Paper-based detection chip as well as preparation method and application thereof

Abstract

The invention provides a paper-based detection chip as well as a preparation method and application thereof, and belongs to the technical field of paper-based detection. The paper-based detection chip comprises top paper and bottom paper, and the quantitation of the top paper is smaller than that of the bottom paper; a preparation raw material of the top paper is low-beating-degree paper pulp, a preparation raw material of the bottom paper is high-beating-degree paper pulp, and the beating degree of the low-beating-degree paper pulp is smaller than that of the high-beating-degree paper pulp; and the paper-based detection chip is formed by compounding top paper and bottom paper. According to the paper-based detection chip disclosed by the invention, rapid spreading and uniform distribution of liquid are realized, the permeation effect and the coffee ring effect in the detection process are effectively inhibited, and the uniformity and the result reliability of paper-based colorimetric detection are improved. The preparation method disclosed by the invention is simple, convenient, efficient, low in cost, simple to operate and easy for large-scale production and application, and does not need to depend on large-scale instruments and equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of paper-based detection, and particularly relates to a paper-based detection chip, a preparation method thereof, and an application thereof. Background Art

[0002] Paper is mainly composed of interwoven plant fibers, and there are a large number of tiny voids between the fibers. These voids form channels similar to capillaries. When the paper comes into contact with a liquid, the surface tension of the liquid will cause the liquid to diffuse along these tiny capillary channels. This capillary force of the paper can achieve pump-free liquid transmission, so paper is widely used as a paper-based detection substrate. However, as a non-uniform network structure material composed of fibers, during the paper-based colorimetric detection process, due to factors such as uneven fiber distribution, different pore sizes, and different evaporation rates of the liquid on the paper in the paper itself, the "coffee ring" effect and the penetration effect are likely to occur, resulting in a decrease in the uniformity of the paper-based colorimetric detection results, which greatly limits the further development of the paper-based colorimetric detection technology.

[0003] At present, a variety of methods for suppressing the "coffee ring" effect have been reported in the literature, mainly including: changing the surface characteristics of the paper substrate, which aims to interfere with the outward capillary flow caused by uneven evaporation; changing the hydrophilicity of the paper substrate to regulate the evaporation rate of the sample droplet on the paper substrate; using laser-induced evaporation and other methods to accelerate the evaporation rate of the droplet, etc. Although these methods can effectively suppress the "coffee ring" effect, there are some limitations. On the one hand, some of these methods are relatively cumbersome to operate and require post-treatment of the paper to change the surface characteristics. For example, adding other types of reagents to the paper increases the complexity of the detection and may also interfere with the detection of specific types of analytes. On the other hand, these methods are mostly limited to the laboratory environment and are difficult to be popularized on a large scale in practical applications.

[0004] Therefore, providing a paper-based detection chip with simple preparation, portable operation, and capable of effectively suppressing the "coffee ring" effect and an optimization method thereof has important practical significance for promoting the practical application of the paper-based colorimetric detection technology and has broad application prospects. Summary of the Invention

[0005] Aiming at the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a paper-based detection chip. Through the structural design of papers with different quantitative amounts and beating degrees, the prepared paper-based detection chip can achieve rapid liquid transmission, improve the detection efficiency, and improve the uniformity of the detection results. At the same time, the preparation method of the paper-based detection chip of the present invention is simple, does not rely on other equipment, does not need to additionally introduce other improving additives, and is easy to be mass-produced and applied.

[0006] To achieve the object of the invention, the technical solution adopted by the present invention is: a paper-based detection chip, the paper-based detection chip comprising a top paper and a bottom paper, the grammage of the top paper being 20-40 g / m 2 , the grammage of the bottom paper being 40-60 g / m 2 , and the grammage of the top paper being less than that of the bottom paper;

[0007] The raw material for preparing the top paper is low beating degree pulp, the raw material for preparing the bottom paper is high beating degree pulp, the beating degree of the low beating degree pulp is 20-40°SR, and the beating degree of the high beating degree pulp is 40-60°SR; the beating degree of the low beating degree pulp is less than that of the high beating degree pulp;

[0008] The paper-based detection chip is made by laminating the top paper and the bottom paper.

[0009] The paper-based detection chip of the present invention comprises a top paper and a bottom paper. The top paper is made of low beating degree pulp, and the bottom paper is made of pulp with a higher beating degree. When performing target detection, the top paper has a lower grammage, more pores and larger pore diameters in the paper, and the binding between paper fibers is relatively loose, which is beneficial to the penetration of liquid on the top paper; the hollow capillary diversion layer formed by laminating the top paper and the bottom paper is beneficial to the diffusion of liquid from the center of the detection area to the periphery, which is beneficial to the uniform distribution of liquid in the detection area, and the hollow capillary diversion layer is beneficial to improving the diffusion speed of liquid on the paper substrate; the bottom paper has a higher beating degree, which is beneficial to delaying the penetration of the liquid droplet, leaving enough time for the diffusion of the liquid droplet in the hollow capillary diversion layer. At the same time, the higher grammage of the bottom paper is beneficial to absorbing the diffused liquid droplet, improving the drying speed of the liquid droplet to be detected. At the same time, the smaller internal pores effectively inhibit the penetration effect of the chromogenic particles in the paper and effectively inhibit the "coffee ring" effect.

[0010] Preferably, the grammage of the top paper in the paper-based detection chip is 20-40 g / m 2 , the grammage of the bottom paper is 40-60 g / m 2 ; the beating degree of the low beating degree pulp is 20-40°SR, and the beating degree of the high beating degree pulp is 40-60°SR. When the grammage and beating degree within the above ranges are selected, the prepared paper-based detection chip has a faster liquid transmission speed and a larger diffusion diameter.

[0011] More preferably, the grammage of the top paper in the paper-based detection chip is 20 g / m 2 , the grammage of the bottom paper is 60 g / m 2 ; the beating degree of the low beating degree pulp is 20°SR, and the beating degree of the high beating degree pulp is 60°SR.

[0012] Preferably, the pulp is at least one of bleached chemical softwood pulp, bleached chemical hardwood pulp, and bleached chemical cotton pulp.

[0013] On the other hand, the present invention provides a method for preparing the above-mentioned paper-based detection chip, and the preparation method includes the following steps:

[0014] S1 Disintegrate and beat the pulp board to obtain low-beating pulp and high-beating pulp respectively;

[0015] S2 Sheet the low-beating pulp obtained in step S1 and dry to obtain the top paper;

[0016] S3 Sheet the high-beating pulp obtained in step S1 and dry to obtain the bottom paper;

[0017] S4 Wet the bottom paper obtained in step S3 to obtain a wet bottom paper; then attach the top paper obtained in step S2 to the wet bottom paper to obtain a composite wet paper;

[0018] S5 Press and dry the composite wet paper obtained in step S4 to obtain a composite dry paper;

[0019] S6 Use a mold to punch the composite dry paper obtained in step S5 to obtain the substrate of the paper-based detection chip;

[0020] S7 Drop a detection agent on the top paper of the substrate of the paper-based detection chip obtained in step S6 and dry to obtain the paper-based detection chip.

[0021] The preparation method of the paper-based detection chip of the present invention obtains pulp raw materials with different beating degrees through beating, and then sheets to obtain the top paper and the bottom paper. Through disintegration and beating, the morphology and properties of the pulp fibers can be changed. The paper-based detection chip obtained by the combination of low-beating pulp fibers and high-beating pulp fibers can take into account the detection efficiency and detection uniformity.

[0022] The present invention attaches the wetted bottom paper to the top paper, which can form a tight bond between the two during the drying process, and at the same time can form a hollow capillary diversion layer structure. The stable hollow capillary diversion layer is conducive to the directional flow of liquid between the top paper and the bottom paper, improving the liquid transmission efficiency and detection accuracy.

[0023] The present invention can punch and manufacture the substrate of the paper-based detection chip according to the need by using punching molds of different shapes, and can prepare paper-based detection chips with unified specifications and sizes, which is convenient for subsequent detection operations and result analysis. The preparation method of the present invention has the advantages of low cost, high efficiency, simple operation, etc., does not require special instruments, and is easy to be mass-produced and applied.

[0024] Preferably, in the step S1, the beating method is beating with a PFI mill, and the consistency of the pulp during beating is 10%; the beating degree of the low beating degree pulp is 20-40°SR, and the beating degree of the high beating degree pulp is 40-60°SR.

[0025] Preferably, in the steps S2 and S3, the papermaking method is papermaking with a Kayser sheet former, the drying temperature is 90-100°C, and the drying time is 10-20 min.

[0026] Preferably, in the step S4, the moisture content of the wet base paper is 80-90%; the wetting method is to attach the base paper to a polyvinyl chloride film and uniformly spray water to fully wet it; the attachment method is to first contact one side of the top paper with the wet base paper, and then slowly attach the top paper to the wet base paper. This slow attachment method avoids the generation of bubbles.

[0027] Preferably, in the step S5, the drying temperature is 90-100°C, the drying vacuum degree is 0.1 Mpa, and the drying time is 10-20 min.

[0028] Preferably, in the step S5, the drying method is to sandwich the composite wet paper after lamination between filter papers and put them into a dryer for 10-20 min of pressure drying.

[0029] Preferably, in the step S6, the mold is a circular steel punch, and the diameter of the circular steel punch is 5-15 mm.

[0030] Preferably, in the step S6, the preparation method of the paper-based detection chip substrate is to punch out circular paper pieces on the composite dry paper with a circular steel punch with a diameter of 5-15 mm, which is the paper-based detection chip substrate.

[0031] Preferably, in the step S7, the dosage of the detection agent is 5-10 μL. Adjust the dosage of the detection agent according to the size of the paper-based detection chip substrate so that it can evenly cover the detection area. After dropping the detection agent on the circular paper-based detection chip substrate in the present invention, it is dried to obtain the final paper-based detection chip.

[0032] In the third aspect, the present invention provides the application of the above-mentioned paper-based detection chip in colorimetric detection.

[0033] Preferably, when the paper-based detection chip is applied to colorimetric detection, the colorimetric detection method is to drop a reagent of a sample to be detected on the top paper of the paper-based detection chip, and then obtain a color development result through a colorimetric reaction.

[0034] Preferably, the dropping amount of the reagent of the sample to be detected is 1-10 μL.

[0035] Preferably, when the paper-based detection chip is applied to colorimetric detection, one end of the base paper of the paper-based detection chip is adhered to the polyvinyl chloride film with double-sided tape. This method provides stable support and fixation for the base of the paper-based detection chip, ensuring that it is not easily displaced or deformed during use, and guaranteeing the accuracy and stability of the detection.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) For the paper-based detection chip of the present invention, by adjusting the beating degree of different pulps and combining the top paper and the base paper with a specific basis weight, the prepared paper-based detection chip can effectively inhibit the adverse effects such as the penetration effect and the chromatographic effect that occur during the colorimetric detection of the paper-based chip, improving the color uniformity and result reliability of the paper-based colorimetric detection.

[0038] (2) Due to its special design, the paper-based detection chip of the present invention significantly improves the diffusion speed and diffusion distance of the liquid to be measured on the paper-based substrate, thereby effectively reducing the usage amount of the sample during the paper-based colorimetric detection and achieving more efficient detection.

[0039] (3) The preparation method of the paper-based detection chip of the present invention is simple. By adopting the process of wetting - compounding - drying, a paper-based detection chip with a hollow capillary diversion layer is prepared. This preparation process is simple and efficient, does not rely on large-scale instrument equipment, is easy to operate, and is suitable for large-scale production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of the liquid penetration comparison between the paper-based detection chip of the present invention and the traditional paper chip substrate;

[0041] Figure 2 It is a scanning electron microscope image of the surface and cross-section of the paper-based detection chip of Example 1 of the present invention and the traditional paper chip substrate;

[0042] Figure 3 It is a comparison diagram of the liquid diffusion speed between the paper-based detection chip of Example 1 of the present invention and the traditional paper chip substrate;

[0043] Figure 4 It is a comparison of the results of detecting alkaline phosphatase using the paper-based detection chip of Example 1 of the present invention and the traditional paper chip substrate;

[0044] Figure 5 It is a comparison of the results of detecting glucose using the paper-based detection chip of Example 1 of the present invention and the traditional paper chip substrate. DETAILED DESCRIPTION OF THE INVENTION

[0045] Next, in combination with the embodiments of the present invention, technical process steps, and specific implementation conditions, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0046] Preparation Example 1

[0047] The bleached chemical cotton pulp board was disintegrated and beaten using the PFI beating method at a beating consistency of 10%, and pulps with beating degrees <20°SR, 20°SR, 30°SR, 40°SR, 50°SR, 60°SR, and 70°SR were obtained respectively and reserved.

[0048] Weigh the pulp with a beating degree of 20°SR, and use a Kersey sheet former to make a sheet with a basis weight of 20 g / m 2 The sheet was dried at 95°C for 15 min to obtain the top sheet, denoted as the top sheet with a beating degree of 20°SR and a basis weight of 20 g / m 2 of the top sheet;

[0049] Weigh the pulp with a beating degree of 60°SR, and use a Kersey sheet former to make a sheet with a basis weight of 60 g / m 2 The sheet was dried at 95°C for 15 min to obtain the bottom sheet, denoted as the bottom sheet with a beating degree of 60°SR and a basis weight of 60 g / m 2 of the bottom sheet.

[0050] Preparation Example 2

[0051] The bleached chemical cotton pulp board was disintegrated and beaten using the PFI beating method at a beating consistency of 10%, and pulps with beating degrees <20°SR, 20°SR, 30°SR, 40°SR, 50°SR, 60°SR, and 70°SR were obtained respectively and reserved.

[0052] Weigh the pulp with a beating degree of 30°SR, and use a Kersey sheet former to make a sheet with a basis weight of 30 g / m 2 The sheet was dried at 90°C for 20 min to obtain the top sheet, denoted as the top sheet with a beating degree of 30°SR and a basis weight of 30 g / m 2 of the top sheet;

[0053] Weigh the pulp with a beating degree of 50°SR, and use a Kersey sheet former to make a sheet with a basis weight of 50 g / m 2 The sheet was dried at 90°C for 20 min to obtain the top sheet, denoted as the top sheet with a beating degree of 50°SR and a basis weight of 50 g / m 2 of the top sheet;

[0054] Preparation Example 3

[0055] The bleached chemical cotton pulp sheets were disintegrated and beaten using the PFI beating method at a beating consistency of 10%, and pulps with beating degrees of <20°SR, 20°SR, 30°SR, 40°SR, 50°SR, 60°SR, and 70°SR were obtained respectively for standby.

[0056] Weigh the pulp with a beating degree of 20°SR, and use a Kayser sheet former to make a paper with a basis weight of 35 g / m 2 The paper was dried at 100 °C for 10 min to obtain the top paper, denoted as the top paper with a beating degree of 20°SR and a basis weight of 35 g / m 2 of the top paper;

[0057] Weigh the pulp with a beating degree of 50°SR, and use a Kayser sheet former to make a paper with a basis weight of 45 g / m 2 The paper was dried at 100 °C for 10 min to obtain the top paper, denoted as the top paper with a beating degree of 50°SR and a basis weight of 45 g / m 2 of the top paper;

[0058] Example 1

[0059] The bottom paper with a beating degree of 60°SR and a basis weight of 60 g / m obtained in Preparation Example 1 was attached to a polyvinyl chloride film and evenly sprayed with water to fully moisten it, so that its moisture content was 90% to obtain a wet bottom paper; then one side of the top paper with a beating degree of 20°SR and a basis weight of 20 g / m obtained in Preparation Example 1 was first brought into contact with the wet bottom paper, and then the top paper was slowly attached to the wet bottom paper to obtain a composite wet paper; the composite wet paper was sandwiched between filter papers and placed in a dryer for pressure drying for 15 min, the drying temperature was 95 °C, and the drying vacuum was 0.1 Mpa to obtain a composite dry paper; circular paper pieces were punched out from the composite dry paper using a circular steel punch with a diameter of 10 mm to obtain the substrate of the paper-based detection chip; 8 μL of the analyte detection agent was dropped on the top paper of the paper-based detection chip substrate and dried naturally to obtain the paper-based detection chip, and its surface and cross-sectional structures are referred to 2 2 Figure 2 .

[0060] Example 2

[0061] The bottom paper with a beating degree of 50°SR and a basis weight of 50 g / m obtained in Preparation Example 2 was attached to a polyvinyl chloride film and evenly sprayed with water to fully moisten it, so that its moisture content was 80% to obtain a wet bottom paper; then the top paper with a beating degree of 30°SR and a basis weight of 30 g / m obtained in Preparation Example 2 2 2 ​​​One side of the top paper first contacts the wet bottom paper, and then the top paper is slowly attached to the wet bottom paper to obtain a composite wet paper; the composite wet paper is sandwiched between filter papers and placed in a dryer together for pressure drying for 20 min, the drying temperature is 90 °C, and the drying vacuum degree is 0.1 Mpa to obtain a composite dry paper; a circular paper piece is punched out on the composite dry paper using a circular steel punch with a diameter of 10 mm to obtain the substrate of the paper-based detection chip; 8 μL of the detection agent for the analyte is dropped on the top paper of the substrate of the paper-based detection chip and dried naturally to obtain the paper-based detection chip.

[0062] Example 3

[0063] The beating degree of the bottom paper obtained in Preparation Example 3 is 50 °SR and the basis weight is 45 g / m 2 is attached to a polyvinyl chloride film, and water is evenly sprayed on it to fully wet it so that its moisture content is 90% to obtain a wet bottom paper; then the beating degree of the top paper obtained in Preparation Example 3 is 20 °SR and the basis weight is 35 g / m 2 One side of the top paper first contacts the wet bottom paper, and then the top paper is slowly attached to the wet bottom paper to obtain a composite wet paper; the composite wet paper is sandwiched between filter papers and placed in a dryer together for pressure drying for 10 min, the drying temperature is 100 °C, and the drying vacuum degree is 0.1 Mpa to obtain a composite dry paper; a circular paper piece is punched out on the composite dry paper using a circular steel punch with a diameter of 10 mm to obtain the substrate of the paper-based detection chip; 8 μL of the detection agent for the analyte is dropped on the top paper of the substrate of the paper-based detection chip and dried naturally to obtain the paper-based detection chip.

[0064] Example 4

[0065] The preparation method of the paper-based detection chip in this example is the same as that in Example 1, the difference is that the beating degree of the top paper of the paper-based detection chip is 40 °SR and the basis weight is 30 g / m 2 ; the beating degree of the bottom paper is 60 °SR and the basis weight is 50 g / m 2 .

[0066] Example 5

[0067] The preparation method of the paper-based detection chip in this example is the same as that in Example 1, the difference is that the beating degree of the top paper of the paper-based detection chip is 20 °SR and the basis weight is 25 g / m 2 ; the beating degree of the bottom paper is 40 °SR and the basis weight is 55 g / m 2 .

[0068] Example 6

[0069] The preparation method of the paper-based detection chip in this example is the same as that in Example 1, the difference is that the beating degree of the top paper of the paper-based detection chip is 20 °SR and the basis weight is 35 g / m 2; The beating degree of the top sheet is 40°SR, and the basis weight is 45 g / m 2 .

[0070] Example 7

[0071] The preparation method of the paper-based detection chip in this example is the same as that in Example 1, except that the beating degree of the top sheet of the paper-based detection chip is 20°SR, and the basis weight is 40 g / m 2 ; The beating degree of the bottom sheet is 60°SR, and the basis weight is 40 g / m 2 .

[0072] Example 8

[0073] The preparation method of the paper-based detection chip in this example is the same as that in Example 1, except that the beating degree of the top sheet of the paper-based detection chip is 60°SR, and the basis weight is 20 g / m 2 ; The beating degree of the bottom sheet is 20°SR, and the basis weight is 60 g / m 2 .

[0074] Example 9

[0075] The preparation method of the paper-based detection chip in this example is the same as that in Example 4, except that the beating degree of the top sheet of the paper-based detection chip is 70°SR, and the basis weight is 30 g / m 2 ; The beating degree of the bottom sheet is 60°SR, and the basis weight is 50 g / m 2 .

[0076] Example 10

[0077] The preparation method of the paper-based detection chip in this example is the same as that in Example 3, except that the beating degree of the top sheet of the paper-based detection chip is 20°SR, and the basis weight is 35 g / m 2 ; The beating degree of the bottom sheet is 70°SR, and the basis weight is 45 g / m 2 .

[0078] Example 11

[0079] The preparation method of the paper-based detection chip in this example is the same as that in Example 1, except that the top sheet of the paper-based detection chip uses unbeaten pulp, and the basis weight is 20 g / m 2 ; The bottom sheet uses unbeaten pulp, and the basis weight is 60 g / m 2 .

[0080] Example 12

[0081] The preparation method of the paper-based detection chip in this example is the same as that in Example 1, except that the beating degree of the top sheet of the paper-based detection chip is 20°SR, and the basis weight is 15 g / m 2; The beating degree of the base paper is 60°SR, and the basis weight is 65 g / m 2 .

[0082] The relevant parameters of the top paper and the base paper in the paper-based detection chips described in Examples 1-12 are shown in Table 1 below.

[0083] Table 1

[0084]

[0085]

[0086] The liquid transfer and diffusion speeds of the paper-based detection chips prepared in Examples 1-12 were compared with those of the traditional paper chip substrates, and the test results are shown in Table 2.

[0087] Method for comparing liquid diffusion speed: Drop 5 μL of rhodamine B dye solution in the central area of the paper-based detection chip of the present invention (denoted as HP Paper). Use the traditional paper chip substrate (Whatman No. 1 filter paper commonly used in paper-based detection, denoted as Regular Paper) as a control. Take videos with a mobile phone and intercept the same-frame pictures to compare the liquid diffusion situation. Use ImageJ software to analyze the extended circular diameter to compare the spreading speed. Take the moment when the droplet lands on the center of the paper chip as the starting frame. Subsequently, at the same frame, take the diameters of the diffusion areas in three different diameter directions of the droplet and calculate the average value as the diameter size of the dye diffusion area. Repeat the droplet addition operation three times to measure the diffusion diameter and take the average value.

[0088] The surface and cross-section scanning electron micrographs of the paper-based detection chip of the present invention and the traditional paper chip substrate are as shown in Figure 2 . It can be clearly seen that the cross-section of the traditional paper chip substrate is a relatively continuous and uniform structure; while the paper-based detection chip described in the present application consists of two layers with significantly different degrees of tightness, forming a hollow capillary diversion layer structure in the middle. The liquid penetration schematic diagrams of the paper-based detection chip of the present invention and the traditional paper chip substrate are as shown in Figure 1 . Figure 1 In a, b, c, and d, they are schematic diagrams of the droplet from dripping, contacting, starting to diffuse, to completely diffusing on the traditional paper chip substrate. It can be found that the traditional paper chip substrate is an overall fiber network structure. After the droplet contacts, it diffuses in all directions. Due to the disorder and complexity of the fiber network, the diffusion resistance is large and the diffusion distance is limited. Figure 1 In e, f, g, and h, they are schematic diagrams of the droplet from dripping, contacting, starting to diffuse, to completely diffusing on the paper-based detection chip of the present invention. When the droplet diffuses to the hollow capillary diversion layer formed by the top paper and the base paper, the fiber arrangement is relatively orderly, and the droplet quickly diffuses and spreads along the diversion layer, with a fast diffusion speed and an increased diffusion distance.

[0089] The liquid diffusion results of the paper-based detection chip (HP Paper) and the traditional paper chip substrate (Regular) described in Example 1 are as follows Figure 3 and Table 2. It can be seen from Figure 3 and Table 2 that the paper-based detection chip (HP Paper) of the present invention has completed diffusion at 0.8 s, while the traditional paper chip substrate (Regular) stops diffusion at 1.4 s, which proves that the paper-based detection chip of the present invention has a faster radial liquid transmission speed; at the same time point, the diffusion diameter of the paper-based detection chip of the present invention is significantly larger than that of the traditional paper chip, which proves that within the same time, the paper-based detection chip of the present invention has an advantage in the radial spreading speed of the liquid; when using the same volume of sample droplets, the paper-based detection chip of the present invention has a larger diffusion diameter, indicating that under the condition of using the same volume of droplets, the paper-based detection chip of the present invention can form a detection area with a larger area, effectively avoiding excessive longitudinal penetration of the sample droplets and loss of planar color intensity, and the detection results are more accurate and reliable.

[0090] Example 13

[0091] The paper-based detection chip prepared in Examples 1-12 was used for the colorimetric detection of alkaline phosphatase (denoted as ALP). The specific method is as follows:

[0092] Colorimetric detection method for alkaline phosphatase (ALP): Prepare the detection reagent: Use phosphate buffer solution (denoted as PBS) to prepare 5-bromo-4-chloro-3-indolyl phosphate (BCIP) / 5-bromo-4-chloro-3-indolyl phosphate (denoted as NBT) detection reagent. The concentration of BCIP in the detection reagent is 3 mmol / L, and the concentration of NBT is 0.6 mmol / L. Drop this detection reagent onto the paper-based detection chip substrate and dry it naturally to obtain the paper-based detection chip for alkaline phosphatase (ALP).

[0093] Drop ALP sample solutions with volumes of 1, 2, 3, 4, and 5 μL and a concentration of 150 U / mL onto the centers of the ALP paper-based detection chip and the traditional paper chip respectively, and observe the area and color change of the color development region.

[0094] The detection results are as follows Figure 4As shown in the figure, in the detection area of the same area, when 5 μL of sample solution is dropped on the traditional paper chip, the detection area is still not fully covered. The paper-based detection chip of the present invention only requires 3 μL of sample solution to cover the detection area, with a faster diffusion rate. At the same time, the paper-based detection chip of the present invention is used to detect ALP with uniform color development and no "coffee ring" effect, while the traditional paper chip has uneven color development and an obvious "coffee ring" effect. This shows that the paper-based detection chip of the present invention has the ability of rapid liquid spreading and can effectively weaken the "coffee ring" effect. Using ImageJ software to analyze the planar color of the detection results, it can be found that the detection results produced by using ordinary traditional paper chips show a ring structure with a light color in the middle and a dark color around, and the color development area is small, while the paper-based detection chip of the present invention has uniform color development in the entire detection area.

[0095] Example 14

[0096] The paper-based detection chips prepared in Examples 1-12 were used for colorimetric detection of glucose (denoted as Glu). The specific method is as follows:

[0097] Colorimetric detection of glucose (Glu): Preparation of the detection agent: Use phosphate buffer solution (denoted as PBS) to prepare a glucose oxidase (denoted as GOD) / horseradish peroxidase (denoted as HRP) / 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (denoted as ABTS) detection agent. The concentration of GOD in the detection agent is 150 U / mL, the concentration of HRP is 30 U / mL, and the concentration of ABTS is 25 mM. Drop this detection agent onto the substrate of the paper-based detection chip and let it dry naturally to obtain a paper-based detection chip for glucose (denoted as Glu).

[0098] Drop 1, 2, 3, 4, and 5 μL of glucose sample solution with a concentration of 5 mM onto the centers of the Glu paper-based detection chip and the traditional paper chip respectively, and observe the area and color change of the color development area. The detection results are as Figure 5 shown. In the detection area of the same area, when 2 μL of sample solution is dropped on the paper-based detection chip of the present invention, the detection area can be fully covered, with a faster diffusion rate. When 5 μL of sample solution is dropped on the traditional paper chip, there is still a white edge in the detection area. At the same time, the paper-based detection chip of the present invention is used to detect Glu with more uniform color development and no "coffee ring" effect, while the traditional paper chip has uneven color development and a relatively obvious "coffee ring" effect.

[0099] Compare the colorimetric detection effects of the paper-based detection chips prepared in Examples 13-14 in colorimetric detection. The test results are shown in Table 2.

[0100] Comparison of colorimetric detection effects: The paper-based detection chip of the present invention (denoted as HP Paper) and the traditional paper chip substrate (denoted as Regular Paper) were used to detect ALP and Glu samples, and the color distribution of the formed color development regions was observed and compared.

[0101] Table 2

[0102]

[0103]

[0104] As can be seen from the data in Table 2, compared with the traditional paper chip substrate, for the paper-based detection chips prepared in Examples 1-6 of the present invention, when the same volume of liquid was added, the diffusion time was 0.8 - 1.1 s, and the average diffusion diameter reached 6.84 - 7.50 mm. At the same time, the results of detecting ALP and Glu showed uniform color development and no "coffee ring" effect. This indicates that the paper-based detection chip prepared by the present invention through the blending of different beating degrees of pulp, combined with a specific basis weight of the top paper and the bottom paper, significantly improves the diffusion speed and diffusion distance of the liquid on the paper-based substrate, can effectively inhibit the penetration effect that occurs during the colorimetric detection of the paper-based chip, has an obvious weakening effect on the "coffee ring" effect, shows uniform color development, and the test results are more reliable.

[0105] Compared with Example 1, in Example 7, when the basis weight of the top paper is the same as that of the bottom paper, although the colorimetric result also has uniform color development, the diffusion distance of the liquid decreases significantly at this time.

[0106] Compared with Example 1, in Example 8, when the beating degree of the top paper is greater than that of the bottom paper, the diffusion distance and penetration speed of the liquid on the top paper decrease significantly at this time.

[0107] Compared with Example 4, in Example 9, when the beating degree of the top paper is greater than the range described in the present application, the diffusion and penetration speed of the liquid on the top paper is slower at this time.

[0108] Compared with Example 3, in Example 10, when the beating degree of the bottom paper is greater than the range described in the present application, the absorption of the liquid by the bottom paper becomes weaker and the detection efficiency becomes slower at this time.

[0109] Compared with Example 1, in Example 11, when the beating degrees of both the top paper and the bottom paper are lower than the range described in the present application, when the liquid is added to the paper-based chip, the liquid is rapidly transmitted. However, due to the lower beating degree and larger voids, it is not conducive to the retention of the chromogenic substance on the bottom paper, and the color development effect decreases.

[0110] Compared with Example 1, in Example 12, when the basis weight of the top paper is lower than the range described in the present application, the strength of the prepared paper-based detection chip decreases significantly after adding the liquid, is easily damaged and separated from the bottom paper.

[0111] All technical personnel should note that although the present invention has been described according to the above specific embodiments, the inventive concept of the present invention is not limited to this invention alone. Any modification using the inventive concept of the present invention will be included within the scope of protection of the patent right of this patent.

Claims

1. A paper-based detection chip, characterized in that, The paper-based detection chip includes a top paper and a bottom paper. The basis weight of the top paper is 20 - 40 g / m², the basis weight of the bottom paper is 40 - 60 g / m², and the basis weight of the top paper is less than that of the bottom paper. The beating degree of the low-beating pulp is 20 - 40°SR, and the beating degree of the high-beating pulp is 40 - 60°SR; the beating degree of the low-beating pulp is less than that of the high-beating pulp. The paper-based detection chip is made by laminating the top paper and the bottom paper.

2. The paper-based detection chip according to claim 1, characterized in that, The pulp is at least one of bleached chemical softwood pulp, bleached chemical hardwood pulp, and bleached chemical cotton pulp.

3. The preparation method of a paper-based detection chip according to claim 1 or 2, characterized in that, The preparation method includes the following steps: S1 Disintegrate and beat the pulp sheets to obtain low-beating pulp and high-beating pulp respectively. S2 Sheet the low-beating pulp obtained in step S1 and dry it to obtain the top paper. S3 Sheet the high-beating pulp obtained in step S1 and dry it to obtain the bottom paper. S4 Wet the bottom paper obtained in step S3 to obtain a wet bottom paper. Then laminate the top paper obtained in step S2 on the wet bottom paper to obtain a composite wet paper. S5 Press and dry the composite wet paper obtained in step S4 to obtain a composite dry paper. S6 Use a mold to punch the composite dry paper obtained in step S5 to obtain the substrate of the paper-based detection chip. S7 Drop a detection agent on the top paper of the substrate of the paper-based detection chip obtained in step S6 and dry it to obtain the paper-based detection chip.

4. The preparation method of a paper-based detection chip according to claim 3, wherein, In step S1, the beating method is to use the PFI mill method for beating, and the mass concentration of the pulp during beating is 10%; the beating degree of the low-beating pulp is 20 - 40°SR, and the beating degree of the high-beating pulp is 40 - 60°SR.

5. The preparation method of a paper-based detection chip according to claim 3, characterized in that, In steps S2 and S3, the sheeting method is to use a Kajaani paper former for sheeting, the drying temperature is 90 - 100°C, and the drying time is 10 - 20 min.

6. The preparation method of a paper-based detection chip according to claim 3, wherein, In step S4, the moisture content of the wet bottom paper is 80 - 90%; the wetting method is to uniformly spray water on the bottom paper when it is laminated on a polyvinyl chloride film to fully wet it; the lamination method is to first contact one side of the top paper with the wet bottom paper and then slowly laminate the top paper on the wet bottom paper.

7. The preparation method of a paper-based detection chip according to claim 3, characterized in that, In step S5, the drying temperature is 90 - 100°C, the drying vacuum degree is 0.1 Mpa, and the drying time is 10 - 20 min.

8. The preparation method of a paper-based detection chip according to claim 3, characterized in that, In step S6, the mold is a circular steel punch, and the diameter of the circular steel punch is 5 - 15 mm.

9. Application of a paper-based detection chip according to any one of claims 1 - 3 in colorimetric detection.

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