Gold nanocone colorimetric sensor array, its preparation method and applications

Abstract

This invention relates to the field of sensor arrays, specifically to a gold nanocone colorimetric sensor array, its preparation method, and its applications. The gold nanocone colorimetric sensor array comprises AuNBPs, His-Fe3O4, TMB, H2O2, and HCl. The AuNBPs are gold nanocones, the His-Fe3O4 are histidine-modified Fe3O4 nanoparticles, and the TMB is 3',3',5',5'-tetramethylbenzidine. The preparation method of the gold nanocone colorimetric sensor array includes the following steps: Step A: Synthesizing AuNBPs; Step B: Synthesizing His-Fe3O4; Step C: Constructing the sensor array; Step D: Optimizing reaction conditions. The gold nanocone colorimetric sensor array has been used for the detection of single substances and baijiu (Chinese liquor). Results show that this invention utilizes the optical properties of AuNBPs and the catalytic activity of His-Fe3O4, possessing the advantages of simplicity, speed, and efficiency, and has potential application value in the field of baijiu detection.

Description

Technical Field

[0001] This invention relates to the field of sensor arrays, specifically to a gold nanocone colorimetric sensor array, its preparation method, and its applications. Background Technology

[0002] The sensing array consists of a series of sensitive substances that can react with the analyte. Through cross-reaction, it can identify multiple or complex analytes. Noble metal nanoparticles have been widely used due to their tunable optical properties. AuNBPs have unique LSPR optical properties, with their color changing continuously with size and morphology. Furthermore, AuNBPs have two tips, which makes them easy to etch.

[0003] Baijiu, a distilled spirit unique to China, is primarily composed of water and ethanol, along with numerous trace components. To date, over 1700 substances have been detected in baijiu, mainly including alcohols, aldehydes, acids, esters, ketones, phenols, and other trace components. Although present in low concentrations, these components, their types, amounts, and proportions significantly influence the flavor and taste of baijiu, thus affecting its quality. However, for the average person, distinguishing between baijiu of different qualities and values ​​is difficult. Given the significant social and economic impact of baijiu, it is necessary to employ appropriate methods for its testing. Currently, baijiu identification primarily utilizes sensory evaluation and instrumental analysis. Sensory evaluation, which comprehensively assesses baijiu through sight, smell, and taste, is widely used in the baijiu industry, ensuring quality control. However, baijiu tasters require extensive training, and the stability of sensory evaluation is easily affected by changes in the external environment. Instrumental analysis is another important method for the identification of baijiu. Techniques such as headspace solid-phase microextraction-mass spectrometry, infrared spectroscopy, and gas chromatography-mass spectrometry have been widely used in the analysis and detection of baijiu. They have advantages such as high accuracy, high sensitivity, and low detection limits. However, due to their large equipment size and complex operation, they cannot meet the needs of real-time on-site detection.

[0004] This invention utilizes the optical properties of AuNBPs and the catalytic activity of His-Fe3O4 to propose a colorimetric sensing array for detecting single substances and baijiu (Chinese liquor) by regulating AuNBPs etching using nanozymes. Figure 1 As shown, under the catalysis of His-Fe3O4, TMB is oxidized to TMB by H2O2 and HCl. 2+ This process induces the etching of AuNBPs. However, the introduction of reducing substances and baijiu (Chinese liquor) affects the oxidation of TMB, further inhibiting the etching of AuNBPs and resulting in different color changes. This method accurately identified 20 single substances and 16 types of baijiu. This colorimetric sensor array has the advantages of simplicity, speed, and efficiency, and has potential application prospects in the baijiu industry. Summary of the Invention

[0005] To address the above problems, this invention provides a gold nanocone colorimetric sensing array, its preparation method, and its applications.

[0006] The gold nanocone colorimetric sensing array is characterized in that: the gold nanocone colorimetric sensing array is composed of AuNBPs, His-Fe3O4, TMB, H2O2 and HCl, wherein AuNBPs are gold nanocones, His-Fe3O4 are histidine-modified Fe3O4 nanoparticles, and TMB is 3',3',5',5'-tetramethylbenzidine.

[0007] Furthermore, the size of the AuNBPs is 70-120 nm, the particle size of the His-Fe3O4 is 50-70 nm, and the volume ratio of His-Fe3O4, H2O2, TMB and HCl is 2-4:2-4:2-4:1-2.

[0008] The method for preparing the gold nanocone colorimetric sensing array is characterized by the following steps:

[0009] Step A: Synthesize Au NBPs;

[0010] Step B: Synthesize His-Fe3O4;

[0011] Step C: Construct the sensor array;

[0012] Step D: Optimize reaction conditions: The addition amounts of His-Fe3O4, H2O2, TMB, and HCl were tested respectively. After the reaction, RGB signal values ​​were extracted using ImageJ and the ED was calculated as an indicator to evaluate the sensing performance. The formula for calculating ED is:

[0013]

[0014] R, G, and B are the red, green, and blue channel values ​​when the analyte is present, respectively, while R0, G0, and B0 are the red, green, and blue channel values ​​when the analyte is absent, respectively.

[0015] Further, step A includes the following steps:

[0016] Step A1: Preparation of seed solution: Dissolve HAuCl4 and sodium citrate in distilled water to obtain a mixed solution of HAuCl4 and sodium citrate. Further add NaBH4 and wait for the solution to gradually turn red. Let the solution stand to obtain the seed solution.

[0017] Step A2: Preparation of growth solution: Under stirring conditions, HAuCl4 and AgNO3 are added to CTAB. After the solution is mixed evenly, ascorbic acid is added. After the solution color changes from yellow to colorless, HCl is added to obtain the growth solution. The CTAB is hexadecyltrimethylammonium bromide.

[0018] Step A3: Preparation of Au NBPs: Add the seed solution prepared in step A1 to the growth solution obtained in step A2 to obtain Au NBPs.

[0019] Further, step B includes the following steps:

[0020] Step B1: Add FeCl3·6H2O to ethylene glycol and stir. After the solution becomes clear and transparent, add sodium acetate and histidine and stir again to obtain a mixed solution.

[0021] Step B2: The mixed solution obtained in step B1 is heated, and the crude product obtained is washed with deionized water and ethanol, centrifuged, and dried to obtain His-Fe3O4.

[0022] Further, in step A1, the concentration of HAuCl4 is 20-80 mM, the concentration of sodium citrate is 5-20 mM, and the concentration of NaBH4 is 5-20 mM.

[0023] In step A2, the concentration of CTAB is 50-200 mM, the concentration of HAuCl4 is 20-80 mM, the concentration of AgNO3 is 5-20 mM, the concentration of ascorbic acid is 50-200 mM, and the concentration of HCl is 0.5-2 M.

[0024] In step A3, the volume of the seed solution is 10–300 μL.

[0025] Further, in step B1, the mass ratio of FeCl3·6H2O, sodium acetate, and histidine is 1-2:4-6:1-2, and the volume of ethylene glycol is 30-50 mL.

[0026] Further, in step B2, the heating temperature is 180–220°C, the heating time is 12–48 h, the drying temperature is 50–80°C, and the drying time is 24–48 h.

[0027] The gold nanocone colorimetric sensor array is used for the detection of a single substance, and includes the following steps:

[0028] Step S1: Mix His-Fe3O4 with a single substance to obtain mixture 1;

[0029] Step S2: Add H2O2 and TMB to mixture 1 obtained in step S1 to obtain mixture 2;

[0030] Step S3: Add HCl and AuNBPs to the mixture 2 obtained in step S2 to obtain the analyte corresponding to the single substance.

[0031] Step S4: Perform 5 experiments on the analyte corresponding to a single substance obtained in step S3. For each single substance, obtain a dataset of 1 substance × 4 array points × 5 replicates.

[0032] Step S5: By extracting the RGB values ​​of the array obtained in step S4, a unique fingerprint spectrum for each single substance is formed, and the array data is further processed using hierarchical clustering analysis (HCA) and linear discriminant analysis (LDA) statistical classification methods.

[0033] The single substance is at least one of the following: ethyl hexanoate, ethyl acetate, ethyl butyrate, ethyl lactate, formaldehyde, acetaldehyde, butyraldehyde, glutaraldehyde, tryptophan, glycine, leucine, histidine, guaiacol, toluene, pyruvic acid, citric acid, butyrate, lactic acid, formic acid, and oxalic acid.

[0034] The His-Fe3O4 concentration is 1 mg / mL, the H2O2 concentration is 1 M, the TMB concentration is 1 mg / mL, and the HCl concentration is 1 M.

[0035] The amount of His-Fe3O4 added is 10-30 μL, the amount of H2O2 added is 10-30 μL, the amount of TMB added is 10-30 μL, the amount of HCl added is 5-10 μL, and the amount of AuNBPs added is 100-150 μL.

[0036] The gold nanocone colorimetric sensor array is used for the detection of baijiu (Chinese liquor), and includes the following steps:

[0037] Step T1: Mix His-Fe3O4 with baijiu (Chinese liquor) to obtain mixture 1;

[0038] Step T2: Add H2O2 and TMB to mixture 1 obtained in step T1 to obtain mixture 2;

[0039] Step T3: Add HCl and AuNBPs to mixture 2 obtained in step T2 to obtain the analyte corresponding to the liquor.

[0040] Step T4: Perform 5 tests on the corresponding baijiu sample obtained in step T3. For each type of baijiu, obtain 1 substance × 4 array points × 5 replicate datasets.

[0041] Step T5: Extract the RGB values ​​of the array obtained in step T4 to form a unique fingerprint spectrum for each type of liquor, and use hierarchical clustering analysis (HCA) and linear discriminant analysis (LDA) statistical classification methods to further process the array data;

[0042] The liquor mentioned is at least one of Hengshui Laobaigan, Langjiu, Baiyunbian, Site, Xifeng, Jiuguijiu, Sanhua, Yanghe, Luzhou Laojiao, Moutai, Fenjiu, Jingzhi, Hongxing Erguotou, Dongjiu, Jiangjin Laobaigan, and Yubingshao.

[0043] The His-Fe3O4 concentration is 1 mg / mL, the H2O2 concentration is 1 M, the TMB concentration is 1 mg / mL, and the HCl concentration is 1 M.

[0044] The amount of His-Fe3O4 added is 10-30 μL, the amount of H2O2 added is 10-30 μL, the amount of TMB added is 10-30 μL, the amount of HCl added is 5-10 μL, and the amount of AuNBPs added is 100-150 μL.

[0045] The beneficial effects of this invention are as follows: This invention utilizes the optical properties of AuNBPs and the catalytic activity of His-Fe3O4 to provide a gold nanocone colorimetric sensor array and its preparation method, which has been applied to the detection of single substances and baijiu (Chinese liquor). Twenty reducing substances were successfully identified with an accuracy of 100%. Furthermore, the practical application capability of the sensor array was explored, and 16 different brands and aroma types of baijiu were accurately distinguished with an accuracy of 100%. The results indicate that this invention has the advantages of simplicity, speed, and efficiency, and has potential application value in the field of baijiu detection. Attached Figure Description

[0046] Figure 1 The diagram illustrates the reaction principle of His-Fe3O4 nanozyme regulating AuNBPs colorimetric sensing array.

[0047] Figure 2 The image shows the TEM characterization of AuNBPs.

[0048] Figure 3 The UV-Vis absorption spectra of AuNBPs of different sizes are shown.

[0049] Figure 4 The images show the TEM and XPS characterizations of His-Fe3O4.

[0050] Figure 5 This is a diagram of the peroxidase-like activity experiment of His-Fe3O4.

[0051] Figure 6 The effect of baijiu (Chinese liquor) on TMB oxidation and AuNBPs etching.

[0052] Figure 7 Analysis of the antioxidant capacity of baijiu (Chinese liquor).

[0053] Figure 8 Optimization of response conditions for AuNBPs sensor arrays.

[0054] Figure 9 This demonstrates the identification of a single substance using an AuNBPs sensor array.

[0055] Figure 10 This demonstrates how AuNBPs sensor arrays can be used to identify baijiu (Chinese liquor). Detailed Implementation

[0056] Example 1: Construction and Optimization of Gold Nanocone Colorimetric Sensing Array

[0057] I. Preparation of Nanomaterials

[0058] (I) Synthesis of AuNBPs of different sizes:

[0059] Preparation of seed solution: Dissolve 25 μL of 50 mM HAuCl4 and 250 μL of 10 mM sodium citrate in 9.7 mL of distilled water and stir for 10 minutes to obtain a mixed solution of HAuCl4 and sodium citrate; add 150 μL of 10 mM refrigerated fresh NaBH4 to the above mixed solution of HAuCl4 and sodium citrate, and under vigorous stirring, the solution gradually turns red. Let the resulting solution stand for two hours to obtain the seed solution.

[0060] Preparation of growth medium: Under stirring conditions, 200 μL of 50 mM HAuCl4 and 200 μL of 10 mM AgNO3 were added to 20 mL of 100 mM CTAB. After the solution was mixed evenly, 160 μL of 100 mM ascorbic acid was added. When the color gradually changed from yellow to colorless, it indicated that Au... 3+ Reduced to Au + 400 μL of 1 M HCl was added to the solution to prepare the growth solution.

[0061] Preparation of AuNBPs of different sizes: 50 μL, 100 μL, 150 μL and 200 μL of seed solution were added to the above growth solution, respectively. After stirring vigorously for 30 s, the solution was placed at room temperature and allowed to stand for 12 h to obtain AuNBPs.

[0062] (II) Synthesis of His-Fe3O4:

[0063] His-Fe3O4 was synthesized by a hydrothermal method: 0.82 g FeCl3·6H2O was added to 40 mL ethylene glycol and stirred until the solution became clear and transparent. Then, 3.6 g sodium acetate and 0.5 g histidine were added and stirred for another 30 min. The mixture was then transferred to a 100 mL high-pressure reactor and heated at 200 °C for 12 h. The crude product was washed with deionized water and ethanol, centrifuged several times, and finally dried in a 60 °C oven for 24 h to obtain His-Fe3O4.

[0064] (III) Characterization of Nanomaterials:

[0065] AuNBPs and His-Fe3O4 were characterized by TEM, XPS, and UV-Vis absorption spectroscopy, respectively.

[0066] The four prepared AuNBPs were bipyramidal with dimensions of 80 nm, 88 nm, 97 nm, and 113 nm, respectively. TEM characterization of the AuNBPs is as follows: Figure 2 As shown, Figure 2 In the diagram, A and E are TEM images of 80 nm Au NBPs, B and F are TEM images of 88 nm Au NBPs, C and G are TEM images of 97 nm Au NBPs, and D and H are TEM images of 113 nm Au NBPs.

[0067] The UV-Vis absorption spectra of AuNBPs are as follows: Figure 3 As shown, each AuNBPs exhibits two characteristic absorption peaks. The transverse plasmon absorption bands of AuNBPs are located at 520, 535, 550 and 549 nm, respectively, and the longitudinal plasmon absorption bands are located at 710, 782, 811 and 850 nm, respectively. These results indicate that AuNBPs were successfully synthesized.

[0068] TEM and XPS analysis of His-Fe3O4, as follows: Figure 4 As shown, Figure 4 In the image, A is the TEM image of His-Fe3O4, and B is the XPS image of His-Fe3O4. His-Fe3O4 shows good dispersibility in aqueous solution, with a particle size of approximately 60 nm. C1s, O1s, N1s, and Fe2p were detected in the XPS spectrum of His-Fe3O4. The peak at 400 eV corresponds to the N1s signal of histidine, confirming that histidine was successfully modified on the surface of the nanoparticles.

[0069] II. Construction of the Sensor Array

[0070] A colorimetric sensing array was constructed based on the catalytic activity of His-Fe3O4 nanozymes and the optical properties of AuNBPs. In an acidic environment, His-Fe3O4 catalyzes the oxidation of TMB by H2O2 to form TMB. 2+ TMB 2+ Further etching of AuNBPs induced surface plasmon resonance, resulting in different color changes. Considering that the color of AuNBPs is affected by size and morphology, four different particle sizes of AuNBPs were used as optical sensing elements to construct a four-dimensional sensing array for the analysis of different single substances and brands of baijiu (Chinese liquor), such as... Figure 5 As shown, Figure 5 In the diagram, A represents the activity analysis of His-Fe3O4 peroxidases, B represents the UV-Vis absorption spectra under different reaction conditions, and C represents the effect of baijiu (Chinese liquor) on the etching of AuNBPs.

[0071] To investigate the peroxidase-like activity of His-Fe3O4 nanozymes, we analyzed the redox reaction between TMB and H2O2, and the results are as follows: Figure 5 As shown in Figure A, when His-Fe3O4 is present, a strong characteristic absorption peak appears near 652 nm in the TMB and H2O2 system. This is because, under the catalysis of His-Fe3O4, TMB is oxidized to TMB by H2O2. + However, almost no absorption peaks were recorded in the TMB, His-Fe3O4+H2O2, His-Fe3O4+TMB, and TMB+H2O2 systems. Therefore, the above results indicate that His-Fe3O4 has peroxidase-like catalytic activity.

[0072] To investigate the detection mechanism of this sensing array, the oxidation process of TMB and the etching effect of Au NBPs were further studied, and the results are as follows: Figure 5 As shown in Figure B, when His-Fe3O4 is added to the system of H2O2 and TMB, TMB is formed near 652 nm. + The characteristic absorption peak is observed at this point, and the solution appears blue. Further introduction of HCl causes the characteristic absorption peak to shift to around 450 nm, and the color changes to yellow. This indicates that TMB... + Further oxidized to TMB 2+ Finally, when AuNBPs were added to the system and reacted for 30 minutes, the characteristic absorption peak of AuNBPs shifted to some extent, accompanied by a decrease in absorbance and a change in solution color from purplish-red to yellow. When baijiu (Chinese white liquor) was added, due to its antioxidant capacity, TMB... 2+ The etching ability of AuNBPs is weakened or suppressed, such as Figure 5 As shown in C.

[0073] To further verify the feasibility of this method, eight different brands of baijiu (Chinese liquor) were added to the above system, and the results are as follows: Figure 6 As shown, Figure 6 In the diagram, A represents the effect of different types of baijiu (Chinese liquor) on TMB oxidation, with the blank group consisting of His-Fe3O4 + H2O2 + TMB, and the experimental group consisting of His-Fe3O4 + H2O2 + TMB + baijiu. B represents the effect of different types of baijiu on Au NBPs etching. Figure 6 As shown in Figure A, compared with the control group, the absorption peak near 652 nm decreased to varying degrees after the addition of baijiu, indicating that the oxidation of TMB was inhibited. This may be due to the antioxidant activity of baijiu. Furthermore, due to differences in fermentation processes and raw materials, the types and contents of antioxidants in baijiu also differ. The total antioxidant capacity of baijiu is as follows: Figure 7 As shown, the eight types of baijiu exhibited drastically different antioxidant capabilities, resulting in varying degrees of inhibition of the reaction between H2O2 and TMB. The inhibitory effect of baijiu on Au NBPs etching was investigated, such as... Figure 6 As shown in Figure B, without the addition of baijiu (Chinese liquor), His-Fe3O4 maximally catalyzes the reaction between H2O2 and TMB and induces AuNBPs etching. However, with the addition of baijiu, due to its antioxidant effect, TMB... 2+ The reduced etching of AuNBPs led to the suppression of the red or blue shift of AuNBP characteristic peaks. Moreover, due to differences in antioxidant capacity, the eight types of baijiu exhibited varying degrees of inhibitory effects on the etching of AuNBPs.

[0074] III. Optimization of Reaction Conditions

[0075] To achieve optimal analytical results while conserving raw materials, the sensing conditions need to be optimized. The addition amounts of 1 mg / mL His-Fe3O4, 1 M H2O2, 1 mg / mL TMB, and 1 M HCl were tested. After the reaction, the RGB signal values ​​were extracted using ImageJ and the ED was calculated as an indicator of sensing performance. The formula for calculating ED is:

[0076] R, G, and B are the red, green, and blue channel values ​​when the analyte is present, respectively, while R0, G0, and B0 are the red, green, and blue channel values ​​when the analyte is absent, respectively.

[0077] The detection performance of the sensor array is closely related to the reaction conditions. Therefore, the usage amounts of His-Fe3O4, H2O2, TMB, and HCl were optimized. The optimal addition amount of each substance was analyzed using ED as the evaluation index. The results are as follows: Figure 8 As shown, Figure 8In the mixture, A represents His-Fe3O4, B represents H2O2, C represents TMB, and D represents HCl. With increasing volumes of His-Fe3O4 and H2O2, the ED gradually increases and then remains essentially constant. This may be related to the TMB content. When the volumes of His-Fe3O4 and H2O2 each reach 20 μL, the ED no longer increases. Figure 8 From points C and D, we know that the optimal volumes for TMB and HCl are 20 μL and 10 μL, respectively. Taking into account both environmental protection and economic benefits, the optimal volumes for His-Fe3O4, H2O2, TMB, and HCl were ultimately determined to be 20 μL, 20 μL, 20 μL, and 10 μL, respectively.

[0078] Implement a 2-cell gold nanocone colorimetric sensor array for the detection of a single substance.

[0079] Ethyl hexanoate, ethyl acetate, ethyl butyrate, ethyl lactate, formaldehyde, acetaldehyde, butyraldehyde, glutaraldehyde, tryptophan, glycine, leucine, histidine, guaiacol, toluene, pyruvic acid, citric acid, butyrate, lactic acid, formic acid, and oxalic acid were selected as analytes to investigate the analytical capability of the sensor array. The specific operation method was as follows: First, 20 μL of His-Fe3O4 and 20 μL of 1 mM analyte were mixed in a 96-well plate to prepare mixture 1; 20 μL of 1 M H2O2 and 20 μL of 1 mg / mL TMB were added to mixture 1 and incubated for 10 min to prepare mixture 2; finally, 10 μL of 1 M HCl and 100 μL of 1 μL of uNBPs were added to mixture 2 sequentially, and the mixed solution was incubated for 30 min to obtain the corresponding analytes.

[0080] Five experiments were conducted on the 20 individual substances to be tested, resulting in a dataset of 20 substances × 4 array points × 5 replicates. By extracting the RGB values ​​of the arrays, a unique fingerprint spectrum was formed for each substance. Statistical classification methods, such as Hierarchical Cluster Analysis (HCA) and Linear Discriminant Analysis (LDA), were then used to further process the array data. HCA is a clustering technique that groups samples with similar properties sequentially by calculating distance. LDA can divide samples into known classes by establishing a series of orthogonal dimensions.

[0081] To evaluate the sensor array's ability to identify different components, tests were conducted on the aforementioned 20 single substances, such as... Figure 9 As shown, Figure 9 In the diagram, A represents the fingerprint spectrum for each individual substance, B represents the HCA analysis spectrum for each substance, and C represents the LDA analysis spectrum for each substance. Due to differences in molecular structure or contained functional groups, the antioxidant capacity of these substances varies considerably, which may, to some extent, inhibit the oxidation of TMB by H2O2, thereby affecting TMB. 2+Etching of AuNBPs. At the end of the reaction, characteristic fingerprints of 20 individual substances were generated by extracting the RGB values ​​of the array points, such as... Figure 9 As shown in Figure A. Taking aldehydes as an example, the color of the sensing array is close to the original color of AuNBPs. This may be due to the presence of the reducing aldehyde group, which has a strong inhibitory effect on the redox reaction between H2O2 and TMB, as well as on the etching of AuNBPs. In contrast to aldehydes, the color of the array points changes significantly when esters are added. This may be related to the weak antioxidant capacity or chemical inertness of esters.

[0082] The recognition capabilities of the colorimetric sensor array were evaluated using both HCA and LDA dimensionality reduction algorithms. Figure 9 The HCA tree diagram shown in Figure B indicates that five parallel samples from the same substance initially cluster tightly together, while different substances remain separate, with no misclassifications. The LDA results are as follows... Figure 9 As shown in Figure C, 20 single substances were successfully distinguished with a recognition accuracy of 100%. Notably, the esters were closely spaced, which may be due to the similarity of their carbonyl group reactivity. These results demonstrate that the colorimetric sensor array possesses excellent recognition capabilities for single substances.

[0083] Example 3: Gold nanocone colorimetric sensor array for the identification of baijiu (Chinese liquor)

[0084] Branded Baijiu Analysis: Based on single-substance detection, 16 different brands and aroma types of baijiu were analyzed to explore the practical application capabilities of the sensor array. The testing methods and data analysis techniques were similar to those for single-substance analysis.

[0085] The 16 types of baijiu are Hengshui Laobaigan, Langjiu, Baiyunbian, Site, Xifeng, Jiuguijiu, Sanhua, Yanghe, Luzhou Laojiao, Maotai, Fenjiu, Jingzhi, Hongxing Erguotou, Dongjiu, Jiangjin Laobaigan, and Yubingshao.

[0086] The specific operation method is as follows: First, in a 96-well plate, 20 μL of His-Fe3O4 and 20 μL of 1 mM baijiu are mixed to prepare mixture 1; 20 μL of 1 M H2O2 and 20 μL of 1 mg / mL TMB are added to mixture 1 and incubated for 10 min to prepare mixture 2; finally, 10 μL of 1 M HCl and 100 μL of 1 μL of uNBPs are added to mixture 2 in sequence, and the mixed solution is incubated for 30 min to obtain the analyte corresponding to the baijiu.

[0087] Five experiments were conducted on the 16 types of baijiu (Chinese liquor) to be tested, resulting in a dataset of 16 baijiu types × 4 array points × 5 replicates. By extracting the RGB values ​​of the arrays, a unique fingerprint spectrum was formed for each type of baijiu. Statistical classification methods, such as hierarchical clustering analysis (HCA) and linear discriminant analysis (LDA), were then used to further process the array data. HCA is a clustering technique that groups samples with similar properties sequentially by calculating distance. LDA can divide samples into known classes by establishing a series of orthogonal dimensions.

[0088] Analysis of the antioxidant capacity of Baijiu (Chinese liquor): Using the absorbance of KMnO4 as an indicator, a standard curve was plotted by reacting different concentrations of ascorbic acid with KMnO4. The antioxidant capacity of Baijiu (expressed as millimolecular equivalents of ascorbic acid) was determined by the reaction between Baijiu and KMnO4.

[0089] To explore the practical application capabilities of colorimetric sensor arrays, further testing was conducted on 16 different brands and aroma types of baijiu (Chinese liquor). Figure 10 As shown, Figure 10 In the diagram, A represents the fingerprint spectra of different brands and aroma types of baijiu, B represents the HCA analysis chart of different brands and aroma types of baijiu, and C represents the LDA analysis chart of different brands and aroma types of baijiu. Baijiu is made from fermented grains and contains not only large amounts of ethanol and water, but also some antioxidants, such as aldehydes, acids, esters, and amino acids. Due to differences in brewing raw materials and fermentation processes, the types and contents of antioxidants in baijiu vary. When added to baijiu, it inhibits the etching of AuNBPs to varying degrees, accompanied by different color changes. For specific baijiu, a unique color response pattern will be exhibited, such as... Figure 10 As shown in Figure A.

[0090] HCA tree diagrams of 16 different brands and aroma types of baijiu are shown below. Figure 10 As shown in Figure B, all baijiu samples were clearly divided into 16 groups, with 5 parallel samples of the same baijiu brand grouped together, and no misclassifications. The LDA tree diagrams for the 16 different brands and aroma types of baijiu are shown below. Figure 10 As shown in Figure C, the LDA results are similar to those of HCA; the 16 types of baijiu were clearly separated with no overlap, achieving a classification accuracy of 100%. Taking Yubing Shao and Baiyunbian as examples, they are relatively close in the graph, which may be due to the similar antioxidant activities of these two types of baijiu. Figure 7 As shown in the figure. The above results demonstrate that this sensor array has a strong ability to identify baijiu (Chinese liquor). Compared with sensory evaluation and instrumental analysis methods, this sensor array has the advantages of being fast, simple, and efficient, and can simultaneously identify different baijiu samples, which helps to achieve real-time, on-site detection of baijiu.

Claims

1. A gold nanocone colorimetric sensor array, characterized by: The composition of the gold nanocone colorimetric sensing array includes AuNBPs, His-Fe3O4, TMB, H2O2 and HCl, wherein AuNBPs are gold nanocones, His-Fe3O4 are histidine-modified Fe3O4 nanoparticles, and TMB is 3,3',5,5'-tetramethylbenzidine. The fabrication method of the gold nanocone colorimetric sensor array comprises the following steps: Step A: Synthesize Au NBPs; Step B: Synthesize His-Fe3O4; Step C: Construct the sensor array; Step D: Optimize reaction conditions: The addition amounts of His-Fe3O4, H2O2, TMB, and HCl were tested respectively. After the reaction, RGB signal values ​​were extracted using ImageJ and the ED was calculated as an indicator to evaluate the sensing performance. The formula for calculating ED is: ； Wherein, G and B are the red, green, and blue channel values ​​when the analyte is present, respectively, and R0, G0, and B0 are the red, green, and blue channel values ​​when the analyte is absent, respectively.

2. The gold nanocone colorimetric sensing array according to claim 1, characterized in that: The Au NBPs have a size of 70~120nm, the His-Fe3O4 has a particle size of 50~70nm, and the volume ratio of His-Fe3O4, H2O2, TMB and HCl is 2~4:2~4:2~4:1~2.

3. The gold nanocone colorimetric sensing array according to claim 1, characterized in that: Step A of the preparation method includes the following steps: Step A1: Preparation of seed solution: Dissolve HAuCl4 and sodium citrate in distilled water to obtain a mixed solution of HAuCl4 and sodium citrate. Further add NaBH4 and wait for the solution to gradually turn red. Let the solution stand to obtain the seed solution. Step A2: Preparation of growth solution: Under stirring conditions, HAuCl4 and AgNO3 are added to CTAB. After the solution is mixed evenly, ascorbic acid is added. After the solution color changes from yellow to colorless, HCl is added to obtain the growth solution. The CTAB is hexadecyltrimethylammonium bromide. Step A3: Preparation of Au NBPs: Add the seed solution prepared in step A1 to the growth solution obtained in step A2 to obtain Au NBPs.

4. The gold nanocone colorimetric sensing array according to claim 1, characterized in that: Step B of the preparation method includes the following steps: Step B1: Add FeCl3·6H2O to ethylene glycol and stir. After the solution becomes clear and transparent, add sodium acetate and histidine and stir again to obtain a mixed solution. Step B2: The mixed solution obtained in step B1 is heated, and the crude product obtained is washed with deionized water and ethanol, centrifuged, and dried to obtain His-Fe3O4.

5. The gold nanocone colorimetric sensing array according to claim 3, characterized in that: In step A1, the concentration of HAuCl4 is 20~80 mM, the concentration of sodium citrate is 5~20 mM, and the concentration of NaBH4 is 5~20 mM. In step A2, the concentration of CTAB is 50-200 mM, the concentration of HAuCl4 is 20-80 mM, the concentration of AgNO3 is 5-20 mM, the concentration of ascorbic acid is 50-200 mM, and the concentration of HCl is 0.5-2 M. In step A3, the volume of the seed solution is 10~300 μL.

6. The gold nanocone colorimetric sensing array according to claim 4, characterized in that: In step B1, the mass ratio of FeCl3·6H2O, sodium acetate, and histidine is 1~2:4~6:1~2, and the volume of ethylene glycol is 30~50 mL.

7. The gold nanocone colorimetric sensing array according to claim 4, characterized in that: In step B2, the heating temperature is 180~220 ℃, the heating time is 12~48 h, the drying temperature is 50~80 ℃, and the drying time is 24~48 h.

8. The use of the gold nanocone colorimetric sensing array according to any one of claims 1 to 2, characterized in that: The gold nanocone colorimetric sensor array is used for the detection of a single substance, and includes the following steps: Step S1: Mix His-Fe3O4 with a single substance to obtain mixture 1; Step S2: Add H2O2 and TMB to mixture 1 obtained in step S1 to obtain mixture 2; Step S3: Add HCl and Au NBPs to the mixture 2 obtained in step S2 to obtain the analyte corresponding to the single substance. Step S4: Perform 5 experiments on the analyte corresponding to the single substance obtained in step S3. For each single substance, obtain a dataset of 1 substance × 4 array points × 5 replicates. Step S5: By extracting the RGB values ​​of the array obtained in step S4, a unique fingerprint spectrum for each single substance is formed, and the array data is further processed using hierarchical clustering analysis (HCA) and linear discriminant analysis (LDA) statistical classification methods. The single substance is at least one of the following: ethyl hexanoate, ethyl acetate, ethyl butyrate, ethyl lactate, formaldehyde, acetaldehyde, butyraldehyde, glutaraldehyde, tryptophan, glycine, leucine, histidine, guaiacol, toluene, pyruvic acid, citric acid, butyrate, lactic acid, formic acid, and oxalic acid. The His-Fe3O4 concentration was 1 mg / mL, the H2O2 concentration was 1 M, the TMB concentration was 1 mg / mL, and the HCl concentration was 1 M. The amount of His-Fe3O4 added is 10~30 μL, the amount of H2O2 added is 10~30 μL, the amount of TMB added is 10~30 μL, the amount of HCl added is 5~10 μL, and the amount of Au NBPs added is 100~150 μL.

9. The use of the gold nanocone colorimetric sensing array according to any one of claims 1 to 2, characterized in that: The gold nanocone colorimetric sensor array is used for the detection of baijiu (Chinese liquor), and includes the following steps: Step T1: Mix His-Fe3O4 with baijiu (Chinese liquor) to obtain mixture 1; Step T2: Add H2O2 and TMB to mixture 1 obtained in step T1 to obtain mixture 2; Step T3: Add HCl and Au NBPs to mixture 2 obtained in step T2 to obtain the analyte corresponding to the liquor. Step T4: Perform 5 tests on the corresponding baijiu sample obtained in step T3. For each type of baijiu, obtain 1 substance × 4 array points × 5 replicate datasets. Step T5: By extracting the RGB values ​​of the array obtained in step T4, a unique fingerprint spectrum for each type of liquor is formed, and the array data is further processed using hierarchical clustering analysis (HCA) and linear discriminant analysis (LDA) statistical classification methods. The liquor mentioned is at least one of Hengshui Laobaigan, Langjiu, Baiyunbian, Site, Xifeng, Jiuguijiu, Sanhua, Yanghe, Luzhou Laojiao, Moutai, Fenjiu, Jingzhi, Hongxing Erguotou, Dongjiu, Jiangjin Laobaigan, and Yubingshao. The His-Fe3O4 concentration was 1 mg / mL, the H2O2 concentration was 1 M, the TMB concentration was 1 mg / mL, and the HCl concentration was 1 M. The amount of His-Fe3O4 added is 10~30 μL, the amount of H2O2 added is 10~30 μL, the amount of TMB added is 10~30 μL, the amount of HCl added is 5~10 μL, and the amount of Au NBPs added is 100~150 μL.

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