Dressing material for naked eye visual wound infection monitoring and preparation method thereof

Abstract

The invention discloses a dressing material for naked eye visual wound infection monitoring and a preparation method thereof, and the preparation method comprises the following steps: adding thionyl chloride into a mixed system of carboxymethyl cellulose fiber and a solvent to obtain acylating chlorinated carboxymethyl cellulose fiber so as to activate carboxyl; and mixing the carboxymethyl cellulose fibers with pH-responsive color-changing dyes such as bromothymol blue or phenol red, and heating to react, so as to obtain the carboxymethyl cellulose fibers covalently grafted with the pH-responsive color-changing dyes. Carboxyl on carboxymethyl cellulose is subjected to acylating chlorination, the reaction activity of the site is improved, the site can chemically react with phenolic hydroxyl on the pH-responsive color-changing dye, the carboxymethyl cellulose fiber covalently grafted with the pH-responsive color-changing dye is obtained, the risk of dye exudation is greatly reduced, and excellent safety is achieved. The dressing material obtained by the invention has an excellent pH-responsive discoloration function, can generate pH-responsive discoloration in a key pH range (pH 6-8) of wound infection indication, achieves the purpose of wound infection indication, and has a wide actual clinical application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of medical dressing materials, and in particular to a dressing material for naked-eye visualized wound infection monitoring and a preparation method thereof. Background Art

[0002] Real-time monitoring of wound status, especially early diagnosis of bacterial infection in wounds, is becoming increasingly important in modern healthcare systems. However, wound infection is a continuous process. When clinical symptoms such as redness, swelling, wound ulceration, and odor appear, the wound has already experienced unexpected delayed healing, which will further cause the spread of infection throughout the body. Clinical infection diagnosis often relies on doctors or nurses to visually observe clinical symptoms, which is subjective and delayed; or to perform wound microbial culture to identify infectious pathogens, which is time-consuming and easily delays treatment, leading to the spread of infection. Therefore, based on the above background, early prevention of infection and continuous monitoring of wound infection status are of great clinical significance.

[0003] Since the dynamic changes of specific biochemical substances can be used to gain insight into the different states of wounds, researchers have used some biochemical substances, such as temperature, pH, reactive oxygen species, uric acid, bacterial toxins, etc., as biomarkers to construct biosensors to monitor the infection status of wounds. Among them, pH, as one of the most effective and simplest biomarkers, has been widely used to construct biosensors to monitor the infection status of wounds. The pH value of a normally healing wound or normal skin is slightly acidic (pH: 4-6). Most pathogenic microorganisms require an alkaline environment to promote their colonization and growth. The pH value of difficult-to-heal wounds is maintained under alkaline conditions for a long time (pH: 7-9), which makes them more susceptible to bacterial infection. Therefore, monitoring the pH value of the wound surface is of great significance for early warning of infection risks.

[0004] Sensors for detecting wound pH mainly include electrochemical and colorimetric sensors. Colorimetric sensors are more attractive because they usually have a lower cost and can directly read visual signals. For example, patent CN118806982A discloses a hydrogel dressing prepared with berberine hydrochloride loaded with biocompatible polyvinyl alcohol and sodium alginate to produce a fluorescent AIE effect. When there is bacterial infection in the wound, the material undergoes a corresponding color change under visible light and emits green fluorescence under ultraviolet light (preferably 365nm). The fluorescence intensity is linearly related to the pH of the wound. The degree of infection can be identified and judged by naked eye observation or smart phone, realizing in situ and rapid detection of bacterial infection in the wound. However, this method relies on berberine hydrochloride molecules to achieve wound pH indication, and only displays color in the red channel under visible light, which is easily affected by the color of the wound exudate itself; and the emission of green fluorescence is limited by the presence of ultraviolet light, which greatly reduces its clinical application prospects.

[0005] Introducing pH-responsive dyes into materials is one of the most common strategies for constructing pH-responsive colorimetric sensors. For example, CN114159615A blends water-soluble pH-responsive dyes such as anthocyanins, curcumin, and phenol red into a polymer hydrogel to detect the pH of exudate from wound surfaces. However, the resulting dressing carries a high risk of dye exudation.

[0006] Therefore, based on the visual infection indication function and biosafety requirements, preparing wound dressing materials with intuitive visual pH indication function and avoiding safety issues caused by dye leakage is of great significance for promoting its actual clinical application. Summary of the Invention

[0007] The purpose of the present invention is to address the above-mentioned problems and provide a dressing material for naked eye visualization of wound infection monitoring and a preparation method thereof, which has practical engineering application prospects in the field of wound infection diagnosis.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A dressing material for naked-eye visualization of wound infection monitoring, the raw materials of the dressing material comprising: cellulose fiber material and pH-responsive color-changing dye.

[0010] The fiber material is carboxymethyl cellulose fiber (CMC).

[0011] The pH-responsive color-changing dye is preferably bromothymol blue (BTB) or phenol red (PR). The pH-responsive color-changing dye can indicate wound infection while effectively avoiding interference from exudate and blood colors, and can effectively enhance naked eye observation.

[0012] A method for preparing a dressing material for naked eye visualization of wound infection monitoring comprises the following steps:

[0013] Step 1. Preparation of chlorinated carboxymethyl cellulose fibers (CMC-COCl):

[0014] CMC, ultra-dry pyridine and ultra-dry N,N-dimethylformamide are mixed and stirred, thionyl chloride is added, and the mixture is heated and stirred for a certain period of time, and then cooled to room temperature; filtered, washed with appropriate amounts of ultra-dry N,N-dimethylformamide, acetone and ultra-dry dichloromethane, and dried under reduced pressure to obtain CMC-COCl.

[0015] Step 2. Preparation of CMC material with pH indicator function:

[0016] The CMC-COCl obtained in step 1 and the pH-responsive color-changing dye are added to ultra-dry pyridine, and the reaction is carried out under temperature-controlled stirring for a certain period of time, followed by filtration, washing with anhydrous ethanol, and drying under reduced pressure to obtain carboxymethyl cellulose fibers covalently grafted with the pH-responsive color-changing dye.

[0017] The present invention achieves chlorination of the carboxyl groups on CMC by adding thionyl chloride, enhancing the reactivity of the carboxyl groups, which then undergo an esterification reaction with the phenolic hydroxyl groups of a pH-responsive color-changing dye, resulting in carboxymethyl cellulose fibers covalently grafted with the pH-responsive color-changing dye. The fiber dressing material obtained by this method exhibits excellent color development properties, high pH sensitivity from acid to alkaline, good safety, low cost, stable material for long-term storage, and easy-to-perform preparation procedures. This method can provide clinical patients with an economical, convenient, and rapid infection indicator tool.

[0018] In step 1, the mass ratio of the added volume of thionyl chloride to CMC is 3:1-6 (v / w), the mass ratio of CMC to super-dry pyridine is 1:20-80 (w / v), and the volume ratio of super-dry pyridine to super-dry N, N-dimethylformamide is 1-5:1. Complexation occurs between super-dry N, N-dimethylformamide and thionyl chloride to activate the carboxyl groups on the carboxymethyl cellulose, and further addition elimination reaction is performed to obtain chlorinated carboxymethyl cellulose fibers. Super-dry pyridine, as a solvent, has the further advantage of being a proton scavenger, avoiding unnecessary generation of hydrogen chloride during the reaction.

[0019] The heating temperature in step 1 is 40-100° C., and the heating time is 1-6 h.

[0020] In step 2, the pH-responsive color-changing dye is BTB or PR, the volume ratio of the mass of CMC-COCl to the ultra-dry pyridine is 1:10-100 (w / v), and the mass ratio of the pH-responsive color-changing dye to CMC-COCl is 1-18:3.

[0021] The esterification reaction in step 2 is carried out at 5-60° C. for 4-48 hours. The chlorinated carboxyl groups on the CMC react with the phenolic hydroxyl groups on the pH-responsive color-changing dye to produce carboxymethyl cellulose fibers covalently grafted with the pH-responsive dye. The reaction conditions are mild and the operation is simple.

[0022] The present invention also provides a pH-responsive color-changing dressing material prepared by the preparation method.

[0023] The present invention also provides application of the pH-responsive color-changing dressing material in the preparation of dressing materials for wound infection monitoring.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The dressing material obtained by the present invention introduces the pH-responsive color-changing dye into the polymer chain through covalent grafting of chemical bonds, which greatly reduces the risk of dye leakage.

[0026] (2) The fiber materials and pH-responsive color-changing dyes used in the preparation of the dressing material obtained by the present invention are both inexpensive, and the preparation process is conventional and easy to operate, with broad engineering prospects.

[0027] (3) The dressing material obtained by the present invention amplifies the pH change of the wound by colorimetrically amplifying the pH change of the wound through the material having the pH color indicating function, and finally amplifies the wound infection that is difficult to detect into a color change that is visually discernible to the naked eye. It can meet the needs of actual clinical application in monitoring the wound infection status, is conducive to the early detection of wound infection, avoids further deterioration of infection, and reduces the physiological and economic burden on patients. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 1 is the reaction equation diagram in Example 1 of the present invention.

[0029] Figure 2 This is an infrared spectrum result diagram of the pH indicating dressing material CB synthesized by the method of the present invention in Example 1 of the present invention, wherein the labeled CMC corresponds to the infrared spectrum of carboxymethyl cellulose fiber, CMC-COCl corresponds to the infrared spectrum of chlorinated carboxymethyl cellulose fiber, and CB corresponds to the infrared spectrum of the pH indicating dressing material CB grafted with BTB.

[0030] Figure 3 This is an X-ray photoelectron spectrometer (XPS) result diagram of the pH indicating dressing material synthesized by the method of the present invention, wherein the marked CMC corresponds to the XPS curve of carboxymethyl cellulose fiber, CMC-COCl corresponds to the XPS curve of chlorinated carboxymethyl cellulose fiber, CB corresponds to the XPS curve of the pH indicating dressing material CB grafted with BTB; CP corresponds to the XPS curve of the pH indicating dressing material CP grafted with PR.

[0031] Figure 4 This is a field emission scanning electron microscope (SEM) image of the pH indicating dressing material CB synthesized by the method of the present invention in Example 1 of the present invention, wherein the label CMC corresponds to the SEM image of carboxymethyl cellulose fiber, and CB corresponds to the SEM image of the pH indicating dressing material CB grafted with BTB.

[0032] Figure 5 The color change diagram of the pH indicator dressing material CB grafted with BTB after adding an equal amount of PBS buffer with a pH of 6.0-8.0.

[0033] Figure 6This is a comparison chart of dye leakage test results when equal amounts of fiber materials obtained in Example 1 and Comparative Example 1 were immersed in equal amounts of PBS buffer (pH=7.4). DETAILED DESCRIPTION

[0034] In order to make the content of the present invention clearer, the present invention will be further described below in conjunction with Examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Those skilled in the art will modify or make equivalent replacements based on understanding the technical solution of the present invention, without departing from the spirit and scope of the technical solution of the present invention, and all should be encompassed within the protection scope of the present invention. The experimental materials used in the following examples are all commercially available unless otherwise specified, and the experimental steps are all standard steps unless otherwise specified.

[0035] Example 1:

[0036] The reaction formula of carboxymethyl cellulose fiber chlorination and covalent grafting pH-responsive color-changing dye BTB is as follows: Figure 1 shown.

[0037] (1) Acylation of carboxymethyl cellulose: Weigh 1 g of CMC and add it to a mixture of 60 mL of ultra-dry pyridine and 50 mL of ultra-dry N,N-dimethylformamide. Stir and dropwise add 1 mL of thionyl chloride to the mixture. Stir the reaction mixture at 85°C for 1 h. Cool the reaction mixture, filter it, and wash it with ultra-dry N,N-dimethylformamide, acetone, and ultra-dry methane. The reaction product is dried under reduced pressure at room temperature to obtain a yellow product, CMC-COCl.

[0038] (2) Covalent grafting of pH-responsive color-changing dyes: BTB-grafted CB was obtained via an esterification reaction between acyl chloride groups and phenolic hydroxyl groups. The specific steps are as follows: 1 g of CMC-COCl, 4 g of BTB, and 60 mL of ultra-dry pyridine were mixed and stirred at 5°C for 6 h. The mixture was filtered, washed with anhydrous ethanol, and dried under reduced pressure at room temperature to obtain an orange fiber product, CB.

[0039] Example 2:

[0040] (1) Acylation of carboxymethyl cellulose: The preparation method is the same as that in Example 1.

[0041] (2) Covalent grafting of pH-responsive color-changing dye: The pH-responsive dye is PR, and the remaining steps are the same as in Example 1.

[0042] Example 3:

[0043] (1) Chlorination of carboxymethyl cellulose: the heating temperature was changed to 100° C. and the heating time was changed to 4 h. The remaining steps were the same as in Example 1.

[0044] (2) Covalent grafting of pH-responsive color-changing dye: The preparation method is the same as that in Example 1.

[0045] Comparative Example 1:

[0046] 1 g of CMC and 4 g of BTB were mixed in 60 mL of ultra-dry pyridine, stirred at 25° C. for 6 h, filtered, washed with anhydrous ethanol, and dried under reduced pressure at room temperature to obtain a yellow fiber product.

[0047] 1. Characterization of the structure and morphology of carboxymethyl cellulose fibers covalently grafted with pH-responsive color-changing dyes

[0048] The structure and morphology of the fiber material obtained by grafting pH-responsive color-changing dye onto CMC were characterized by Fourier transform infrared spectroscopy (FT-IR), XPS and SEM.

[0049] (1) FT-IR was performed using a NICOLET iS50 spectrophotometer (Thermo Scientific, USA) equipped with an ATR (attenuated total reflectance) accessory. The CB material obtained in Example 1 was characterized by FT-IR. Figure 2 As shown, 3347, 3393 and 3382 cm -1 The stretching vibrations of OH groups in CMC, CMC-COCl, and CB molecules are 2917, 2928, and 2880 cm -1 The stretching vibration of the C=O of the carboxyl group in the CMC molecule is located at 1586 cm -1 After acyl chloride modification, the infrared spectrum of CMC-COCl molecule is newly located at 1747 cm -1 The characteristic peak is due to the stretching vibration of C=O of -COCl. After the esterification reaction, the intensity of the carboxyl peak of the CB molecule is significantly weakened compared with that of CMC-COCl, and the stretching vibration of C=O representing the ester group is located at 1733 cm -1 , proving the successful occurrence of the esterification reaction of the grafted BTB dye.

[0050] (2) XPS was performed using a Thermo Scientific K-Alpha instrument from the United States. XPS characterization was performed on the CB and CP materials obtained in Example 1 and Example 2. Figure 3As shown in the figure, compared to CMC, the XPS curve of the CMC-COCl molecule has a new characteristic peak representing Cl 2p at 200eV, confirming the successful occurrence of the chlorination reaction. After the esterification reaction, the characteristic peak representing Cl 2p disappears in the XPS curves of the CB and CP molecules, while a characteristic peak representing S2p in the pH-responsive dye molecules BTB and PR clearly appears at 169eV, further proving that the pH-responsive dye molecules BTB and PR were successfully grafted onto the CMC molecules after chlorination through the esterification reaction.

[0051] (3) SEM was performed using an instrument model SU 8600 (Hitachi). The surface morphology of the CB material obtained in Example 1 was observed using SEM. Figure 4 It can be seen that the covalent grafting of BTB dye did not cause significant changes in the surface morphology of carboxymethyl cellulose fibers.

[0052] 2. Verification of the pH-responsive color-changing performance of carboxymethyl cellulose fibers covalently grafted with pH-responsive color-changing dyes in vitro

[0053] The CB material obtained in Example 1 was cut into 5 experimental samples and 1 blank control sample of substantially the same shape and size. Equal amounts of PBS buffer solutions with pH values ​​of 6.0, 6.5, 7.0, 7.5, and 8.0 were added dropwise to the 5 experimental samples. After 30 seconds, the color change of the fiber material was observed and photographed. Figure 5 As shown, the CB material exhibits yellow color at acidic pH (pH = 6.0, 6.5); at neutral pH (pH = 7.0), the CB fibers turn green; and as the pH becomes alkaline (pH = 7.5, 8.0), the color of the CB material further changes from green to blue. This validation experiment demonstrates that carboxymethyl cellulose fibers covalently grafted with BTB dye exhibit excellent pH-responsive color change properties, capable of visually reflecting the pH transition from acidic to alkaline via a color change from yellow to green and then to blue, as seen with the naked eye. When an infection occurs, the pH of a wound shifts from a normal pH state (pH: 4-6) to an alkaline pH state (pH: 7-9). This CB dressing material can indicate changes in wound pH through a color change from yellow to green, as seen with the naked eye. Furthermore, the green and blue colors clearly distinguish the common yellowish color of wound exudate or the red color of blood, preventing interference with the color indication of the indicator dressing from exudate and blood. In summary, the CB dressing material obtained in Example 1 has good pH-responsive color-changing performance, can achieve intuitive and clear pH indication of wound infection, and has great potential for practical clinical application.

[0054] 3. Dye exudation experiment of carboxymethyl cellulose fiber covalently grafted with pH-responsive color-changing dye

[0055] The same mass of the CB material obtained in Example 1 and the fiber material obtained in Comparative Example 1 were respectively immersed in the same amount of PBS buffer (pH=7.4), and photographed and recorded after 6 hours. Figure 6 As shown, in Example 1, the CB material obtained by covalently grafting BTB dye remained orange after immersion for 6 hours, and the supernatant was clear and colorless. In contrast, in Comparative Example 1, the fiber material obtained by physically blending CMC with BTB dye showed significant discoloration, with the supernatant turning significantly blue. This exudation experiment demonstrates that, compared to physical blending with BTB dye, the preparation method of the present invention, through chemical covalent grafting of BTB dye, effectively prevents dye exudation, thus avoiding the safety issues associated with dye exudation.

[0056] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a dressing material for naked eye visualization of wound infection monitoring, characterized in that: The method includes adding thionyl chloride to a mixed system of carboxymethyl cellulose fiber and a solvent to obtain chlorinated carboxymethyl cellulose fiber to activate the carboxyl group; then mixing with a pH-responsive color-changing dye and heating the mixture to obtain carboxymethyl cellulose fiber covalently grafted with a pH-responsive color-changing dye, which can be used for naked eye visualization of wound infection monitoring.

2. The method for preparing a dressing material for naked eye visualization wound infection monitoring according to claim 1, characterized in that: The specific steps include: Step 1, preparing chlorinated carboxymethyl cellulose fiber (CMC-COCl): carboxymethyl cellulose fiber (CMC), ultra-dry pyridine and ultra-dry N,N-dimethylformamide are mixed and stirred, thionyl chloride is added, heated and stirred for a certain period of time, and then cooled to room temperature; filtered, washed with appropriate amounts of ultra-dry N,N-dimethylformamide, acetone and ultra-dry dichloromethane, and dried under reduced pressure to obtain CMC-COCl; Step 2, preparing a CMC material with a pH indicating function: adding the CMC-COCl obtained in step 1 and a pH-responsive color-changing dye to ultra-dry pyridine, controlling the temperature and stirring to react for a certain period of time, filtering, washing with anhydrous ethanol, and drying under reduced pressure to obtain carboxymethyl cellulose fibers covalently grafted with a pH-responsive color-changing dye.

3. The method for preparing a dressing material for naked eye visualization wound infection monitoring according to claim 2, characterized in that: The pH-responsive color-changing dye is one or more of bromothymol blue (BTB) and phenol red (PR) containing phenolic hydroxyl groups.

4. The method for preparing a dressing material for naked eye visualization wound infection monitoring according to claim 2, characterized in that: In the step 1, the mass ratio of the added volume of thionyl chloride to CMC is 3:1-6 (v / w), the mass ratio of CMC to ultra-dry pyridine is 1:20-80 (w / v), and the volume ratio of ultra-dry pyridine to ultra-dry N,N-dimethylformamide is 1-5:

1.

5. The method for preparing a dressing material for naked eye visualization wound infection monitoring according to claim 2, characterized in that: In the step 1, the heating temperature is 40-100° C. and the heating time is 1-6 hours.

6. The method for preparing a dressing material for naked eye visualization wound infection monitoring according to claim 2, characterized in that: In the step 2, the mass ratio of CMC-COCl to ultra-dry pyridine is 1:10-100 (w / v), and the mass ratio of pH-responsive color-changing dye to CMC is 1-18:

3.

7. The method for preparing a dressing material for naked eye visualization wound infection monitoring according to claim 2, characterized in that: In the step 2, the reaction temperature is 5-60° C., and the reaction time is 4-48 h.

8. A pH-responsive color-changing dressing, characterized in that: Contains a material prepared by the method according to any one of claims 1 to 7.

9. Use of the pH-responsive color-changing dressing according to claim 8 in the preparation of a wound infection monitoring dressing.

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