Portable fluorescence sensor for rapidly and intelligently detecting sulfite content in food and preparation method of portable fluorescence sensor

Abstract

The invention discloses a portable fluorescence sensor for rapidly and intelligently detecting the content of sulfite in food and a preparation method thereof. The sensing chip has specific interaction with sulfite (bisulfite) through the molecular sensor LCMQ, changes of dual optical signals of color and fluorescence are generated, and the content of sulfite (bisulfite) in food is quantitatively detected through capture, recognition and analysis of a portable instant detection platform of a sensing chip-smart phone. The method has the characteristics of simplicity in preparation, low cost, high sensitivity, high selectivity, rapidness and readability, provides an intelligent and effective means for detection of sulfite (bisulfite) in food, provides powerful technical guarantee for self-monitoring and market supervision of food manufacturers, has great application prospects, and has great popularization significance.

Description

Technical Field

[0001] This invention belongs to the field of food detection technology, and particularly relates to a sensor chip for rapid and intelligent detection of sulfites using both color and fluorescence changes, as well as a method for synthesizing a fluorescent probe with a molecular switch in the chip and a method for preparing the chip. Background Technology

[0002] Sulfites (or bisulfites) are strong reducing agents widely used in food additives to inhibit bacterial spoilage, oxidation, and microbial reactions in food. Therefore, in agricultural product processing, sulfites (or bisulfites) are commonly used as bleaching agents and preservatives. Furthermore, sulfites (or bisulfites) play a crucial role in some physiological processes; however, many studies have shown a close association between exposure to high doses of sulfites and respiratory diseases, cardiovascular diseases, and some neurological disorders. To protect consumer health, there is an urgent need to develop rapid, quantitative detection methods for sulfites.

[0003] Traditional methods for detecting sulfites (hydrogen sulfites) mainly include titration analysis, ion chromatography, and high-performance liquid chromatography (HPLC). However, these methods require complex pretreatment steps, expensive equipment, and are time-consuming, making them unsuitable for rapid on-site emergency detection. Molecular sensor technology, due to its advantages of high sensitivity, good selectivity, ease of operation, and low-cost detection equipment, has gradually developed into a powerful analytical tool. Furthermore, by fabricating molecular sensors into portable chips, they can be used for intelligent on-site detection. The main principle of portable chip sensing technology is to utilize changes in the optical properties (absorption or emission) of the sensor unit as the output signal to achieve the detection of the analyte.

[0004] Currently, there are three main types of sulfite (hydrogen sulfite) fluorescent probes: (1) SO3-based 2- / HSO3 - It undergoes a nucleophilic reaction with levulinic ester, producing a signal change that enhances fluorescence. However, these fluorescent probes containing ester groups are easily hydrolyzed or amined to remove the ester groups, producing a false appearance of enhanced fluorescence. (2) Using SO3 2- / HSO3 - Addition reactions with aldehyde groups occur in acidic environments, producing enhanced fluorescence signal changes. These fluorescent probes generally have low sensitivity. Furthermore, numerous biomolecules containing thiol and amino groups interfere with their selection, resulting in poor selectivity. (3) Utilizing SO3 2- / HSO3 -Nucleophilic addition reactions with active C=C bonds produce changes in ratiometric fluorescence signals. However, these fluorescent probes often exhibit a blue shift in emission wavelength upon interaction with sulfites, and the shorter wavelength is unfavorable for detection in practical samples. Therefore, developing responsive Deep Red fluorescent probes based on specific chemical reactions and integrating them into portable sensing chips for high-sensitivity, high-selectivity intelligent on-site detection of sulfites in food is both crucial and extremely challenging.

[0005] Food safety is a fundamental public concern, increasingly attracting widespread attention. Therefore, there is an urgent need to develop a novel, simple, and easy-to-operate portable intelligent detection technology to detect sulfites (hydrogen sulfites) in food. Sensor chips represent a highly promising portable, real-time detection technology, and smartphones, due to their advanced intelligence, are expected to become a new type of portable intelligent detection device. Therefore, this study uses a smartphone as the detection platform, develops integrated data processing software, and builds a smartphone imaging-data processing system. This system efficiently processes and fits the sensor chip's output signal, thus constructing a "sensor chip-smartphone" portable, real-time detection platform. This platform enables rapid, on-site quantitative monitoring of sulfites (hydrogen sulfites) in food, providing strong technical support for food manufacturers' self-monitoring and market supervision. Summary of the Invention

[0006] One of the objectives of this invention is to overcome the shortcomings of existing tools for detecting sulfites (hydrogen sulfites) in food and to provide a portable, real-time detection platform based on a "sensor chip-smartphone" to enable rapid, on-site quantitative monitoring of sulfites (hydrogen sulfites) in food.

[0007] To achieve the above and other related objectives, the present invention provides the following technical solution: a portable fluorescent sensor for rapid and intelligent detection of sulfite content in food, comprising a compound with rhodamine as the fluorophore and quinoline as the recognition group, having the chemical formula [C 32 H 28 N2O3] 2+ The structure is as follows:

[0008]

[0009] To achieve the above and other related objectives, the present invention provides the following technical solution: A method for preparing a portable fluorescence sensor for rapid and intelligent detection of sulfite content in food, comprising the following steps:

[0010] Step 1: Place 3-diethylaminophenol and phthalic anhydride in toluene and reflux under an argon atmosphere for 2-4 hours; after cooling to 40-60°C, add 10 ml of sodium hydroxide aqueous solution and continue stirring at 85-95°C for 4-6 hours; after the reaction is complete, pour the mixture into ice water and acidify with hydrochloric acid while stirring, and keep at room temperature for 1-2 hours; filter the resulting precipitate and wash with ethanol to obtain intermediate product 1.

[0011] Step 2: Compound 1 and 1-(quinolin-3-yl)ethyl ketone were added to methanesulfonic acid and heated at 85-95°C for 6-12 hours. After the reaction was completed, the mixture was cooled to room temperature and saturated brine (saturated brine at room temperature) was added. The aqueous layer was extracted with dichloromethane. The organic layers were combined, dried with sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by silica gel column chromatography to obtain intermediate 2.

[0012] Step 3: Add intermediate product 2 and trifluorosulfonate to the solvent and react at a reaction temperature of 25-120℃ for 0.5-24 hours. Remove the solvent and obtain the molecular sensor LCMQ by silica gel column chromatography.

[0013] The preferred technical solution is as follows: In step 3, the solvent is one of dichloromethane, acetonitrile, dimethyl sulfoxide, toluene, ethylene glycol methyl ether, methanesulfonic acid, and concentrated phosphoric acid.

[0014] 4. The method for preparing a portable fluorescent sensor for rapid and intelligent detection of sulfite content in food according to claim 2, characterized in that, in step 1, the mass ratio of 3-diethylaminophenol and phthalic anhydride is 0.5-1.5:0.5-1.5.

[0015] The preferred technical solution is as follows: In step 2, the mass ratio of compound 1 to 1-(quinolin-3-yl)acetone is 0.5-1.5:0.5-1.5.

[0016] The preferred technical solution is as follows: In step 3, the mass ratio of intermediate product 2 to trifluoromethanesulfonate is 1.0-2.0:1.0-8.0.

[0017] To achieve the above and other related objectives, the present invention provides the following technical solution: the application of the portable fluorescence sensor for rapid and intelligent detection of sulfite content in food in food testing.

[0018] The preferred technical solution is: placing Whatman filter paper in a 1-4×10 -3 The filter paper is immersed in a portable fluorescence sensor solution with a mole / L concentration, then removed and placed in a vacuum drying oven to dry. The dried filter paper is then collected and integrated into the sensing area of ​​the chip.

[0019] The preferred technical solution is as follows: a portable instant detection platform for detecting sulfites in food using a "sensor chip-smartphone" architecture. This platform includes a smartphone, a sensor chip, recognition and data processing software, and an ultraviolet lamp. The chip, loaded with a portable fluorescence sensor, exhibits a colorimetric change after specifically responding to sulfites in the food sample, and also shows a fluorescence change under ultraviolet light. This colorimetric change can be captured by the smartphone and identified by the data processing software, and the sulfite content can be accurately read based on the established RGB value standard curve.

[0020] Beneficial effects

[0021] By employing the above-described technical solution, the advantages of this invention compared to the prior art are:

[0022] 1. The portable sensor chip of this invention uses LCMQ, a rhodamine derivative with a quinoline-onium backbone as the recognition site, as its main chromogenic reagent. It is suitable for rapid and highly sensitive detection of sulfites in pure aqueous solutions. LCMQ itself exhibits extremely weak fluorescence, and upon interaction with sulfites, it displays a dual visual response of color deepening and near-infrared fluorescence enhancement. This molecular sensor has a simple structure, is easy to synthesize, exhibits a specific response to sulfites, and can overcome interference from various strongly nucleophilic species.

[0023] 2. The portable sensor chip of this invention can be integrated into a portable instant detection platform combining a sensor chip and a smartphone. In practical applications, food samples only need to undergo simple pretreatment before being added to the chip's sensing area to produce obvious color and fluorescence changes. These colorimetric and fluorescence changes can be captured and identified by the detection platform, and the output signal of the sensor chip can be efficiently calculated and fitted to achieve direct reading of the sulfite content in the food sample.

[0024] 3. The detection method of this invention is not limited by expensive large-scale instruments. It can be completed under normal room temperature and other mild conditions, making it convenient, simple, fast, economical, and practical. The portable instant detection platform of "sensor chip-smartphone" can provide strong technical support for prominent issues such as food safety, enabling early detection and handling of potential problems such as excessive additives. It has great application potential in the field of public food safety. Attached Figure Description

[0025] Figure 1 The one-dimensional hydrogen nuclear magnetic spectrum of the molecular sensor LCMQ in Embodiment 1 of the present invention, with the horizontal axis representing chemical shift and the vertical axis representing signal intensity.

[0026] Figure 2(A) The ultraviolet spectrum of the molecular sensor LCMQ for sulfite in Example 1 of the present invention, with wavelength on the horizontal axis and absorbance on the vertical axis. (B) The fluorescence spectrum of the molecular sensor LCMQ for sulfite in Example 1 of the present invention, with wavelength on the horizontal axis and fluorescence intensity on the vertical axis.

[0027] Figure 3 (A) The response time of the molecular sensor LCMQ in Example 1 of the present invention to sulfite, with the horizontal axis representing time and the vertical axis representing fluorescence intensity. Also, a diagram showing the effect of adding sulfite to the molecular sensor LCMQ in Example 1 of the present invention, and the change in fluorescence of the solution over time.

[0028] Figure 4 The portable sensor chip in Embodiment 1 of the present invention enables the visual detection of sulfites of different concentrations.

[0029] Figure 5 (A) The linear relationship between the B(RGB) value and the sulfite concentration of the portable sensor chip in Embodiment 1 of the present invention. (B) The linear relationship between the R(RGB) value and the sulfite concentration of the portable sensor chip in Embodiment 1 of the present invention.

[0030] Figure 6 (A) A diagram showing the selectivity of the portable sensor chip against different interfering substances under sunlight. (B) A diagram showing the selectivity of the portable sensor chip against different interfering substances under fluorescence.

[0031] Figure 7 (A) Images showing the detection effect of the portable sensor chip in Example 1 of this invention on sulfites in food (red wine, white sugar, and Yi noodles). (B) The sulfite content in food (red wine, white sugar, and Yi noodles) was determined by the portable sensor chip in Example 1 and the GB / T 33088-2016 standard. Detailed Implementation

[0032] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can understand other advantages and effects of the present invention from the content disclosed in these embodiments.

[0033] Please see Figure 1-7It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation of the invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effectiveness or purpose of the invention, should fall within the scope of the disclosed technical content. The following embodiments are provided to better understand the invention, but are not intended to limit it. Unless otherwise specified, the experimental materials used in the following embodiments were purchased from conventional consumables and biochemical reagent stores.

[0034] Example 1

[0035] A molecular sensor LCMQ for detecting sulfites, with the chemical formula [C 32 H 28 N2O3] 2+ And the molecule has the following structure:

[0036]

[0037] 1.1 The specific synthetic route is as follows:

[0038]

[0039] The preparation method steps are as follows:

[0040] Step (1), preparation of compound 1:

[0041] A mixture of 3-diethylaminophenol and phthalic anhydride was placed in a suitable amount of toluene and refluxed under an argon atmosphere for 2-4 hours. After cooling to 40-60°C, 50 mL of a 35% (w / w) aqueous solution of sodium hydroxide was added, and the mixture was stirred at 90°C for 4-6 hours. After the reaction was complete, the mixture was slowly poured into ice water while stirring and acidified with concentrated hydrochloric acid (36% (w / w)) for 1-2 hours at room temperature. The resulting precipitate was filtered and washed with ethanol to give compound 1.

[0042] Step (2), preparation of compound 2:

[0043] Compound 1 and 1-(quinolin-3-yl)ethyl ketone were dissolved in methanesulfonic acid and heated at 90 °C for 6–12 hours. After the reaction was complete, the mixture was cooled to room temperature and saturated brine was added. The aqueous layer was extracted with dichloromethane. The combined organic layers were dried over sodium sulfate, filtered, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography to give compound 2.

[0044] Step (3), preparation of the molecular sensor LCMQ:

[0045] Compound 2, methyl trifluoromethanesulfonate, and dichloromethane (an organic solvent) were sequentially added to a 100 mL double-necked round-bottom flask. The reaction mixture was then stirred at room temperature under a nitrogen atmosphere for 6–12 hours. The reaction was stopped, and the crude product was filtered off and purified using a silica gel column to obtain the purple solid fluorescent probe LCMQ. The one-dimensional proton NMR spectrum of the obtained fluorescent probe is attached. Figure 1 .

[0046] 1.2 Preparation of test reagents:

[0047] (1) Preparation of probe solution: Accurately weigh 3.9 mg LCMQ and dissolve it in 5 mL of dimethyl sulfoxide to prepare a solution with a probe concentration of 1 mM.

[0048] (2) Preparation of sulfite stock solution: Accurately weigh 2.6 mg NaHSO3, dissolve it in PBS (pH=7.4) to prepare a 1 mM solution.

[0049] 1.3 The fabrication process of the portable sensor chip for detecting sulfite content in food according to the present invention:

[0050] Whatman filter paper (size: 1.6 cm in diameter) was immersed in an LCMQ solution of a certain concentration for a certain period of time. Then, the filter paper was removed and dried in a vacuum drying oven. The dried filter paper was collected and integrated into the sensing area of ​​the chip. The filter paper loaded with the LCMQ molecular sensor exhibited corresponding fluorescence color changes and colorimetric changes after interacting with sulfite. The specific procedure is as follows:

[0051] (1) Dissolve the probe molecule in one or more of the following solvents: phosphoric acid, acetonitrile, chloroform, dimethyl sulfoxide, N,N-dimethylformamide, and phosphate buffer, to prepare a final concentration of 1×10⁻⁶. -3 -4×10 -3 probe solution in moles per liter;

[0052] (2) Soak Whatman filter paper thoroughly in 5-20 mL of the above probe solution containing probe molecules for 5-25 min. Remove the filter paper loaded with probe, dry it, and use it for subsequent experiments.

[0053] 1.4 Components and Principles of the Portable Real-Time Detection Platform for "Sensor Chip-Smartphone":

[0054] Using a smartphone as the detection platform and integrating data processing software, a smartphone imaging-data processing system is built to efficiently calculate and fit the output signal of the sensor chip, thus constructing a portable, real-time detection platform based on the sensor chip. This platform mainly consists of four parts: a smartphone, a sensor chip, recognition and data processing software, and a UV lamp. The basic principle is that the LCMQ molecular sensor chip specifically responds to sulfite in food samples, exhibiting a colorimetric change and a fluorescence change under UV light. This colorimetric change can be captured by the portable, real-time detection platform based on the established RGB value standard curve and the fluorescence RGB or color RGB values ​​output by the smartphone to accurately read the sulfite content.

[0055] Example 2

[0056] Please see Figure 2 The spectral response of the molecular sensor LCMQ to sulfite.

[0057] The spectral response of the molecular sensor to sulfite was verified using the LCMQ from Example 1. The 1 mM probe solution from Example 1 was diluted to a concentration of 1.0 × 10⁻⁶ with 2 mL of a mixture of dimethyl sulfoxide and PBS. -5 Moles per liter. For example... Figure 2 As shown, the absorbance and fluorescence intensity of the solution gradually increased with increasing sulfite concentration, eventually reaching stability after adding 0.5 times the molar amount of sulfite as the probe. The molecular sensor was excited at 610 nm, emitted at 670 nm, and exhibited a Stokes shift of 60 nm. This demonstrates that the molecular sensor can achieve highly sensitive detection of sulfite.

[0058] Example 3

[0059] Please see Figure 3 The response time of the molecular sensor LCMQ to sulfite.

[0060] The response time of the molecular sensor to sulfite was verified using the LCMQ from Example 1. The 1 mM probe solution from Example 1 was diluted to a concentration of 1.0 × 10⁻⁶ with 2 mL of a mixture of dimethyl sulfoxide and PBS. -5 Moles per liter. For example... Figure 3 As shown, when 0.5 times the molar amount of sulfite as the probe is added to the solution, it can emit a strong red fluorescence instantly, and complete the solution diffusion and full reaction within 6 seconds. At this time, the fluorescence intensity is increased by 60 times. Figure 3 The results showed that the solution of probe LCMQ could rapidly detect sulfite, exhibiting a significant change in Deep Red fluorescence intensity, demonstrating good application prospects.

[0061] Example 4

[0062] Please see Figure 4 A portable sensor chip enables the visual detection of sulfites at different concentrations.

[0063] The portable sensor chip from Example 1 was used to evaluate its ability to visually detect different concentrations of sulfite. Figure 6 The results were obtained by recording the color and fluorescence changes of the sensor chip under visible light and 365nm ultraviolet light using a smartphone imaging system. The sensor chip's fluorescence changed from light green to red, and its color changed from pale yellow to red, exhibiting excellent dual visual response. The results demonstrate that the sensor chip exhibits good practical applicability.

[0064] Example 5

[0065] Please see Figure 5 The linear relationship between B(RGB) or R(RGB) values ​​and sulfite in portable sensor chips.

[0066] The linear relationship between the B(RGB) value and sulfite was evaluated using the portable sensor chip in Example 1. Figure 5 Figure A shows the curve of the B value as a function of sulfite concentration in the RGB color change under sunlight. The results indicate that the B value in the portable sensor chip is related to the sulfite concentration in the range of 0-2.4 × 10⁻⁶. -5 The linear relationship is good within the mole / liter range. The linear relationship between the B(RGB) value and sulfite of the chip was evaluated using the portable sensor chip in Example 1. Figure 5 Figure B shows the curve of the R value in the RGB color change under a 365nm UV lamp as a function of sulfite concentration. The results indicate that the R value in the portable sensor chip is related to the sulfite concentration within the range of 0-2.4×10⁻⁶. -5 The linear relationship is good within the mole / liter range. Therefore, LCMQ has excellent ability to quantitatively detect sulfite.

[0067] Example 6

[0068] Please see Figure 6 Selectivity of portable sensor chips under sunlight or 365nm ultraviolet light.

[0069] The selectivity of the portable sensor chip for sulfites was evaluated using the portable sensor chip described in Example 1. Figure 6 A represents the color change of the portable sensor chip under sunlight when 2.4 molar amounts of various interfering substances are added to it. The interfering substances include: NO2. - Cl - ,ClO - HPO4 2- SO4 2-CO3 2- Ca 2+ Zn 2+ NH4 + K + Mg 2+ GSH, Hcy, S 2- HSO3 - When 2.4 molar amounts of sulfite were added to the LCMQ solution, the portable sensor chip changed from colorless to dark blue. However, the addition of other interfering species did not change the color of the portable sensor chip. Figure 6 B represents the color change of the portable sensor chip under a 365nm UV lamp when 2.4 molar amounts of various interfering substances are added to it. The interfering substances include: NO2. - Cl - ,ClO - HPO4 2- SO4 2- CO3 2- Ca 2+ Zn 2+ NH4 + K + Mg 2+ GSH, Hcy, S 2- When 2.4 molar amounts of sulfite were added to the LCMQ solution, the portable sensor chip changed from colorless to a bright red. However, the addition of other interfering species did not cause any color change in the portable sensor chip. These results demonstrate that the portable sensor chip exhibits good selectivity for sulfite and has practical applicability.

[0070] Example 7

[0071] Please see Figure 7 The portable, real-time detection platform, combining sensor chips and smartphones, enables the visualized quantitative detection of sulfite content in actual food samples (red wine, white sugar, and Yi noodles).

[0072] The portable sensor chip described in Example 1 was used to detect the sulfite content in red wine, white sugar, and Yi Mian (a type of noodle). The pretreatment method for red wine was as follows: accurately pipette 1 mL of red wine, dilute it 50–200 times with a dimethyl sulfoxide (DMSO) PBS mixture (pH = 7.4), and seal for later use. The pretreatment method for sugar samples was as follows: accurately weigh 0.1–0.5 g of white sugar, grind it thoroughly into powder, and set aside. The pretreatment method for dried fruit and vegetable samples was as follows: accurately weigh 0.1–0.5 g of Yi Mian, chop it, place it in a DMSO PBS mixture (pH = 7.4), stir for 1–5 hours, centrifuge at 8000 rpm / min for 15–30 minutes, and collect the supernatant for later use. The specific procedure for detection was as follows: use a pipette to add a small amount of sample to the sensing area of ​​the chip, and use the portable sensor chip to accurately detect the sulfite content in red wine, white sugar, and Yi Mian. Figure 7 Image A is an image of a paper sensor chip used to detect sulfites in food samples (red wine, white sugar, and Yi Mian noodles). Figure 7 The sulfite content in food samples (red wine, white sugar, and Yi Mian noodles) was determined using a portable sensor chip and the pararosaniline hydrochloride method, respectively. Quantitative results showed that the sulfite content measured by this invention was almost identical to that obtained using the pararosaniline hydrochloride method, with an accuracy rate as high as 93.33-98.31%. This provides strong technical support for real-time, on-site quantitative detection of sulfite concentration.

[0073] Example 8: A portable fluorescence sensor for rapid and intelligent detection of sulfite content in food and its preparation method.

[0074] A portable sensor chip for intelligent detection of sulfite (hydrogen sulfite) content in food is characterized by its ability to quantitatively detect the sulfite content in food based on the fluorescence and color changes of the molecular sensor in the chip.

[0075] A molecular sensor for sulfite detection, comprising a compound with rhodamine as the fluorophore and quinoline as the recognition group, having the chemical formula [C 32 H 28 N2O3] 2+ The structure is as follows:

[0076]

[0077] A method for preparing a molecular sensor for sulfite detection, characterized by the following specific synthetic route:

[0078]

[0079] The preparation method includes the following steps:

[0080] Step (1): Place the mixture of 3-diethylaminophenol and phthalic anhydride in an appropriate amount of toluene and reflux under an argon atmosphere for 2-4 hours. After cooling to 40-60°C, add 50 mL of 35% (mass fraction) sodium hydroxide aqueous solution and continue stirring at 90°C for 4-6 hours. After the reaction is complete, slowly pour the mixture into ice water while stirring and acidifying with concentrated hydrochloric acid, maintaining at room temperature for 1-2 hours. Filter the resulting precipitate and wash with ethanol to obtain intermediate product 1.

[0081] Step (2): Compound 1 and 1-(quinolin-3-yl)ethyl ketone were dissolved in methanesulfonic acid and heated at 90°C for 6-12 hours. After the reaction was complete, the mixture was cooled to room temperature and saturated brine was added. The aqueous layer was extracted with dichloromethane. The organic layers were combined, dried over sodium sulfate, filtered, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography to give intermediate 2.

[0082] Step (3): Dissolve intermediate product 2 and trifluorosulfonate in a solvent and react at a reaction temperature of 25-120°C for 0.5-24 hours. Remove the solvent and obtain the molecular sensor LCMQ by silica gel column chromatography.

[0083] In step (3), the solvent is one of dichloromethane, acetonitrile, dimethyl sulfoxide, toluene, ethylene glycol methyl ether, methanesulfonic acid, and concentrated phosphoric acid.

[0084] In step (1), the ratio of 3-diethylaminophenol to phthalic anhydride is 1:1.

[0085] In step (2), the ratio of compound 1 to 1-(quinolin-3-yl)ethyl ketone is 1:1.

[0086] In step (3), the ratio of intermediate product 2 to trifluoromethanesulfonate is 1.5:5.

[0087] The above-mentioned sensors are used in the food industry, where the food products include alcoholic beverages, sugary foods, and noodle products.

[0088] A portable sensor for detecting sulfite, characterized by preparation by placing Whatman filter paper (size: 0.8-2 cm in diameter) in a 1-4 × 10 -3 The filter paper is soaked in LCMQ solution at a certain mol / L for a certain period of time, then removed and placed in a vacuum drying oven to dry. The dried filter paper is then collected and integrated into the sensing area of ​​the chip.

[0089] The aforementioned intelligent portable real-time detection platform for detecting sulfites in food, based on a "sensor chip-smartphone," is characterized by integrating four main components: a smartphone, a sensor chip, recognition and data processing software, and an ultraviolet lamp. Specifically, the chip loaded with the molecular sensor LCMQ exhibits a colorimetric change upon specific response to sulfites in the food sample, and also displays fluorescence under ultraviolet light. This colorimetric change can be captured by the smartphone and identified by the data processing software. The sulfite content is accurately read based on the established RGB value standard curve.

[0090] The above description is merely a preferred embodiment for explaining the present invention and is not intended to limit the present invention in any way. Therefore, any modifications or changes made to the present invention under the same inventive spirit should still be included within the scope of protection intended by the present invention.

Claims

1. A portable fluorescence sensor for rapid and intelligent detection of sulfite content in food, characterized in that: A compound with rhodamine as the fluorophore and quinoline as the recognition group, having the chemical formula [C 32 H 28 N2O3] 2+ The structure is as follows:

2. A method for preparing a portable fluorescence sensor for rapid and intelligent detection of sulfite content in food as described in claim 1, characterized in that: Includes the following steps: Step 1: Place 3-diethylaminophenol and phthalic anhydride in toluene and reflux under an argon atmosphere for 2-4 hours; after cooling to 40-60°C, add 10 ml of sodium hydroxide aqueous solution and continue stirring at 85-95°C for 4-6 hours; after the reaction is complete, pour the mixture into ice water and acidify with hydrochloric acid while stirring, and keep at room temperature for 1-2 hours; filter the resulting precipitate and wash with ethanol to obtain intermediate product 1. Step 2: Compound 1 and 1-(quinolin-3-yl)ethyl ketone were added to methanesulfonic acid and heated at 85-95°C for 6-12 hours. After the reaction was completed, the mixture was cooled to room temperature and saturated brine (saturated brine at room temperature) was added. The aqueous layer was extracted with dichloromethane. The organic layers were combined, dried with sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by silica gel column chromatography to obtain intermediate 2. Step 3: Add intermediate product 2 and trifluorosulfonate to the solvent and react at a reaction temperature of 25-120℃ for 0.5-24 hours. Remove the solvent and obtain the molecular sensor LCMQ by silica gel column chromatography.

3. The method for preparing a portable fluorescence sensor for rapid and intelligent detection of sulfite content in food according to claim 2, characterized in that: In step 3, the solvent is one of dichloromethane, acetonitrile, dimethyl sulfoxide, toluene, ethylene glycol methyl ether, methanesulfonic acid, and concentrated phosphoric acid.

4. The method for preparing a portable fluorescence sensor for rapid and intelligent detection of sulfite content in food according to claim 2, characterized in that: In step 1, the mass ratio of 3-diethylaminophenol to phthalic anhydride is 0.5-1.5:0.5-1.

5.

5. The method for preparing a portable fluorescence sensor for rapid and intelligent detection of sulfite content in food according to claim 2, characterized in that: In step 2, the mass ratio of compound 1 to 1-(quinolin-3-yl)acetone is 0.5-1.5:0.5-1.

5.

6. The method for preparing a portable fluorescence sensor for rapid and intelligent detection of sulfite content in food according to claim 2, characterized in that: In step 3, the mass ratio of intermediate product 2 to trifluoromethanesulfonate is 1.0-2.0:1.0-8.

0.

7. The application of the portable fluorescence sensor for rapid and intelligent detection of sulfite content in food as described in claim 1 in food testing.

8. The application of the portable fluorescence sensor for rapid and intelligent detection of sulfite content in food according to claim 7 in food detection: characterized in that: Place the Whatman filter paper in a 1-4×10 -3 The filter paper is immersed in a portable fluorescence sensor solution with a mole / L concentration, then removed and placed in a vacuum drying oven to dry. The dried filter paper is then collected and integrated into the sensing area of ​​the chip.

9. The application of the portable fluorescence sensor for rapid and intelligent detection of sulfite content in food according to claim 7 in food detection: characterized in that: This includes a portable, real-time detection platform for intelligently detecting sulfites in food using a "sensor chip-smartphone" architecture. The platform comprises a smartphone, a sensor chip, identification and data processing software, and a UV lamp. The chip, equipped with a portable fluorescence sensor, exhibits a colorimetric change upon specific response to sulfites in the food sample, and also displays fluorescence under UV light. This colorimetric change can be captured by the smartphone and identified by the data processing software, accurately determining the sulfite content based on an established RGB value standard curve.

Images