阅读说明：本技术 一种AuNPs-p-Ti3C2Tx复合材料及其制备方法和应用 (AuNPs-p-Ti3C2TxComposite material and preparation method and application thereof ) 是由 孙宗保 刘小裕 张新爱 邹小波 牛增 潘浩东 李君奎 高云龙 于 2021-06-03 设计创作，主要内容包括：本发明提供了一种AuNPs-p-Ti-(3)C-(2)T-(x)复合材料及其制备方法和应用,属于复合材料制备、传感器制备和肉制品质量检测技术领域；在本发明中,首先制备了AuNPs-p-Ti-(3)C-(2)T-(x)复合材料,然后基于该复合材料制备了双分子印迹传感器,所述双分子印迹传感器操作简便、快速灵敏,具有出色的选择性、高稳定性和极低的检测限,能够同时检测尸胺与腐胺的含量总和,在评价猪肉新鲜度上有着很好的应用。(The invention provides AuNPs-p-Ti 3 C 2 T x Composite material andthe preparation method and the application thereof belong to the technical field of composite material preparation, sensor preparation and meat product quality detection; in the present invention, AuNPs-p-Ti is first prepared 3 C 2 T x The composite material is used for preparing the double-molecular imprinting sensor based on the composite material, the double-molecular imprinting sensor is simple and convenient to operate, is quick and sensitive, has excellent selectivity, high stability and extremely low detection limit, can be used for simultaneously detecting the content sum of cadaverine and putrescine, and has good application in evaluating pork freshness.)

1. AuNPs-p-Ti₃C₂T_xComposite material, characterized in that the composite material consists of a two-dimensional transition metal carbonitride p-Ti having a large number of pores₃C₂T_xIs prepared by compounding with gold nano-particles AuNPs, and the composite material is a porous two-dimensional lamellar structure, wherein the AuNPs are immobilized on p-Ti₃C₂T_xBetween the surface of the sheet and the sheet.

2. AuNPs-p-Ti₃C₂T_xThe preparation method of the composite material is characterized by comprising the following steps:

porous p-Ti₃C₂T_xThe powder is dispersed inObtaining p-Ti in pure water₃C₂T_xAdding AuNPs solution into the dispersion, mixing and standing, centrifuging, washing and centrifuging to obtain the composite material, which is marked as AuNPs-p-Ti₃C₂T_x。

3. The AuNPs-p-Ti of claim 2₃C₂T_xA method for producing a composite material, characterized in that the p-Ti₃C₂T_xp-Ti in the Dispersion₃C₂T_xThe dosage ratio of the powder to the pure water is 5-6 mg: 1 mL.

4. The AuNPs-p-Ti of claim 2₃C₂T_xA method for producing a composite material, characterized in that the p-Ti₃C₂T_xThe molar ratio of the dispersion to the AuNPs solution was 1: 0.5 to 5; wherein the concentration of the AuNPs solution is 1-5 g/mL.

5. AuNPs-p-Ti as defined in claim 1₃C₂T_xThe double molecular imprinting sensor of the composite material is characterized in that the double molecular imprinting sensor adopts AuNPs-p-Ti₃C₂T_xThe composite material is a sensitizing material, cadaverine and putrescine are double molecular templates, and the AuNPs-p-Ti-based composite material is prepared by an electropolymerization method₃C₂T_xThe dual-template molecularly imprinted sensor.

6. AuNPs-p-Ti-based as claimed in claim 5₃C₂T_xThe preparation method of the composite material double-template molecularly imprinted sensor is characterized by comprising the following steps of:

mixing AuNPs-p-Ti₃C₂T_xDispersing in pure water, dripping on a screen printing electrode, and drying to obtain high-conductivity AuNPs-p-Ti₃C₂T_x/SPCE; electropolymerizing cadaverine and putrescine on a high-conductivity sensing interface by cyclic voltammetry to construct a MIP layer, drying, and eluting template molecules to obtain the AuN-based molecular sievePs-p-Ti₃C₂T_xBimolecular imprinting sensor of composite material, marked as MIP/AuNPs-p-Ti₃C₂T_x/SPCE。

7. AuNPs-p-Ti-based as claimed in claim 6₃C₂T_xThe preparation method of the double-template molecular imprinting sensor of the composite material is characterized in that the AuNPs-p-Ti₃C₂T_xThe dosage ratio of the water to pure water is 1-6 g:1mL, 20. mu.L drop application.

8. AuNPs-p-Ti-based as claimed in claim 6₃C₂T_xThe preparation method of the composite material double-template molecularly imprinted sensor is characterized in that the MIP layer is constructed by the following method:

mixing AuNPs-p-Ti₃C₂T_xSoaking the SPCE in a PBS solution containing cadaverine, putrescine and a functional monomer MAA (methacrylic acid) and electropolymerizing under the conditions of CV scanning for 5-30 cycles, potential range of 0-0.8V and scanning speed of 50 mV/s; the molar ratio of cadaverine to putrescine to MAA is 1: 1: 1 to 7.

9. AuNPs-p-Ti-based as claimed in claim 6₃C₂T_xThe preparation method of the composite material double-template molecularly imprinted sensor is characterized in that the elution conditions are as follows: eluting for 10-45 min by using 20-50 mL of methanol/acetic acid; the volume ratio of methanol to acetic acid in the methanol/acetic acid is 9: 1.

10. AuNPs-p-Ti-based as claimed in claim 5₃C₂T_xThe application of the composite material dual-template molecular imprinting sensor in detecting the freshness of pork products.

Technical Field

The invention belongs to the technical field of composite material preparation, sensor preparation and meat product quality detection, and particularly relates to AuNPs-p-Ti₃C₂T_xComposite material and its preparation method and application.

Background

The production and processing processes of the meat products are very easy to be polluted by microorganisms, so that nutrient substances are decomposed, the meat products are rotten and deteriorated, and the sensory quality, the physical property and the chemical property are changed. Eating deteriorated meat products can be harmful to human health and may cause diseases and even death. High levels of Biogenic Amines (BAs) can be detected during the spoilage of meat products and are therefore often used as indicators to assess product freshness. Cadaverine and putrescine are characteristic markers of pork spoilage, and the freshness of pork products can be evaluated by measuring a biological amine index (BAI, BAI = putrescine + cadaverine), so that the occurrence of human poisoning events caused by the intake of high-concentration exogenous biological amine can be fundamentally avoided.

The biogenic amine is mainly detected by adopting high performance liquid chromatography, gas chromatography and capillary electrophoresis, but the detection processes of the methods are complex, time-consuming and labor-consuming, and the application of the methods in actual detection is limited. In recent years, due to the fact that an electrochemical sensing technology is high in sensitivity, high in response speed, low in cost and easy to miniaturize, and a molecular imprinting technology has the characteristics of selective identification and wide applicability, a molecular imprinting polymer serving as an identification element can still keep good stability under severe conditions, and the molecular imprinting technology and the electrochemical sensing technology are combined through more and more researches, so that the selectivity of an electrochemical sensor is remarkably improved, and analysis and detection of complex samples are achieved. However, most of the constructed biological amine sensors only detect a single target object, and the measurement of the sum of various biological amines is complicated, the analysis time is long, the detection limit is high, the biological amine sensors are easy to interfere, and the conductivity of the sensors is not high.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides AuNPs-p-Ti₃C₂T_xComposite material and its preparation method and application. In the present invention, AuNPs-p-Ti is first prepared₃C₂T_xThe composite material is used for preparing the double-molecular imprinting sensor based on the composite material, the double-molecular imprinting sensor is simple and convenient to operate, is quick and sensitive, has excellent selectivity, high stability and extremely low detection limit, can be used for simultaneously detecting the content sum of cadaverine and putrescine, and has good application in evaluating pork freshness.

The invention firstly provides AuNPs-p-Ti₃C₂T_xComposite material consisting of a two-dimensional transition metal carbonitride p-Ti having a large number of pores₃C₂T_xIs prepared by compounding with gold nano-particles AuNPs, the composite material is of a porous two-dimensional lamellar structure, and the AuNPs are immobilized on p-Ti₃C₂T_xHas large specific surface area and excellent conductivity between the surface and the sheet layer.

The invention also provides the AuNPs-p-Ti₃C₂T_xThe preparation method of the composite material specifically comprises the following steps:

(1) porous Ti₃C₂T_xPreparation of powder:

mixing HF solution with Ti₃AlC₂Mixing the powders, stirring, centrifuging, dispersing the precipitate in pure water, ultrasonic centrifuging to obtain supernatant, and adding CuSO₄Mixing, stirring, and adding 5 wt%HF, standing for reaction, centrifuging, and drying the supernatant to obtain porous Ti₃C₂T_xPowder, denoted as p-Ti₃C₂T_x。

(2) Preparation of AuNPs solution:

mixing chloroauric acid (HAuCl)₄·4H₂O) heating to be vigorously boiled, quickly adding a certain amount of trisodium citrate aqueous solution under stirring, wherein the solution is quickly changed into grey from light yellow, then changed into blue, purple and black, gradually stabilizing into wine red, continuously heating and stirring for 15 min, then standing to room temperature, carrying out centrifugal purification, taking the precipitate, and re-dispersing in pure water to obtain a gold nano solution, which is marked as AuNPs solution.

Wherein the mass fraction of the chloroauric acid is 0.01 percent, the mass fraction of the trisodium citrate aqueous solution is 1 percent, and the volume is 2.5 mL; the centrifugation condition is 10000 rpm for 10 minutes; the proportion of the precipitate to the pure water is 1-5 g:1 mL; all glassware used in the experimental process needs to be treated overnight by aqua regia and then is used after being completely washed by pure water.

(3) Composite material AuNPs-p-Ti₃C₂T_xThe preparation of (1):

porous p-Ti₃C₂T_xDispersing the powder in pure water to obtain p-Ti₃C₂T_xAdding AuNPs solution into the dispersion, mixing and standing, centrifuging, washing and centrifuging to obtain the composite material, which is marked as AuNPs-p-Ti₃C₂T_x。

The p-Ti₃C₂T_xp-Ti in the Dispersion₃C₂T_xThe dosage ratio of the powder to the pure water is 5-6 mg: 1 mL; p-Ti₃C₂T_xThe molar ratio of the dispersion to the AuNPs solution was 1: 0.5 to 5; the proportion of the precipitate to pure water is 1-6 g:1 mL.

The invention also provides a method based on the AuNPs-p-Ti₃C₂T_xComposite material double molecular imprinting sensor, which is made of AuNPs-p-Ti₃C₂T_xThe composite material is a sensitizing materialAmine and putrescine are double molecular templates, and the double-template molecularly imprinted sensor is prepared by an electropolymerization method.

The invention also provides the AuNPs-p-Ti-based material₃C₂T_xThe preparation method of the composite material bimolecular imprinting sensor specifically comprises the following steps:

mixing AuNPs-p-Ti₃C₂T_xDispersing in pure water, dripping on a screen printing electrode, and drying to obtain high-conductivity AuNPs-p-Ti₃C₂T_x/SPCE; electropolymerizing cadaverine and putrescine on a high-conductivity sensing interface by cyclic voltammetry to construct a MIP layer, drying, and eluting template molecules to obtain the AuNPs-p-Ti-based material₃C₂T_xBimolecular imprinting sensor of composite material, marked as MIP/AuNPs-p-Ti₃C₂T_x/SPCE。

Further, the AuNPs-p-Ti₃C₂T_xThe dosage ratio of the water to pure water is 1-6 g:1mL, 20. mu.L drop application.

Further, the MIP layer is constructed by the following method: AuNPs-p-Ti₃C₂T_xthe/SPCE was immersed in a 0.1 mol/L PBS solution (pH 8.0) containing cadaverine, putrescine and the functional monomer MAA methacrylic acid in a molar ratio of 1: 1: 1-7; the electropolymerization conditions are as follows: CV scanning for 5-30 cycles, wherein the potential range is 0V-0.8V, and the scanning speed is 50 mV/s; the volume ratio of methanol to acetic acid in methanol/acetic acid is 9: 1, the using amount of the methanol/acetic acid is 20-50 mL, and the elution time is 10-45 min.

The invention also provides the AuNPs-p-Ti-based material₃C₂T_xThe application of the composite material bimolecular imprinting sensor in detecting the freshness of pork products.

Compared with the prior art, the invention has the beneficial effects that:

(1) in the invention, a novel two-dimensional structure nano material two-dimensional transition metal carbonitride (MXenes) is adopted, and the composite material has the advantages of high specific surface area, metal conductivity, flexible and adjustable components, controllable minimum nano layer thickness and the like.In the invention, the MXenes material Ti is added₃C₂T_xPreparation of p-Ti with a large number of pores by introducing a porous structure₃C₂T_xSolve the problem of Ti₃C₂T_xThe defects of re-accumulation, few surface active sites, diffusion of electrolyte ions and low transmission rate of electrons exist, and the electron transmission efficiency is well improved.

(2) The invention discovers AuNPs and p-Ti through experiments₃C₂T_xCan produce synergistic effect to amplify the signal of the sensor, p-Ti₃C₂T_xComposite material AuNPs-p-Ti prepared by combining AuNPs₃C₂T_xAnd the composite material is used as a sensitizing material of the sensor and combined with p-Ti₃C₂T_xThe high specific surface area and the good conductivity of AuNPs, so that the high specific surface area and the good conductivity of AuNPs are cooperated to enhance the performance of the sensor.

(3) According to the invention, double-template molecules (cadaverine and putrescine) are combined with a functional monomer MAA by an electrochemical polymerization method, a layer of compact Molecular Imprinting (MIP) membrane is formed on a high-conductivity sensing interface, an eluted imprinting cavity is used as an identification element, and when the liquid to be detected contains cadaverine and putrescine, the imprinting cavity is specifically identified and adsorbed by the imprinting cavity, so that the change of an electrochemical signal is caused, and the accurate and rapid detection of the freshness index BAI of the meat product is realized. In the detection process, the double-template molecular imprinting sensor can detect single cadaverine and single putrescine and can detect the total concentration of the cadaverine and the putrescine simultaneously, so that the evaluation of the freshness of the pork is more convenient and efficient. And the molecularly imprinted polymer is used as an identification element, and the cadaverine and putrescine in the pork are specifically identified according to the on/off strategy of the double-template molecularly imprinted, so that the anti-interference capability of the sensor is greatly improved.

(4) The sensor prepared by the invention shows wide linear response when the logarithmic (log) value of BAI is within the range of 0.1-1 mmol/L, the detection limit is as low as 0.037 mu mol/L, the sensor is successfully used for meat product analysis, the sensitivity and stability in the detection process are high, the detection time is shortened, the operation is simple, no special requirement is required for detection personnel, the rapid detection of the BAI content can be achieved, and the sensor can be well applied to the detection of the freshness of meat products.

Drawings

FIG. 1 is Ti₃AlC₂And p-Ti₃C₂T_xXRD pattern of (a).

FIG. 2 is p-Ti₃C₂T_xSEM image of (d).

FIG. 3 is p-Ti₃C₂T_xXPS spectra of (a).

FIG. 4 is a UV-Vis image of AuNPs, wherein the inset is a TEM image.

FIG. 5 shows AuNPs-p-Ti composite material₃C₂T_xSEM-EDS elemental profile of (a).

FIG. 6 is a diagram based on AuNPs-p-Ti₃C₂T_xThe construction of the composite material bimolecular imprinting sensor and the schematic diagram of the electrochemical detection of cadaverine and putrescine.

In FIG. 7, A is p-Ti with different molar ratios₃C₂T_xWith AuNPs at 10 mmol/LM [ Fe (CN)₆]^3−/4−CV plot in solution; and B is a corresponding histogram.

Figure 8 is an optimization of the molar ratio between bimodal molecules (cadaverine and putrescine) and functional monomers.

In FIG. 9, A is an optimized graph of the number of electropolymerization cycles; b is an optimization chart of elution time; c is an optimization chart of the re-adsorption time.

FIG. 10 is a graph of the log (log) values of the BAI obtained as a function of the corresponding response currents, where A is the DPV response plot for different concentrations of BAI (0.1. mu.M, 0.5. mu.M, 1. mu.M, 5. mu.M, 10. mu.M, 50. mu.M, 0.1 mM, 0.5 mM, 1 mM) based on a dual-template molecularly imprinted sensor; b is the corresponding standard curve.

Detailed Description

The invention will be further described with reference to the following figures and specific examples, but the scope of the invention is not limited thereto.

In the embodiment of the invention, biological amine index BAI (BAI = putrescine + cadaverine) is used as an index to detect the freshness of the meat product, and the evaluation standard is as follows: the BAI content is less than 48.9 mu mol/L, the BAI is fresh, 48.9-195.7 mu mol/L is acceptable in the initial putrefaction stage, 195.7-489.3 mu mol/L is inferior in quality, and more than 489.3 mu mol/L is putrefaction.

Example 1: AuNPs-p-Ti₃C₂T_XPreparation of composite materials

（1）p-Ti₃C₂T_xThe preparation of (1):

2.0 g of Ti was added to 30 mL of a 40% by mass HF solution₃AlC₂Continuously stirring the powder for 24 hours at 25 ℃; centrifuging to obtain precipitate, and repeatedly washing with pure water until pH of the washing solution is 6.0; then the obtained precipitate is dried for 24 hours in vacuum at the temperature of 30 ℃ to obtain Ti₃C₂T_xAnd (3) powder.

Taking 1.0 g of Ti₃C₂T_xThe powder was dispersed in 250 mL of pure water, and after sonication for 1 h, the suspension was centrifuged at 10,000 rpm for 15 min and the supernatant was collected. Taking 80 mL of supernatant and 80 mL of 0.2 mol/L CuSO₄Mixing, and stirring at room temperature for 30 min; the precipitate was centrifuged, washed repeatedly with pure water until the pH of the washing solution was 6.0, and then 40 mL of 5% by mass HF was added and allowed to stand for 10 min. Finally, centrifuging to obtain precipitate, repeatedly washing with pure water until pH of the washing solution is 5.0, vacuum drying the washing solution at 30 deg.C for 24 hr to obtain porous Ti₃C₂T_xPowder, denoted as p-Ti₃C₂T_x。

(2) Preparing gold nanoparticle AuNPs solution:

100 mL of chloroauric acid (HAuCl) with the mass fraction of 0.01 percent is taken₄·4H₂O) adding the mixture into a 250 mL round-bottom flask, heating the mixture to be vigorously boiled, and quickly adding 2.5 mL trisodium citrate aqueous solution with the mass fraction of 1% while stirring; during the period, the solution quickly changes from light yellow to gray, then changes to blue, purple and black, then gradually stabilizes to wine red, and continuously heats and stirs for 15 min; standing to room temperature, maintaining at 10000 rpm for 10 min for centrifugal purification, taking 2 g of precipitate, re-dispersing in 1mL of pure water to obtain gold nano solution, and recordingAuNPs solution.

（3）AuNPs-p-Ti₃C₂T_XPreparing a composite material:

taking the p-Ti prepared in the step (1)₃C₂T_X5.8 mg of the powder was dispersed in 1mL of pure water to obtain p-Ti₃C₂T_XAdding the AuNPs solution prepared in the step (2) into the dispersion, mixing and stirring for 1 h, wherein p-Ti₃C₂T_xThe molar ratio of the dispersion to the AuNPs solution was 1: 0.5-5, standing the mixture for 24 hours, centrifuging, washing with pure water for 3 times to obtain a precipitate, taking 3 g of the precipitate, dispersing in 1mL of pure water to obtain the composite material, and marking as AuNPs-p-Ti₃C₂T_XAnd storing at 4 deg.C.

FIG. 1 is Ti₃AlC₂And p-Ti₃C₂T_xThe XRD pattern of (A) and (B), as can be seen from the figure, is related to Ti₃AlC₂In contrast, p-Ti₃C₂T_XThe XRD result in the range of 5-70 degrees shows that the characteristic diffraction peak of Al disappears at 39 degrees, which indicates that Ti₃AlC₂The Al layer in (b) was successfully etched and the lamellar structure was not affected.

FIG. 2 is p-Ti₃C₂T_xSEM image of (1), as shown in FIG. 2, p-Ti₃C₂T_XThe Al layer is successfully extracted and etched at the same time, and the Al layer is in a unique lamellar structure. The XPS results of FIG. 3 further demonstrate that p-Ti₃C₂T_XAnd (4) successfully preparing the material.

FIG. 4 is a UV-Vis (ultraviolet-visible spectrum) diagram of AuNPs, wherein the inset is a TEM image. From the uv-vis spectrum, AuNPs exhibited a typical absorption peak at 526 nm, and the corresponding TEM images (inset) further confirmed the successful preparation of gold nanoparticles with an average particle size of about 25 nm.

The SEM-EDS mapping image shown in FIG. 5 shows that AuNPs are uniformly distributed in p-Ti₃C₂T_XLayer and the content ratio of the elements Au, Ti and C in the final composite material is about 1: 6: 4. by combining the above characterization results, it can be obtainedConclusion AuNPs-p-Ti₃C₂T_XComposites have been successfully prepared.

Example 2: based on AuNPs-p-Ti₃C₂T_xPreparation of composite material bimolecular imprinting sensor

FIG. 6 is a diagram based on AuNPs-p-Ti₃C₂T_xThe double molecular imprinting sensor and the schematic diagram for carrying out electrochemical detection on cadaverine and putrescine, wherein the sensor is based on AuNPs-p-Ti₃C₂T_xThe preparation method of the bimolecular imprinting sensor is shown in fig. 6:

20 μ L of the composite material AuNPs-p-Ti obtained in example 1 was taken₃C₂T_xDripping the mixture on a screen printing electrode (SPCE), and drying for 3-5 min by an infrared lamp to obtain a high-conductivity sensing interface AuNPs-p-Ti₃C₂T_x/SPCE; then AuNPs-p-Ti₃C₂T_xthe/SPCE was immersed in a 0.1 mol/L PBS solution (pH 8.0) containing cadaverine template, putrescine template and functional Monomer (MAA) in a molar ratio of 1: 1: 1-7; scanning for 5-30 cycles by Cyclic Voltammetry (CV), and constructing an MIP layer on the surface of the electrode, wherein the potential range is 0-0.8V, and the scanning rate is 50 mV/s; after drying at 40 ℃, the mixture was dried in 30 mL of a volume ratio of 9: 1, washing the electrode with methanol/acetic acid for 10-45 min to remove template molecules, and preparing the AuNPs-p-Ti-based electrode₃C₂T_xThe bimolecular imprinting sensor is marked as MIP/AuNPs-p-Ti₃C₂T_x/SPCE。

In the embodiment, in order to obtain the maximum response current, the composite material AuNPs-p-Ti is also subjected to₃C₂T_xMiddle p-Ti₃C₂T_xThe molar ratio of the dispersion to the AuNPs solution was optimized.

FIG. 7 shows AuNPs-p-Ti composite material₃C₂T_XIn the preparation of (2), p-Ti₃C₂T_xThe molar ratio of the dispersion to the AuNPs solution is optimized, and as can be seen from FIG. 7, when p-Ti₃C₂T_xThe molar ratio of the dispersion to the AuNPs solution was in the range of 1: 0.5-1: in the range of 2, the current is correspondingly contained with AuNPsThe amount increases, but when the molar ratio exceeds 1: 2, the current response reaches a maximum and stabilizes, since AuNPs are at p-Ti₃C₂T_XThe solid loading on the catalyst is saturated. Thus selecting p-Ti₃C₂T_XThe molar ratio of AuNPs is 1: 2 preparing composite material AuNPs-p-Ti₃C₂T_X。

Example 3:

in this example, in order to increase the response current, the molar ratio of cadaverine, putrescine and the functional monomer MAA is optimized to prepare the MIP membrane.

Fig. 8 is an optimization diagram of the molar ratio between the bimodal molecules (cadaverine and putrescine) and the functional monomer, and it can be seen from fig. 8 that when the molar ratio of the three is 1: 1: 1-1: 1: 5, which helps to form more imprinted cavities, while the molar ratio exceeds 1: 1: 5, the response current is reduced because the formed electron channel is covered by an excessive amount of monomer. Thus, in this example, the molar ratio of cadaverine, putrescine template and MAA was selected to be 1: 1: 5 to establish a sensor.

Example 4:

in this embodiment, in order to increase the detection signal of the sensor, the experimental parameters of electropolymerization cycle number, elution time and reabsorption time are optimized respectively.

FIG. 9 is a graph of optimization of various experimental parameters, wherein A is a graph of optimization of the number of electropolymerization cycles; b is an optimization chart of elution time; c is an optimization chart of the re-adsorption time. As shown in fig. 9A, the current response was optimized within 5 to 30 cycles of electropolymerization, the current response increased from 5 to 20 as the number of scanning cycles, the peak current reached a maximum at 20 cycles and then decreased as the number of scanning cycles further increased, and thus, the optimum number of electropolymerization cycles was selected to be 20; as shown in fig. 9B, the elution time is optimized within 10-45 min, more imprinting cavities are exposed as the elution time increases, electrons are more easily transferred on the surface of the sensor, and thus an increased response current is obtained, and the response current reaches the maximum when the elution time reaches 35 min and gradually stabilizes after 35 min, so that the complete elution time of the template on the imprinting cavities is 35 min; as shown in fig. 9C, the re-adsorption time is optimized within 10-45 min, and initially, the imprinting cavity and the target substance are incompletely combined, so that a large number of imprinting cavities are exposed, and thus a large response current is obtained, after 30 min, the adsorption of the imprinting cavity on the cadaverine and the putrescine gradually reaches a saturation state, and the response current also tends to be stable, so that 30 min is selected as the optimal adsorption time in the embodiment.

Example 5:

AuNPs-p-Ti-based building method based on optimized conditions of examples 3 and 4₃C₂T_xThen 0.1 mol/L PBS solution is used for preparing standard mixed solution of cadaverine and putrescine with different concentrations, and the prepared AuNPs-p-Ti-based sensor is used₃C₂T_xDouble molecular imprinting sensor MIP/AuNPs-p-Ti₃C₂T_xthe/SPCE is immersed in the standard mixed solution for re-adsorption for a period of time, and then differential pulse stripping voltammetry (DPV) measurement is carried out in 0.1 mol/L PBS solution containing 5 mmol/L thionine, wherein the specific parameters are as follows: the pulse amplitude is 0.05V, the pulse period is 0.2 s, the pulse width is 0.04 s, and the potential range is from-1.0V to 0.2V.

FIG. 10 is a graph of the log (log) values of the BAI obtained as a function of the corresponding response currents, where A is the DPV response plot for different concentrations of BAI (0.1. mu.M, 0.5. mu.M, 1. mu.M, 5. mu.M, 10. mu.M, 50. mu.M, 0.1 mM, 0.5 mM, 1 mM) based on a dual-template molecularly imprinted sensor; b is the corresponding standard curve. As can be seen from the figure, the AuNPs-p-Ti base₃C₂T_xThe standard curve of the double molecular imprinting sensor is y =8.17x +26.65 when the biogenic amine is detected, the good linear relation is shown between the range of 0.1 mu M and 1 mM, the detection Limit (LOD) is as low as 0.037 mu M, and the requirement of monitoring the freshness of pork in real time can be met.

Example 6:

5 pork samples (Zhenjiang pork, commercially available) were prepared which were kept at 4 ℃ for different days (0 day, 2 days, 5 days, 10 days, 15 days), minced with a meat mincer, 1.0 g of the sample was added to 20 mL of 40% by mass ethanol, extracted in a water bath at 40 ℃ for 1 h, followed by filtration of the extract and evaporation to near dryness in a vacuum rotary evaporator at 60 ℃. Re-dissolving the residue in 10 mL of PBS (pH 7.0) to obtain a solution to be tested for biogenic amine, analyzing the i-t curve of the salted pork sample by adopting a standard addition method under the optimal experimental conditions, repeatedly measuring each sample for 3 times and calculating the recovery rate of each sample.

TABLE 1 analysis of BAI in Yao meat samples (n =3)

As shown in table 1, the average recovery of all samples was between 94% and 103% and the Relative Standard Deviation (RSD) was below 5%, indicating that the prepared sensor is feasible for rapid detection of the salted meat sample BAI. In addition, when the salted pig trotter product is stored at 4 deg.C for about 5 days, it begins to decay initially, and after 15 days, the quality tends to deteriorate gradually.

The present invention is not limited to the above-described embodiments, and any obvious improvements, substitutions or modifications can be made by those skilled in the art without departing from the spirit of the present invention.