CN114460073B - Hydrogel, preparation method thereof and application thereof in pH detection - Google Patents
Hydrogel, preparation method thereof and application thereof in pH detection Download PDFInfo
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Abstract
The invention discloses hydrogel, a preparation method thereof and application thereof in pH detection, and belongs to the technical field of pH detection. The technical scheme includes that phenol red and chitosan are combined through a Mannich reaction to generate an alkylamine derivative, and then the polymer dye is obtained; preparing a polymer dye solution, a gelatin solution, a sodium alginate solution and a glutaraldehyde solution respectively, mixing the sodium alginate solution and the glutaraldehyde solution to obtain a mixed solution, and adding the polymer dye solution and the gelatin solution into the mixed solution to prepare the hydrogel. The invention is applied to the aspect of pH detection, solves the problems that the existing hydrogel and pH dye are combined only through physical action, and the indicator is easy to leak, and the detection accuracy and sensitivity are low, and has the characteristics of low price, high universality, good stability, portability and durability.
Description
Technical Field
The invention belongs to the technical field of pH detection, and particularly relates to hydrogel, a preparation method thereof and application thereof in the aspect of pH detection.
Background
The pH detection technique is a technique applied to various industries, and a plurality of instruments and substances are currently used for detecting pH values, such as pH meters, pH test papers and pH indicators. However, the above detection means have many problems in that pH is expensive, portability is lacking, and popularity is insufficient; the pH test paper has insufficient accuracy and cannot be reused; the pH indicator is oxidized and degraded, and has poor stability.
In order to solve the above problems, more and more researchers have been devoted to research on smart materials for visually detecting pH, in which pH-sensitive colorimetric dyes having a significant color change and enabling inexpensive, continuous pH detection are becoming a research hotspot. The hydrogel is a water-swellable polymer material, has a unique three-dimensional structure, higher porosity and high biocompatibility, is easy to manufacture, is applied to development of biological and chemical sensors, becomes a protective indicator, and is an ideal material for realizing visual detection of pH. At present, it has been reported that pH dyes are protected by hydrogels, such as embedding phenol red into a sol-gel matrix, and adding phenol red into hydrogels by impregnation, to overcome the oxidative degradation problems indicated at present.
However, the hydrogel and the pH dye are combined only by physical action, and the problems of easy leakage of the indicator and low detection accuracy and sensitivity still exist.
Disclosure of Invention
Aiming at the defects existing in the prior art, the technical problem to be solved by the invention is to overcome the problems that the existing hydrogel and the pH dye are combined only through physical action, and the indicator is easy to leak and the detection accuracy and sensitivity are low, the invention provides the hydrogel which has low price, high universality, good stability, portability and durability, the preparation method thereof and the application thereof in the aspect of pH detection.
In order to solve the technical problems, the invention adopts the following technical scheme:
in one aspect, the present invention provides a method for preparing a hydrogel comprising:
the preparation method of the polymer dye comprises the steps of combining phenol red and chitosan through a Mannich reaction to generate an alkylamine derivative, and obtaining the polymer dye;
the preparation method comprises the steps of preparing a polymer dye solution, a gelatin solution, a sodium alginate solution and a glutaraldehyde solution respectively, mixing the sodium alginate solution and the glutaraldehyde solution to obtain a mixed solution, and adding the polymer dye solution and the gelatin solution into the mixed solution to prepare the hydrogel;
preparing a polymer dye solution comprises dissolving the polymer dye and chitosan in acetic acid to obtain the polymer dye solution.
Preferably, the polymer dye preparation step includes: and combining phenol red, formaldehyde and chitosan through a Mannich reaction to generate an alkylamine derivative, thus obtaining the polymer dye.
Preferably, in the hydrogel preparation step
The preparation of sodium alginate solution comprises the following steps: 1 part of sodium alginate is dissolved in 100 parts of water to obtain sodium alginate solution;
the preparation of glutaraldehyde solution in the hydrogel preparation step comprises: dissolving 4 parts of glutaraldehyde with the mass concentration of 25% in 100 parts of water to prepare glutaraldehyde solution;
the volume ratio of the sodium alginate solution to the glutaraldehyde solution in the mixed solution is 1:0.25-2.
Preferably, in the hydrogel preparation step
The preparation of the polymer dye solution specifically comprises the following steps: 1 part of chitosan and 0.02 part of the polymer dye are dissolved in 100 parts of 1% acetic acid, and the mixture is stirred at room temperature overnight to obtain a polymer dye solution;
the preparation of the gelatin solution comprises: dissolving 1 part of gelatin in 100 parts of water to obtain a gelatin solution;
the mass ratio of the chitosan to the gelatin is 1:0.25-3.
Preferably, the preparation method of the polymer dye specifically comprises the following steps:
dissolving 1 part of phenol red in 50 parts of N, N-dimethylformamide and 0.04 part of formaldehyde in a reaction vessel to obtain a phenol red formaldehyde solution;
1 part of chitosan is dissolved in 100 parts of 1% acetic acid to obtain chitosan solution;
adding the phenol red formaldehyde solution into the chitosan solution, stirring at a constant speed of 60 ℃, and reacting for 24 hours to obtain a reacted solution;
1M NaOH was added to the post-reaction solution to obtain a precipitate, which was centrifugally filtered, washed with ethanol, and dried in an oven at 60℃to obtain the polymer dye.
The invention also provides a hydrogel prepared by the preparation method of the hydrogel in any one of the technical schemes.
The invention also provides application of the hydrogel in pH detection, and the hydrogel is prepared by any technical scheme.
Preferably, the method comprises:
preparing a standard solution with the pH value of 1-12, putting the prepared hydrogel into the standard solution, displaying different colors on the hydrogel, reading RGB data by using a mobile phone to perform photographing analysis, drawing a standard curve according to data analysis of three signals of RGB, obtaining the relation between RGB and pH, and obtaining RGB data by photographing in subsequent use, and finding out the corresponding pH according to the standard curve.
Preferably, the hydrogel is a hydrogel sphere.
Compared with the prior art, the invention has the beneficial effects that:
the hydrogel provided by the invention has the advantages that the phenol red and the chitosan are combined through chemical bonds, so that the leakage of dye is prevented, the stability is high, and the detection precision is high; the prepared hydrogel ball has better biocompatibility, and has the advantages of low price, high universality, good stability, portability and durability.
Drawings
FIG. 1 is a schematic diagram of a reaction process of phenol red and chitosan provided by an embodiment of the invention;
FIG. 2 is a flow chart of the preparation of hydrogel according to an embodiment of the present invention;
FIG. 3 shows absorbance results before and after storage of the hydrogel provided in example 1 of the present invention;
FIG. 4 shows the pH measured before and after storage of the hydrogel according to example 1 of the present invention;
FIG. 5 shows the sensitivity test results of the hydrogel according to example 1 of the present invention;
FIG. 6 is a photograph of a hydrogel provided by example 1 of the present invention;
FIG. 7 is a hydrogel calibration curve a provided by example 1 of the present invention;
FIG. 8 is a hydrogel standard curve b provided by example 1 of the present invention;
FIG. 9 is a hydrogel calibration curve c provided by example 1 of the present invention;
FIG. 10 shows the results of mechanical strength test of hydrogels provided in examples 1-4 of the present invention;
FIG. 11 shows the results of the swelling ratio experiments of hydrogels provided in examples 1 to 4 of the present invention;
FIG. 12 is a schematic view showing the result of the color reaction of the hydrogels provided in examples 5 to 9 of the present invention.
Detailed Description
The following detailed description of the technical solutions in the specific embodiments of the present invention will be given with reference to the accompanying drawings. It is apparent that the described embodiments are only some specific implementations, but not all implementations, of the general technical solution of the present invention. All other embodiments, which are obtained by those skilled in the art based on the general inventive concept, fall within the scope of the present invention.
In one aspect, the present invention provides a method for preparing a hydrogel comprising:
s1: the preparation method of the polymer dye comprises the step of combining phenol red with chitosan through a Mannich reaction to generate an alkylamine derivative, and the polymer dye is obtained. In this step, phenol red is combined with chitosan by Mannich reaction, as shown in FIG. 1, phenol red contains activated CH-and NH of chitosan 2 And formaldehyde to generate alkylamine derivatives to form stable polymers, which are beneficial to preventing dye leakage, improving the stability of phenol red and simultaneously maintaining the detection sensitivity of the phenol red. In a preferred embodiment, the polymer dye preparation step comprises: and combining phenol red, formaldehyde and chitosan through a Mannich reaction to generate an alkylamine derivative, thus obtaining the polymer dye.
S2: the preparation method of the hydrogel comprises the steps of respectively preparing a polymer dye solution, a gelatin solution, a sodium alginate solution and a glutaraldehyde solution, mixing the sodium alginate solution with the glutaraldehyde solution to obtain a mixed solution, and adding the polymer dye solution and the gelatin solution into the mixed solution to prepare the hydrogel, as shown in fig. 2. Preparing a polymer dye solution comprises dissolving the polymer dye and chitosan in acetic acid to obtain the polymer dye solution. In this step, the process of preparing the hydrogel is specifically limited, and it is required to ensure both the mechanical strength of the hydrogel and the sensitivity of phenol red, so that the content control of each component in the hydrogel preparation process is very critical. It should be noted that, the technical scheme of the application is to continue forming hydrogel by phenol red containing stable polymer formed by chemical bond, because the direct use of polymer dye can also indicate pH, but has oxidation and degradation problems, and has poor stability, and the oxidative degradation can be prevented by preparing hydrogel, so that the stability is further improved.
In a preferred embodiment, the preparing sodium alginate solution in the hydrogel preparation step comprises: 1 part of sodium alginate is dissolved in 100 parts of water to obtain sodium alginate solution; the preparation of glutaraldehyde solution in the hydrogel preparation step comprises: dissolving 4 parts of glutaraldehyde with the mass concentration of 25% in 100 parts of water to prepare glutaraldehyde solution; the volume ratio of the sodium alginate solution to the glutaraldehyde solution in the mixed solution is 1:0.25-2. The technical scheme specifically limits the dosage relation of the sodium alginate solution and the glutaraldehyde solution, because the prepared hydrogel has higher swelling rate and stability under the proportion. It is understood that the volume ratio of the sodium alginate solution to the glutaraldehyde solution in the mixed solution may also be any point value ratio within the range of 1:0.5, 1:1, and the like. Further, the preparation of the polymer dye solution in the hydrogel preparation step specifically comprises the following steps: 1 part of chitosan and 0.02 part of the polymer dye are dissolved in 100 parts of 1% acetic acid, and the mixture is stirred at room temperature overnight to obtain a polymer dye solution; the preparation of the gelatin solution comprises: dissolving 1 part of gelatin in 100 parts of water to obtain a gelatin solution; the mass ratio of the chitosan to the gelatin is 1:0.25-3. The dosage relation of chitosan and gelatin is limited, so that the color development time in detection can be ensured to be short, and the stability is good. It is understood that the mass ratio of chitosan to the gelatin may also be any point value ratio within the range of 1:0.5, 1:0.75, 1:1, 1:2, and the like. If the content of gelatin and glutaraldehyde is too low, the mechanical strength of the hydrogel is too low, and the hydrogel cannot be molded; too high a content affects sensitivity. According to the technical scheme, the use amount of each raw material is limited, so that the mechanical strength of the hydrogel is ensured, and the sensitivity is not influenced.
In a preferred embodiment, the polymer dye preparation step specifically comprises:
dissolving 1 part of phenol red in 50 parts of N, N-dimethylformamide and 0.04 part of formaldehyde in a reaction vessel to obtain a phenol red formaldehyde solution;
1 part of chitosan is dissolved in 100 parts of 1% acetic acid to obtain chitosan solution;
adding the phenol red formaldehyde solution into the chitosan solution, stirring at a constant speed of 60 ℃, and reacting for 24 hours to obtain a reacted solution;
1M NaOH was added to the post-reaction solution to obtain a precipitate, which was centrifugally filtered, washed with ethanol, and dried in an oven at 60℃to obtain the polymer dye.
The invention also provides a hydrogel prepared by the preparation method of the hydrogel in any one of the technical schemes. The hydrogel has the advantages of good stability, good biocompatibility, high universality, portability and durability.
The invention also provides application of the hydrogel in pH detection, and the hydrogel is prepared by any technical scheme. On one hand, the phenol red and the chitosan are combined through chemical bonds, so that the hydrogel is favorable for preventing dye leakage and has high stability; on the other hand, the prepared hydrogel ball has better biocompatibility, and has the advantages of low price, high universality, good stability, portability and durability. Preferably, the hydrogel is a hydrogel sphere. The spherical hydrogel has the characteristics of strong structural stability, difficult damage and easy recovery during detection.
In a preferred embodiment, the method comprises the steps of: preparing a standard solution with the pH value of 1-12, putting the prepared hydrogel into the standard solution, displaying different colors on the hydrogel, reading RGB data by using a mobile phone to perform photographing analysis, drawing a standard curve according to data analysis of three signals of RGB, obtaining the relation between RGB and pH, and obtaining RGB data by photographing in subsequent use, and finding out the corresponding pH according to the standard curve.
In order to more clearly and in detail describe the hydrogels provided by the embodiments of the present invention, the preparation methods thereof and the application thereof in pH detection, the following description will be made with reference to specific embodiments.
Example 1
1. Preparation of a phenol red chitosan polymer dye:
dissolving 1 part of phenol red in 50 parts of N, N-dimethylformamide and 0.04 part of formaldehyde in a reaction vessel to obtain a phenol red formaldehyde solution; 1 part of chitosan is dissolved in 100 parts of 1% acetic acid to obtain chitosan solution; adding a phenol red formaldehyde solution into a chitosan solution, stirring at a constant speed of 60 ℃, and reacting for 24 hours to obtain a reacted solution; 1M NaOH was added to the post-reaction solution to obtain a precipitate, which was centrifugally filtered, washed with ethanol, and dried in an oven at 60℃to obtain a polymer dye.
2. Preparation of intelligent hydrogels indicating pH:
preparing a polymer dye solution: 1 part of chitosan and 0.02 part of polymer dye are dissolved in 100 parts of 1% acetic acid, and stirred at room temperature overnight to obtain polymer dye solution;
preparing gelatin solution: 1 part of gelatin is dissolved in 100 parts of water to obtain gelatin solution;
preparing sodium alginate solution: 1 part of sodium alginate is dissolved in 100 parts of water to obtain sodium alginate solution;
preparing glutaraldehyde solution: dissolving 4 parts of glutaraldehyde with the mass concentration of 25% in 100 parts of water to prepare glutaraldehyde solution;
mixing the sodium alginate solution with glutaraldehyde solution to obtain a mixed solution, and adding the polymer dye solution and the gelatin solution into the mixed solution to prepare the hydrogel.
The mass ratio of the chitosan to the gelatin is 1:0.5; the volume ratio of the sodium alginate solution to the glutaraldehyde solution in the mixed solution is 1:0.5.
3. pH detection using hydrogels
Preparing a standard solution with the pH of 1-12, putting the prepared hydrogel into the standard solution, displaying different colors on the hydrogel, as shown in fig. 6, reading RGB data by using a mobile phone to perform photographing analysis, drawing a standard curve according to data analysis of three signals of RGB, as shown in fig. 7-9, obtaining the relationship between RGB and pH, and in subsequent use, obtaining RGB data by photographing, and finding the corresponding pH according to the standard curve.
Example 2
The preparation of the phenol red chitosan polymer dye was the same as in example 1;
the intelligent hydrogel indicating the pH was prepared as in example 1, except that the volume ratio of the sodium alginate solution to the glutaraldehyde solution in the mixed solution was 1:0.25.
example 3
The preparation of the phenol red chitosan polymer dye was the same as in example 1;
the intelligent hydrogel indicating the pH was prepared as in example 1, except that the volume ratio of the sodium alginate solution to the glutaraldehyde solution in the mixed solution was 1:1.
example 4
The preparation of the phenol red chitosan polymer dye was the same as in example 1;
the intelligent hydrogel indicating the pH was prepared as in example 1, except that the volume ratio of the sodium alginate solution to the glutaraldehyde solution in the mixed solution was 1:2.
example 5
The preparation of the phenol red chitosan polymer dye was the same as in example 1;
the intelligent hydrogel indicating pH was prepared as in example 1, except that the mass ratio of chitosan to gelatin was 1:0.25.
example 6
The preparation of the phenol red chitosan polymer dye was the same as in example 1;
the intelligent hydrogel indicating pH was prepared as in example 1, except that the mass ratio of chitosan to gelatin was 1:0.75.
example 7
The preparation of the phenol red chitosan polymer dye was the same as in example 1;
the intelligent hydrogel indicating pH was prepared as in example 1, except that the mass ratio of chitosan to gelatin was 1:1.
example 8
The preparation of the phenol red chitosan polymer dye was the same as in example 1;
the intelligent hydrogel indicating pH was prepared as in example 1, except that the mass ratio of chitosan to gelatin was 1:2.
example 9
The preparation of the phenol red chitosan polymer dye was the same as in example 1;
the intelligent hydrogel indicating pH was prepared as in example 1, except that the mass ratio of chitosan to gelatin was 1:3.
performance testing
The hydrogel prepared in example 1 was tested for stability and sensitivity, and specific:
1. storing the hydrogel in an aqueous solution, and measuring the absorbance of the solution, wherein the absorbance is unchanged after the storage for 7 days as shown in figure 3, which shows that the stability is good and the leakage is avoided;
2. the hydrogel is stored for 7 days, and the hydrogel is put into a solution with the same pH, as shown in figure 4 (wherein the left column represents the RGB data of the hydrogel when the pH of the solution is 6.5, and the right column represents the RGB data of the hydrogel when the pH is 9), so that the RGB data of the hydrogel is unchanged, and the storage stability is good;
3. the pH of the solution is changed to obtain the color change time of the phenol red and the hydrogel after the pH change, and as shown in figure 5, the color of the phenol red and the color of the hydrogel are rapidly changed along with the pH change, which indicates that the sensitivity of the hydrogel prepared by the technical scheme is consistent with the sensitivity of the phenol red indicator.
The mechanical strength test and the swelling ratio test are carried out on the hydrogels prepared in examples 1-4, and the results are shown in fig. 10 and 11, and it can be found that the hydrogels have better mechanical strength and swelling ratio when the volume ratio of the sodium alginate solution to the glutaraldehyde solution is 1:0.5.
As can be seen from the graph 12, the hydrogel prepared in examples 1 and 5-9 has short development time and high sensitivity when the mass ratio of chitosan to gelatin is 1:0.5.
Claims (5)
1. A method for preparing a hydrogel, comprising:
the preparation method of the polymer dye comprises the steps of combining phenol red and chitosan through a Mannich reaction to generate an alkylamine derivative, and obtaining the polymer dye;
the preparation method comprises the steps of preparing a polymer dye solution, a gelatin solution, a sodium alginate solution and a glutaraldehyde solution respectively, mixing the sodium alginate solution and the glutaraldehyde solution to obtain a mixed solution, and adding the polymer dye solution and the gelatin solution into the mixed solution to prepare the hydrogel;
preparing a polymer dye solution, which comprises dissolving the polymer dye and chitosan in acetic acid to obtain the polymer dye solution;
the preparation method of the polymer dye specifically comprises the following steps:
dissolving 1 part of phenol red in 50 parts of N, N-dimethylformamide and 0.04 part of formaldehyde in a reaction vessel to obtain a phenol red formaldehyde solution;
1 part of chitosan is dissolved in 100 parts of 1% acetic acid to obtain chitosan solution;
adding the phenol red formaldehyde solution into the chitosan solution, stirring at a constant speed of 60 ℃, and reacting for 24 hours to obtain a reacted solution;
adding 1M NaOH into the reacted solution to obtain precipitate, centrifugally filtering, washing with ethanol, and drying in an oven at 60 ℃ to obtain the polymer dye;
in the hydrogel preparation step
The preparation of sodium alginate solution comprises the following steps: 1 part of sodium alginate is dissolved in 100 parts of water to obtain sodium alginate solution;
the preparation of glutaraldehyde solution in the hydrogel preparation step comprises: dissolving 4 parts of glutaraldehyde with the mass concentration of 25% in 100 parts of water to prepare glutaraldehyde solution;
the volume ratio of the sodium alginate solution to the glutaraldehyde solution in the mixed solution is 1:0.25-2;
the preparation of the polymer dye solution specifically comprises the following steps: 1 part of chitosan and 0.02 part of the polymer dye are dissolved in 100 parts of 1% acetic acid, and the mixture is stirred at room temperature overnight to obtain a polymer dye solution;
the preparation of the gelatin solution comprises: dissolving 1 part of gelatin in 100 parts of water to obtain a gelatin solution;
the mass ratio of the chitosan to the gelatin is 1:0.25-3.
2. A hydrogel prepared by the method of claim 1.
3. Use of a hydrogel for pH detection, wherein the hydrogel is prepared according to claim 1.
4. Use of a hydrogel according to claim 3 for pH detection, comprising:
preparing a standard solution with the pH value of 1-12, putting the prepared hydrogel into the standard solution, displaying different colors on the hydrogel, reading RGB data by using a mobile phone to perform photographing analysis, drawing a standard curve according to data analysis of three signals of RGB, obtaining the relationship between RGB and pH, photographing to obtain RGB data in subsequent use, and finding out the corresponding pH according to the standard curve.
5. The use of the hydrogel according to claim 4 for pH detection, wherein the hydrogel is a hydrogel sphere.
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