A pda-sh / pda tag for distinguishing trans-2-hexenal and cis-3-hexenal and a preparation method thereof

Abstract

The application discloses a PDA-SH / PDA label for distinguishing trans-2-hexenal and cis-3-hexenal and a preparation method thereof, and belongs to the technical field of chemical detection. The preparation method of the PDA-SH / PDA label is as follows: 10,12-tricosadiynoic acid is modified by mercapto modification to obtain mercapto tricosadiynoic acid; 10,12-tricosadiynoic acid and mercapto tricosadiynoic acid are mixed in an organic solvent at a molar ratio of 2-5:1, the organic solvent is removed, and granular matter is obtained; the granular matter is dispersed into an aqueous solution, heated, and treated by ultrasonic waves to obtain a suspension, which is placed for standby; the suspension is shaken, placed under ultraviolet light irradiation for polymerization, and the PDA-SH / PDA label is obtained. The label can be used for quickly and visually distinguishing trans-2-hexenal and cis-3-hexenal, and the detection method is simple.

Description

Technical Field

[0001] This invention relates to the field of chemical detection technology, specifically to a PDA-SH / PDA tag for distinguishing between trans-2-hexenal and cis-3-hexenal and its preparation method. Background Technology

[0002] trans-2-hexenal, also known as "leaf aldehyde," has the molecular formula C6H. 10 O, naturally found in camphor oil, apples, cucumbers, strawberries, etc., can be used to blend food flavorings such as apple, strawberry, berry, and tea. Cis-3-hexenal, also known as "green leaf aldehyde," has the molecular formula C6H. 10 O, with a strong grassy aroma reminiscent of crushed strawberry and grape leaves, is naturally present in tea.

[0003]

[0004] Trans-2-hexenal and cis-3-hexenal are isomers of each other and are both food additives. Distinguishing between these isomers typically requires specific techniques and instruments, such as gas chromatography-mass spectrometry (Gas Chromatography-Mass Spectrometry, etc.). (Tan Lirong, Cheng Min, Lin Weibin. Study on the detection of restricted substances trans-2-hexenal, α-hexylcinnamaldehyde, and coumarin in peppermint flavoring by gas chromatography-mass spectrometry [J]. Journal of Food Safety and Quality Inspection, 2018.). However, these methods face problems such as high cost and complex instruments, making them difficult to widely adopt in the market. Therefore, a visual and rapid detection technology for trans-2-hexenal and cis-3-hexenal has significant development potential.

[0005] Polydiacetylene (PDA) is an environmentally responsive conjugated polymer with a unique structure and excellent optical properties, showing great promise for applications in photoelectric sensing. Its synthesis begins with the self-assembly of the diacetylene monomer DA in chloroform solution, forming highly ordered DA supramolecular structures. When exposed to 254 nm ultraviolet light, adjacent DA molecules polymerize through a 1,4-addition reaction, forming a cross-linked conjugated structure, resulting in a blue color. When the polymerized PDA is exposed to stimuli such as temperature or chemical changes, the cross-linked structure distorts, turning the color red. This unique optical property makes polydiacetylene widely used in colorimetric sensors.

[0006] Chinese patent document CN113402646A discloses a method for detecting silver ions. This invention involves adding an ethanol solution of 10,12-tetradecanoic acid to an aqueous solution of disodium ethylenediaminetetraacetate dropwise under stirring conditions at room temperature in the dark. The suspension is then left to stand at a low temperature overnight to allow self-assembly, resulting in a colorless supramolecular suspension. This colorless supramolecular suspension is then polymerized under ultraviolet irradiation to obtain a blue poly(diacetylene) vesicle suspension for use in aqueous environments with Ag. + Visual detection; Chinese patent document with publication number CN110501316A discloses a method for detecting Pb in a water environment using polyacetylene liposomes. 2+ This invention provides a visual detection method for Pb in an aqueous environment. First, a polyacetylene liposome solution is prepared, and then the polyacetylene liposome solution is used to detect Pb in the aqueous environment. 2+ Visual detection.

[0007] However, in the current technology, no polyacetylene-based material has been used for the visual and rapid detection and differentiation of trans-2-hexenal and cis-3-hexenal. Summary of the Invention

[0008] This invention provides a method for preparing a PDA-SH / PDA tag for distinguishing between trans-2-hexenal and cis-3-hexenal. The reaction conditions are mild and the steps are simple. The prepared PDA-SH / PDA tag can be used to quickly and visually distinguish between trans-2-hexenal and cis-3-hexenal.

[0009] The specific technical solution adopted is as follows:

[0010] A method for preparing a PDA-SH / PDA tag for distinguishing between trans-2-hexenal and cis-3-hexenal includes the following steps:

[0011] (1) 10,12-Toccodiynoic acid (TCDA) was modified by thiolization to obtain thiolized occodiynoic acid (TCDA-SH);

[0012] (2) 10,12-Toccodiyne acid and mercapto-toccodiyne acid were mixed in an organic solvent at a molar ratio of 2-5:1 to generate liposomes. The organic solvent was then removed to obtain particulate matter. The particulate matter was dispersed in an aqueous solution, heated, and ultrasonically treated to obtain a suspension, which was then allowed to stand for later use.

[0013] (3) Shake the suspension well and place it under ultraviolet light for polymerization to obtain the PDA-SH / PDA label used to distinguish between trans-2-hexenal and cis-3-hexenal.

[0014] The structural formulas of 10,12-tridocadiynic acid and mercapto-tridocadiynic acid are shown below:

[0015]

[0016]

[0017] This invention is based on the chemical principle that trans-2-hexenal attacks the thiol group of PDA-SH, disrupting the hydrogen bond between the thiol and carboxyl groups, leading to a distortion of the conjugated structure. Simultaneously, cis-3-hexenal is unstable in solution and converts to trans-2-hexenal. PDA-SH / PDA tags are prepared using TCDA and TCDA-SH. These tags exhibit different degrees of color change upon contact with trans-2-hexenal and cis-3-hexenal, enabling rapid and visual detection and differentiation between the two.

[0018] Preferably, in step (1), the thiolization modification method is as follows: 10,12-tetracarbazide acid and Lawson's reagent are thoroughly mixed in chloroform, heated in a water bath, and thiolized tricarbazide acid is obtained by separation.

[0019] Preferably, in step (2), 10,12-triscardiyneic acid and thiolated triscardiyneic acid are mixed in a molar ratio of 4:1. Under the above-mentioned preferred molar ratio, the prepared PDA-SH / PDA tag has good stability, good color development effect, and good color development speed.

[0020] In step (2), the organic solvents include, but are not limited to, chloroform, dichloromethane, or diethyl ether.

[0021] Preferably, in step (2), the heating conditions are: 50-100℃ water bath heating for 15-30 min; and ultrasonic treatment time for 15-30 min. The above conditions allow TCDA-SH and TCDA to dissolve better and complete self-assembly.

[0022] Preferably, in step (2), the settling time is ≥20 min, and the settling process can ensure the stability of TCDA / TCDA-SH.

[0023] Preferably, in step (3), the ultraviolet light wavelength is 254nm and the ultraviolet light irradiation time is 18-20min.

[0024] This invention also provides a PDA-SH / PDA tag prepared by the method described above for distinguishing between trans-2-hexenal and cis-3-hexenal. This PDA-SH / PDA tag has a unique structure and excellent optical properties. It is composed of polyacetylene and modified polyacetylene. When exposed to trans-2-hexenal or cis-3-hexenal, its conformation changes, further leading to a color change, making it ideal for independent and visual rapid detection.

[0025] When the PDA-SH / PDA tag solution is used for the rapid visual detection of trans-2-hexenal and cis-3-hexenal, the hexenal solution is added dropwise to the PDA-SH / PDA tag solution, and the hexenal solution is determined to be either trans-2-hexenal or cis-3-hexenal based on different color changes or indicators such as red chromaticity (r), red color difference (RCS), and colorimetric response (CR).

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] (1) This invention utilizes Lawson's reagent to form thiolated ...

[0028] (2) This invention breaks through the limitations of traditional methods for detecting and distinguishing trans-2-hexenal and cis-3-hexenal, which are complex, time-consuming, and expensive in terms of instruments. The method of this invention has mild reaction conditions, simple detection method, can quickly distinguish trans-2-hexenal and cis-3-hexenal, and can achieve visual identification, which is economical and practical.

[0029] (3) Trans-2-hexenal and cis-3-hexenal are isomers of each other. When they react with PDA-SH / PDA tags, they produce specific color differences. This invention provides a new approach for visual and rapid detection and differentiation of isomers. Attached Figure Description

[0030] Figure 1 The image shows the infrared spectra of TCDA and TCDA-SH in Example 1, where B is a magnified view of A.

[0031] Figure 2Transmission electron micrographs of PDA, PDA-SH, and PDA-SH / PDA tags are shown, where A is PDA, B is PDA-SH, and C is PDA-SH / PDA tag.

[0032] Figure 3 The images show the nanoparticle size distribution before and after the reaction of the PDA-SH / PDA tag. In the images, A is the statistical chart of the average particle size and B is the statistical chart of the polymer dispersion coefficient.

[0033] Figure 4 The image shows the blue-red phase transitions of trans-2-hexenal and cis-3-hexenal solutions for PDA-SH / PDA tags. In the image, A is the optical image, B is the red color difference RCS graph, and C is the absorbance as a function of wavelength.

[0034] Figure 5 The blue-red phase color transition diagrams for PDA-SH / PDA tags processed with different volume fractions of 50% trans-2-hexenal and cis-3-hexenal solutions are shown. In the diagram, A is the red color difference RCS statistical graph and B is the optical image.

[0035] Figure 6 Optical images showing the blue-red phase transitions that occur when processing 100 μL of trans-2-hexenal and cis-3-hexenal solutions of different mass fractions for PDA-SH / PDA tags.

[0036] Figure 7 The data characterization graphs are for PDA-SH / PDA tags after processing 100 μL of trans-2-hexenal and cis-3-hexenal solutions with different mass fractions. In the graphs, A is the blue PB statistical graph of the system, B is the colorimetric response CR statistical graph, C is the red color difference RCS statistical graph, and D is the a* statistical graph.

[0037] Figure 8 Optical images showing the blue-red phase color transitions that occur when trans-2-hexenal solution and cis-3-hexenal mixed solutions in different proportions are processed for PDA-SH / PDA tags.

[0038] Figure 9 Data characterization graphs are generated for PDA-SH / PDA tags after processing trans-2-hexenal solution and cis-3-hexenal mixed solutions in different proportions. Among them, A is the red color difference RCS graph, B is the a* graph, C is the colorimetric response CR graph, and D is the red chromaticity r graph. Detailed Implementation

[0039] The present invention will be further illustrated below with reference to the embodiments and accompanying drawings. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically specified in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer.

[0040] Example 1

[0041] (1) Preparation of PDA-SH / PDA tags

[0042] Weigh 0.04 g of 10,12-tocadionic acid (TCDA) and 0.025 g of Lawesson reagent (LR) into 4 mL of CHCl3 and mix thoroughly using a vortex mixer. Heat in a water bath at 100 °C for 20 min to promote the reaction. Then add 30 mL of CHCl3 to dilute and mix well. Wash with 20 μL of HCl and 20 μL of NaCl sequentially, and dry with 0.01 g of anhydrous MgSO4. Mix thoroughly using a vortex mixer to separate the organic layer from the aqueous layer. Take the organic layer, dry it with nitrogen gas to remove chloroform, and obtain mercapto-tocadionic acid (TCDA-SH) on the tube wall.

[0043] Weigh 0.16g TCDA and add it to the bottom of a centrifuge tube containing the TCDA-SH sample, making the molar ratio of TCDA-SH:TCDA 1:4. Add 4mL CHCl3 to the centrifuge tube to induce liposome assembly. Remove chloroform by nitrogen blowing until only a small amount of particulate matter remains on the tube wall. Add 0.4mL 0.1% CNC nanofibers and then add 37.5mL ultrapure water to obtain a mixed solution. Heat the mixed solution in an 80℃ water bath for 20min, and then sonicate it for 20min using an ultrasonic cell disruptor (300W) to obtain a suspension. Place the suspension in a 4℃ refrigerator for 20h.

[0044] Remove the suspension, add 100mL of purified water to adjust it to a suitable concentration, shake well, take 1mL into a centrifuge tube, and polymerize under 254nm ultraviolet light for 18min to obtain the PDA-SH / PDA tag solution.

[0045] (2) Characterization of PDA-SH / PDA tags

[0046] The changes in the infrared absorption spectrum of TCDA before and after thiolization were characterized using Fourier transform infrared (FTIR) spectroscopy. The FTIR spectrometer recording range was 4000-400 cm⁻¹. -1 The resolution is 4cm. -1 The number of scans was 32, and the results are as follows: Figure 1 As shown in A and B, this indicates the successful implementation of thiolization modification and the successful preparation of thiolized tricarboxydiynic acid.

[0047] The morphology of the PDA-SH / PDA tag was characterized using transmission electron microscopy, and the results are as follows: Figure 2 As shown in C, PDA-SH and PDA were prepared simultaneously, and their TEM images are shown in Figures 1-2. Figure 2 As shown in Figures A and B, the TCDA system typically forms well-dispersed cross-linked vesicle structures. However, due to the space occupancy issues of the functionalized head groups, thiol groups in TCDA-SH exhibit mutual repulsion, making it difficult to form stable cross-linked vesicle structures. However, when TCDA-SH and TCDA samples are assembled in a specific ratio, the original intermolecular forces between TCDA-SH and TCDA molecules are disrupted using an ultrasonic cell disruptor. The two then assemble in a specific ratio, forming hydrogen bonds between -COSH and -COOH, resulting in a stable structure. In transmission electron microscopy (TEM) images, the TCDA sample shows a polymerized state, while the TCDA-SH sample does not exhibit a cross-linked polymerized state within the field of view. This phenomenon further supports the formation of TCDA-SH. The PDA-SH / PDA sample exhibits the strongest degree of polymerization, indicating that derivatization of PDA can enhance intramolecular forces, leading to better cross-linking.

[0048] PDA-SH / PDA solutions before polymerization, after polymerization, and after reaction with trans-2-hexenal (E2) and cis-3-hexenal (Z3) were analyzed using a nanoparticle size and potential analyzer. Samples were placed in the instrument's groove, and measurements were performed using the software. Each sample group was repeated three times. The average particle size (Z-average) and polymer dispersion index (PDI) of each sample group were recorded and analyzed. The experimental results are shown below. Figure 3 As shown in Figures A and B, after polymerization, the particle size in the PDA-SH / PDA liposome solution system rapidly increased, indicating an increase in the degree of polymerization. The nanoparticle size of the PDA-SH / PDA solution decreased rapidly after reacting with E2, but showed no significant change after reacting with Z3. It is speculated that E2 reacts with the intramolecular thiol groups, disrupting the hydrogen bonds formed between the thiol and carboxyl groups, leading to a distortion of the conjugated structure. The reaction of Z3 with the PDA-SH / PDA solution did not significantly alter the intramolecular structure. From the polymer dispersibility index before and after the reaction, the increased stability of the PDA-SH / PDA solution after polymerization indicates the formation of carbon-carbon two- and three-bond cross-linked structures. The reactions of E2 and Z3 with the solution disrupted the intermolecular forces, reducing the stability of the reaction system solution.

[0049] (3) PDA-SH / PDA tag detection distinguishes between trans-2-hexenal and cis-3-hexenal.

[0050] A small amount of PDA-SH / PDA tag solution was placed in a 2 mL plastic centrifuge tube, and small volumes of trans-2-hexenal solution were added to investigate the relationship between trans-2-hexenal concentration, reaction time, and absorbance of the PDA-SH / PDA tag solution at a specific wavelength. The reaction was vortexed (1000 rpm for 10 s) to ensure uniformity. 150 μL of the test solution was transferred to each well using a pipette, and its position was recorded. The absorbance was measured at a specific wavelength. Each sample was repeated three times.

[0051] When used as a colorimetric sensor, the sensitivity of a PDA to the analyte is calculated based on absorbance and quantitatively evaluated by the colorimetric response CR (%), defined as the relative change from blue to red. The formula for calculating CR is:

[0052]

[0053] Among them, PB b and PB a These represent the percentage change in system blue color (PB) before and after the reaction between the PDA-SH / PDA label and the analyte. The formula for calculating PB (%) is:

[0054]

[0055] Among them, A blue and A red The absorbance values ​​are the blue (λ = ~650 nm) and red (λ = ~550 nm) forms of the system, respectively. Therefore, a larger CR (%) value indicates a greater color change from blue to red, meaning the sensor reacts more strongly with the target product.

[0056] The color change of the sensor was evaluated using digital images of the PDA-SH / PDA tag solution before and after the reaction with trans-2-hexenal and cis-3-hexenal. Images were captured using Huawei mobile phone color recognition software to monitor the color change of the solution. During operation, the shooting conditions were controlled, and the R, G, B, L*, a*, and b* values ​​exceeding 30×30 pixels were analyzed using the smartphone's built-in color recognition software, where R represents red, G represents green, B represents blue, L* represents brightness, a* represents red-green, and b* represents yellow-blue. The signal was calculated using the equation (R / B) / (R0 / B0), where R0, B0 and R, B are the values ​​of the red and blue elements of the film before and after exposure, respectively. The signal was normalized relative to a control sample. The red-green-blue (RGB) values ​​of the tag solution were measured, and the red color difference RCS (%) was calculated. Red intensity can be represented by red chromaticity (r). The formula for calculating RCS (%) is as follows: Where r sampleThe values ​​were measured after the PDA-SH / PDA tag solution reacted with different concentrations of trans-2-hexenal and cis-3-hexenal solutions. r0 was measured after the TCDA-SH / TCDA tag underwent UV photopolymerization for 30 seconds. max This is measured after the PDA-SH / PDA label is exposed to 1M NaOH. The higher the RCS% value, the greater the degree of color change, indicating a greater degree of reaction between the label and the target product.

[0057] Using a pipette, 100 μL of 50% (v / v) trans-2-hexenal and cis-3-hexenal solutions were added dropwise to 1 mL of PDA-SH / PDA solution. The mixture was gently shaken, and after reacting for 10 min, images were taken for RGB data analysis. Figure 4 As shown. From Figure 4 As can be seen from A, the PDA-SH / PDA solution turns pink after reacting with trans-2-hexenal and pale purple after reacting with cis-3-hexenal solution; from Figure 4 As can be seen from B, the red color difference (%) is greater after the solution reacts with trans-2-hexenal; from Figure 4 The value of C indicates that the absorbance of the solution is enhanced after reacting with trans-2-hexenal. All the above results show that, under the same reaction time, PDA-SH / PDA reacts with the same amount of trans-2-hexenal and cis-3-hexenal to produce different phenomena. PDA-SH / PDA label solution can be used to distinguish and visualize trans-2-hexenal and cis-3-hexenal.

[0058] Using a pipette, 20, 40, 60, 80, and 100 μL of 50% trans-2-hexenal solution and 50% cis-3-hexenal solution were respectively added dropwise to 1 mL of PDA-SH / PDA solution. The color changes were characterized numerically as follows: Figure 5 As shown in A, with slight oscillation, three parallel experiments were performed to investigate the dose-effect relationship of the PDA-SH / PDA tag in recognizing trans-2-hexenal and cis-3-hexenal samples. The reaction phenomena are as follows. Figure 5 As shown in B, it can be seen that for cis-3-hexenal, when the added volume exceeds 60 μL, the color change of the solution system tends to be uniform; for trans-2-hexenal, the upper limit of the reaction is relatively higher, and the reaction is more vigorous, suggesting that the PDA-SH / PDA solution is more sensitive to trans-2-hexenal.

[0059] Using a pipette, 100 μL of trans-2-hexenal solutions with volume fractions of 10%, 20%, 30%, 40%, and 50%, and cis-3-hexenal solutions with volume fractions of 10%, 20%, 30%, 40%, and 50%, respectively, were added dropwise to 1 mL of PDA-SH / PDA solution. The solution was gently shaken. Three parallel experiments were performed. The physical phenomena and reaction observations are shown in the figure below. Figure 6 As shown, the data representation of its color changes is as follows: Figure 7 As shown in Figure AD, the concentration effect of the PDA-SH / PDA tag on the identification and differentiation of trans-2-hexenal and cis-3-hexenal samples was investigated. It can be seen from the figure that when the same volume of trans-2-hexenal and cis-3-hexenal is added, the degree of reaction increases with the increase of the added concentration. If the same mass of trans-2-hexenal and cis-3-hexenal is added to the solution, the solution with trans-2-hexenal has a greater degree of reaction, and the pair of isomers can be clearly distinguished by visual identification.

[0060] Trans-2-hexenal and cis-3-hexenal were prepared into mixed solvents with different proportions. The volume fractions (fv) of trans-2-hexenal were 1%, 2%, 3%, 4%, and 5%, respectively, and the volume fractions (fv') of cis-3-hexenal were 9%, 8%, 7%, 6%, and 5%, respectively. In total, the sum of the volume fractions of trans-2-hexenal and cis-3-hexenal was 10%, with the remaining volume made up with ultrapure water. 1 mL of the prepared mixed reagent was added to 1 mL of PDA-SH / PDA label solution. The color change of the solution was as follows... Figure 8 As shown.

[0061] The absorbance (CR) value of the label solution after reaction with solutions of trans-2-hexenal and cis-3-hexenal in different proportions was calculated at a specific wavelength using the above analytical method. A graph was plotted with CR, r, a, and RCS values ​​on the ordinate and fv on the abscissa. Figure 9 As shown in AD, the color change of the solution is greater as the volume fraction of trans-2-hexenal in the solution increases, which further indicates that the activation energy of the reaction between PDA-SH / PDA solution and trans-2-hexenal is lower than that of the reaction with cis-3-hexenal. To a certain extent, the relative levels of the two isomers can be determined by observing the degree of color change.

[0062] Example 2

[0063] (1) Preparation of PDA-SH / PDA tags

[0064] Weigh 0.03 g TCDA and 0.017 g LR into 3 mL CHCl3 and mix. Vortex thoroughly and heat in a water bath at 100 °C for 20 min to promote the reaction. Then add 30 mL CHCl3 to dilute and mix well. Wash successively with 20 μL HCl and 20 μL NaCl, and dry with 0.01 g anhydrous MgSO4. Mix thoroughly using a vortex mixer to separate the organic layer from the aqueous layer. Take the organic layer, dry it with nitrogen gas to remove chloroform, and obtain TCDA-SH on the tube wall.

[0065] Weigh 0.12g TCDA and add it to the bottom of a centrifuge tube containing the TCDA-SH sample, making the molar ratio of TCDA-SH:TCDA 1:4. Add 4mL of dichloromethane to the centrifuge tube to generate liposomes. Remove the dichloromethane by nitrogen blowing until only a small amount of particulate matter remains on the tube wall. Add 0.4mL of 0.1% CNC nanofibers and then add 37.5mL of ultrapure water to obtain a mixed solution. Heat the mixed solution in an 80℃ water bath for 20min and then sonicate it for 20min using an ultrasonic cell disruptor (300W) to obtain a suspension.

[0066] The suspension was placed in a 4°C refrigerator. After 20 hours, it was removed from the refrigerator, 150 mL of purified water was added, and the mixture was shaken well. 1 mL of the solution was then placed in a centrifuge tube and polymerized under 254 nm UV light for 18 minutes to obtain the PDA-SH / PDA tag solution.

[0067] (2) PDA-SH / PDA tag detection distinguishes between trans-2-hexenal and cis-3-hexenal.

[0068] The analytical method is the same as in Example 1. This label can be used to visually identify and distinguish between trans-2-hexenal and cis-3-hexenal.

[0069] Example 3

[0070] (1) Preparation of PDA-SH / PDA tags

[0071] Weigh 0.1 g TCDA and 0.08 g LR into 5 mL CHCl3 and mix. Vortex thoroughly and heat in a water bath at 100 °C for 20 min to promote the reaction. Then add 30 mL CHCl3 to dilute and mix well. Wash successively with 20 μL HCl and 20 μL NaCl, and dry with 0.01 g anhydrous MgSO4. Mix thoroughly using a vortex mixer to separate the organic layer from the aqueous layer. Take the organic layer, dry it with nitrogen gas to remove chloroform, and TCDA-SH will be obtained on the tube wall.

[0072] Weigh 0.4g of TCDA and add it to the bottom of a centrifuge tube containing the TCDA-SH sample, making the molar ratio of TCDA-SH:TCDA 1:4. Add 4mL of CHCl3 to the centrifuge tube to induce liposome assembly. Remove chloroform by nitrogen blowing until only a small amount of particulate matter remains on the tube wall. Add 0.5mL of 0.1% CNC nanofibers and then add 37.5mL of ultrapure water to obtain a mixed solution. Heat the mixed solution in a 70℃ water bath for 30min and then sonicate it for 30min using an ultrasonic cell disruptor (power 200W) to obtain a suspension.

[0073] The suspension was placed in a 4°C refrigerator. After 20 hours, it was removed from the refrigerator, 150 mL of purified water was added, and the mixture was shaken well. 1 mL of the solution was then placed in a centrifuge tube and polymerized under 254 nm UV light for 18 minutes to obtain the PDA-SH / PDA tag solution.

[0074] (2) PDA-SH / PDA tag detection distinguishes between trans-2-hexenal and cis-3-hexenal.

[0075] The analytical method is the same as in Example 1. This label can be used to visually identify and distinguish between trans-2-hexenal and cis-3-hexenal.

[0076] The embodiments described above provide a detailed explanation of the technical solutions of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, or similar substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a PDA-SH / PDA tag for distinguishing between trans-2-hexenal and cis-3-hexenal, characterized in that, Includes the following steps: (1) Thioylation modification of 10,12-tetracarbadiynic acid yields thiolated tetracarbadiynic acid; (2) 10,12-tetarodiyne acid and mercaptotarodiyne acid are mixed in an organic solvent at a molar ratio of 2-5:1 to generate liposomes. After removing the organic solvent, particulate matter is obtained. The particulate matter is dispersed in an aqueous solution, heated in a water bath at 50-100°C for 15-30 min, and ultrasonically treated to obtain a suspension. The suspension is then allowed to stand for later use. (3) Shake the suspension well and place it under ultraviolet light for polymerization. The ultraviolet light wavelength is 254 nm and the ultraviolet light irradiation time is 18-20 min to obtain the PDA-SH / PDA label used to distinguish between trans-2-hexenal and cis-3-hexenal.

2. The method for preparing a PDA-SH / PDA tag for distinguishing between trans-2-hexenal and cis-3-hexenal according to claim 1, characterized in that, In step (1), the thiolization modification method is as follows: 10,12-tetracarbazide acid and Lawson's reagent are thoroughly mixed in chloroform, heated in a water bath, and thiolized tricarbazide acid is obtained by separation.

3. The method for preparing a PDA-SH / PDA tag for distinguishing between trans-2-hexenal and cis-3-hexenal according to claim 1, characterized in that, In step (2), 10,12-tetarodiyne acid and mercapto-tetarodiyne acid are mixed in a molar ratio of 4:

1.

4. The method for preparing a PDA-SH / PDA tag for distinguishing between trans-2-hexenal and cis-3-hexenal according to claim 1, characterized in that, In step (2), the organic solvent includes chloroform, dichloromethane, or diethyl ether.

5. The method for preparing a PDA-SH / PDA tag for distinguishing between trans-2-hexenal and cis-3-hexenal according to claim 1, characterized in that, The ultrasonic treatment time is 15-30 minutes.

6. The method for preparing a PDA-SH / PDA tag for distinguishing between trans-2-hexenal and cis-3-hexenal according to claim 1, characterized in that, In step (2), the settling time is ≥20 min.

7. A PDA-SH / PDA tag prepared by the method for preparing a PDA-SH / PDA tag for distinguishing between trans-2-hexenal and cis-3-hexenal according to any one of claims 1-6.

Images