A bionic olfactory sensor and its preparation method and application

Abstract

The present invention discloses a bionic olfactory sensor and its preparation method and application, which belongs to the field of electrochemical biosensors. The working electrode of the bionic olfactory sensor is modified by a ZIF-8@SWCNT solution, a MOR1-1 / AuNPs / PB solution and a bovine serum albumin solution. The preparation method comprises: in situ growing a metal organic framework ZIF-8 on a single-walled carbon nanotube to obtain a ZIF-8@SWCNT solution, drop-coating the solution on the surface of a glassy carbon electrode, drying it in a dust-free environment, electro-depositing the MOR1-1 / AuNPs / PB solution on the electrode surface, refrigerating it until completely dry, and finally drop-coating a bovine serum albumin solution and refrigerating it until completely dry. The bionic olfactory sensor of the present invention can be used for the detection of hexanal content in grapes, and has high sensitivity, specificity and good stability.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical biosensors, and in particular to a bionic olfactory sensor and a preparation method and application thereof. Background Art

[0002] Hexanal is a common flavor compound in foods, found in meat products, cooking oils, and fruits and vegetables such as grapes, apples, and tomatoes. As one of the main volatile compounds released during food storage due to lipid oxidation, hexanal is considered a key oxidation indicator of food quality deterioration. Furthermore, the types and levels of odor molecules released by fruits vary at different stages of development. Hexanal concentration varies significantly with fruit maturity, making it a key indicator of fruit maturity. Therefore, hexanal detection has important practical value for food quality monitoring and fruit maturity testing.

[0003] Currently, common methods for detecting hexanal include gas chromatography-mass spectrometry (GC-MS), gas-sensitive material sensors, and electronic noses. GC-MS can accurately quantify compounds, but traditional GC-MS instruments are large, require a demanding working environment, and require complex and time-consuming sample pretreatment, making them inadequate for rapid analysis. Gas-sensitive sensors have a simpler structure, low energy consumption, a compact size, and high sensitivity, but are significantly affected by the experimental environment, have poor stability and reproducibility, and lack selectivity for odorous compounds. Electronic noses can analyze the volatile components of a sample as a whole, thereby obtaining its specific "fingerprint information," but are unable to specifically and quantitatively detect a single compound (such as hexanal). Currently, biomimetic electrochemical sensors based on olfactory receptors hold broad application prospects in volatile organic compound (VOC) analysis. Due to their high sensitivity and specificity, good stability, low sample volume, rapid response, and simple operation, they are more suitable for detecting hexanal in samples.

[0004] The method of receptor immobilization in a sensor is a key factor affecting its performance, closely related to the properties of the nanomaterial, receptor function, and loading capacity. ZIF-8 is a porous material with a uniform crystal structure, high surface area, and excellent water stability. It can effectively improve the loading efficiency and stability of proteins and increase the affinity and activity of immobilized biomolecules. However, the poor conductivity of ZIF-8 limits its application in various fields. SWCNTs have excellent electrical properties. Their combination with ZIF-8 can significantly amplify the sensor's electrical signal and, as a dual-support material, provide a large number of active sites for receptor attachment. Prussian blue, as an inorganic conductive film, has high electrochemical properties and excellent biocompatibility. It can provide facile assembly and precise interaction with active sites at functional interfaces in sensing and biomedical applications. Gold nanoparticles are widely used for biomolecule immobilization due to their excellent stability and catalytic properties.

[0005] At present, there are no reports on the use of biosensors based on AuNPs / PB / ZIF-8@SWCNT for the detection of hexanal in food, which is a technical gap. Summary of the Invention

[0006] In order to overcome the defects of current detection technology, the main purpose of the present invention is to provide a bionic olfactory sensor based on AuNPs / PB / ZIF-8@SWCNT immobilization technology, which is modified by ZIF-8@SWCNT solution, MOR1-1 / AuNPs / PB solution and bovine serum albumin solution, and has the advantages of good selectivity, sensitivity and stability.

[0007] Another object of the present invention is to provide a method for preparing the above-mentioned bionic olfactory sensor.

[0008] Another object of the present invention is to provide an application of the above-mentioned bionic olfactory sensor in the quantitative detection of hexanal.

[0009] The above-mentioned purpose of the present invention is achieved through the following technical methods:

[0010] The present invention provides a biomimetic olfactory sensor, wherein the working electrode is modified by a ZIF-8@SWCNT solution, a mouse olfactory receptor (MOR1-1) / gold nanoparticles (AuNPs) / Prussian blue (PB) solution, and a bovine serum albumin solution, and is prepared by layer-by-layer assembly, as follows:

[0011] (1) preparing a ZIF-8@SWCNT nanocomposite material, comprising: preparing a SWCNT solution by ultrasonication and stirring, adding 2-methylimidazole and then ultrasonication, then adding a zinc nitrate solution and stirring, standing at room temperature for 24 hours, centrifuging and washing the reaction product and then freeze-drying it, and preparing a solution with the freeze-dried product;

[0012] (2) preparing a MOR1-1 / AuNPs / PB solution, comprising: adding the MOR1-1 solution to the AuNPs solution, shaking and standing at 4° C., and then adding the prepared MOR1-1 / AuNPs solution to the PB solution and stirring;

[0013] (3) Surface pretreatment of the working electrode;

[0014] (4) 8 μL of ZIF-8@SWCNT solution was added dropwise to the surface of the working electrode after surface pretreatment and allowed to dry at room temperature;

[0015] (5) Electrodepositing the MOR1-1 / AuNPs / PB solution onto the electrode surface described in step (3) and drying at 4°C;

[0016] (6) Add 6 μL of bovine serum albumin solution dropwise to the electrode surface described in step (4) and air-dry at 4°C to obtain a modified working electrode;

[0017] (7) The modified working electrode, reference electrode, and counter electrode are combined into a three-electrode system to obtain a bionic olfactory sensor.

[0018] The bionic olfactory sensor of the present invention is based on the AuNPs / PB / ZIF-8@SWCNT fixation technology and is modified by a ZIF-8@SWCNT solution, a MOR1-1 / AuNPs / PB solution, and a bovine serum albumin solution, wherein:

[0019] ZIF-8 is a type of porous material with a uniform crystal structure, high specific surface area, good water stability and good biocompatibility.

[0020] SWCNTs have excellent electrical properties, high-efficiency electrochemical surface area, low cost, non-toxicity, stable chemical properties, and are easy to composite with other nanomaterials.

[0021] MOR1-1 is a mouse olfactory receptor heterologously expressed in yeast cells. It can specifically recognize hexanal molecules and induce intracellular signal transduction.

[0022] As an inorganic conductive film with high electrochemical performance and excellent biocompatibility, PB can provide facile assembly and precise interaction with active sites at functional interfaces for sensing and biomedical applications.

[0023] Gold nanoparticles have good stability and strong catalytic properties, and can immobilize biomolecules by forming gold-sulfur bonds with receptor proteins.

[0024] Preferably, the concentration of the SWCNT solution is 1.5 mg / mL, and the SWCNT material is dispersed in a polyvinylpyrrolidone (PVPP) solution;

[0025] The concentration of the zinc nitrate solution is 16.5 mg / mL, which is obtained by dissolving zinc nitrate in methanol solution;

[0026] The concentration of the ZIF-8@SWCNT solution is 1 mg / mL, which is obtained by dissolving ZIF-8@SWCNT in chitosan solution;

[0027] The concentration of the MOR1-1 solution is 0.1 mg / mL, which is obtained by dissolving MOR1-1 in PBS solution;

[0028] The concentration of the AuNPs solution is 34 mmol / L, and is obtained by dissolving AuNPs in a deionized water solution;

[0029] The PB solution was prepared by dissolving 0.125 g FeCl3, 0.1644 g K3[Fe(CN)6], 1.491 g KCl and 2 mL concentrated hydrochloric acid in 200 mL chitosan solution;

[0030] The concentration of the bovine serum albumin solution is 0.5 mg / mL, and the solution is obtained by dissolving bovine serum albumin in PBS solution.

[0031] Preferably, the concentration of the polyvinyl pyrrolidone solution is 5 mg / mL, which is obtained by dissolving polyvinyl pyrrolidone in deionized water;

[0032] The MOR1-1 / AuNPs solution is composed of a MOR1-1 solution and an AuNPs solution in a volume ratio of 3:2;

[0033] The MOR1-1 / AuNPs / PB solution is composed of a MOR1-1 / AuNPs solution and a PB solution in a volume ratio of 3:67.

[0034] Preferably, the preparation method of the ZIF-8@SWCNT is as follows: preparing 2 mL of a 1.5 mg / mL SWCNT solution, ultrasonicating for 30 minutes, stirring at 800 rpm for 1 hour, adding 18 mg of 2-methylimidazole, ultrasonicating for 30 minutes, and then adding 2 mL of a 16.5 mg / mL zinc nitrate solution. The mixture is stirred at 1000 rpm for 5 minutes, and allowed to stand at room temperature for 24 hours. The reaction product is centrifuged and washed with methanol and freeze-dried; the freeze-dried product is prepared into a 1 mg / mL solution to obtain a ZIF-8@SWCNT nanocomposite material.

[0035] Preferably, the PBS solution is a 0.1M PBS solution with a pH of 7.4.

[0036] Preferably, in step (3), the working electrode is a glassy carbon electrode, and the surface pretreatment step is: polishing the glassy carbon electrode into a mirror surface on a polishing cloth with 0.3 μm and 0.05 μm aluminum oxide powders in turn, then rinsing with ultrapure water and drying with nitrogen.

[0037] Preferably, the reference electrode is an Ag / AgCl electrode, and the counter electrode is a platinum electrode.

[0038] The present invention also provides application of the bionic olfactory sensor in quantitative detection of hexanal.

[0039] Preferably, the step of quantitatively detecting hexanal using the bionic olfactory sensor comprises:

[0040] (a) The biomimetic olfactory sensor was immersed in a 5 mM potassium ferricyanide solution and electrochemically tested using differential pulse voltammetry in a scanning range of -0.2 to 0.6 V. The electrodes were then gently rinsed and dried at room temperature. Six μL of hexanal solutions of varying concentrations were then added dropwise. After incubation at room temperature for 10 minutes, the electrode surfaces were gently rinsed and electrochemically tested using differential pulse voltammetry in a scanning range of -0.2 to 0.6 V.

[0041] (b) according to the obtained current change value and hexanal concentration, with hexanal concentration as the horizontal axis and current change value as the vertical axis, the data were linearly fitted to obtain a standard curve;

[0042] (c) The actual sample solution is tested using the same electrochemical method, and the current change value is calculated. The current change value is substituted into the standard curve of the linear fitting to calculate the concentration of hexanal in the actual sample.

[0043] Preferably, the actual samples include meat products, edible oils, and fruits and vegetables including grapes, apples, and tomatoes.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The biomimetic olfactory sensor constructed using the MOR1-1 / AuNPs / PB / ZIF-8@SWCNT nanocomposite material in the present invention has good electrochemical properties. The ZIF-8@SWCNT and AuNPs / PB materials effectively enhance the immobilization capacity and stability of the receptor, thereby improving the detection range and sensitivity of the biosensor.

[0046] (2) The bionic olfactory sensor of the present invention has good selectivity, can accurately detect hexanal, and has strong anti-interference ability. The bionic olfactory sensor of the present invention has no current response to interferences such as valeraldehyde, heptanal, octanal, and hexanol.

[0047] (3) The bionic olfactory sensor of the present invention has good stability and reproducibility. The RSD values ​​of six olfactory sensors repeated six times were 1.4%, and the sensor could still maintain more than 80% of the initial signal after being stored in a refrigerator at 4°C for 9 days.

[0048] (4) The bionic sensor of the present invention can be used for highly sensitive detection of hexanal in food. It has a simple preparation process, a wide detection range, a low detection line, and good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Schematic diagram of the overall structure of the bionic olfactory sensor in the embodiment.

[0050] Figure 2 Figure 1 is a cyclic voltammogram of the working electrodes modified with different materials in Example 1 in 5 mM potassium ferrocyanide solution (pH 7.4); wherein: a represents the bare electrode (GCE), b represents ZIF-8@SWCNT / GCE, c represents AuNPs-PB / ZIF-8@SWCNT / GCE, d represents MOR1-1 / AuNPs-PB / ZIF-8@SWCNT / GCE, e represents BAS / MOR1-1 / AuNPs-PB / ZIF-8@SWCNT / GCE, and f represents the cyclic voltammogram of the working electrodes modified with different materials in Example 1 in 5 mM potassium ferrocyanide solution (pH 7.4). -9 BAS / MOR1-1 / AuNPs-PB / ZIF-8@SWCNT / GCE incubated with M hexanal for 30 min.

[0051] Figure 3 Figure 1 is the differential pulse voltammetry curve of the working electrodes modified with different materials in 5 mM potassium ferrocyanide solution (pH 7.4) in Example 1; wherein: a represents the bare electrode (GCE), b represents ZIF-8@SWCNT / GCE, c represents AuNPs-PB / ZIF-8@SWCNT / GCE, d represents MOR1-1 / AuNPs-PB / ZIF-8@SWCNT / GCE, e represents BAS / MOR1-1 / AuNPs-PB / ZIF-8@SWCNT / GCE, and f represents the modified working electrodes with 10 -9 BAS / MOR1-1 / AuNPs-PB / ZIF-8@SWCNT / GCE incubated with M hexanal for 30 min.

[0052] Figure 4 This is a current-potential response curve of the bionic olfactory sensor in Example 2 to different concentrations of hexanal in a potassium ferricyanide solution within a scanning range of -0.2 to 0.6 V.

[0053] Figure 5 This is the standard curve of the response current of the bionic olfactory sensor in Example 2 to different concentrations of hexanal.

[0054] Figure 6 This is a bar graph of the current responses of the bionic olfactory sensor in Example 3 to a blank control, different interferents, and hexanal.

[0055] Figure 7 These are the detection results of hexanal in grapes at different developmental stages using the bionic olfactory sensor and gas chromatography in Example 4. DETAILED DESCRIPTION

[0056] The present invention will be described in further detail below with reference to examples and drawings, but the embodiments of the present invention are not limited thereto.

[0057] The hexanal solution in the present invention was prepared by the following method: a fresh 0.1 M hexanal stock solution was prepared with dimethyl sulfoxide (DMSO), and then serially diluted 1:10 with 0.01 M PBS (pH 7.2-7.4) to obtain hexanal solutions of different concentrations. PBS was used instead of the odorant as a blank control.

[0058] Example 1

[0059] The overall structure of the bionic olfactory sensor is as follows: Figure 1 As shown, it consists of a reference electrode 4, a counter electrode 1, a working electrode 3, and a modification material 2 solidified on the surface of the working electrode, wherein the modification material 2 is prepared from a ZIF-8@SWCNT solution, a MOR1-1 / AuNPs / PB solution, and a bovine serum albumin solution. The bionic olfactory sensor incubated with the hexanal solution is placed in an electrolyte solution 5 to detect the content of hexanal.

[0060] Prepare a bionic olfactory sensor, the specific steps are as follows:

[0061] (1) First, a ZIF-8@SWCNT nanocomposite was prepared. 2 mL of a 1.5 mg / mL SWCNT solution was ultrasonicated for 30 min and stirred at 800 rpm for 1 h. 18 mg of 2-methylimidazole was added. After ultrasonication for 30 min, 2 mL of a 16.5 mg / mL zinc nitrate solution was added. The mixture was stirred at 1000 rpm for 5 min and allowed to stand at room temperature for 24 h. The reaction product was washed by centrifugation with methanol and freeze-dried. The freeze-dried product was prepared into a 1 mg / mL solution to obtain a ZIF-8@SWCNT nanocomposite.

[0062] (2) Preparation of MOR1-1 / AuNPs / PB solution. 0.1 mg / mL MOR1-1 solution was added to 34 mM AuNPs solution at a volume ratio of 3:2, and the mixture was shaken and allowed to stand at 4°C for 1 hour. The prepared MOR1-1 / AuNPs solution was then added to the PB solution at a volume ratio of 3:67 and stirred.

[0063] (3) Pre-treat the working electrode surface. Polish the glassy carbon electrode to a mirror finish using 0.3 μm and 0.05 μm alumina powders on a polishing cloth, rinse with ultrapure water, and blow dry with nitrogen.

[0064] (4) The modification steps of the working electrode are as follows: first, 8 μL of ZIF-8@SWCNT solution was added dropwise to the surface of the working electrode that had been surface pretreated and air-dried at room temperature; then, MOR1-1 / AuNPs / PB solution was electro-deposited onto the surface of the electrode and air-dried at 4°C; finally, 6 μL of bovine serum albumin solution was added dropwise to the surface of the electrode and air-dried at 4°C to obtain the modified working electrode.

[0065] (5) The modified working electrode, reference electrode, and counter electrode are combined into a three-electrode system to obtain a bionic olfactory sensor.

[0066] The biomimetic olfactory sensor prepared in Example 1 was tested by cyclic voltammetry and differential pulse voltammetry, respectively. The specific steps were as follows: a bare electrode was modified with ZIF-8@SWCNT, AuNPs-PB / ZIF-8@SWCNT, MOR1-1 / AuNPs-PB / ZIF-8@SWCNT, BAS / MOR1-1 / AuNPs-PB / ZIF-8@SWCNT, and 10 -9 The working electrodes modified with BAS / MOR1-1 / AuNPs-PB / ZIF-8@SWCNT and incubated with M hexanal for 30 min were immersed in 5 mM potassium ferrocyanide solution, and electrochemical tests were carried out by cyclic voltammetry and differential pulse voltammetry with a scan range of -0.2 to 0.6 V and a scan rate of 100 mV / s.

[0067] Figure 2 and Figure 3 The cyclic voltammetry curves and differential pulse voltammetry curves of working electrodes modified with different materials in potassium ferricyanide solution are shown in Figure 1, where a represents a bare electrode, b represents a working electrode modified with ZIF-8@SWCNT, c represents a working electrode modified with AuNPs-PB / ZIF-8@SWCNT, d represents a working electrode modified with MOR1-1 / AuNPs-PB / ZIF-8@SWCNT, e represents a working electrode modified with BAS / receptor-AuNPs-PB / ZIF-8@SWCNT, and f represents a working electrode modified with 10 -9The BAS / MOR1-1 / AuNPs-PB / ZIF-8@SWCNT working electrode was modified with M-hexanal after incubation for 30 minutes. When ZIF-8@SWCNT was modified on the electrode, the peak current dropped sharply compared to the bare electrode due to the weak conductivity of ZIF-8. When AuNPs-PB was electrodeposited on the above electrode surface, AuNPs-PB / ZIF-8@SWCNT displayed a significant peak current value. This was due to the synergistic effect of AuNPs and PB significantly promoting electron transfer. The modification of the electrode surface with MOR1-1 / AuNPs-PB / ZIF-8@SWCNT resulted in a decrease in the peak current, indicating successful immobilization of the receptor on the electrode surface. The sensor was incubated with BSA to block nonspecific binding sites on the electrode surface, which also resulted in a decrease in the peak current value. When BSA / MOR1-1 / AuNPs-PB / ZIF-8@SWCNT / GCE was incubated with hexanal for 30 min, the peak current value further decreased, which was due to the blocking effect of the formed receptor-hexanal complex. The results indicated the successful construction of the olfactory electrochemical sensor and the feasibility of detecting hexanal.

[0068] Example 2

[0069] Prepare a bionic olfactory sensor, the specific steps are as follows:

[0070] (1) First, a ZIF-8@SWCNT nanocomposite was prepared. 2 mL of a 1.5 mg / mL SWCNT solution was prepared, ultrasonicated for 30 min, stirred at 800 rpm for 1 h, 18 mg of 2-methylimidazole was added, and ultrasonicated for 30 min. Then, 2 mL of a 16.5 mg / mL zinc nitrate solution was added. The mixture was stirred at 1000 rpm for 5 min and allowed to stand at room temperature for 24 h. The reaction product was washed by centrifugation with methanol and freeze-dried. The freeze-dried product was prepared into a 1 mg / mL solution to obtain a ZIF-8@SWCNT nanocomposite.

[0071] (2) Preparation of MOR1-1 / AuNPs / PB solution. 0.1 mg / mL MOR1-1 solution was added to 34 mM AuNPs solution at a volume ratio of 3:2, and the mixture was shaken and allowed to stand at 4°C for 1 hour. The prepared MOR1-1 / AuNPs solution was then added to the PB solution at a volume ratio of 3:67 and stirred.

[0072] (3) Pre-treat the working electrode surface. Polish the glassy carbon electrode to a mirror finish using 0.3 μm and 0.05 μm alumina powders on a polishing cloth, rinse with ultrapure water, and blow dry with nitrogen.

[0073] (4) The modification steps of the working electrode are as follows: first, 8 μL of ZIF-8@SWCNT solution was added dropwise to the surface of the working electrode that had been surface pretreated and air-dried at room temperature; then, MOR1-1 / AuNPs / PB solution was electro-deposited onto the surface of the above electrode and air-dried at 4°C; finally, 6 μL of bovine serum albumin solution was added dropwise to the surface of the above electrode and air-dried at 4°C to obtain the modified working electrode.

[0074] (5) The modified working electrode, reference electrode, and counter electrode are combined into a three-electrode system to obtain a bionic olfactory sensor.

[0075] The biomimetic olfactory sensor prepared in Example 2 was tested using differential pulse voltammetry. The specific steps were as follows: the modified electrode was immersed in a potassium ferricyanide solution and electrochemical testing was performed using differential pulse voltammetry with a scan range of -0.2 to 0.6 V. The electrode was then gently rinsed, dried at room temperature, and 6 μL of hexanal solution was added dropwise. After drying at room temperature for 10 minutes, electrochemical detection was performed using differential pulse voltammetry with a scan range of -0.2 to 0.6 V.

[0076] The DPV curves of the biomimetic olfactory sensor prepared in Example 2 in response to different concentrations of hexanal under the electrochemical conditions of a scanning range of -0.2 to 0.6 V and a scanning rate of 100 mV / s are shown in FIG. Figure 4 As shown, the peak current of DPV gradually decreases with the increase of hexanal concentration, indicating that the bionic olfactory sensor of the present invention has excellent electrochemical performance.

[0077] The standard curve of the response current of the bionic olfactory sensor to different concentrations of hexanal in Example 2 is as follows: Figure 5 As shown, the DPV response value is shown with 10 -1 ~10 -6 Hexanal has a good linear relationship within the concentration range of M, and the regression equation is △I=75.31-4.56LgC Hexanal (M), with a correlation coefficient of 0.9963 and a 1.36×10 -15 The low detection line of M indicates that the bionic olfactory sensor of the present invention can be used for the quantitative detection of hexanal.

[0078] Example 3

[0079] Prepare a bionic olfactory sensor, the specific steps are as follows:

[0080] (1) First, a ZIF-8@SWCNT nanocomposite was prepared. 2 mL of a 1.5 mg / mL SWCNT solution was prepared, ultrasonicated for 30 min, stirred at 800 rpm for 1 h, 18 mg of 2-methylimidazole was added, and ultrasonicated for 30 min. Then, 2 mL of a 16.5 mg / mL zinc nitrate solution was added. The mixture was stirred at 1000 rpm for 5 min and allowed to stand at room temperature for 24 h. The reaction product was washed by centrifugation with methanol and freeze-dried. The freeze-dried product was prepared into a 1 mg / mL solution to obtain a ZIF-8@SWCNT nanocomposite.

[0081] (2) Preparation of MOR1-1 / AuNPs / PB solution. 0.1 mg / mL MOR1-1 solution was added to 34 mM AuNPs solution at a volume ratio of 3:2, and the mixture was shaken and allowed to stand at 4°C for 1 hour. The prepared MOR1-1 / AuNPs solution was then added to the PB solution at a volume ratio of 3:67 and stirred.

[0082] (3) Pre-treat the working electrode surface. Polish the glassy carbon electrode to a mirror finish using 0.3 μm and 0.05 μm alumina powders on a polishing cloth, rinse with ultrapure water, and blow dry with nitrogen.

[0083] (4) The modification steps of the working electrode are as follows: first, 8 μL of ZIF-8@SWCNT solution was added dropwise to the surface of the working electrode that had been surface pretreated and air-dried at room temperature; then, MOR1-1 / AuNPs / PB solution was electro-deposited onto the surface of the above electrode and air-dried at 4°C; finally, 6 μL of bovine serum albumin solution was added dropwise to the surface of the above electrode and air-dried at 4°C to obtain the modified working electrode.

[0084] (5) The modified working electrode, reference electrode, and counter electrode are combined into a three-electrode system to obtain a bionic olfactory sensor.

[0085] The biomimetic olfactory sensor prepared in Example 3 was tested using differential pulse voltammetry. The specific steps were as follows: the biomimetic olfactory sensor was immersed in potassium ferricyanide solution and electrochemical testing was performed using differential pulse voltammetry with a scanning range of -0.2 to 0.6 V. The electrodes were then gently rinsed and dried at room temperature, and 6 μL of 0.01 M PBS (pH 7.4) buffer, valeraldehyde (10 -9 M), heptaldehyde (10 -9 M), octanal (10 -9 M), hexanol (10 -9 M), hexanal (10 -9 M) and hexanal mixture (5×10 -9M valeraldehyde, heptanal, octanal, hexanol, and hexanal (mixed at a ratio of 1:1:1:1:1) were incubated at room temperature for 10 min, and then electrochemical detection was carried out by differential pulse voltammetry in the scanning range of -0.2 to 0.6 V.

[0086] The current response bar graph of the biomimetic olfactory sensor prepared in Example 3 to different interfering substances, blank control and hexanal in the scanning range of -0.2 to 0.6 V is as follows: Figure 6 As shown, it can be seen that the current response value of the bionic olfactory sensor to hexanal and hexanal mixture is significantly higher than that of the blank control group and interfering substances (pentanal, heptanal, octanal, hexanol), indicating that the olfactory receptor has good specificity for hexanal and good anti-interference ability to the structural analogues of hexanal.

[0087] Example 4

[0088] Prepare a bionic olfactory sensor, the specific steps are as follows:

[0089] (1) First, a ZIF-8@SWCNT nanocomposite was prepared. 2 mL of a 1.5 mg / mL SWCNT solution was ultrasonicated for 30 min and stirred at 800 rpm for 1 h. 18 mg of 2-methylimidazole was added. After ultrasonication for 30 min, 2 mL of a 16.5 mg / mL zinc nitrate solution was added. The mixture was stirred at 1000 rpm for 5 min and allowed to stand at room temperature for 24 h. The reaction product was washed by centrifugation with methanol and freeze-dried. The freeze-dried product was prepared into a 1 mg / mL solution to obtain a ZIF-8@SWCNT nanocomposite.

[0090] (2) Preparation of MOR1-1 / AuNPs / PB solution. 0.1 mg / mL MOR1-1 solution was added to 34 mM AuNPs solution at a volume ratio of 3:2, and the mixture was shaken and allowed to stand at 4°C for 1 hour. The prepared MOR1-1 / AuNPs solution was then added to the PB solution at a volume ratio of 3:67 and stirred.

[0091] (3) Pre-treat the working electrode surface. Polish the glassy carbon electrode to a mirror finish using 0.3 μm and 0.05 μm alumina powders on a polishing cloth, rinse with ultrapure water, and blow dry with nitrogen.

[0092] (4) The modification steps of the working electrode are as follows: first, 8 μL of ZIF-8@SWCNT solution was added dropwise to the surface of the working electrode that had been surface pretreated and air-dried at room temperature; then, MOR1-1 / AuNPs / PB solution was electro-deposited onto the surface of the above electrode and air-dried at 4°C; finally, 6 μL of bovine serum albumin solution was added dropwise to the surface of the above electrode and air-dried at 4°C to obtain the modified working electrode.

[0093] (5) The modified working electrode, reference electrode, and counter electrode are combined into a three-electrode system to obtain a bionic olfactory sensor.

[0094] The biomimetic olfactory sensor prepared in Example 4 was tested using differential pulse voltammetry. The specific steps were as follows: the biomimetic olfactory sensor was immersed in a potassium ferricyanide solution and electrochemically tested using differential pulse voltammetry within a scan range of -0.2 to 0.6 V. The electrodes were then gently rinsed, dried at room temperature, and 6 μL of grape samples from different developmental stages were added dropwise. After incubation at room temperature for 10 minutes, electrochemical detection was performed using differential pulse voltammetry within a scan range of -0.2 to 0.6 V.

[0095] For actual sample testing: 10g of frozen Sunshine Rose fruit was removed from the stems and transferred to a dry grinder. 0.05g of D-gluconolactone and 0.25mg of Vitamin C were added and the frozen grapes were quickly dry-ground in the blender into a homogeneous powder. The resulting grape powder was then mixed with 10mL of 0.2M citric acid / phosphate buffer (pH 3.2), aerated with nitrogen, sealed, and shaken at 4°C for 24h. The extract was then centrifuged at 4°C for 20min (10,000g), the supernatant filtered, 0.2g of polyvinylpyrrolidone added, and filtered through a 0.2μm filter for analysis and detection of hexanal content.

[0096] The results of the bionic olfactory sensor and gas chromatography prepared in Example 4 for the detection of hexanal in grape samples at different developmental stages are as follows: Figure 7 As shown, it can be seen that the response trend of the bionic olfactory sensor to hexanal is basically consistent with the detection result of gas chromatography, and can be applied to the analysis and detection of hexanal content in actual samples.

[0097] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A bionic olfactory sensor, characterized in that: The working electrode is modified with a ZIF-8@SWCNT solution, a MOR1-1 / AuNPs / PB solution, and a bovine serum albumin solution, where PB is Prussian blue. The preparation is done by layer-by-layer assembly, including the following steps: (1) preparing a ZIF-8@SWCNT nanocomposite material, comprising: preparing a SWCNT solution, ultrasonicating and stirring, adding 2-methylimidazole, ultrasonicating, adding a zinc nitrate solution, stirring, and standing at room temperature for 24 hours. The reaction product is centrifuged, washed, and freeze-dried, and the freeze-dried product is used to prepare a solution; (2) preparing a MOR1-1 / AuNPs / PB solution, comprising: adding the MOR1-1 solution to the AuNPs solution, shaking and standing the mixture at 4° C., and then adding the obtained MOR1-1 / AuNPs solution to the PB solution and stirring; (3) Surface pretreatment of the working electrode; (4) 8 μL of ZIF-8@SWCNT solution was added dropwise to the surface of the working electrode after surface pretreatment and allowed to dry at room temperature; (5) Electrodepositing the MOR1-1 / AuNPs / PB solution onto the surface of the working electrode after surface pretreatment in step (3) and drying at 4°C; (6) Add 6 μL of bovine serum albumin solution dropwise to the surface of the working electrode dried in step (4) and air-dry at 4°C to obtain a modified working electrode; (7) The modified working electrode in step (6) is combined with a reference electrode and a counter electrode to form a three-electrode system to obtain a bionic olfactory sensor.

2. The bionic olfactory sensor according to claim 1, characterized in that The concentration of the SWCNT solution is 1.5 mg / mL, and the SWCNT material is dispersed in a polyvinyl pyrrolidone solution; The concentration of the zinc nitrate solution is 16.5 mg / mL, which is obtained by dissolving zinc nitrate in a methanol solution; The concentration of the ZIF-8@SWCNT solution is 1 mg / mL, which is obtained by dissolving ZIF-8@SWCNT in chitosan solution; The concentration of the MOR1-1 solution is 0.1 mg / mL, which is obtained by dissolving MOR1-1 in PBS solution; The concentration of the AuNPs solution is 34 mmol / L, and is obtained by dissolving AuNPs in a deionized water solution; The PB solution was prepared by dissolving 0.125 g FeCl3, 0.1644 g K3[Fe(CN)6], 1.491 g KCl and 2 mL concentrated hydrochloric acid in 200 mL chitosan solution; The concentration of the bovine serum albumin solution is 0.5 mg / mL, and the solution is obtained by dissolving bovine serum albumin in PBS solution.

3. The bionic olfactory sensor according to claim 2, characterized in that The concentration of the polyvinyl pyrrolidone solution is 5 mg / mL, and is obtained by dissolving polyvinyl pyrrolidone in deionized water; The MOR1-1 / AuNPs solution is composed of a MOR1-1 solution and an AuNPs solution in a volume ratio of 3:2; The MOR1-1 / AuNPs / PB solution is composed of a MOR1-1 / AuNPs solution and a PB solution in a volume ratio of 3:

67.

4. The bionic olfactory sensor according to claim 1, characterized in that The ZIF-8@SWCNT preparation method comprises the following steps: preparing 2 mL of a 1.5 mg / mL SWCNT solution, ultrasonicating the solution for 30 minutes, stirring the solution at 800 rpm for 1 hour, adding 18 mg of 2-methylimidazole, and ultrasonicating the solution for 30 minutes. Then, adding 2 mL of a 16.5 mg / mL zinc nitrate solution, stirring the mixture at 1000 rpm for 5 minutes, and standing the mixture at room temperature for 24 hours. The reaction product is washed by centrifugation with methanol and freeze-dried. The freeze-dried product is then prepared into a 1 mg / mL solution to obtain a ZIF-8@SWCNT nanocomposite material.

5. The bionic olfactory sensor according to claim 2, characterized in that: The PBS solution is a 0.1M PBS solution with a pH of 7.

4.

6. The bionic olfactory sensor according to claim 1, characterized in that In step (3), the working electrode is a glassy carbon electrode, and its surface pretreatment step is: polishing the glassy carbon electrode into a mirror surface on a polishing cloth with 0.3μm and 0.05μm aluminum oxide powders in turn, then rinsing with ultrapure water and drying with nitrogen.

7. The bionic olfactory sensor according to claim 1, characterized in that The reference electrode is an Ag / AgCl electrode, and the counter electrode is a platinum electrode.

8. Use of the bionic olfactory sensor according to any one of claims 1 to 7 in the quantitative detection of hexanal.

9. The use according to claim 8, characterized in that The step of quantitatively detecting hexanal using the bionic olfactory sensor comprises: (a) The biomimetic olfactory sensor was immersed in a 5 mM potassium ferricyanide solution and electrochemically tested using differential pulse voltammetry in a scan range of -0.2 to 0.6 V. The electrodes were then gently rinsed and dried at room temperature. Six μL of hexanal solutions of varying concentrations were then added dropwise, incubated at room temperature for 10 min, and the electrode surfaces were gently rinsed. Electrochemical detection was then performed using differential pulse voltammetry in a scan range of -0.2 to 0.6 V. (b) according to the obtained current change value and hexanal concentration, with hexanal concentration as the horizontal axis and current change value as the vertical axis, the data were linearly fitted to obtain a standard curve; (c) The actual sample solution is tested using the same electrochemical method, and the current change value is calculated. The current change value is substituted into the standard curve of the linear fitting to calculate the concentration of hexanal in the actual sample.

10. The use according to claim 9, characterized in that The actual samples include meat products, edible oils, and fruits and vegetables including grapes, apples, and tomatoes.

Images