Fluorescence-colorimetric dual-mode sensing system and application thereof in detection of Luzhou-flavor liquor

Abstract

The invention discloses a fluorescence-colorimetric dual-mode sensing system and application thereof in detection of Luzhou-flavor liquor, and belongs to the technical field of liquor detection. The fluorescence-colorimetric dual-mode sensing system is composed of CDs (at) MOF, a color developing agent and H2O2; wherein the CDs (at) MOF is a composite material formed by modifying a metal organic framework through quantum dots. The fluorescence-colorimetric dual-mode sensing system provided by the invention has the advantage of multiple fluorescence signals, the detection accuracy and efficiency are effectively improved, and the detection accuracy and sensitivity are improved under the synergistic effect of the quantum dots; meanwhile, the preparation method of the fluorescence-colorimetric dual-mode sensing system is simple, good in stability, high in sensitivity, easy to standardize and industrially produce, and beneficial to the production of the Luzhou-flavor liquor sensor.

Description

Technical Field

[0001] The invention belongs to the technical field of liquor detection, and specifically relates to a fluorescence-colorimetry dual-mode sensing system and application thereof. Background Art

[0002] With the improvement of national economy and living standards, as well as the deepening of consumers' rational consumption concept, the quality requirements for Luzhou-flavor liquor are getting higher and higher. The complex brewing process makes it easy for the liquor to introduce impurities or be contaminated during the production process. There are also unscrupulous vendors who want to make profits from it, and various counterfeit and inferior products appear. At present, the traditional liquor detection methods include sensory evaluation, high-performance liquid chromatography, gas chromatography and chromatography-mass spectrometry. Sensory evaluation is the most widely used detection method at present, which mainly relies on the taster's sense of smell, taste, vision and touch to evaluate and divide the grade and quality of liquor. Sensory evaluation is easily disturbed by the taster himself and the surrounding environment, and there are large errors, and it cannot form a standardized detection method. High-performance liquid chromatography, gas chromatography and chromatography-mass spectrometry technology all require large instruments and equipment for detection, which have the disadvantages of subjectivity, expensive instruments and equipment, and cumbersome operation, and are not suitable for liquor detection.

[0003] In recent years, visual sensing detection methods have played an important role in the authenticity identification of Chinese liquor. Basically, they use the redox reaction, hydrogen bond, electrostatic interaction and other interactions of flavor compounds such as organic acids and furfural in liquor with nano-precious metals, quantum dots, dyes and other sensing materials in liquor to produce intuitive color changes. Therefore, the visual array sensor can realize the identification of liquor origin, year, flavor, etc. Compared with traditional detection methods such as professionals, spectroscopy, chromatography, etc., the visual array sensor has the characteristics of simplicity, speed and instrument-free. Although the visual array sensor detection method provides a new solution for the authenticity identification of Chinese liquor, its actual application in the rapid detection of liquor still has problems such as the detection results are greatly affected by water, ethanol and flavor compounds in liquor other than the response to the sensing material, and the instability of nano-precious metals, quantum dots and other sensing materials. Therefore, there are still many problems to be solved in the development and application of Chinese liquor rapid detection devices based on various sensing materials. Summary of the invention

[0004] In view of the above technical problems, the present invention aims to provide a quantum dot-doped metal organic framework sensor material, preparation method and application for effectively detecting Wuliangye series liquors.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] In a first aspect, the present invention provides a fluorescence-colorimetric dual-mode sensing system, which is composed of CDs@MOF, a color developer and H2O2; wherein the CDs@MOF is a composite material formed by modifying a metal organic framework with quantum dots.

[0007] In the above fluorescence-colorimetric dual-mode sensing system, the concentration of the CDs@MOF is 1 mg / mL.

[0008] In the above-mentioned fluorescence-colorimetric dual-mode sensing system, the volume of the color developer is 50 μL, and the color developer is a mixture of ABTS, OPD and TMB; wherein the concentration of ABTS is 3 mg / mL, the concentration of OPD is 10.8 mg / mL, and the concentration of TMB is 1.2 mg / mL.

[0009] In the above fluorescence-colorimetry dual-mode sensing system, the volume of H2O2 is 50 μL and its concentration is 1M.

[0010] In the above fluorescence-colorimetric dual-mode sensing system, the CDs@MOF is prepared by: synthesizing CDs and MOF separately by a hydrothermal method, and then synthesizing them by electrostatic adsorption and stirring;

[0011] The specific preparation method comprises the following steps:

[0012] (1) Add Alizarin Red to water, dissolve it completely by ultrasonication, transfer it to a reaction vessel, react at 200°C for 3 h, cool it to room temperature, and filter out the unreacted substances with a 0.22 μm filter membrane to obtain a CDs solution;

[0013] (2) FeCl3·6H2O solution, diaminoterephthalic acid solution, ZrCl4 solution, DMF and acetic acid were mixed and transferred to a reactor for reaction at 120°C for 12 h, cooled to room temperature, washed and vacuum dried to obtain MOF powder;

[0014] (3) Add MOF powder to water, sonicate to fully dissolve it, then add CDs solution, stir to fully adsorb it, wash, and vacuum dry to obtain CDs@MOF.

[0015] In the specific preparation method of the above CDs@MOF, in step (1), the volume of water is 10 mL, and the amount of Alizarin Red added is 0.1 g.

[0016] In the specific preparation method of the above CDs@MOF, in step (2), the volumes of FeCl3·6H2O solution, diaminoterephthalic acid solution, ZrCl4 solution, DMF and acetic acid are 5 mL, 10 mL, 5 mL, 5 mL and 5 mL respectively.

[0017] In the specific preparation method of the above CDs@MOF, in step (3), the volume of water is 12 mL, the amount of MOF powder added is 20 mg, and the amount of CDs solution added is 3 mL.

[0018] Furthermore, in the specific preparation method of the above-mentioned CDs@MOF, the FeCl3·6H2O solution, diaminoterephthalic acid solution and ZrCl4 solution are prepared as follows: 8 mmol of FeCl3·6H2O, diaminoterephthalic acid and ZrCl4 are added to 30 mL of DMF respectively, and the FeCl3·6H2O solution, diaminoterephthalic acid solution and ZrCl4 solution are obtained after ultrasonic treatment to fully dissolve them.

[0019] In a second aspect, the present invention provides an application of the above-mentioned fluorescence-colorimetry dual-mode sensing system to detect Luzhou-flavor liquor: HAC-NaAC buffer solution is added to the fluorescence-colorimetry dual-mode sensing system and mixed evenly, and then the Luzhou-flavor liquor to be tested is added for sufficient reaction, the fluorescence intensity and ultraviolet intensity are measured, and the data are analyzed using PCA, HCA and LDA; based on the differences in the content and types of reducing substances in different Luzhou-flavor liquors, different degrees of changes in fluorescence intensity and ultraviolet absorption peaks will be caused, and a unique fingerprint spectrum is obtained according to different changes in fluorescence and colorimetric signals.

[0020] Furthermore, in the above application of detecting Luzhou-flavor liquor, the amount of HAC-NaAC buffer added was 600 μL, and the amount of Luzhou-flavor liquor to be tested added was 100 μL; the optimal reaction conditions were pH=3.6 and reaction time of 25 min.

[0021] Furthermore, in the above application of detecting Luzhou-flavor liquor, when measuring fluorescence intensity, the fluorescence intensities at 420nm, 460nm and 500nm are extracted respectively; when measuring ultraviolet intensity, the absorbance values ​​at 420nm, 450nm and 655nm are extracted respectively.

[0022] The beneficial effects of the present invention are as follows: CDs and MOF are firstly synthesized by a hydrothermal method, and CDs@MOF is synthesized by electrostatic adsorption and stirring because the two materials carry one positive and one negative charge on their surfaces. Compared with MOF alone, CDs@MOF produces a synergistic effect and has stronger peroxidase activity. With three color developers, ABTS, OPD and TMB, a fluorescence and colorimetric dual-mode sensing array is constructed to realize the detection of reducing substances and Luzhou-flavor liquor.

[0023] Using the peroxidase activity of CDs@MOF, combined with three enzyme substrates ABTS, OPD and TMB, a fluorescence and colorimetric dual-mode sensor array was constructed, and the reducing substances and Luzhou-flavor liquor were successfully detected. In the presence of H2O2, CDs@MOF oxidizes the enzyme substrate into the corresponding oxidized substrate. The addition of reducing substances or Luzhou-flavor liquor reduces the oxidized substrate to varying degrees, thereby causing changes in color or fluorescence and forming a unique fingerprint. The recognition effect was evaluated using three pattern recognition methods, PCA, HCA and LDA, all of which showed good discrimination ability.

[0024] The fluorescence-colorimetric dual-mode sensing system provided by the present invention has the advantages of multiple fluorescence signals, effectively improves the accuracy and efficiency of detection, and improves the accuracy and sensitivity of detection under the synergistic effect of quantum dots; at the same time, the preparation method of the fluorescence-colorimetric dual-mode sensing system is simple, the stability is good, the sensitivity is high, and it is easy to standardize and industrialize production, which is conducive to the production of Wuliangye series wine sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Characterization of the CDs@MOF material of the present invention;

[0026] Figure 2 The fluorescence spectra of 19 kinds of Luzhou-flavor liquors detected by the fluorescence-colorimetry dual-mode sensing system of the present invention are shown in FIG.

[0027] Figure 3 The UV-visible spectra of 19 kinds of Luzhou-flavor liquors detected by the fluorescence-colorimetry dual-mode sensing system of the present invention;

[0028] Figure 4 The fluorescence pattern recognition of 19 kinds of Luzhou-flavor liquors detected by the fluorescence-colorimetry dual-mode sensing system of the present invention;

[0029] Figure 5 The invention discloses colorimetric pattern recognition for detecting 19 kinds of Luzhou-flavor liquors using the fluorescence-colorimetry dual-mode sensing system.

[0030] Figure 2 and Figure 3 In (A, B, C), different colors refer to 19 kinds of Luzhou-flavor liquors and blank controls. The English in the color annotations in the figure correspond to the English names of the 19 Luzhou-flavor liquors and the blank controls. Specifically, the color annotations are the blank controls and the Luzhou-flavor liquors numbered 1 to 19 arranged in sequence from top to bottom (as shown in Table 1); the English in the horizontal axis in (D) are the Luzhou-flavor liquors numbered 1 to 19 arranged in sequence from left to right; the English in the vertical axis in (E) correspond to the English in the 19 kinds of Luzhou-flavor liquors numbered 1 to 19 arranged in sequence from bottom to top. DETAILED DESCRIPTION

[0031] The technical solution of the present invention can be specifically implemented in the following manner.

[0032] 1. Fluorescence-colorimetry dual-mode sensing system

[0033] 1. Synthesis of CDs@MOF

[0034] (1) Add 0.1 g of Alizarin Red to 10 mL of first-grade water, sonicate for 30 min to fully dissolve it, transfer it to a reactor and react at 200 °C for 3 h, cool it to room temperature, filter out the unreacted material with a 0.22 μm filter membrane to obtain a CDs solution, and store it in a refrigerator at 4 °C away from light.

[0035] (2) Add 8 mmol of FeCl3·6H2O, diaminoterephthalic acid and ZrCl4 to 30 mL of DMF respectively, and sonicate for 10 min to fully dissolve them to obtain FeCl3·6H2O solution, diaminoterephthalic acid solution and ZrCl4 solution; take 5 mL of FeCl3·6H2O solution, 10 mL of diaminoterephthalic acid solution, 5 mL of ZrCl4 solution, 5 mL of DMF and 5 mL of acetic acid, stir and mix well, then transfer to a reactor and react at 120°C for 12 h, cool to room temperature, wash with methanol and ethanol for 3 times respectively, and then vacuum dry at 60°C for 12 h to obtain MOF powder, which is stored at room temperature.

[0036] (3) Add 20 mg of MOF powder to 12 mL of primary water and dissolve it completely by ultrasound. Then add 3 mL of CDs solution and stir for 6 h to allow it to be fully adsorbed. Wash it three times with primary water and then vacuum dry it at 60 °C for 12 h to obtain CDs@MOF powder, which is stored at room temperature.

[0037] 2. Characterization of CDs@MOF

[0038] The prepared CDs@MOF material was characterized by TEM, Zeta potential, FT-IR and XRD. Figure 1 As shown, where: (A) is the TEM image of CDs; (B) is the TEM image of MOF; (C) is the elemental analysis of MOF; (D) is the TEM image of CDs@MOF; (E) is the Zeta potential; (F) is the UV absorption wavelength image; (G) is the XRD image; and (H) is the FT-IR image.

[0039] Depend on Figure 1It can be seen that CDs are spherical, evenly distributed in ethanol, and have a size of less than 10nm; MOF is octahedral, with a size of μm level. Elemental analysis shows that there are C, N, O, Fe and Zr elements in MOF, and each element is evenly distributed on the surface of the material; Zeta potential results show that the surface of CDs is negatively charged, and the surface of MOF is positively charged. Through stirring, based on the electrostatic self-assembly between particles, the surface of CDs@MOF is negatively charged. The above characterization results all indicate the successful preparation of CDs@MOF materials.

[0040] 2. Application of fluorescence-colorimetry dual-mode sensing system in detecting Luzhou-flavor liquor

[0041] 1. Detection of reducing substances

[0042] 15 kinds of reducing substances, including acid, aldehyde, alcohol, ester, amino acid, ketone, etc., were selected as detection objects. 50 μL CDs@MOF, 50 μL ABTS (3 mg / mL) / OPD (10.8 mg / mL) / TMB (1.2 mg / mL) and 50 μL H2O2 (1M) were added to 600 μL HAC-NaAC buffer and mixed evenly. After reacting for 25 minutes, 100 μL reducing substances (all at a concentration of 0.1 mM) were added and mixed. The pH was adjusted to 3.6. After reacting for 25 minutes, the fluorescence intensity (420 nm, 460 nm and 500 nm) and UV intensity (420 nm, 450 nm and 655 nm) were measured three times.

[0043] The data were analyzed using PCA, HCA and LDA. The results showed that PCA, HCA and LDA could classify 15 reducing substances (hexanol, pentanol, butanol, propionic acid, ethyl acetate, ethyl lactate, acetone, formic acid, formaldehyde, valine, acetic acid, ethyl acetate, glutamic acid, acetaldehyde and citric acid). Both the fluorescence and colorimetric sensor arrays had good recognition capabilities for reducing substances.

[0044] 2. Detection of Luzhou-flavor Liquor

[0045] 19 kinds of Luzhou-flavor liquors were selected as the test objects, and the information of the 19 kinds of Luzhou-flavor liquors is shown in Table 1. In 600μL HAC-NaAC buffer, 50μL CDs@MOF, 50μL ABTS (3mg / mL) / OPD (10.8mg / mL) / TMB (1.2mg / mL) and 50μL H2O2 (1M) were added and mixed evenly, and then reacted for 25min, and then 100μL of the Luzhou-flavor liquor sample to be tested (the concentration was 0.1mM) was added and mixed, and the pH was adjusted to 3.6. After reacting for 25min, the fluorescence intensity (420nm, 460nm and 500nm) and UV intensity (420nm, 450nm and 655nm) were measured three times.

[0046] Table 119 Information on Luzhou-flavor Liquor

[0047] serial number Distilled spirits Alcohol content (%) serial number Distilled spirits Alcohol content (%) 1 Wuliang Touqu Premium 52 11 Wuliangye 52 2 Wuliangtouqu 52 12 Mian Rou Jian Zhuang 50 3 Wuliang Special Liquor 52 13 Sharp Village Highlights 50 4 Wuliangtequ 52 14 Jianzhuang Daguang 50 5 Wuliangchun 35° 35 15 Rich and powerful 52 6 Wuliangchun 45° 45 16 Oriental Beauty 52 7 Wuliangchun 50° 50 17 Xinglong Top Grade 52 8 Wuliangchun Silver Packaging 50 18 Hot 58 9 Wuliangchun red 50 19 Crooked Mouth 52 10 Wuliangchun Gold 50

[0048] During the fermentation process of Luzhou-flavor liquor, microorganisms will decompose the grain raw materials, and the generated aromatic substances contain a large amount of antioxidant components. Due to the difference in brewing process, the reducing components and content in Luzhou-flavor liquor will be different. When Luzhou-flavor liquor is added, it will cause different changes in fluorescence and colorimetric signals, thus producing a unique fingerprint spectrum. The results of measuring Luzhou-flavor liquor by the fluorescence-colorimetric dual-mode sensing system are as follows: Figure 2 and 3 shown. Figure 2 Fluorescence spectra, (A) ABTS, (B) OPD, (C) TMB, Luzhou-flavor liquor fluorescence sensing array fingerprint (D) bar graph, (E) heat map. Figure 3 (A) is ABTS, (B) is OPD, (C) is TMB, (D) is the histogram of the fluorescence sensor array of Luzhou-flavor liquor, and (E) is the heat map. Figure 2 and 3 It can be seen from the spectra that there are indeed changes in different Luzhou-flavor liquors. In order to further intuitively reflect the differences between Luzhou-flavor liquors, columnar and thermal map fingerprints were drawn, indicating that both fluorescence and colorimetry can detect Luzhou-flavor liquors well.

[0049] In order to evaluate the effect of fluorescence and colorimetric sensor arrays on distinguishing and identifying Luzhou-flavor liquor, PCA, HCA and LDA were used for analysis respectively. Figure 4 As shown in the figure, (A) is PCA, (B) is HCA, and (C) is LDA. In the PCA analysis, the three parallel samples of different Luzhou-flavor liquors are close to each other, and there is no sample overlap. In the HCA and LDA analysis, the same Luzhou-flavor liquors preferentially form a cluster, and there is no misclassification. The recognition accuracy of PCA, HCA, and LDA all reached 100%. The colorimetric sensor array analysis results are shown in the figure. Figure 5 As shown in the figure, (A) is PCA, (B) is HCA, and (C) is LDA. In the PCA analysis, except for the partial overlap between Wuliang Touqu Jingpin and Wuliangchun 50° liquor, other Luzhou-flavor liquors can be well distinguished, and the recognition of different Luzhou-flavor liquors by HCA and LDA also reached 100%. Both the fluorescence and colorimetric sensor arrays have strong classification capabilities for the recognition of Luzhou-flavor liquors and have strong practical application capabilities.

Claims

1. A fluorescence-colorimetric dual-mode sensing system, characterized in that: It is composed of CDs@MOF, color developer and H2O2; The CDs@MOF is a composite material formed by modifying a metal organic framework with quantum dots.

2. A fluorescence-colorimetric dual-mode sensing system according to claim 1, characterized in that: The concentration of the CDs@MOF was 1 mg / mL.

3. A fluorescence-colorimetric dual-mode sensing system according to claim 1, characterized in that: The volume of the color developing agent is 50 μL, and the color developing agent is a mixture of ABTS, OPD and TMB; Among them, the concentration of ABTS is 3 mg / mL, the concentration of OPD is 10.8 mg / mL, and the concentration of TMB is 1.2 mg / mL.

4. The fluorescence-colorimetry dual-mode sensing system according to claim 1, characterized in that: The volume of H2O2 is 50 μL, and its concentration is 1M.

5. The fluorescence-colorimetry dual-mode sensing system according to claim 2, characterized in that: The CDs@MOF is prepared by: synthesizing CDs and MOF separately by a hydrothermal method, and then synthesizing them by electrostatic adsorption stirring; The specific preparation method comprises the following steps: (1) Add Alizarin Red to water, dissolve it completely by ultrasonication, transfer it to a reaction vessel, react at 200°C for 3 h, cool it to room temperature, and filter out the unreacted substances with a 0.22 μm filter membrane to obtain a CDs solution; (2) FeCl3·6H2O solution, diaminoterephthalic acid solution, ZrCl4 solution, DMF and acetic acid were mixed and transferred to a reactor for reaction at 120°C for 12 h, cooled to room temperature, washed and vacuum dried to obtain MOF powder; (3) Add MOF powder to water, sonicate to fully dissolve it, then add CDs solution, stir to fully adsorb it, wash, and vacuum dry to obtain CDs@MOF.

6. A fluorescence-colorimetry dual-mode sensing system according to claim 5, characterized in that: In step (1), the volume of water is 10 mL, and the amount of Alizarin Red added is 0.1 g; In step (2), the volumes of FeCl3·6H2O solution, diaminoterephthalic acid solution, ZrCl4 solution, DMF and acetic acid are 5 mL, 10 mL, 5 mL, 5 mL and 5 mL respectively; In step (3), the volume of water was 12 mL, the amount of MOF powder added was 20 mg, and the amount of CDs solution added was 3 mL.

7. A fluorescence-colorimetry dual-mode sensing system according to claim 6, characterized in that: The FeCl3·6H2O solution, diaminoterephthalic acid solution and ZrCl4 solution are prepared as follows: 8 mmol of FeCl3·6H2O, diaminoterephthalic acid and ZrCl4 are added to 30 mL of DMF respectively, and the FeCl3·6H2O solution, diaminoterephthalic acid solution and ZrCl4 solution are obtained after fully dissolving them by ultrasonic treatment.

8. Use of the fluorescence-colorimetry dual-mode sensing system according to any one of claims 1 to 7 for detecting Luzhou-flavor liquor, characterized in that: HAC-NaAC buffer was added to the fluorescence-colorimetry dual-mode sensing system and mixed evenly. Then, the Luzhou-flavor liquor to be tested was added for sufficient reaction. The fluorescence intensity and UV intensity were measured, and the data were analyzed using PCA, HCA and LDA. Based on the differences in the content and types of reducing substances in different Luzhou-flavor liquors, different degrees of changes in fluorescence intensity and UV absorption peaks will be caused. According to different changes in fluorescence and colorimetric signals, a unique fingerprint spectrum was obtained.

9. Application of the fluorescence-colorimetry dual-mode sensing system according to claim 8 to detecting Luzhou-flavor liquor, characterized in that: The amount of HAC-NaAC buffer added was 600 μL, and the amount of Luzhou-flavor liquor added was 100 μL; the optimal reaction conditions were pH=3.6 and reaction time of 25 min.

10. The use of the fluorescence-colorimetry dual-mode sensing system according to claim 8 for detecting Luzhou-flavor liquor, characterized in that: When measuring the fluorescence intensity, the fluorescence intensities at 420nm, 460nm and 500nm were extracted respectively; when measuring the ultraviolet intensity, the absorbance values ​​at 420nm, 450nm and 655nm were extracted respectively.

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