Preparation method and application of ratiometric fluorescent paper-based sensor

Abstract

The invention discloses a preparation method and application of a ratiometric fluorescent paper-based sensor. The preparation method comprises the following steps: (1) preparing a UiO-66-NH2-rhodamine B composite material; and (2) dropwise adding a suspension containing the UiO-66-NH2-rhodamine B composite material into the hydrophilic sensing area of the paper-based substrate, and carrying out a reaction I to obtain the ratiometric fluorescent paper-based sensor, the surface of the paper-based substrate is modified by using carboxymethyl cellulose to introduce a large number of carboxyl groups; the paper-based substrate comprises a hydrophilic sensing area and a hydrophobic area. Due to the built-in self-calibration characteristic of the ratiometric fluorescence sensor disclosed by the invention, the interference of factors irrelevant to analysis can be inhibited, and higher sensitivity and more obvious visual detection effect are shown in qualitative and quantitative analysis processes.

Description

Technical Field

[0001] The present application relates to a preparation method and application of a ratiometric fluorescent paper-based sensor, and belongs to the technical field of fluorescent sensing materials and environmental monitoring. Background Art

[0002] Amino acids are the basic units of protein molecules in organisms and are closely related to life activities. Among the 20 natural amino acids, arginine is an amino acid with a guanidine group and the strongest alkalinity. Arginine not only provides nitric oxide to the body and promotes vasodilation, but also plays an important role in improving human immune function and maintaining hormone levels. If the arginine content in the body is abnormal, it will cause health problems and even threaten life. Therefore, the detection of arginine is very necessary.

[0003] Fluorescent probes have been widely developed in the field of analytical sensing due to their simple technology, convenient detection, and high sensitivity. Generally speaking, fluorescence detection technology performs target analysis by monitoring the change in fluorescence intensity caused by the interaction between the target analyte and the fluorescent probe. However, most fluorescent sensors use only a single detection signal, which leads to interference from factors unrelated to the analyte, such as the parameters of the detection instrument, the microenvironment of the probe, etc. In order to overcome these limitations, another fluorescent signal is usually introduced into the structure of the single-emission probe to construct a ratiometric fluorescence sensor with dual-emission characteristics. The intensity ratio of two independent signals is used instead of the absolute intensity to quantify the analyte. The ratio of the two peaks can effectively offset the error, provide more reliable sensing results for detection, and greatly improve the sensitivity of the probe. In addition, the change in emission color output can be observed when the ratiometric fluorescence sensor reacts with the analyte. Compared with single-emission fluorescence detection, in ratiometric sensing, not only the change in color brightness can be observed, but also the change in hue can be more easily tracked. The change in hue is usually easier to be recognized by the naked eye. Based on the obvious color change of the ratiometric probe, it is combined with paper material to construct a portable paper-based sensor. The paper substrate has the advantages of low cost, easy storage and biodegradability. The paper-based surface contains a large number of hydroxyl groups, which can be functionalized by different chemical modification methods to immobilize various chemical sensors.

[0004] Metal-organic frameworks (MOFs) have attracted widespread attention as a new type of sensing material. Since the pore size and shape of MOFs can be easily adjusted to match different luminescent guests, their unique structure allows MOFs to be used as the main framework to prepare ratiometric fluorescence sensors. Fluorescent dyes are inexpensive and readily available luminophores with advantages such as stable optical properties, high quantum yield, and a wide range of emission wavelengths. Due to the aggregation-induced quenching (ACQ) effect, the fluorescence of dyes in the solid state is weakened or disappears, which limits their application. Therefore, the introduction of dyes into porous MOFs can not only effectively avoid the ACQ effect of dyes, but also the electrostatic or coordination interactions between dyes and MOFs can regulate the fluorescence properties of the synthesized composites.

[0005] Researchers have found that ratiometric fluorescence sensors composed of dye molecules and MOFs usually rely on the fluorescence resonance energy transfer (FRET) mechanism. Its main advantage is that the donor and acceptor fluorophores can be selected so that the emission peaks before and after the response do not overlap, making the test results more obvious. Therefore, choosing the right building block is the key to preparing multi-component ratiometric fluorescent probes.

[0006] Among many fluorescent dyes, the absorption and emission spectra of rhodamine B (RhB) are at longer wavelengths (both at 560-585nm). In the FRET system, it can act as an energy acceptor, and MOFs are selected as energy donors to construct a ratiometric fluorescence sensing platform. In addition, MOFs materials are usually in a powder state. During the analysis process, there are disadvantages such as complex operation and difficult recovery, which is not conducive to on-site detection. Therefore, it is necessary to establish a stable solid-state sensing platform to improve the portability of the material. Summary of the invention

[0007] The purpose of the present invention is to provide a method for constructing a ratiometric fluorescent paper-based sensing platform and apply it to the visual screening of arginine.

[0008] Based on this purpose, the present invention firstly prepares a ratiometric fluorescent probe UiO-66-NH2@RhB, covalently fixes it to the surface of a paper-based material, and realizes sensitive detection of arginine through obvious color changes under ultraviolet light.

[0009] According to one aspect of the present application, a method for preparing a ratiometric fluorescent paper-based sensor is provided, the preparation method comprising the following steps:

[0010] (1) Preparation of UiO-66-NH2@Rhodamine B composite materials;

[0011] (2) dropping a suspension containing the UiO-66-NH2@Rhodamine B composite material into the hydrophilic sensing area of ​​the paper-based substrate, reacting I, and obtaining the ratiometric fluorescent paper-based sensor;

[0012] The surface of the paper-based substrate is modified by carboxymethyl cellulose to introduce carboxyl groups;

[0013] The paper-based substrate includes a hydrophilic sensing region and a hydrophobic region.

[0014] Optionally, the diameter of the hydrophilic sensing area is 4.0 mm to 6.0 mm.

[0015] Optionally, the area of ​​the hydrophobic region is 8.0 mm×8.0 mm to 12.0 mm×12.0 mm.

[0016] Optionally, the hydrophobic region is made by wax jet printing.

[0017] Optionally, the ratio of UiO-66-NH2:RhB is 1:0.5 to 1:1.5.

[0018] Optionally, the ratio of UiO-66-NH2:RhB is selected from any value of 1:0.5, 1:1, 1:1.5 or a range between any two of the above.

[0019] Optionally, in step (1), the method for preparing the UiO-66-NH2@Rhodamine B composite material comprises:

[0020] In a sealed container, a mixture containing zirconium chloride, 2-aminoterephthalic acid, rhodamine B, and a solvent is subjected to reaction II, centrifuged, and dried to obtain the UiO-66-NH2@Rhodamine B composite material.

[0021] Optionally, the molar ratio of the zirconium chloride to the 2-aminoterephthalic acid is 2:1 to 1:2.

[0022] Optionally, the molar ratio of the zirconium chloride to the rhodamine B is 1:1 to 4:1.

[0023] Optionally, the solvent is selected from at least one of ethanol, formic acid, acetic acid, DMF and concentrated hydrochloric acid.

[0024] Optionally, the solvent for synthesizing the MOFs material is selected from at least one of ethanol / formic acid, acetic acid / DMF, DMF, and concentrated hydrochloric acid / DMF.

[0025] Optionally, the temperature of the reaction II is 110 to 140° C., and the time of the reaction II is 12 to 24 hours.

[0026] Optionally, the temperature of the reaction II is selected from any value of 110°C, 120°C, 130°C, 140°C, or a range between any two of the above points.

[0027] Optionally, the time of reaction II is selected from any value among 12h, 16h, 20h, 24h or a range between any two of the above points.

[0028] Optionally, the centrifugation is performed 5 to 9 times.

[0029] Optionally, the washing solvent during centrifugation is selected from at least one of water, ethanol, methanol and DMF.

[0030] Optionally, the drying temperature is 50-70° C., and the drying time is 6-24 hours.

[0031] Optionally, the drying temperature is selected from any value of 50°C, 55°C, 60°C, 65°C, 70°C or a range between any two of the above points.

[0032] Optionally, the drying time is selected from any value among 6h, 12h, 18h, 20h, 24h or a range between any two of the above points.

[0033] Optionally, in step (2), the concentration of the suspension is 0.5 to 6.0 mg / mL.

[0034] Optionally, the concentration of the suspension is selected from any value of 0.5 mg / mL, 1.0 mg / mL, 2.0 mg / mL, 3.0 mg / mL, 4.0 mg / mL, 5.0 mg / mL, 6.0 mg / mL or a range between any two of the above points.

[0035] Optionally, in step (2), the temperature of reaction I is 40 to 70° C., and the time of reaction I is 10 to 30 min.

[0036] Optionally, the temperature of the reaction I is selected from any value of 40°C, 50°C, 60°C, 70°C, or a range between any two of the above points.

[0037] Optionally, the reaction time I is selected from any value among 10 min, 15 min, 20 min, 30 min, or a range between any two of the above points.

[0038] According to another aspect of the present application, a method for detecting arginine is provided, the detection method comprising:

[0039] Dropping arginine solutions of different concentrations to be tested onto the hydrophilic sensing area of ​​the ratiometric fluorescent paper-based sensor, acquiring an image, processing the image to obtain the blue value of the image, and obtaining a linear relationship between the blue value and the arginine concentration;

[0040] The ratio fluorescent paper-based sensor is selected from the ratio fluorescent paper-based sensor prepared by the preparation method described above.

[0041] Optionally, the detection range of the ratiometric fluorescent paper-based sensor for arginine is 0.2-2.0 mM.

[0042] Optionally, the detection range of the ratiometric fluorescent paper-based sensor for arginine is selected from any value among 0.2 mM, 0.5 mM, 0.8 mM, 1.0 mM, 1.5 mM, 2.0 mM or a range between any two of the above values.

[0043] Optionally, the ratiometric fluorescent paper-based sensor has good selectivity for arginine.

[0044] As a specific implementation, the present application is implemented through the following technical solutions:

[0045] 1. A ratiometric fluorescent paper-based sensing platform UiO-66-NH2@RhB@paper was constructed and applied to the on-site detection of arginine. The preparation method comprises the following preparation steps:

[0046] Step a, preparing UiO-66-NH2@RhB composite material;

[0047] Step b, construction of a portable paper-based platform;

[0048] Among them, the specific steps of preparing the UiO-66-NH2@RhB composite material in step a are:

[0049] (1) 466.0 mg of ZrCl4, 181.0 mg of 2-aminoterephthalic acid and 240.0 mg of rhodamine B were weighed and dissolved in ethanol and 30% formic acid, ultrasonically treated for 10 min, and stirred for 20 min to obtain a uniform mixture.

[0050] (2) The mixed solution was transferred to a reactor and reacted in an oven at 120°C for 12 h.

[0051] (3) The product of step (2) was collected, washed with ethanol and centrifuged five times, and vacuum dried at 60°C for 12 h.

[0052] Step b: The construction steps of the portable paper-based platform are:

[0053] (1) A Whatman grade no. 41 quantitative filter paper surface was drawn using a Xerox Phaser 8560DN wax printer. The paper platform consisted of a circular hydrophilic sensing area (5.0 mm in diameter) and a square hydrophobic area (10.0 mm × 10.0 mm).

[0054] (2) Carboxymethyl cellulose (0.2 mg / mL) was added to a calcium chloride solution (10 mM, 25 mL), stirred for 10 min, and heated in an oven at 40°C for 15 min. After cooling, the wax-printed paper substrate was placed in the mixed solution and shaken at 160 rpm for 60 min. The functionalized paper substrate was then washed with deionized water and dried naturally.

[0055] (3) UiO-66-NH2@RhB was dispersed in deionized water and ultrasonicated for 20 min to obtain a uniform suspension. The UiO-66-NH2@RhB aqueous solution (4.0 mg / mL) was dropped into the sensing area and heated in an oven at 60 °C for 15 min to prepare the paper-based sensor.

[0056] Based on the ratio fluorescence paper-based sensing platform, the visual detection of arginine is characterized by the specific detection method:

[0057] (1) Arginine aqueous solutions of different concentrations were dropped into the detection area.

[0058] (2) The paper-based sensor was placed in a homemade darkroom and the image was captured using a camera under 365 nm ultraviolet light.

[0059] (3) Use Photoshop software to extract the blue value of the image.

[0060] (4) The relationship between the blue value of the image and the arginine concentration was analyzed and the detection limit of the paper-based sensor was calculated.

[0061] In this application, a ratiometric fluorescent paper-based sensing platform is constructed by regulating the ratio of MOFs and RhB (rhodamine B), the reaction temperature and reaction time during the material synthesis process, the carboxymethyl modified filter paper and the concentration of the suspension loaded on the paper base. Due to its built-in self-calibration characteristics, the ratiometric fluorescent sensor can suppress the interference of factors unrelated to the analysis, and exhibits higher sensitivity and more obvious visual detection effects in the qualitative and quantitative analysis process. The ratiometric fluorescent probe UiO-66-NH2@RhB has good selectivity for arginine in aqueous solution through the fluorescence "on" mechanism and uses the fluorescence intensity ratio of the two emission peaks as a detection index to effectively avoid errors caused by environmental factors, so that the detection sensitivity of the complex to arginine is greatly improved. In addition, a portable sensing platform is developed by combining the ratiometric fluorescent probe with a paper substrate. Under ultraviolet light irradiation, the color tone of the paper-based sensor based on UiO-66-NH2@RhB changes significantly during the detection process. This study provides a convenient and effective method for on-site detection of arginine.

[0062] The beneficial effects of this application include:

[0063] 1) The paper-based sensor provided in this application is simple to prepare, easy to operate, and low in price. It can achieve rapid, sensitive, and highly selective detection of arginine. Its good stability makes it have market development prospects.

[0064] 2) The preparation method of in situ encapsulated dye MOFs provided in this application is simple and uses a "one-pot method" to achieve controllable preparation of materials. Compared with single-emission fluorescence sensors, ratiometric fluorescence probes use relative fluorescence intensity I MOF / I Dye Instead of absolute fluorescence intensity as the output signal, the interference of external factors on the experiment is avoided, and the sensitivity and accuracy of the sensing are effectively improved. The paper-based sensor based on UiO-66-NH2@RhB not only shows changes in color brightness, but also exhibits hue differences that are easily recognized by the naked eye. This portable device provides a promising method for on-site detection of arginine. In view of the above advantages, the ratiometric fluorescent probe UiO-66-NH2@RhB has broad application prospects in environmental monitoring, food safety and other fields. In summary, the simple and effective preparation of this material has important scientific significance and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 This is the synthesis process of UiO-66-NH2@RhB prepared in Example 1 of the present application.

[0066] Figure 2 This is the XRD characterization diagram of UiO-66-NH2@RhB prepared in Example 1 of the present application.

[0067] Figure 3 This is the IR characterization diagram of UiO-66-NH2@RhB prepared in Example 1 of the present application.

[0068] Figure 4 This is the selectivity of the ratiometric fluorescent probe UiO-66-NH2@RhB for arginine in Example 1 of the present application.

[0069] Figure 5 This is a diagram showing the construction process of the paper-based sensor in Example 6 of the present application and the visual detection effect of arginine; ((a) is a schematic diagram of the preparation process of the paper-based sensor; (b) is a diagram showing the visual detection effect of the paper-based sensor on arginine). DETAILED DESCRIPTION

[0070] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0071] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0072] In the examples of the present application, the instruments used for characterization of the ratiometric fluorescent probe composite material are as follows:

[0073] Instrument Model Manufacturer Powder X-ray Diffractometer Malvern Panalytical Infrared spectrometer Thermo Fisher Scientific Fluorescence Spectrometer Hitachi Manufacturing Co., Ltd. UV-Vis Spectrophotometer Beijing Puxi General Instrument Co., Ltd. digital camera Nikon Corporation

[0074] Example 1 Preparation of UiO-66-NH2@RhB composite material

[0075] (1) 466.0 mg of ZrCl4, 181.0 mg of 2-aminoterephthalic acid and 240.0 mg of rhodamine B were weighed and dissolved in ethanol and 30% formic acid, ultrasonically treated for 10 min, and stirred for 20 min to obtain a uniform mixture.

[0076] (2) The mixed solution was transferred to a reactor and reacted in an oven at 120°C for 12 h.

[0077] (3) The product of step (2) was collected, washed with ethanol and centrifuged five times, and vacuum dried at 60°C for 12 h.

[0078] from Figure 1 As can be seen from the figure, the construction process of the ratiometric fluorescent probe. Figure 2 It can be seen that the ratiometric fluorescent probe has good phase purity. Figure 3 The chemical composition of the ratiometric fluorescent probe can be seen from Figure 4 It can be seen that the ratiometric light probe has good selectivity for arginine.

[0079] Example 2 Preparation of UiO-66-NH2@RhB composite material

[0080] (1) 466.0 mg of ZrCl4, 181.0 mg of 2-aminoterephthalic acid and 240.0 mg of rhodamine B were weighed and dissolved in DMF and acetic acid, ultrasonically treated for 10 min, and stirred for 20 min to obtain a uniform mixture.

[0081] (2) The mixed solution was transferred to a reactor and reacted in an oven at 120°C for 12 h.

[0082] (3) The product of step (2) was collected, washed with ethanol and centrifuged five times, and vacuum dried at 60°C for 12 h.

[0083] Example 3 Preparation of UiO-66-NH2@RhB composite material

[0084] (1) 466.0 mg of ZrCl4, 181.0 mg of 2-aminoterephthalic acid and 240.0 mg of rhodamine B were weighed and dissolved in ethanol and 30% formic acid, ultrasonically treated for 10 min, and stirred for 20 min to obtain a uniform mixture.

[0085] (2) The mixed solution was transferred to a reactor and reacted in an oven at 120°C for 24 h.

[0086] (3) The product of step (2) was collected, washed with ethanol and centrifuged five times, and vacuum dried at 60°C for 12 h.

[0087] Example 4 Preparation of UiO-66-NH2@RhB composite material

[0088] (1) 466.0 mg of ZrCl4, 181.0 mg of 2-aminoterephthalic acid and 240.0 mg of rhodamine B were weighed and dissolved in ethanol and 30% formic acid, ultrasonically treated for 10 min, and stirred for 20 min to obtain a uniform mixture.

[0089] (2) The mixed solution was transferred to a reactor and reacted in an oven at 160°C for 12 h.

[0090] (3) The product of step (2) was collected, washed with ethanol and centrifuged five times, and vacuum dried at 60°C for 12 h.

[0091] Example 5 Preparation of UiO-66-NH2@RhB composite material

[0092] (1) 466.0 mg of ZrCl4, 181.0 mg of 2-aminoterephthalic acid and 240.0 mg of rhodamine B were weighed and dissolved in ethanol and 30% formic acid, ultrasonically treated for 10 min, and stirred for 20 min to obtain a uniform mixture.

[0093] (2) The mixed solution was transferred to a reactor and reacted in an oven at 120°C for 12 h.

[0094] (3) The product of step (2) was collected, washed with ethanol and centrifuged five times, and vacuum dried at 70°C for 6 h.

[0095] Example 6 Construction steps of portable paper-based platform

[0096] (1) A Xerox Phaser 8560DN wax printer was used to draw the surface of Whatman grade no. 41 quantitative filter paper. The paper platform consists of a circular hydrophilic sensing area (diameter 5.0 mm) and a square hydrophobic area (10 mm×10 mm).

[0097] (2) Carboxymethyl cellulose (0.2 mg / mL) was added to a calcium chloride solution (10 mM, 25 mL), stirred for 10 min, and heated in an oven at 40°C for 15 min. After cooling, the wax-printed paper substrate was placed in the mixed solution and shaken at 160 rpm for 60 min. The functionalized paper substrate was then washed with deionized water and dried naturally.

[0098] (3) UiO-66-NH2@RhB was dispersed in deionized water and ultrasonicated for 20 min to obtain a uniform suspension. The UiO-66-NH2@RhB aqueous solution (4.0 mg / mL) was dropped into the hydrophilic sensing area and heated in an oven at 60 °C for 15 min to prepare a paper-based sensor. Figure 5 The construction process of the paper-based sensor and the visual detection effect of arginine can be seen in the figure.

[0099] Example 7 Construction steps of portable paper-based platform

[0100] (1) A Xerox Phaser 8560DN wax printer was used to draw the surface of Whatman grade no. 41 quantitative filter paper. The paper platform consists of a circular hydrophilic sensing area (diameter 5.0 mm) and a square hydrophobic area (10 mm×10 mm).

[0101] (2) Carboxymethyl cellulose (0.2 mg / mL) was added to a calcium chloride solution (10 mM, 25 mL), stirred for 10 min, and heated in an oven at 40°C for 15 min. After cooling, the wax-printed paper substrate was placed in the mixed solution and shaken at 160 rpm for 60 min. The functionalized paper substrate was then washed with deionized water and dried naturally.

[0102] (3) UiO-66-NH2@RhB was dispersed in deionized water and ultrasonicated for 20 min to obtain a uniform suspension. The UiO-66-NH2@RhB aqueous solution (4.0 mg / mL) was dropped into the hydrophilic sensing area and heated in an oven at 60 °C for 30 min to prepare a paper-based sensor.

[0103] Example 8 Construction steps of portable paper-based platform

[0104] (1) A Xerox Phaser 8560DN wax printer was used to draw the surface of Whatman grade no. 41 quantitative filter paper. The paper platform consists of a circular hydrophilic sensing area (diameter 5.0 mm) and a square hydrophobic area (10 mm×10 mm).

[0105] (2) Carboxymethyl cellulose (0.2 mg / mL) was added to a calcium chloride solution (10 mM, 25 mL), stirred for 10 min, and heated in an oven at 40°C for 15 min. After cooling, the wax-printed paper substrate was placed in the mixed solution and shaken at 160 rpm for 60 min. The functionalized paper substrate was then washed with deionized water and dried naturally.

[0106] (3) UiO-66-NH2@RhB was dispersed in deionized water and ultrasonicated for 20 min to obtain a uniform suspension. The UiO-66-NH2@RhB aqueous solution (4 mg / mL) was dropped into the sensing area and heated in an oven at 40 °C for 15 min to prepare the paper-based sensor.

[0107] Example 9 Construction steps of portable paper-based platform

[0108] (1) A Xerox Phaser 8560DN wax printer was used to draw the surface of Whatman grade no. 41 quantitative filter paper. The paper platform consists of a circular hydrophilic sensing area (diameter 5.0 mm) and a square hydrophobic area (10 mm×10 mm).

[0109] (2) Carboxymethyl cellulose (0.2 mg / mL) was added to a calcium chloride solution (10 mM, 25 mL), stirred for 10 min, and heated in an oven at 40°C for 15 min. After cooling, the wax-printed paper substrate was placed in the mixed solution and shaken at 160 rpm for 60 min. The functionalized paper substrate was then washed with deionized water and dried naturally.

[0110] (3) UiO-66-NH2@RhB was dispersed in deionized water and ultrasonicated for 20 min to obtain a uniform suspension. UiO-66-NH2@RhB aqueous solution (0.5 mg / mL) was dropped into the sensing area and heated in an oven at 60 °C for 15 min to prepare a paper-based sensor.

[0111] Example 10 Steps for constructing a portable paper-based platform

[0112] (1) A Xerox Phaser 8560DN wax printer was used to draw the surface of Whatman grade no. 41 quantitative filter paper. The paper platform consists of a circular hydrophilic sensing area (diameter 5.0 mm) and a square hydrophobic area (10 mm×10 mm).

[0113] (2) Carboxymethyl cellulose (0.2 mg / mL) was added to a calcium chloride solution (10 mM, 25 mL), stirred for 10 min, and heated in an oven at 40°C for 15 min. After cooling, the wax-printed paper substrate was placed in the mixed solution and shaken at 160 rpm for 60 min. The functionalized paper substrate was then washed with deionized water and dried naturally.

[0114] (3) UiO-66-NH2@RhB was dispersed in deionized water and ultrasonicated for 20 min to obtain a uniform suspension. The UiO-66-NH2@RhB aqueous solution (6.0 mg / mL) was dropped into the sensing area and heated in an oven at 60 °C for 15 min to prepare the paper-based sensor.

[0115] Embodiment 11

[0116] The paper-based sensors prepared in Examples 6 to 10 were applied to the detection of arginine, and the steps were as follows:

[0117] (1) The composite material constructed in Example 1 is used as a ratiometric fluorescent probe, and Example 6 is used as a portable sensing platform;

[0118] (2) Detection of arginine concentration gradient: drop arginine solutions of different concentrations onto the hydrophilic sensing area on the paper substrate, and acquire images using a digital camera in a homemade darkroom. The blue value of the images is extracted using Photoshop software.

[0119] (3) Working curve drawing: Linear relationship between the blue value of the image and the arginine concentration

[0120] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a ratiometric fluorescent paper-based sensor, characterized in that: The preparation method comprises the following: (1) Preparation of UiO-66-NH2@Rhodamine B composite materials; (2) dropping a suspension containing the UiO-66-NH2@Rhodamine B composite material into the hydrophilic sensing area of ​​the paper-based substrate, reacting I, and obtaining the ratiometric fluorescent paper-based sensor; The surface of the paper-based substrate is modified by carboxymethyl cellulose to introduce carboxyl groups; The paper-based substrate includes a hydrophilic sensing region and a hydrophobic region.

2. The preparation method according to claim 1, characterized in that: The diameter of the hydrophilic sensing area is 4.0 mm to 6.0 mm.

3. The preparation method according to claim 1, characterized in that: The area of ​​the hydrophobic region is 8.0 mm×8.0 mm to 12.0 mm×12.0 mm.

4. The preparation method according to claim 1, characterized in that: In the step (1), the preparation method of the UiO-66-NH2@Rhodamine B composite material comprises: In a sealed container, a mixture containing zirconium chloride, 2-aminoterephthalic acid, rhodamine B, and a solvent is subjected to reaction II, centrifuged, and dried to obtain the UiO-66-NH2@Rhodamine B composite material.

5. The preparation method according to claim 4, characterized in that: The molar ratio of the zirconium chloride to the 2-aminoterephthalic acid is 2:1 to 1:2; Preferably, the molar ratio of the zirconium chloride to the rhodamine B is 1:1 to 4:

1.

6. The preparation method according to claim 4, characterized in that: The solvent is selected from at least one of ethanol, formic acid, acetic acid, DMF, and concentrated hydrochloric acid; Preferably, the temperature of the reaction II is 110-140° C., and the time of the reaction II is 12-24 h.

7. The preparation method according to claim 4, characterized in that: The number of centrifugation is 5 to 9 times; Preferably, the washing solvent during the centrifugation is selected from at least one of water, ethanol, methanol and DMF; Preferably, the drying temperature is 50-70° C., and the drying time is 6-24 hours.

8. The preparation method according to claim 1, characterized in that: In the step (2), the concentration of the suspension is 0.5 to 6.0 mg / mL; Preferably, in step (2), the temperature of reaction I is 40 to 70° C., and the time of reaction I is 10 to 30 min.

9. A method for detecting arginine, characterized in that: The detection method comprises: Dropping arginine solutions of different concentrations to be tested onto the hydrophilic sensing area of ​​the ratiometric fluorescent paper-based sensor, acquiring an image, processing the image to obtain the blue value of the image, and obtaining a linear relationship between the blue value and the arginine concentration; The ratio fluorescent paper-based sensor is selected from the ratio fluorescent paper-based sensor prepared by the preparation method according to any one of claims 1 to 8.

10. The detection method according to claim 9, characterized in that: The detection range of the ratiometric fluorescent paper-based sensor for arginine is 0.2-2.0 mM.

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