A dry analytical reagent for detecting α-amylase

Abstract

A dry analytical reagent for detecting α - amylase, which successively includes an upper support layer, a diffusion layer, a reagent layer, a support body and a lower support layer from top to bottom. The diffusion layer, the reagent layer and the support body are successively arranged at the middle position between the upper support layer and the lower support layer. The two ends of the upper support layer and the lower support layer are bonded through an intermediate support layer. A sample addition hole and a test hole are respectively arranged at the middle positions of the upper support layer and the lower support layer. The diffusion layer is an isotropic porous diffusion membrane; the diffusion layer includes polymer microspheres, an adhesive and a surfactant. The adhesive is concentrated on the surface of the polymer microspheres and the adjacent regions of adjacent polymer microspheres, bonding the polymer microspheres into a coherent three - dimensional lattice. The porosity of the diffusion layer is 30 - 50%, and the particle size of the polymer microspheres is 3 - 30 μm. In the preparation process of the dry analytical reagent of the present invention, no organic solvent is used, the production and preparation process is environmentally friendly, the diffusion layer has the characteristic of isotropy, and the measurement range of the test result is wide.

Description

Technical Field

[0001] The present invention relates to a dry analytical reagent for detecting α-amylase, belonging to the field of clinical diagnosis. Background Art

[0002] In recent years, acute pancreatitis has become one of the most common acute abdominal diseases, with an incidence rate of about 2% and a mortality rate of about 10%. Therefore, accurate and timely prediction and active treatment of acute pancreatitis have become an important research topic in the field of clinical medicine. After the occurrence of acute pancreatitis, patients often have obvious symptoms. An important examination item is the blood amylase (AMY) examination. In acute pancreatitis, AMY increases significantly, and the greater the increase, the greater the possibility of acute pancreatitis.

[0003] The clinical detection methods of α-amylase are divided into wet chemistry method and dry chemistry method. Among them, the wet chemistry method is a commonly used analytical method. Once the reagent is prepared (for more than half an hour), it can analyze a large number of clinical samples at the same time. However, with the outbreak of the COVID-19 pandemic and the increasing demand for emergency testing, the clinical requirement for the reporting time of biochemical analysis has become shorter, which has promoted the gradual development of emergency biochemical testing technology from traditional wet chemistry to dry chemistry. Compared with the conventional wet chemistry analysis method, the dry chemistry analysis method has the advantages of fast detection speed, easy preservation of detection reagents, no need to prepare any liquid reagents, low detection threshold requirements, strong adaptability to occasions, etc. According to the test requirements, it can perform personalized project combination testing on scattered samples at any time and place, especially suitable for scenarios such as emergency departments, primary clinics, blood stations, physical examination institutions, and testing laboratories.

[0004] Currently, the commonly used dry analytical reagent is a multi-layer film dry slice. This kind of product continues the coating technology of photographic film, coats various required functional layers such as a diffusion layer, a light blocking layer, and a reagent layer on a transparent support, with the sample addition hole on the diffusion layer and the test hole on the reverse side of the support. The concentration of the analyte is analyzed by measuring the change in the reflected light density. The test results of such multi-layer film dry slices are accurate, but the production process is complex. The production of the diffusion layer requires the use of a variety of organic solvents, generating a large amount of organic waste gas, which is harmful to the environment and increases the risk of the production process. Another type is a plastic support layer, with a reaction area at one end including a sample layer and a reagent layer. The reagent layer uses a fabric as a reagent carrier, and both sample addition and testing are carried out on its upper part.

[0005] Patent CN200710043466.X discloses a dry chemical test strip for quantitatively determining α-amylase. Among them, the diffusion layer uses commercially available filter paper, glass fiber, non-woven fabric, nylon film, synthetic fiber, etc. The blood filtering membrane uses commercially available products. The reaction layer adopts the form of liquid immersion and drying. The blood filtering layer, reagent layer and diffusion layer need to be made separately and then assembled. The dry chemical test strip made by this method is similar to a pH test strip and can only achieve semi-quantitative analysis and cannot be used for clinical diagnosis. The patent with the patent number 201910469655.6 discloses a multi-layer film dry tablet for quantitatively determining α-amylase. Among them, the diffusion layer is still prepared by an organic solvent system, which is extremely unfriendly to the environment. Summary of the Invention

[0006] In order to overcome the drawbacks of the prior art, the present invention provides a dry analytical reagent for detecting α-amylase. During the preparation process, no organic solvents are used, the production and preparation process is environmentally friendly, the diffusion layer has the characteristic of isotropy, and the test results have high accuracy and a wide measurement range.

[0007] The technical solution adopted by the present invention to solve its technical problems is:

[0008] A dry analytical reagent for detecting α-amylase, the dry analytical reagent sequentially includes an upper support layer, a diffusion layer, a reagent layer, a support body and a lower support layer from top to bottom. The diffusion layer, the reagent layer and the support body are sequentially arranged at the middle position between the upper support layer and the lower support layer. The two ends of the upper support layer and the lower support layer are bonded by an intermediate support layer at the pores. Sampling holes and test holes are respectively arranged at the middle positions of the upper support layer and the lower support layer. The diffusion layer is an isotropic porous diffusion membrane; it includes polymer microspheres, an adhesive and a surfactant. The adhesive is concentrated on the surface of the polymer microspheres and the adjacent regions of adjacent polymer microspheres, and the polymer microspheres are adhered into a coherent three-dimensional lattice. The porosity of the diffusion layer is 30-50%, and the particle size of the polymer microspheres is 3-30 μm; the reagent layer includes 0.5-10 g of small molecule oligosaccharide substrate, buffer solution, 2.5-50 g of activator, 0.5-25 g of surfactant, 0.2-10 g of stabilizer, 0.2-50 KU of α-glucosidase and 1-50 g of water-soluble high molecular polymer. The addition amount of each component is the addition amount per square meter.

[0009] For the above-mentioned dry analytical reagent for detecting α-amylase, the polymer microspheres include one of polystyrene, poly(styrene-methyl methacrylate), poly(styrene-divinylbenzene), polymethyl methacrylate, poly(methyl methacrylate-butyl acrylate), poly(styrene-butyl acrylate), poly(methylstyrene-tert-butylstyrene-methyl methacrylate) and poly(styrene-methyl methacrylate hydroxyethyl ester-divinylbenzene); the adhesive is composed of one or more of pure acrylic emulsion or styrene-acrylic emulsion.

[0010] The above dry analytical reagent for α-amylase detection, wherein the binder is preferably a pure acrylic emulsion prepared by copolymerizing acrylic acid, methacrylic acid, and acrylate monomers.

[0011] The above dry analytical reagent for α-amylase detection, wherein the binder is one of poly(n-butyl acrylate-acrylic acid), polyethyl acrylate, poly(butyl acrylate-methacrylic acid), poly(n-butyl methacrylate), or poly(methyl methacrylate-butyl acrylate).

[0012] The above dry analytical reagent for α-amylase detection, wherein the wet film thickness of the expansion layer is 60 - 600 μm, the dry film thickness after drying at 10°C - 60°C is 20 - 200 μm, the addition amount of polymer microspheres per square meter is 20 - 500 g, and the weight of the binder added accounts for 0.5% - 5.0% of the weight of the polymer microspheres.

[0013] The above dry analytical reagent for α-amylase detection, wherein the wet film thickness of the reagent layer is 50 - 500 μm, the dry film thickness after drying at 10 - 60°C is 5 - 50 μm, and the small molecule oligosaccharide substrate is a modified maltotriose derivative or a modified maltoheptaose derivative, preferably a modified maltoheptaose derivative.

[0014] The above dry analytical reagent for α-amylase detection, wherein the modified maltoheptaose derivative is 4,6-ethylidene-4-nitrophenyl-4-α-D-maltoheptaose.

[0015] The above dry analytical reagent for α-amylase detection, wherein the pH value of the buffer solution is 5.5 - 9.0, and the buffer solution contains tris(hydroxymethyl)aminomethane (tris), phosphate, borate, citric acid or citrate, lysine; the sodium salt or potassium salt of N,N-bis(2-hydroxyethyl)glycine, N-2-hydroxyethylpiperazine-N'-2-hydroxypropane-3-sulfonic acid, the sodium salt or potassium salt of N-2-hydroxyethylpiperazine-N'-3-sulfonic acid, the sodium salt or potassium salt of N-[tris(hydroxymethyl)methyl]-3-aminopropanesulfonic acid, and the sodium salt or potassium salt of N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid.

[0016] The above-mentioned dry analytical reagent for α-amylase detection, wherein the surfactant is a non-ionic surfactant, specifically including one of octylphenoxypolyethylene glycol ether, nonylphenoxypolyethylene glycol ether, polyoxyethylene sorbitan monolaurate, and octyl glucoside, and preferably a non-ionic surfactant having a chain structure composed of 8 to 15 interconnected oxyethylene or oxypropylene groups; the activator is calcium ion and chloride ion; the stabilizer is one or more of polysaccharides or disaccharides; the water-soluble polymer is one or more of gelatin, gelatin derivatives, agarose, dextran, polyvinyl alcohol, polyacrylamide, and hydrophilic cellulose derivatives.

[0017] For the above-mentioned dry analytical reagent for α-amylase detection, the upper support, the lower support, and the middle support are all transparent plastic substrates with a light transmittance of more than 80% under light with a wavelength of 200nm - 900nm, including one of polyethylene terephthalate, polycarbonate, polypropylene, and polyethylene, and its thickness is 50 - 300μm, preferably 100 - 200μm.

[0018] The beneficial effects of the present invention are:

[0019] In the preparation process of the dry analytical reagent for α-amylase detection of the present invention, no organic solvent is used, and the production and preparation process is environmentally friendly. The polymer microspheres with a specific composition of the present invention have good chemical stability and high rigidity, and can protect the spatial structure and chemical properties of α-amylase, thereby ensuring that the amount of α-amylase substrate in the test determination process is not interfered with. The diffusion layer has the characteristic of isotropy. The activity of α-amylase is detected by using a modified maltoheptaose derivative. The enzyme hydrolysis reaction is simple, the stoichiometric relationship is clearer, the determination error is small, the measurement range is wide, it meets the requirements of point-of-care diagnosis and on-site diagnosis, and has great clinical application value. Description of the Drawings

[0020] Figure 1 It is a schematic structural diagram of the multi-layer film dry chemical reagent strip of the present invention;

[0021] Figure 2 It is a schematic overall structure diagram of the continuous iron dissolution device;

[0022] Figure 3 It is a schematic overall structure diagram of the pressure swing adsorption system;

[0023] Figure 4 It is a schematic enlarged structure diagram of the pressure swing adsorption device.

[0024] In the figure: 1. Upper support layer; 1-1. Sampling hole; 2. Diffusion layer; 3. Reagent layer; 4. Support; 5. Lower support layer; 5-1. Test hole; 6. Middle support layer. Detailed Embodiments

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0026] A dry analytical reagent for detecting α-amylase, comprising, from top to bottom, an upper support layer 1, a diffusion layer 2, a reagent layer 3, a support body 4, and a lower support layer 5. The diffusion layer, reagent layer, and support body are sequentially arranged in a middle position between the upper and lower support layers, and the pores at both ends of the upper and lower support layers are bonded together by an intermediate support layer 6. A sample addition well 1-1 and a test well 5-1 are respectively arranged in the middle position of the upper and lower support layers 1 and 5, and the sample addition well and the test well positions correspond to each other. The reagent layer and diffusion layer distributed on the support body are structural layers for dropwise diffusion of a sample to be tested to produce a colorimetric reaction, the support body layer is a structural layer that serves as a support and a light-transmitting carrier, and the upper, lower, and intermediate support layers serve as inner packaging structures for fixing and protecting the support body on which the reagent layer and diffusion layer are distributed.

[0027] The diffusion layer 2 is an isotropic porous diffusion membrane with a wet film thickness of 60-600 μm and a dry film thickness of 20-200 μm after drying at 10°C-60°C. The diffusion layer comprises polymer microspheres and a binder. The binder is concentrated on the surface of the polymer microspheres and in the areas adjacent to adjacent polymer microspheres, bonding the polymer microspheres into a coherent three-dimensional lattice. The three-dimensional lattice structure exhibits a high pore volume. By controlling the particle size distribution of the polymer microspheres and the amount of binder added, an isotropic porous diffusion layer with varying porosity and pore size distribution is formed. This is used to rapidly absorb, uniformly distribute, meter, and rapidly transmit a variety of analytes, thereby analyzing substances of varying molecular weight distribution and composition in biological fluids. The polymer microspheres have a particle size between 3-30 μm and are added in an amount of 20-500 g per square meter, preferably 50-300 g per square meter. The binder is added in an amount of 0.5-5.0% per square meter of the weight of the polymer microspheres. The porosity of the diffusion layer is 30-50%. The relative molecular mass of α-amylase is approximately 54-62 kDa, and it is a type of enzyme biomacromolecule. Therefore, diffusion pathways ranging from hundreds of nanometers to micrometers are required to ensure efficient and rapid penetration and diffusion of α-amylase in the liquid to be analyzed in the diffusion layer. The polymer microspheres used in the present invention have a particle size of 3-30 μm, and the amount of adhesive added is controlled within a relatively low range to form a high porosity in the diffusion layer, thereby ensuring more diffusion pathways and thus ensuring efficient and rapid penetration and diffusion of α-amylase in the diffusion layer.

[0028] The reagent layer comprises 0.5 - 10 g of small molecule oligosaccharide substrate, buffer solution, 2.5 - 50 g of activator, 0.5 - 25 g of surfactant, 0.2 - 10 g of stabilizer, 0.2 - 50 KU of α - glucosidase, and 1 - 50 g of water - soluble high - molecular polymer. The addition amount of each component is the addition amount per square meter. The wet film thickness of the reagent layer is 50 - 500 μm, and the dry film thickness after drying at 10 - 60 °C is 5 - 50 μm. The small molecule oligosaccharide substrate is a modified maltotriose derivative or a modified maltoheptaose derivative. Existing dry - chemical test reagent strips still use macromolecular natural starch as the chromogenic substrate. However, the molecular structure of natural starch is uncertain and diverse, resulting in large variations in the enzymatic hydrolysis reaction and large measurement errors, which will affect the accuracy of detection. In the dry - chemical reagent layer of the present invention, a modified small molecule oligosaccharide is innovatively selected as the chromogenic substrate. The enzymatic hydrolysis reaction is simple, the stoichiometric relationship is clearer, and the concentration of α - amylase can be measured more accurately.

[0029] Preferably, 4,6 - ethylidene - 4 - nitrophenyl - 4 - α - D - maltoheptaose is used as the chromogenic substrate. The nitrophenyl in the substrate is an indicator marker connected to the reducing end of the polysaccharide, and the ethylidene is connected to the non - reducing end of the polysaccharide, which can protect the substrate and effectively reduce the hydrolysis of the substrate by α - glucosidase, improving the stability of the reagent.

[0030] The surfactants in the diffusion layer and the reagent layer are of the same type, both being non - ionic surfactants, specifically including one of p - octylphenoxy polyoxyethylene ether, p - nonylphenoxy polyoxyethylene ether, polyoxyethylene sorbitan monolaurate, and octyl glucoside. Preferably, a non - ionic surfactant having a chain structure composed of 8 to 15 interconnected oxyethylene or oxypropylene groups can be purchased from Rohm and Haas Co. under the Triton trademark (X - 100, 102, 165, 305, and 405 are particularly useful), preferably one of Triton X - 100, 102, 165, 305, and 405, and more preferably Triton X - 100.

[0031] The preparation process of the dry - type analytical reagent for α - amylase detection in the present invention is as follows:

[0032] (1) The reagent layer: The reagent solution is coated on the support. Known coating methods can be used, preferably wire bar coating, blade coating, or extrusion coating. The wet film thickness of the reagent layer is preferably 50 - 500 μm and it is dried within the range of 10°C - 60°C. The dry film thickness of the reagent layer is preferably 5 - 50 μm. By controlling the film thickness of the reagent layer, the optimal test speed and test sensitivity can be obtained. If the film thickness of the reagent layer is too small, the concentration of the reaction substrate cannot meet the highest requirements of the test range, thus affecting the applicable range of the dry film; if the film thickness is too large, the time for the same amount of the sample to be analyzed to come into full contact with the reaction substrate is too long, resulting in an affected reaction rate, thus affecting the kinetic data and test results of the test.

[0033] (2) The diffusion layer: The slurry is coated on the reagent layer prepared in (1). Known coating methods can be used, preferably wire bar coating, blade coating, or extrusion coating. The wet film thickness of the diffusion layer is preferably 60 - 600 μm and it is dried within the range of 10°C - 60°C. The dry film thickness of the diffusion layer is preferably 20 - 200 μm. The film thickness of the diffusion layer affects the diffusion effect and filtration effect of the liquid to be analyzed.

[0034] (3) The material prepared in step (2) is cut into small pieces of 1.2 cm 2 , and a customized white PET plastic sheet is used as the upper support layer, lower support layer, and middle support layer, and is fixed and assembled into a dry analytical reagent.

[0035] The present invention is used for determining α - amylase in a body fluid sample. As the body fluid, it can be blood, urine, etc.; as the body fluid sample, blood or urine can be directly used, or a sample subjected to appropriate pretreatment can also be used.

[0036] The detection method of the dry analytical reagent for α - amylase of the present invention is as follows:

[0037] About 10 μL of the liquid to be tested is dropped onto a porous diffusion layer with uniform properties and incubated at about 37 °C for 5 minutes. While the liquid to be tested rapidly diffuses uniformly in all four directions through the diffusion layer, it also diffuses longitudinally towards the reagent layer, forming a uniform concentration distribution. Serum AMY hydrolyzes 4,6-ethylidene-4-nitrophenyl-4-α-D-maltoheptaose (E-G7-NP) to generate 4,6-ethylidene-maltopentaose (E-G5), 4,6-ethylidene-maltotetraose (E-G4), 4,6-ethylidene-maltotriose (E-G3), 4-nitrophenyl maltose (G2-NP), 4-nitrophenyl maltotriose (G3-NP), and 4-nitrophenyl maltotetraose (G4-NP) fragments. The three generated 4-nitrophenyl maltopolysaccharides are hydrolyzed by α-glucosidase into 4-nitrophenol (NP) and glucose. NP dissociates into 4-nitrophenoxide ions at the pH of the reaction solution, showing a yellow color. Reflection density detection is carried out on the color change reaction generated by the dry analytical reagent from the support side by the two-point rate method, and the concentration of α-amylase in the liquid to be tested is calculated using a pre-made calibration curve. The reaction equation of the target substance α-amylase with the corresponding substance in the dry analytical reagent is as follows:

[0038]

[0039]

[0040] The preparation process of the dry analytical reagent for detecting α-amylase of the present invention does not require organic solvents, is environmentally friendly, has good stability, is easy to store and preserve, has high detection accuracy, and a wide linear range.

[0041] The present invention will be further described below in conjunction with embodiments.

[0042] Example 1

[0043] A reagent layer coating solution composed as shown in Table 1 below is coated on a colorless and transparent 175-μm PET film support 4 and dried at a constant temperature of 40 °C until the dried thickness reaches 15 μm. Then, a diffusion layer coating solution composed as shown in Table 2 below is coated on the above coating and dried at a constant temperature of 35 °C until the dried thickness reaches 100 μm. After drying, it is cut into small pieces of 1.2 cm 2 and then a white PET plastic sheet is used as the upper support layer 1, the lower support layer 5, and the intermediate support layer 6. After assembly, it can be used for determination.

[0044] Table 1 Reagent layer formula

[0045] Reagent <![CDATA[Coating amount / m 2 > Gelatin 10g 4,6-Ethylidene-4-nitrophenyl-4-α-D-maltoheptaose 2.5g N-2-Hydroxyethylpiperazine-N'-2-ethanesulfonate buffer pH 7.0 Calcium chloride 0.3g Sodium chloride 12g Triton X-100 1.5g Sucrose 1.2g α-Glucosidase 6.5 KU

[0046] Table 2 Diffusion layer formula

[0047] Material <![CDATA[Coating amount / m 2 > Poly(styrene-butyl acrylate) microspheres (10 μm) 150g Poly(butyl acrylate-acrylic acid) emulsion 3g Surfactant 1.5g

[0048] For 30 clinical serum specimens, the correlation between the method of the present invention and the analysis of multiple test samples using the p-nitrophenol maltose method was investigated. The results are as Figure 2 shown. A good correlation can be obtained by comparing the present invention with the reference method.

[0049] Example 2

[0050] A reagent layer coating solution composed of the following Table 3 was coated on a colorless and transparent 175-μm PET film support 4 and dried at a constant temperature of 37°C to a thickness of 10 μm after drying. Then, a diffusion layer coating solution composed of the following Table 4 was coated on the above coating and dried at a constant temperature of 40°C to a thickness of 150 μm after drying. After drying, it was cut into small pieces of 1.2 cm 2 and then white PET plastic sheets were used as the upper support layer 1, the lower support layer 5, and the middle support layer 6. It can be used for measurement after assembly.

[0051] Table 3 Reagent Layer Formulation

[0052] Reagent <![CDATA[Coating amount / m 2 > Gelatin 6g 4,6-Ethylidene-4-nitrophenyl-4-α-D-maltoheptaose 4.0g N-2-Hydroxyethylpiperazine-N'-2-ethanesulfonate buffer pH 7.0 Calcium chloride 0.3g Sodium chloride 12g Triton X-100 1.5g Sucrose 1.2g α-Glucosidase 7.5 KU

[0053] Table 4 Diffusion Layer Formulation

[0054] Material <![CDATA[Coating amount / m 2 > Poly(styrene-methacrylic acid) microspheres (25 μm) 100g Poly(butyl acrylate-methacrylic acid) emulsion 1.5g Surfactant 1g

[0055] For 30 clinical serum specimens, the correlation between the method of the present invention and the analysis of multiple test samples using the p-nitrophenol maltose method was investigated. The results are as Figure 3 shown. A good correlation can be obtained by comparing the present invention with the reference method.

[0056] Example 3

[0057] A reagent layer coating solution composed of the following Table 5 was coated on a colorless and transparent 175-μm PET film support 4 and dried at a constant temperature of 40°C to a thickness of 20 μm after drying. Then, a diffusion layer coating solution composed of the following Table 6 was coated on the above coating and dried at a constant temperature of 45°C to a thickness of 100 μm after drying. After drying, it was cut into small pieces of 1.2 cm 2 and then white PET plastic sheets were used as the upper support layer 1, the lower support layer 5, and the middle support layer 6. It can be used for measurement after assembly.

[0058] Table 5 Reagent Layer Formulation

[0059] Reagent <![CDATA[Coating amount / m 2 > Gelatin 10g 4,6-Ethylidene-4-nitrophenyl-4-α-D-maltoheptaose 5.0g N-2-Hydroxyethylpiperazine-N'-2-ethanesulfonate buffer pH 7.0 Calcium chloride 0.3g Sodium chloride 12g Triton X-100 1.5g Sucrose 1.2g α-Glucosidase 10 KU

[0060] Table 6 Diffusion Layer Formulation

[0061] Material <![CDATA[Coating amount / m 2 > Poly(styrene-divinylbenzene) microspheres (5 μm) 150g Poly(butyl acrylate-methacrylic acid) emulsion 4g Surfactant 2g

[0062] For 30 clinical serum specimens, the correlation between the method of the present invention and the analysis of multiple test samples using the p-nitrophenyl maltose method was investigated. The results are as Figure 4 shown. A good correlation can be obtained by comparing the present invention with the reference method.

[0063] The above embodiments are only used to illustrate the technical concept and characteristics of the present invention, and the purpose is to enable those of ordinary skill in the art to understand the content of the present invention and implement it accordingly. However, it should not be used to limit the protection scope of the present invention. Any equivalent substitution or improvement made based on the essence of the content of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A dry analytical reagent for detecting α-amylase. The dry analytical reagent sequentially includes an upper support layer (1), a diffusion layer (2), a reagent layer (3), a support (4), and a lower support layer (5) from top to bottom. The diffusion layer, the reagent layer, and the support are sequentially arranged at an intermediate position between the upper support layer and the lower support layer. Both ends of the upper support layer and the lower support layer are bonded through an intermediate support layer (6). Sampling holes (1-1) and test holes (5-1) are respectively arranged at the intermediate positions of the upper support layer (1) and the lower support layer (5). It is characterized in that: The diffusion layer (2) is an isotropic porous diffusion membrane, which includes polymer microspheres, an adhesive, and a surfactant. The adhesive is concentrated on the surface of the polymer microspheres and in the regions adjacent to adjacent polymer microspheres, and bonds the polymer microspheres into a coherent three-dimensional lattice. The porosity of the diffusion layer (2) is 30 - 50%, and the particle size of the polymer microspheres is 3 - 30 μm; the reagent layer (3) includes 0.5 - 10 g of a small molecule oligosaccharide substrate, a buffer solution, 2.5 - 50 g of an activator, 0.5 - 25 g of a surfactant, 0.2 - 10 g of a stabilizer, 0.2 - 50 KU of α-glucosidase, and 1 - 50 g of a water-soluble high molecular polymer. The addition amounts of each component are the amounts added per square meter; The polymer microspheres include one of poly(styrene-methacrylic acid), poly(styrene-divinylbenzene), polymethyl methacrylate, poly(methyl methacrylate-butyl acrylate), poly(styrene-butyl acrylate), poly(methylstyrene-tert-butylstyrene-methacrylic acid), and poly(styrene-2-hydroxyethyl methacrylate-divinylbenzene); The adhesive is one of poly(n-butyl acrylate-acrylic acid), polyethyl acrylate, poly(n-butyl acrylate-methyl methacrylic acid), poly(n-butyl methacrylate), or poly(methyl methacrylate-butyl acrylate); The wet film thickness of the diffusion layer is 60 - 600 μm, and the dry film thickness after drying at 10°C - 60°C is 20 - 200 μm. The addition amount of the polymer microspheres per square meter is 20 - 500 g, and the added weight of the adhesive accounts for 0.5% - 5.0% of the weight of the polymer microspheres; The small molecule oligosaccharide substrate is 4,6-ethylidene-4-nitrophenyl-4-α-D-maltoheptaose.

2. The dry analytical reagent for detecting α-amylase according to claim 1, characterized in that: The wet film thickness of the reagent layer is 50 - 500 μm, and the dry film thickness after drying at 10 - 60°C is 5 - 50 μm.

3. The dry analytical reagent for detecting α-amylase according to claim 2, characterized in that: The pH value of the buffer solution is 5.5 - 9.0, and the buffer solution contains one of tris(hydroxymethyl)aminomethane (tris), phosphate, borate, citric acid or citrate, lysine, N,N-bis(2-hydroxyethyl)glycine, N-2-hydroxyethylpiperazine-N'-2-hydroxypropane-3-sulfonate, N-2-hydroxyethylpiperazine-N'-3-sulfonate, N-[tris(hydroxymethyl)methyl]-3-aminopropanesulfonate, and N-2-hydroxyethylpiperazine-N'-2-ethanesulfonate.

4. The dry analytical reagent for detecting α-amylase according to claim 3, characterized in that: The surfactant is a non-ionic surfactant, including one of p-octylphenoxypolyethoxyethanol, p-nonylphenoxypolyethoxyethanol, polyoxyethylene sorbitan monolaurate, and octyl glucoside; the activator is calcium ions and chloride ions; the stabilizer is one or more of polysaccharides or disaccharides; the water-soluble high molecular polymer is one or more of gelatin, gelatin derivatives, agarose, dextran, polyvinyl alcohol, polyacrylamide, and hydrophilic cellulose derivatives.

5. The dry analytical reagent for detecting α-amylase according to claim 4, characterized in that: The upper support (1), lower support (5) and intermediate support (6) are all transparent plastic substrates with a light transmittance of more than 80% under light with a wavelength of 200 nm - 900 nm, including one of polyethylene terephthalate, polycarbonate, polypropylene and polyethylene, and having a thickness of 50 - 300 μm.

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