabilizing complex reagent, the enzyme-stabilizing complex reagent is used to ensure the normal activity of the enzyme, thereby obtaining a quantum dot-based phenol gas sensor; wherein the enzyme-stabilizing complex reagent is a mixed solution of chloride, glycerol and phosphate buffer.

[0027] During detection, the specific catalytic effect of the polyphenol oxidase on phenol in the gas to be detected is utilized to oxidize phenol into an o-dihydroxyphenol compound, and the o-dihydroxyphenol compound is further oxidized into o-benzoquinone, and at the same time, two-electron reduction of oxygen is performed, thereby generating a current signal on the working electrode of the planar electrochemical three-electrode or the gate surface of a high electron mobility transistor (HEMT) chip, thereby realizing specific detection of phenol in the gas to be detected.

[0028] In some embodiments, the quantum dot-based phenol gas sensor proposed by the present invention has a response of 0.155 to 5ppm phenol when operating at room temperature, and also has a good response to 10ppb phenol gas, with strong detection specificity and high sensitivity.

[0029] In some embodiments, the quantum dots are sulfide colloidal quantum dots, preferably lead sulfide quantum dots, cadmium sulfide quantum dots, bismuth sulfide quantum dots, etc.

[0030] In some embodiments, the sulfide colloidal quantum dots are prepared by an organic hot injection method. For example, for lead sulfide colloidal quantum dots, the PbS colloidal quantum dots containing oleic acid on the surface are synthesized by a nucleation reaction of a lead source and bis(trimethylsilyl) sulfide. The preferred size of the sulfide colloidal quantum dots is 1-10 nm, preferably 1-5 nm, and more preferably 3-4 nm. A sulfide colloidal quantum dot solution with a concentration of 5-15 mg / mL is prepared by an organic hot injection method. And colloidal quantum dots of different sizes can be synthesized by regulating the temperature of hot injection. For example, in some embodiments, the hot injection temperature is 95 ° C, and the size of the corresponding quantum dots is 3.09 nm, the hot injection temperature is 100 ° C, and the size of the corresponding quantum dots is 3.50 nm, the hot injection temperature is 110 ° C, and the size of the corresponding quantum dots is 3.59 nm, and the hot injection temperature is 120 ° C. The size of the corresponding quantum dots is 3.71 nm. Colloidal quantum dots of different sizes are synthesized to regulate the interface between biomolecules and fixed matrix materials; in a preferred embodiment, the hot injection temperature is 95-120°C, the hot injection reaction time is 30-50s, and then quickly transferred to a cold water bath and cooled to room temperature.

[0031] The quantum dot film formed by the quantum dot solution on the working electrode of the planar electrochemical three-electrode or on the gate surface of the high electron mobility transistor (HEMT) chip has a thickness of preferably 500-600 nm to facilitate the electron transfer between the enzyme modification layer and the electrode. The polyphenol oxidase preparation of the present invention is usually a polyphenol oxidase freeze-dried powder.

[0032] The present invention uses a solid phase one-step labeling method to chemically cross-link polyphenol oxidase on the surface of quantum dots, transfer the enzyme solution to the above-mentioned quantum dot film, and form an enzyme-quantum dot binding interface after incubation. In some embodiments, the concentration of the enzyme solution is 0.5-3 mg / mL, preferably 1-1.5 mg / mL, and the volume ratio of the enzyme solution to the quantum dot solution used to form the quantum dot film is 0.5:1-1.5:1; the enzyme solution is incubated on the quantum dot sensor film, and the incubation temperature is 25-37°C and the incubation time is 0.5-1h.

[0033] Different from liquid or solid sensors, the present invention is an enzyme-based gas sensor. The enzyme on the quantum dot sensor film may be affected by the airflow, in which water is easily volatilized, resulting in enzyme inactivation or reduced sensitivity. In order to maintain the activity and catalytic effect of the enzyme, the present invention also drips a mixed solution of chloride, phosphate buffer and glycerol on the phenol sensor formed by solid phase labeling, which the present invention calls an enzyme-stabilizing composite reagent, so that the gate surface of the electrochemical planar three-electrode or high electron mobility transistor (HEMT) chip is completely covered, so that the detection can ensure the normal operation of the sensing detection.

[0034] In some embodiments, the volume ratio of PBS to glycerol in the enzyme stabilizing complex reagent is 1:1-10:1, preferably 2:1-6:1; the molar concentration of the chloride is 1-10 mM, preferably 5-10 mM. Preferably, the chloride can be potassium chloride, sodium chloride, etc.

[0035] In some embodiments, in order to achieve quantitative detection, the quantum dot-based phenol gas sensor of the present invention detects phenol gas standards containing different concentrations, obtains the current response curve of the sensor at different concentrations, and fits the curve. Through the fitting relationship between the current response value and the concentration, quantitative detection of phenol in the gas to be tested can be achieved.

[0036] In some embodiments, the enzyme solution is transferred to the quantum dot sensor film by drop coating, spin coating, etc., and the enzyme-stabilizing complex reagent is covered on the quantum dot binding interface.

[0037] For quantum dot sensors formed on the working electrode of the planar electrochemical three-electrode, an electrochemical workstation is used to perform electrochemical gas sensing performance tests; for quantum dot sensors formed on the gate surface of a high electron mobility transistor (HEMT) chip, a semiconductor parameter instrument is used to perform gas sensing-electrical performance tests.

[0038] The following are the sources of reagents and instruments used in the embodiments of the present invention: Electrochemical planar three-electrode: purchased from Botan Technology (Weihai) Co., Ltd.

[0039] Electrochemical workstation CHI760E: purchased from Shanghai Chenhua Instrument Co., Ltd.

[0040] Polyphenol oxidase (mushroom): purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0041] Glycerol solution (100%, sterile): purchased from Beijing Inokai Technology Co., Ltd.

[0042] Phosphate buffered saline (PBS): purchased from Beijing Inokai Technology Co., Ltd., 10× PBS (0.1 M, pH 7.2-7.4).

[0043] Toluene: purchased from Sinopharm Chemical Reagent Co., Ltd.

[0044] Potassium chloride: purchased from Beijing Inokai Technology Co., Ltd.

[0045] V-1530T constant temperature heating platform: purchased from Dongguan V-1530T Automation Technology Co., Ltd.

[0046] Semiconductor parameter analyzer: Keysight B1500A is a Keysight semiconductor device parameter analyzer.

[0047] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the art can be used. The raw materials or instruments used are all conventional products that can be obtained commercially, including but not limited to the raw materials or instruments used in the examples of this application.

[0048] The following are examples: Example 1 A phenol gas sensor based on quantum dots and its preparation method: (1) Synthesis of colloidal quantum dots: 1.8 g of lead oxide was placed in a three-necked flask, 6 mL of oleic acid and 20 mL of octadecene were added, stirred at high speed, and vacuumed and heated to 90 °C to prepare a lead oleate precursor. After vacuuming for 8 hours, the temperature of the precursor was raised to 120 °C. In a glove box, 280 μL of TMS was taken with a pipette and dissolved in the vacuumed octadecene (10 mL) to prepare a sulfur precursor. The sulfur precursor was rapidly hot-injected into the lead precursor under a nitrogen environment, that is, the hot injection temperature was 120 °C. After reacting for 30 s, the heating jacket was turned off and removed, and the three-necked flask was placed in a pre-prepared cold water bath for rapid cooling. The cooled PbS quantum dot source solution was pipetted into a centrifuge tube in four batches using a dropper. A certain amount of acetone was first added for centrifugal washing, and the supernatant was discarded. The remaining product was dispersed and dissolved in toluene, and then acetone was added for centrifugal washing. The speed of each centrifugation is 8000 rpm, and the time is controlled within 10 minutes. After three centrifugations, the black precipitate obtained is the PbS colloidal quantum dots with rich organic ligands on the surface, and the corresponding first exciton absorption peak position of the quantum dots is 1200 nm.

[0049] (2) Preparation of quantum dot film: The obtained PbS colloidal quantum dots were dissolved in toluene to prepare a solution with a concentration of 10 mg / mL. The quantum dot solution was drop-coated on the working electrode of the planar electrochemical three-electrode to form a quantum dot film with a thickness of about 550 nm.

[0050] (3) Prepare enzyme solution: Dissolve 1 mg of polyphenol oxidase lyophilized powder in 1 mL of PBS solution and shake for 10 min until fully dissolved.

[0051] (4) Preparation of enzyme stabilizing complex reagent: prepare a mixed solution of KCl, phosphate buffered saline (PBS) and glycerol. The concentration of KCl in the mixed solution is 5 mM, and the volume ratio of PBS to glycerol is 8:2.

[0052] (5) Coupling of enzyme and quantum dots: The prepared enzyme solution was drop-coated on the prepared quantum dot film (the volume ratio of enzyme solution to quantum dot solution was 1:1), and incubated at a constant temperature of 37°C for 1 h to form a stable enzyme-quantum dot binding interface.

[0053] (6) Measurement of the gas-sensitive performance of quantum dot gas sensors: Add the enzyme-stabilizing complex reagent until it completely covers the three electrodes on the electrochemical plane, introduce a certain concentration of phenol gas through a high-precision gas distribution system, and determine the potential of the constant potential current-time test based on the position of the redox peak through the cyclic voltammetry test curve.

[0054] Example 2 A phenol gas sensor based on quantum dots and its preparation method: (1) Synthesis of colloidal quantum dots: The other steps are the same as step (1) of Example 1, except that the hot injection temperature is 110°C. After reacting for 30 seconds, the mixture is quickly transferred to a cold water bath and cooled to room temperature to obtain colloidal quantum dots with rich organic ligands on the surface. The first exciton absorption peak position of the quantum dots is 1100 nm.

[0055] (2) Preparation of quantum dot film: The obtained colloidal quantum dots were dissolved in toluene to prepare a solution with a concentration of 10 mg / mL. The quantum dot solution was drop-coated on the working electrode of the planar electrochemical three-electrode to form a quantum dot film with a thickness of about 550 nm.

[0056] (3) Prepare enzyme solution: Dissolve 1 mg of polyphenol oxidase lyophilized powder in 1 mL of PBS solution and shake for 10 min until fully dissolved.

[0057] (4) Preparation of enzyme stabilizing complex reagent: prepare a mixed solution of KCl, phosphate buffered saline (PBS) and glycerol. The concentration of KCl in the mixed solution is 5 mM, and the volume ratio of PBS to glycerol is 8:2.

[0058] (5) Coupling of enzyme and quantum dots: The prepared enzyme solution was drop-coated on the prepared quantum dot film with a volume ratio of 1:1 between the enzyme solution and the quantum dot solution. The solution was incubated at a constant temperature of 37°C for 1 h to form a stable enzyme-quantum dot binding interface.

[0059] (6) Measurement of the gas-sensitive performance of quantum dot gas sensors: Add the enzyme-stabilizing complex reagent until it completely covers the three electrodes on the electrochemical plane, introduce a certain concentration of phenol gas through a high-precision gas distribution system, and determine the potential of the constant potential current-time test based on the position of the redox peak through the cyclic voltammetry test curve.

[0060] Example 3 A phenol gas sensor based on quantum dots and its preparation method: (1) Synthesis of colloidal quantum dots: The other steps are the same as step (1) of Example 1, except that the hot injection temperature is 100°C. After reacting for 30 seconds, the mixture is quickly transferred to a cold water bath and cooled to room temperature to obtain colloidal quantum dots with rich organic ligands on the surface. The first exciton absorption peak position of the quantum dots is 1000 nm.

[0061] (2) Preparation of quantum dot film: The obtained colloidal quantum dots were dissolved in toluene to prepare a solution with a concentration of 10 mg / mL. The quantum dot solution was drop-coated on the working electrode of the planar electrochemical three-electrode to form a quantum dot film with a thickness of about 550 nm.

[0062] (3) Prepare enzyme solution: Dissolve 1 mg of polyphenol oxidase lyophilized powder in 1 mL of PBS solution and shake for 10 min until fully dissolved.

[0063] (4) Preparation of enzyme stabilizing complex reagent: prepare a mixed solution of KCl, phosphate buffered saline (PBS) and glycerol. The concentration of KCl in the mixed solution is 5 mM, and the volume ratio of PBS to glycerol is 8:2.

[0064] (5) Coupling of enzyme and quantum dots: The prepared enzyme solution was drop-coated on the prepared quantum dot film with a volume ratio of 1:1 between the enzyme solution and the quantum dot solution. The solution was incubated at a constant temperature of 37°C for 1 h to form a stable enzyme-quantum dot binding interface.

[0065] (6) Measurement of the gas-sensitive performance of quantum dot gas sensors: Add the enzyme-stabilizing complex reagent until it completely covers the three electrodes on the electrochemical plane, introduce a certain concentration of phenol gas through a high-precision gas distribution system, and determine the potential of the constant potential current-time test based on the position of the redox peak through the cyclic voltammetry test curve.

[0066] Example 4 A phenol gas sensor based on quantum dots and its preparation method: (1) Synthesis of colloidal quantum dots: The other steps are the same as step (1) of Example 1, except that the hot injection temperature is 95°C. After reacting for 30 seconds, the mixture is quickly transferred to a cold water bath and cooled to room temperature to obtain colloidal quantum dots with rich organic ligands on the surface. The first exciton absorption peak position of the quantum dots is 950 nm.

[0067] (2) Preparation of quantum dot film: The obtained colloidal quantum dots were dissolved in toluene to prepare a solution with a concentration of 10 mg / mL. The quantum dot solution was drop-coated on the working electrode of the planar electrochemical three-electrode to form a quantum dot film with a thickness of about 550 nm.

[0068] (3) Prepare enzyme solution: Dissolve 1 mg of polyphenol oxidase lyophilized powder in 1 mL of PBS solution and shake for 10 min until fully dissolved.

[0069] (4) Preparation of enzyme stabilizing complex reagent: prepare a mixed solution of KCl, phosphate buffered saline (PBS) and glycerol. The concentration of KCl in the mixed solution is 5 mM, and the volume ratio of PBS to glycerol is 4:1.

[0070] (5) Coupling of enzyme and quantum dots: The prepared enzyme solution was drop-coated on the prepared quantum dot film with a volume ratio of 1:1 between the enzyme solution and the quantum dot solution. The solution was incubated at 37 °C for 1 h to form a stable enzyme-quantum dot binding interface.

[0071] (6) Measurement of the gas-sensitive performance of quantum dot gas sensors: Add the enzyme-stabilizing complex reagent until it completely covers the three electrodes on the electrochemical plane, introduce a certain concentration of phenol gas through a high-precision gas distribution system, and determine the potential of the constant potential current-time test based on the position of the redox peak through the cyclic voltammetry test curve.

[0072] Example 5 A phenol gas sensor based on quantum dots and its preparation method: (1) Synthesis of colloidal quantum dots: same as step (1) in Example 1.

[0073] (2) Preparation of quantum dot film: The obtained colloidal quantum dots were dissolved in toluene to prepare a solution with a concentration of 10 mg / mL. The quantum dot solution was drop-coated on the working electrode of the planar electrochemical three-electrode to form a quantum dot film with a thickness of about 550 nm.

[0074] (3) Prepare enzyme solution: Dissolve 1.5 mg of enzyme lyophilized powder in 1 mL of PBS solution and shake for 10 min until fully dissolved.

[0075] (4) Preparation of enzyme stabilizing complex reagent: prepare a mixed solution of KCl, phosphate buffered saline (PBS) and glycerol. The concentration of KCl in the mixed solution is 5 mM, and the volume ratio of PBS to glycerol is 4:1.

[0076] (5) Coupling of enzyme and quantum dots: The prepared enzyme solution was drop-coated on the prepared quantum dot film with a volume ratio of 1:1 between the enzyme solution and the quantum dot solution. The solution was incubated at 37 °C for 1 h to form a stable enzyme-quantum dot binding interface.

[0077] (6) Measurement of the gas-sensing performance of quantum dot gas sensors. The enzyme-stabilizing complex reagent was added dropwise until it completely covered the three electrodes of the electrochemical plane. A certain concentration of phenol gas was introduced through a high-precision gas distribution system. The potential of the constant potential current-time test was determined based on the position of the redox peak through the cyclic voltammetry test curve.

[0078] Example 6 A phenol gas sensor based on quantum dots and its preparation method: (1) Synthesis of colloidal quantum dots: same as step (1) in Example 1.

[0079] (2) Preparation of quantum dot film: The obtained colloidal quantum dots were dissolved in toluene to prepare a solution with a concentration of 10 mg / mL. The quantum dot solution was drop-coated on the working electrode of the planar electrochemical three-electrode to form a quantum dot film with a thickness of about 550 nm.

[0080] (3) Prepare enzyme solution: Dissolve 0.5 mg of polyphenol oxidase lyophilized powder in 1 mL of PBS solution and shake for 10 min until fully dissolved.

[0081] (4) Preparation of enzyme stabilizing complex reagent: prepare a mixed solution of KCl, phosphate buffered saline (PBS) and glycerol. The concentration of KCl in the mixed solution is 3 mM, and the volume ratio of PBS to glycerol is 2:1.

[0082] (5) Coupling of enzyme and quantum dots: The prepared enzyme solution was drop-coated on the prepared quantum dot film with a volume ratio of enzyme solution to quantum dot solution of 0.5:1. The film was incubated at a constant temperature of 25 °C for 1 h to form a stable enzyme-quantum dot binding interface.

[0083] (6) Measurement of the gas-sensitive performance of quantum dot gas sensors: Add the enzyme-stabilizing complex reagent until it completely covers the three electrodes on the electrochemical plane, introduce a certain concentration of phenol gas through a high-precision gas distribution system, and determine the potential of the constant potential current-time test based on the position of the redox peak through the cyclic voltammetry test curve.

[0084] Example 7 A phenol gas sensor based on quantum dots and its preparation method: (1) Synthesis of colloidal quantum dots: same as step (1) in Example 1.

[0085] (2) Preparation of quantum dot film: The obtained colloidal quantum dots were dissolved in toluene to prepare a solution with a concentration of 10 mg / mL. The quantum dot solution was drop-coated on the gate of the HEMT chip by the drop coating method to form a quantum dot film with a thickness of about 550 nm.

[0086] (3) Prepare enzyme solution: Dissolve 2 mg of polyphenol oxidase lyophilized powder in 1 mL of PBS solution and shake for 10 min until fully dissolved.

[0087] (4) Preparation of enzyme stabilizing complex reagent: prepare a mixed solution of KCl, phosphate buffered saline (PBS) and glycerol. The concentration of KCl in the mixed solution is 8 mM, and the volume ratio of PBS to glycerol is 6:1.

[0088] (5) Coupling of enzyme and quantum dots: The prepared enzyme solution was drop-coated on the prepared quantum dot film with a volume ratio of enzyme solution to quantum dot solution of 1.5:1. The film was incubated at a constant temperature of 37 °C for 1 h to form a stable enzyme-quantum dot binding interface.

[0089] (6) Measurement of the gas-sensing and electrical properties of quantum dot gas sensor chips. Add the enzyme-stabilizing complex reagent to cover the chip gate area, introduce a certain concentration of phenol gas through a high-precision gas distribution system, and test the transfer characteristic curve and the output characteristic curve under different phenol concentrations.

[0090] Comparative Example 1 This comparative example provides a quantum dot gas sensor, which is different from Example 1 only in that the prepared lead sulfide quantum dot solution is directly drop-coated on the surface of the working electrode to prepare the quantum dot thin film sensor.

[0091] Test Example 1 Cyclic voltammetry test curves of quantum dot-based phenol gas sensor in different concentrations of phenol gas: The various performance tests of the quantum dot-based phenol gas sensor were completed in the CHI760 electrochemical workstation. By changing the concentration of the phenol gas introduced (diluting the phenol gas with air and accurately mixing the gas to obtain phenol-air mixed gas of different concentrations), the cyclic voltammetry test curve was obtained. Figure 1 As shown, the cyclic voltammetry test curves of the quantum dot gas sensor prepared in Example 1 were tested at different phenol concentrations, and it was found that with the increase of phenol gas concentration, the intensity of the reduction peak gradually decreased, confirming that the prepared quantum dot gas sensor has a good response to phenol gas.

[0092] Test Example 2 Response of quantum dot-based phenol gas sensor to phenol gas: The gas-sensitive performance of the device was tested at room temperature using a Chenhua electrochemical workstation. First, air was introduced into the test chamber, then 5 ppm of phenol (phenol-air mixture, in which the concentration of phenol was 5 ppm), and then air was introduced to obtain the gas-sensitive response curve.

[0093] like Figure 2 As shown, at room temperature, the quantum dot gas sensors prepared in Example 1 (represented as PbS-1200nm-Ppo in the figure), Example 2 (represented as PbS-1100nm-Ppo in the figure), Example 3 (represented as PbS-1000nm-Ppo in the figure), and Example 4 (represented as PbS-950nm-Ppo in the figure) were tested for 5 ppm phenol. It can be found from the figure that the sensors prepared in each embodiment show good response recovery characteristics, which confirms that the prepared quantum dot gas can sensitively detect phenol gas at room temperature and has excellent response characteristics.

[0094] Test Example 3 Specificity of quantum dot-based phenol gas sensor: Consistent with the conditions of Test Example 2, 9 interfering gases including phenol gas were tested at room temperature. Figure 3The response test results of the quantum dot gas sensor prepared in Example 1 to 100 ppm ethanol (a mixture of ethanol gas and air, wherein the concentration of ethanol gas is 100 ppm, and the others are the same) at room temperature, 5 ppm phenol, 100 ppm ammonia, 100 ppm hydrogen sulfide, 100 ppm benzene, 50 ppm nitric oxide, 100 ppm acetone, 100 ppm p-xylene, and 50 ppm nitrogen dioxide; Figure 3 As shown, it is found that the response of the gas sensor prepared in Example 1 to phenol gas is much higher than that of the other eight interfering gases, so the sensor shows excellent specificity to phenol gas.

[0095] Based on the above performance test results, it is shown that the response of the quantum dot gas sensor prepared in the embodiment of the present invention to 5 ppm phenol gas at room temperature is 0.155, and it has excellent selectivity and good repeatability.

[0096] At the same time, the response recovery curve of the sensor prepared in Example 1 under the concentration of phenol (100 ppb-20 ppm) was tested. Figure 4 As shown, the current response of the sensor at different concentrations is obtained, indicating that the concentration can be quantitatively calibrated through the fitting relationship between the response value and the concentration.

[0097] Comparative Example 2 The rest is the same as Example 1, except that the enzyme stabilizing complex reagent prepared in step (4) contains only phosphate buffer solution PBS, and does not contain potassium chloride and glycerol.

[0098] Comparative Example 3 The rest is the same as Example 1, except that the enzyme-stabilizing complex reagent prepared in step (4) contains only phosphate buffer solution PBS and glycerol, and does not contain potassium chloride, and the volume ratio of PBS to glycerol is 8:2.

[0099] Comparative Example 4 The rest is the same as Example 1, except that the enzyme stabilizing complex reagent prepared in step (4) contains only phosphate buffer solution PBS and potassium chloride, and does not contain glycerol, and the concentration of potassium chloride in the complex reagent is 5 mM.

[0100] The quantum dot sensors obtained in Comparative Examples 2, 3 and 4 were tested for phenol gas sensing performance (5 ppm phenol test for 8 cycles). It was found that the baseline drift of the sensors prepared in Comparative Examples 2 and 4 was relatively serious, such as Figure 5 and Figure 6 As shown; the sensor prepared in comparative example 3 has a more stable baseline than that in comparative example 2, but the sensor baseline current is smaller.

[0101] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A phenol gas sensor based on quantum dots, characterized in that: It comprises a quantum dot sensor film, polyphenol oxidase on the surface of the quantum dot sensor film, and an enzyme stabilizing composite reagent covering the polyphenol oxidase; The quantum dot sensing film is a film formed by transferring a quantum dot solution to a working electrode of a planar electrochemical three-electrode, or to a gate surface of a high electron mobility transistor chip; the polyphenol oxidase forms an enzyme-quantum dot binding interface with the quantum dot sensing film; The enzyme-stabilizing complex reagent covers the quantum dot binding interface to ensure the normal activity of the enzyme, wherein the enzyme-stabilizing complex reagent is a mixed solution of chloride, glycerol and phosphate buffer; When the sensor is working, the specific catalytic effect of the polyphenol oxidase on the phenol in the gas to be detected is utilized to cause an oxidation reaction of the phenol gas to generate a current signal, thereby realizing the specific detection of the phenol in the gas to be detected.

2. The sensor according to claim 1, characterized in that The quantum dots are sulfide colloidal quantum dots.

3. The sensor according to claim 1, characterized in that The volume ratio of phosphate buffer to glycerol in the enzyme stabilizing complex reagent is 1:1 to 10:

1.

4. The sensor according to claim 1, characterized in that The molar concentration of the chloride in the enzyme stabilizing complex reagent is 1-10 mM.

5. The preparation method according to claim 4, characterized in that: The chloride is sodium chloride and / or potassium chloride.

6. The method for preparing a phenol gas sensor based on quantum dots according to any one of claims 1 to 5, characterized in that: The steps include: (1) Transferring the quantum dot solution to the working electrode of the planar electrochemical three-electrode, or to the gate surface of the high electron mobility transistor chip, to form a quantum dot sensing film; (2) dissolving the polyphenol oxidase preparation in PBS buffer reagent to obtain an enzyme solution, transferring it to the quantum dot sensor film, and incubating to form an enzyme-quantum dot binding interface; (3) Covering the quantum dot binding interface with an enzyme-stabilizing composite reagent, the enzyme-stabilizing composite reagent is used to ensure the normal activity of the enzyme, thereby obtaining a quantum dot-based phenol gas sensor; wherein the enzyme-stabilizing composite reagent is a mixed solution of chloride, glycerol and phosphate buffer; When the sensor is working, the specific catalytic effect of the polyphenol oxidase on the phenol in the gas to be detected is utilized to cause an oxidation reaction of the phenol gas to generate a current signal, thereby realizing the specific detection of the phenol in the gas to be detected.

7. The preparation method according to claim 6, characterized in that: The concentration of sulfide colloidal quantum dots in the quantum dot solution is 5-15 mg / mL.

8. The preparation method according to claim 6, characterized in that: The polyphenol oxidase preparation in step (2) is polyphenol oxidase freeze-dried powder.

9. The preparation method according to claim 6, characterized in that: The volume ratio of the quantum dot solution used to form the quantum dot sensor film in step (1) to the enzyme solution transferred to the quantum dot sensor film in step (2) is 1:(0.5-1.5), and the concentration of the enzyme in the enzyme solution is 0.5-3 mg / mL.

10. The preparation method according to claim 6, characterized in that: The incubation in step (3) is performed at 25-37° C. for 0.5-1 h.

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