Microenvironment humidity control concentric circle device for improving color development uniformity of paper-based chip and preparation method thereof

Abstract

The invention discloses a microenvironment humidity control concentric circle device for improving the color development uniformity of a paper-based chip and a preparation method of the microenvironment humidity control concentric circle device, and belongs to the technical field of paper-based colorimetric detection. The microenvironment humidity control concentric circle device comprises a paper substrate, a hydrophobic ring, a hydrophilic ring, a detection area and a hydrophobic layer, the area, except the hydrophilic ring, the detection area and the hydrophobic ring, of the paper substrate is a hydrophobic layer. The detection area, the hydrophilic ring and the hydrophobic layer of the paper substrate are prepared by means of silk-screen printing, no harmful reagent is used, no pollution is caused to the environment, the flowability and the infiltration capacity of ink are improved by selecting the ethyl acetate with the mass fraction of 5%-10%, the coffee ring effect of the detection area can be inhibited, the color development uniformity of the paper-based chip is improved, and more importantly, the detection accuracy of the paper-based chip is improved. The microenvironment humidity control concentric circle device with the paper-based chip uniform in color development is low in cost and convenient to carry, and the colorimetric detection efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of paper-based colorimetric detection, and in particular relates to a microenvironment humidity control concentric circle device for improving the uniform color development of a paper-based chip and a preparation method thereof. Background Art

[0002] In colorimetric detection, the capillary microflow caused by uneven evaporation flux toward the edge, the solute flow with the capillary microflow will lead to the formation of "coffee ring" pattern, which will cause color gradient interference in colorimetric detection. For example, in the glucose enzymatic reaction, the fluid transport of small molecules is the reason for the partial loss of color.

[0003] At present, in order to reduce the interference of "coffee ring" contrast color detection, different methods have been used in some studies, such as using hydrothermal method to uniformly modify zinc nanoparticles on the surface of paper to overcome the "coffee ring" effect; by modifying chitosan on the surface of filter paper, effective fixation of biological molecules can be achieved, thereby obtaining patterned colorimetric results, improving detection sensitivity and user-friendliness. However, these two methods are complicated to operate and costly. In addition, there is also the method of reducing the interference of "coffee ring" contrast color detection by adjusting the intrinsic properties of paper, such as adjusting the base paper structure by changing the papermaking process such as beating degree, realizing the regulation of paper whiteness, tensile strength and liquid absorption height; by changing the fiber type and ratio, customizing the construction of paper base, etc., the "coffee ring" phenomenon can be effectively weakened and the uniform distribution of color signals can be improved. However, the method of adjusting the intrinsic properties of paper is cumbersome, time-consuming and labor-intensive. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention aims to provide a microenvironment humidity control concentric circle device for improving the uniform color development of paper-based chips and a preparation method thereof, such as Figure 1 As shown, a hydrophilic ring is used instead of a hydrophilic circle as the detection area, saturated salt water is added to the hydrophilic outer ring area to increase the local environmental humidity of the outer ring, and the evaporation rate of the hydrophilic-hydrophobic interface detection reagent or sample solution in the inner ring is slowed down, thereby ensuring the uniformity of the distribution of the effective ingredients in the inner ring detection reagent or sample solution and reducing the uneven color development caused by the "coffee ring" effect.

[0005] The specific technical solutions are as follows: A microenvironment humidity control concentric circle device for improving the uniform color development of a paper-based chip, the microenvironment humidity control concentric circle device comprising a paper substrate, a hydrophobic ring, a hydrophilic ring, a detection area and a hydrophobic layer; the detection area is a circle with a diameter of 5-10 mm, the hydrophobic ring is a ring with an inner diameter of 5-10 mm and an outer diameter of 10-20 mm, and the hydrophilic ring is a ring with an inner diameter of 10-20 mm and an outer diameter of 15-25 mm; the hydrophobic layer, the hydrophilic ring and the detection area have the same center.

[0006] In some embodiments, the area of ​​the paper substrate other than the hydrophilic ring, the detection area and the hydrophobic ring is a hydrophobic layer.

[0007] The present invention also provides a method for preparing a microenvironment humidity control concentric circle device for improving the uniform color development of a paper-based chip, the preparation method comprising the following steps: S1 Paper substrate selection: Select filter paper as the paper substrate; S2 Printing ink: Printing ink on the paper substrate to form a hydrophilic ring, a hydrophobic layer and a detection area on the filter paper; S3 salt solution treatment: add saturated salt solution to the hydrophilic ring and make it completely wet; S4: adding reagents: adding detection reagents and sample solutions to the detection area; S5 Sealing: The device is placed in a sealed bag for storage so that the colorimetric reaction can be carried out in a closed environment.

[0008] In some embodiments, the paper substrate in step S1 is one of Whatman No. 1, Whatman No. 2, Whatman No. 3, Whatman No. 4, and Whatman No. 5 filter papers.

[0009] In some of the embodiments, the specific method of printing ink in step S2 is: select a screen printing plate with a mesh number of 80~400, transfer the UV crystal convex oil to the paper substrate by screen printing, let the UV crystal convex oil stand on the paper substrate for 0.5~7 minutes for full penetration, and then irradiate with a UV light source to cure the UV crystal convex oil, and the curing time is 1~15 seconds; then select a screen printing plate with a mesh number of 80~400, and print ethyl acetate with a mass fraction of 5%~10% on the cured UV crystal convex oil by screen printing; finally, dry at 10~100°C to form a hydrophilic ring and a hydrophobic boundary.

[0010] In some of the embodiments, the specific method of the salt solution treatment in step S3 is: dripping a saturated sodium chloride salt solution on the hydrophilic ring to completely soak it.

[0011] In some embodiments, the specific method of adding reagents in step S4 is: first drop the detection reagent on the detection area to ensure that the detection reagent is evenly distributed in the detection area, and then dry it at 50-80°C; finally drop the sample solution on the detection area to ensure that the sample solution is distributed in the detection area.

[0012] In some of the embodiments, the specific method of sealing in step S5 is: using a sealing bag to provide a closed environment required for the detection reaction.

[0013] The present invention has the following advantages: (1) The present invention can suppress the "coffee ring" effect in the detection area and improve the color uniformity of the paper-based chip.

[0014] (2) The present invention is low-cost, easy to carry, and can improve the efficiency of colorimetric detection.

[0015] (3) The present invention prepares the detection area, hydrophilic ring and hydrophobic layer of the paper substrate by screen printing, does not use harmful reagents, does not pollute the environment, and uses ethyl acetate with a mass fraction of 5% to 10% to improve the fluidity and penetration ability of the ink. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the preparation of the detection device of the present invention; Figure 2 This is a comparison chart of the color uniformity effect of the paper-based chip of Examples 1 to 4 and Comparative Example 1; Among them, 1 is a hydrophilic ring, 2 is a detection area, 3 is a hydrophobic ring, 4 is a saturated salt solution, and 5 is a detection reagent. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings, technical process steps, specific implementation conditions and materials in the embodiments of the present invention to clearly and completely describe the technical solutions in 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0018] like Figure 1 As shown, Whatman No. 1 filter paper was selected as the paper substrate, and a screen printing plate with a mesh size of 200 was selected. The UV crystal convex oil was transferred to the paper substrate by screen printing. After the UV crystal convex oil was allowed to stand on the paper substrate for 5 minutes for full penetration, it was irradiated with a UV light source to cure the UV crystal convex oil for 8 seconds; then a screen printing plate with a mesh size of 200 was selected, and 8% ethyl acetate was printed on the cured UV crystal convex oil by screen printing; finally, it was dried at 50°C to form a hydrophilic ring and a hydrophobic boundary. A saturated sodium chloride salt solution was added to the hydrophilic ring to completely infiltrate it. The detection reagent was dropped on the detection area to ensure that the detection reagent was evenly distributed in the detection area. Example

[0019] The microenvironment humidity control concentric circle device for improving the color uniformity of paper-based chips prepared in Example 1 can be used to improve the color uniformity of colorimetric detection of nitrite content. Under acidic conditions, nitrite reacts with p-aminobenzenesulfonic acid to form a diazonium salt, which then combines with NED to form a colored azo compound, thereby performing colorimetric detection. Take an appropriate amount of NaNO 2 (molecular weight: 69 g / mol) was dried in a forced air drying oven at 120°C. Then 100 mg of NaNO was dried to constant weight. 2 Dissolve in an appropriate amount of deionized water and then dilute to 100 mL to obtain a nitrite mother solution with a molar concentration of 14.49 mM (in terms of NO 2 - The A solution was composed of 330 mM citric acid and 50 mM sulfonamide, and the B solution was composed of 10 mM NED. The A solution and the B solution were mixed in equal volumes to obtain the Griess reagent. Figure 1 As shown, during the detection, 2.5 μL of Griess reagent was dripped into the center of the detection area of ​​the microenvironment humidity control concentric circle device for improving the color uniformity of the paper-based chip prepared in Example 1, and then 2.5 μL of nitrite solution was dripped into the detection area using a pipette in the order of nitrite solution concentration gradient (0, 7, 14, 28, 72, 144, 360, 720, 1080, 1440, 2880, 7200 μM), and the device was placed in a sealed bag for sealed storage, so that the colorimetric reaction was carried out in a closed environment, thereby improving the color uniformity of the paper-based chip. Example

[0020] like Figure 1 As shown, Whatman No. 1 filter paper is selected as the paper substrate, and a screen printing plate with a mesh number of 200 is selected. The UV crystal convex oil is transferred to the paper substrate by screen printing. After the UV crystal convex oil is allowed to stand on the paper substrate for 5 minutes for full penetration, it is irradiated with a UV light source to cure the UV crystal convex oil, and the curing time is 8 seconds; then a screen printing plate with a mesh number of 200 is selected, and 8% ethyl acetate is printed on the cured UV crystal convex oil by screen printing; finally, it is dried at 50°C to form a hydrophilic ring and a hydrophobic boundary. Lithium bromide saturated salt solution is dripped on the hydrophilic ring to make it completely infiltrated. The detection reagent is dripped in the detection area to ensure that the detection reagent is evenly distributed in the detection area. Then, nitrite colorimetric detection is performed, and the reagents and process parameters used in this colorimetric detection are the same as those in Example 2. Example

[0021] like Figure 1As shown, Whatman No. 1 filter paper is selected as the paper substrate, and a screen printing plate with a mesh number of 200 is selected. The UV crystal convex oil is transferred to the paper substrate by screen printing. After the UV crystal convex oil is allowed to stand on the paper substrate for 5 minutes for full penetration, it is irradiated with a UV light source to cure the UV crystal convex oil, and the curing time is 8 seconds; then a screen printing plate with a mesh number of 200 is selected, and 8% ethyl acetate is printed on the cured UV crystal convex oil by screen printing; finally, it is dried at 50°C to form a hydrophilic ring and a hydrophobic boundary. A saturated salt solution of magnesium chloride is dripped on the hydrophilic ring to completely infiltrate it. First, the detection reagent is dripped into the detection area to ensure that the detection reagent is evenly distributed in the detection area. Then, a nitrite colorimetric detection is performed, and the reagents and process parameters used in this colorimetric detection are the same as those in Example 2. Example

[0022] like Figure 1 As shown, Whatman No. 1 filter paper is selected as the paper substrate, and a screen printing plate with a mesh number of 200 is selected. The UV crystal convex oil is transferred to the paper substrate by screen printing. After the UV crystal convex oil is allowed to stand on the paper substrate for 5 minutes for full penetration, it is irradiated with a UV light source to cure the UV crystal convex oil, and the curing time is 8 seconds; then a screen printing plate with a mesh number of 200 is selected, and 8% ethyl acetate is printed on the cured UV crystal convex oil by screen printing; finally, it is dried at 50°C to form a hydrophilic ring and a hydrophobic boundary. Deionized water is dripped on the hydrophilic ring to make it completely infiltrated. First, the detection reagent is dripped on the detection area to ensure that the detection reagent is evenly distributed in the detection area. Then, nitrite colorimetric detection is performed. The reagents and process parameters used in this colorimetric detection are the same as those in Example 2. Example

[0023] like Figure 1 As shown, Whatman No. 1 filter paper is selected as the paper substrate, and a screen printing plate with a mesh number of 200 is selected. The UV crystal convex oil is transferred to the paper substrate by screen printing. After the UV crystal convex oil is allowed to stand on the paper substrate for 5 minutes for full penetration, it is irradiated with a UV light source to cure the UV crystal convex oil, and the curing time is 8 seconds; then a screen printing plate with a mesh number of 200 is selected, and 8% ethyl acetate is printed on the cured UV crystal convex oil by screen printing; finally, it is dried at 50°C to form a hydrophilic ring and a hydrophobic boundary. No reagent is added to the hydrophilic ring. The detection reagent is dropped in the detection area to ensure that the detection reagent is evenly distributed in the detection area. Then, nitrite colorimetric detection is performed, and the reagents and process parameters used in this colorimetric detection are the same as those in Example 2.

[0024] The color development results of Examples 3, 4, 5, and 6 are compared. Figure 2It can be seen that compared with the case where no reagent is added to the hydrophilic ring, the colorimetric detection of the microenvironment humidity-controlled concentric circle device for improving the color uniformity of the paper-based chip by adding water to the hydrophilic ring is relatively uniform, while the blank group shows a very obvious "coffee ring" effect. This result shows that water evaporation increases the humidity of the microenvironment, reduces the evaporation rate of the hydrophilic-hydrophobic boundary sample solution and the detection reagent mixture, and is beneficial to reducing the "coffee ring" effect; the relative humidity of the saturated solutions of lithium bromide and magnesium chloride is low, that is, they continuously absorb moisture from the environment, reducing the vapor pressure in the closed environment. In the microenvironment created by these two saturated inorganic salts, the evaporation of the liquid in the "detection area" becomes faster, which is manifested as an enhancement of the "coffee ring" effect compared with the blank group; the relative humidity of the saturated solution of sodium chloride and deionized water is high, that is, they will release moisture into the environment, increasing the vapor pressure in the closed environment. Compared with the blank group, the evaporation of the liquid in the "detection area" is inhibited, which is manifested as a decrease in the blank area of ​​the "wetting center" region. In summary, the microenvironment humidity control concentric circle device for improving the color uniformity of paper-based chips provided by the present invention is conducive to reducing the "coffee ring" effect in paper-based color detection and facilitates the visualization of paper-based color detection.

[0025] Technical personnel should note that although the present invention has been described according to the above specific implementation methods, the inventive concept of the present invention is not limited to this invention, and any modification using the inventive concept will be included in the scope of protection of this patent.

Claims

1. A micro-environment humidity control concentric circle device for improving the uniform color development of paper-based chips, characterized in that: The microenvironment humidity control concentric circle device includes a paper substrate, a hydrophobic ring, a hydrophilic ring, a detection area and a hydrophobic layer; the detection area is a circle with a diameter of 5-10 mm, the hydrophobic ring is a ring with an inner diameter of 5-10 mm and an outer diameter of 10-20 mm, and the hydrophilic ring is a ring with an inner diameter of 10-20 mm and an outer diameter of 15-25 mm; the hydrophobic layer, the hydrophilic ring and the detection area have the same center.

2. A micro-environment humidity control concentric circle device for improving the color uniformity of paper-based chips as claimed in claim 1, characterized in that: The area of ​​the paper substrate other than the hydrophilic ring, the detection area and the hydrophobic ring is a hydrophobic layer.

3. A method for preparing a microenvironment humidity control concentric circle device for improving the uniform color development of a paper-based chip as described in any one of claims 1 to 2, characterized in that: The preparation method comprises the following steps: S1 Paper substrate selection: Select filter paper as the paper substrate; S2 Printing ink: Printing ink on the paper substrate to form a hydrophilic ring, a hydrophobic layer and a detection area on the filter paper; S3 salt solution treatment: add saturated salt solution to the hydrophilic ring and make it completely wet; S4: adding reagents: adding detection reagents and sample solutions to the detection area; S5 Sealing: The device is placed in a sealed bag for storage so that the colorimetric reaction can be carried out in a closed environment.

4. The method for preparing a microenvironment humidity control concentric circle device for improving the uniform color development of a paper-based chip as claimed in claim 3, characterized in that: The paper substrate in step S1 is one of Whatman No. 1, Whatman No. 2, Whatman No. 3, Whatman No. 4, and Whatman No. 5 filter papers.

5. The method for preparing a microenvironment humidity control concentric circle device for improving the uniform color development of a paper-based chip as claimed in claim 3, characterized in that: The specific method of printing ink described in step S2 is: select a screen printing plate with a mesh number of 80~400, transfer the UV crystal convex oil to the paper substrate by screen printing, let the UV crystal convex oil stand on the paper substrate for 0.5~7 minutes for full penetration, and then irradiate with a UV light source to cure the UV crystal convex oil, and the curing time is 1~15 seconds; then select a screen printing plate with a mesh number of 80~400, and print 5%~10% ethyl acetate by screen printing on the cured UV crystal convex oil; finally, dry at 10~100°C to form a hydrophilic ring and a hydrophobic boundary.

6. The method for preparing a microenvironment humidity control concentric circle device for improving the uniform color development of a paper-based chip as claimed in claim 3, characterized in that: The specific method of the salt solution treatment in step S3 is: dripping a saturated sodium chloride salt solution on the hydrophilic ring to completely soak it.

7. The method for preparing a microenvironment humidity control concentric circle device for improving the uniform color development of a paper-based chip as claimed in claim 3, characterized in that: The specific method of adding reagents in step S4 is: first drop the detection reagent on the detection area to ensure that the detection reagent is evenly distributed in the detection area, and finally drop the sample solution on the detection area to ensure that the sample solution is distributed in the detection area.

8. The method for preparing a microenvironment humidity control concentric circle device for improving the uniform color development of a paper-based chip as claimed in claim 3, characterized in that: The specific method of sealing in step S5 is: using a sealing bag to provide a closed environment required for the detection reaction.

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