High-strength CBM-g-CMC + CNF antibacterial composite membrane as well as preparation method and application thereof

Abstract

The invention discloses a high-strength CBM-g-CMC + CNF antibacterial composite membrane and a preparation method and application thereof.The preparation method comprises the steps that EDC is added into a CMC solution, magnetic stirring is conducted for 1 h at the temperature of 60 DEG C, then NHS and 0.5% of carbohydrate are added to combine with a module 3, stirring is conducted for 24 h in the nitrogen atmosphere at the temperature of 22 DEG C, dialysis is conducted, and a CBM-g-CMC composite material is obtained; the CBM-g-CMC material and a CNF solution are mixed in proportion, after a CBM-g-CMC + CNF mixed solution is prepared, hexadecyl trimethyl ammonium bromide is added, and a co-deposition reaction solution is formed; and after ultrasonic treatment and vacuumizing treatment, carrying out suction filtration by using a filter membrane, and drying to obtain the CBM-g-CMC + CNF composite film. The CBM is firstly conjugated with a carboxymethyl cellulose (CMC) molecular chain through an amido bond to form a covalent integrated structure CBM-g-CMC, and then the CBM-g-CMC is adsorbed to the surfaces of cellulose nanofibers (CNFs) by virtue of the specific adsorption function of the CBM. The double modification of CNF and CBM not only improves the mechanical strength and thermal stability of the CMC membrane, but also improves the moisture insulation performance and surface hydrophobicity of the CMC membrane, and expands the application range of the CMC base membrane in various scenes with strict requirements on moisture control and surface performance.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of carboxymethyl cellulose-based composite films, and in particular to a high-strength CBM-g-CMC+CNF antibacterial composite film and a preparation method and application thereof. Background Art

[0002] Carboxymethyl cellulose (CMC) is an important polysaccharide derivative obtained by chemical modification of cellulose. It has excellent water solubility, film-forming ability and hydrocolloid properties, and has broad application prospects in food packaging, biomedicine, smart gels and other fields. Carboxymethyl cellulose (CMC) has good adhesion to human dermal fibroblasts and promotes cell proliferation. It can absorb exudates, promote angiogenesis and autolysis and debridement, and is widely used in antimicrobial agent carriers, wound dressings and related fields. However, the mechanical properties of pure CMC film are poor and lack antibacterial properties. Existing CMC dressing materials are mostly used to cover wounds to promote healing, and are rarely used specifically in skin surface care materials, which limits their application scenarios.

[0003] Carbohydrate binding modules (CBMs) are independent, non-catalytic domains found widely in carbohydrate-activated enzymes (CAZymes). Their primary function is to precisely direct the attached catalytic module to the target substrate, thereby enhancing the enzyme's ability to bind to the substrate. They possess highly specific recognition and selective affinity. To further enhance the mechanical properties of CMC-based membranes, a CBM grafting method was employed. CBMs were first conjugated to CMC molecular chains via amides to form a covalently integrated structure. The CBMs then utilized their specific adsorption to adsorb onto cellulose nanofibers (CNFs), improving the mechanical strength of CMC-based films and broadening their application areas. Summary of the Invention

[0004] Technical Problem: The present invention provides a high-strength CBM-g-CMC+CNF antibacterial composite membrane, its preparation method, and application. By utilizing the specific recognition ability and selective affinity of carbohydrate binding modules (CBM) and cellulose fibers, the CBM (cellulose binding module) is first conjugated to the CMC (carboxymethyl cellulose) molecular chain through an amide bond to form a covalently integrated structure. Subsequently, with the help of the specific adsorption function of the CBM, it is adsorbed to the surface of cellulose nanofibers (CNFs). Due to the dual modification effects of CBM and CNF, the prepared CBM-g-CMC+CNF composite membrane significantly improves mechanical properties and stability while retaining the core functions of traditional wound dressings (such as water vapor permeability, moisture retention, and cytocompatibility), while also possessing antibacterial properties.

[0005] Technical solution: To solve the above technical problems, the present invention provides a method for preparing a high-strength CBM-g-CMC+CNF antibacterial composite film, comprising the following steps:

[0006] S1 grafting: 1-Ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC) was added to the CMC solution and magnetically stirred at 60°C for 1 hour. N-hydroxysuccinimide (NHS) and a carbohydrate binding module (CBM) were then added. The mixture was stirred at 22°C under a nitrogen atmosphere for 24 hours, and unreacted EDC, NHS, and other small molecule reagents were removed by dialysis to obtain a CBM-g-CMC composite material.

[0007] S2 blending: CBM-g-CMC material and CNF solution were mixed in a certain proportion and magnetically stirred for 6 hours to ensure uniform dispersion to prepare CBM-g-CMC + CNF mixed solution;

[0008] S3 antibacterial modification: The antibacterial agent was added to the CBM-g-CMC+CNF solution and treated at 25°C and a vibration rate of 100 rpm for 1 hour to form a co-deposition reaction solution.

[0009] S4 Film Formation: The co-deposition reaction solution was ultrasonically treated and vacuumed to remove air bubbles. The solution was then filtered through a hydrophilic filter membrane and dried to produce a CBM-g-CMC+CNF composite film.

[0010] Furthermore, the concentration of the carbohydrate binding module in step S1 is 0.9 mg / ml, and the amount of the carbohydrate binding module added is 0.5%-2%.

[0011] Furthermore, in the grafting step S1, the carbohydrate binding module CBM is one or more of CBM1, CBM2, and CBM3.

[0012] Furthermore, the solid content of CNF in step S2 is 0.5%-5%.

[0013] Furthermore, in step S2, the volume ratio of CBM-g-CMC to CNF is 1:1-1:10.

[0014] Furthermore, the antibacterial agent in step S3 is one or more of cetyltrimethylammonium bromide (CTAB), penicillin, nano silver ions, and chitosan.

[0015] The present invention also provides the above-mentioned high-strength CBM-g - The CBM-g-CMC+CNF antibacterial composite membrane is obtained by the CMC+CNF antibacterial composite membrane preparation method.

[0016] The present invention also provides the use of the CBM-g-CMC+CNF antibacterial composite film obtained by the above-mentioned high-strength CBM-g-CMC+CNF antibacterial composite film preparation method in medical dressings and packaging.

[0017] CBMs have a specific adsorption capacity for cellulose, allowing them to immobilize and adsorb CNFs within the amidated CBM-g-CMC. The high aspect ratio and strong stiffness of CNFs further strengthen the composite film. The conjugation of CBMs not only enhances the internal cohesion of the matrix but also enhances its strength through specific adsorption when combined with CNFs. This system effectively improves the structural integrity and mechanical properties of CMC-based films.

[0018] Beneficial effects: Compared with the prior art, the technical solution of the present invention has the following beneficial effects: the present invention utilizes the amidation of CBM and CMC to improve the mechanical properties of the CMC base film, and at the same time, CNF is blended with the amidated CBM-g-CMC film. Due to the high aspect ratio and good rigidity of CNF, the mechanical properties of the CMC base film are further improved. Due to the dual effects of CBM and CNF, the obtained CBM-g-CMC+CNF composite film has high mechanical strength, good tensile strength and environmental stability, which expands the application field of the CMC base film.

[0019] The CBM and CNF prepared by the present invention are used in combination with CTAB to enhance the antibacterial effect. The prepared composite film has good antibacterial properties and significantly improves the antibacterial activity against Escherichia coli and Staphylococcus aureus. It can be used in the fields of medical excipients and food packaging.

[0020] The dual modification of CNF and CBM in the present invention not only improves the mechanical strength and thermal stability of the CMC membrane, but also improves its moisture barrier performance and surface hydrophobicity, expanding the application of CMC-based membranes in various scenarios with strict requirements on moisture control and surface performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the total reflection Fourier transform infrared (ATR-FTIR) spectra (pure CMC (blue line), CBM (black line) and CBM-g-CMC (red line)).

[0022] Figure 2 This is the XPS analysis diagram (pure CMC film (black curve) and CBM-g-CMC (red curve))

[0023] Figure 3 Mechanical properties of CMC-based films: (a) dry strength, (b) wet strength, (c) alkaline pH, and (d) acidic pH conditions.

[0024] Figure 4 This is a graph showing the burst resistance of CMC films.

[0025] Figure 5 This is the thermal stability analysis diagram of CMC base film (a is TGA curve, b is DTG curve)

[0026] Figure 6 These are antibacterial test diagrams (Group a is Escherichia coli, Group b is Staphylococcus aureus experiment; No. 1 is the blank control group, 2 is pure CMC, 3 is CMC+CTAB (i.e. CTAB is added to CMC), 4 is CBM-g-CMC+CTAB, i.e. CTAB-modified CBM-g-CMC composite liquid, and 5 is CBM-g-CMC+CNF+CTAB, i.e. CBM-g-CMC+CNF composite liquid modified with CTAB).

[0027] Figure 7 (a) Water vapor and (b) water contact angle diagrams of CMC-based membranes (orange is CMC, green is CMC+CNF, purple is CBM-g-CMC+CNF, and yellow is CMC+CBM+CNF).

[0028] (+ represents blending, -g- represents conjugated grafting) DETAILED DESCRIPTION

[0029] The technical solution of the present invention is described in detail below with reference to the accompanying drawings.

[0030] Example 1

[0031] S1 grafting: 1-Ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC, 5.0 mmol) was added to a 0.1% CMC solution and magnetically stirred at 60°C for 1 h. N-hydroxysuccinimide (NHS, 5.0 mmol) and 0.5% carbohydrate binding module 3 (CBM3, 0.9 mg / ml) were then added. The mixture was stirred at 22°C under a nitrogen atmosphere for 24 h and then dialyzed to remove unreacted EDC, NHS, and other small molecule reagents to obtain a CBM-g-CMC composite.

[0032] S2 blending: CBM-g-CMC material and CNF solution were mixed in the ratio of 1:1, 1:5, 1:8, and 1:10, respectively, and magnetically stirred for 6 hours to ensure uniform dispersion to prepare CBM-g-CMC + CNF mixed solution;

[0033] S3 antibacterial modification: cetyltrimethylammonium bromide (CTAB) was added to the CBM-g-CMC+CNF solution and treated at 25°C and a vibration rate of 100 rpm for 1 hour to form a co-deposition reaction solution.

[0034] S4 Film Formation: The co-deposition reaction solution was ultrasonically treated and vacuumed to remove air bubbles. The solution was then filtered through a 0.22 μm hydrophilic filter membrane and dried to produce a CBM-g-CMC+CNF composite film.

[0035] Example 2

[0036] S1 grafting: 1-Ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC, 5.0 mmol) was added to a 1% CMC solution and magnetically stirred at 60°C for 1 h. N-hydroxysuccinimide (NHS, 5.0 mmol) and 0.8% carbohydrate binding module 3 (CBM3, 0.9 mg / ml) were then added. The mixture was stirred at 22°C under a nitrogen atmosphere for 24 h, and unreacted EDC, NHS, and other small molecule reagents were removed by dialysis to obtain a CBM-g-CMC composite.

[0037] S2 blending: CBM-g-CMC material and CNF solution were mixed in the ratio of 1:1, 1:5, 1:8, and 1:10, respectively, and magnetically stirred for 6 hours to ensure uniform dispersion to prepare CBM-g-CMC + CNF mixed solution;

[0038] S3 antibacterial modification: cetyltrimethylammonium bromide (CTAB) was added to the CBM-g-CMC+CNF solution and treated at 25°C and a vibration rate of 100 rpm for 1 hour to form a co-deposition reaction solution.

[0039] S4 Film Formation: The co-deposition reaction solution was ultrasonically treated and vacuumed to remove air bubbles. The solution was then filtered through a 0.22 μm hydrophilic filter membrane and dried to produce a CBM-G-CMC+CNF composite film.

[0040] Example 3

[0041] S1 grafting: 1-Ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC, 5.0 mmol) was added to a 1% CMC solution and magnetically stirred at 60°C for 1 h. N-hydroxysuccinimide (NHS, 5.0 mmol) and 2% carbohydrate binding module 3 (CBM3, 0.9 mg / ml) were then added. The mixture was stirred at 22°C under a nitrogen atmosphere for 24 h, and unreacted EDC, NHS, and other small molecule reagents were removed by dialysis to obtain a CBM-g-CMC composite.

[0042] S2 blending: CBM-g-CMC material and CNF solution were mixed in the ratio of 1:1, 1:5, 1:8, and 1:10, respectively, and magnetically stirred for 6 hours to ensure uniform dispersion to prepare CBM-g-CMC + CNF mixed solution;

[0043] S3 antibacterial modification: cetyltrimethylammonium bromide (CTAB) was added to the CBM-g-CMC+CNF solution and treated at 25°C and a vibration rate of 100 rpm for 1 hour to form a co-deposition reaction solution.

[0044] S4 Film Formation: The co-deposition reaction solution was ultrasonically treated and vacuumed to remove air bubbles. The solution was then filtered through a 0.22 μm hydrophilic filter membrane and dried to produce a CBM-g-CMC+CNF composite film.

[0045] The carbohydrate binding module 3 in Examples 1-3 can be replaced with one or more of carbohydrate binding module 1 (CBM1) or carbohydrate binding module 2. The antimicrobial agent cetyltrimethylammonium bromide (CTAB) can be replaced with one or more of penicillin, nanosilver ions, or chitosan. The solid content of the CNF is 0.5%-5%.

[0046] Example 4

[0047] Total reflection Fourier transform infrared (ATR-FTIR) spectroscopy (recorded in VERTEX 80V (Brooker, Germany) mode in the range of 4000–400 cm-1) was used to verify the formation of amide bond coupling between CBM and CMC. Figure 1 The FTIR spectra of pure CMC (blue line), CBM (black line) and CBM-g-CMC (red line) are compared to identify the characteristic chemical changes. In the spectrum of CMC, 1610 cm -1 The prominent band near 1120 cm is attributed to the asymmetric stretching vibration of the carboxylic acid group (-COO), while the -1 The strong absorption near 1610 cm corresponds to the COC stretching of the polysaccharide backbone. After carbodiimide-mediated amide covalent coupling, the FTIR spectrum of CBM-g-CMC undergoes significant changes: -1 There is an enhanced band near 1430 cm, indicating overlapping contributions from the original COO and the newly formed amide I bond (C=O stretching). -1 A significant absorption increase can be observed near 1120 cm, which corresponds to the CN stretching vibration and is a sign of amide bond formation, proving that the CBM is successfully conjugated to the CMC chain via the amide bond. -1 The COC peak at α remained relatively unchanged, indicating that the core cellulose backbone structure of CMC was not destroyed during the coupling process.

[0048] Example 5

[0049] To further verify the successful grafting of CBM onto the CMC skeleton, the elemental composition of CMC and CBM-g-CMC films was analyzed using X-ray photoelectron spectroscopy (XPS, UK). Figure 2 . As can be seen from the figure, there is a significant difference between pure CMC (black curve) and CBM-g-CMC (red curve), and the CBM-g-CMC sample has an obvious and sharp N1s peak near 400eV, indicating that the nitrogen-containing groups have been successfully introduced. The nitrogen content in CMC increased from 0.00% to 5.57% in CBM-g-CMC, and the corresponding atomic percentages of carbon and oxygen were also adjusted accordingly. This nitrogen signal is attributed to the nitrogen element of the CBM band, further confirming the FTIR results discussed previously. The addition of CBM not only contributes to the dual force enhancement strategy, but also introduces functional groups that can improve the interfacial interactions of cellulose nanofibers in the composite system.

[0050] To verify the dual modification effect of CNF and CBM on CMC-based membranes, the mechanical properties, moisture barrier properties, surface hydrophobicity, and antibacterial properties of pure CMC membranes, CMC+CNF membranes, CBM+CMC+CNF, and CBM-g-CMC+CNF composite films were compared and analyzed. The pure CMC membrane was prepared by directly treating CMC with ultrasonic treatment and vacuum treatment to remove air bubbles in the system, and then filtering through a hydrophilic filter membrane. The CMC+CNF membrane was prepared by directly blending CMC and CNF in a certain proportion, then treating it with ultrasonic treatment and vacuum treatment to remove air bubbles in the system, and then filtering through a hydrophilic filter membrane. The CBM+CMC+CNF was prepared by blending CMC, CBM, and CNF in a certain proportion, then treating it with ultrasonic treatment and vacuum treatment to remove air bubbles in the system, and then filtering through a hydrophilic filter membrane. No amidation treatment was performed. The CBM-g-CMC+CNF composite membrane was prepared by any of the methods described in Examples 1-3.

[0051] Example 6

[0052] The sample films were cut into strips of approximately 10 mm in width and 70 mm in length. The stress and strain of the films were measured under dry, wet, acidic, and alkaline conditions using a universal tensiometer (SHIMADZU, Japan) at a tensile rate of 2 mm / min. The wet, acidic, and alkaline treatment conditions were as follows: the samples were treated in deionized water, 0.5 mol L -1 NaOH and 0.5 mol L -1 Soak in HCl for 2 hours, wipe off the moisture, and then test.

[0053] The mechanical properties of CMC-based films were systematically investigated by stress-strain tests in dry, wet, alkaline and acidic environments. Figure 3 and Table 1, as Figure 3Figure a shows the stress-strain curves of the films under dry conditions. The pure CMC film (black curve) exhibits limited tensile strength (~3.8 MPa) and low elongation at break (0.7%), indicating its inherent brittleness. The addition of CNF (red curve) improves the dry tensile strength of the film, as CNF reinforces the cellulose matrix by forming a more cohesive network. The tensile strength of the CBM-g-CMC + CNF film (blue curve) dramatically increases, reaching ~60 MPa. This nearly 16-fold increase compared to pure CMC can be attributed to the synergistic effect of CBM coupling and CNF reinforcement; CBM-g-CMC also exhibits a nearly 30% improvement compared to its blend. More importantly, the addition of CBM and its modifiers significantly improves the strain properties of the CMC material, from 0.7% to 3.1%. Ductility and stretchability are critical properties for medical and packaging materials. Covalently grafting CBM molecules onto CMC chains creates additional crosslinks within the matrix, contributing to improved mechanical properties.

[0054] like Figure 3 As shown in Figure 2b, the CBM-g-CMC+CNF film (blue curve) continues to outperform all other formulations, achieving a tensile strength of approximately 125.6 MPa and a strain of 5.9%. This demonstrates that the CBM-g-CMC+CNF film maintains its mechanical strength even at high water content, which is crucial for wound dressing applications, where water retention and strength under hydrated conditions are key factors.

[0055] like Figure 3 As shown in Figure c, the CBM-g-CMC+CNF film exhibits excellent mechanical properties under alkaline conditions, maintaining high tensile strength and elongation. This indicates that chemical modification of CMC with CBM not only improves the mechanical properties of CMC but also imparts additional stability to CMC under different pH conditions.

[0056] Figure 3 d shows the stress-strain curve of the membrane tested under acidic conditions. The mechanical strength of the pure CMC membrane (black curve) decreases significantly, with a sharp drop in tensile strength at lower strain values. The CBM-g-CMC + CNF membrane, on the other hand, maintains its integrity, with only a slight decrease in strength under acidic conditions. This behavior demonstrates the robustness of the amide-linked CBM-g-CMC structure, which remains stable even in acidic environments and could expand the application of wound dressings in a wide range of pH conditions.

[0057] In summary, the mechanical properties of CMC-based films indicate that the incorporation of CNF and CBM plays a crucial role in the significant improvement of the strength, elasticity, and environmental stability of CMC films. The results show that CBM-g-CMC + CNF composites not only provide enhanced dry and wet strength but also provide better stability under certain pH conditions, which can be applied to advanced wound care applications and other biomedical applications.

[0058] Table 1: Mechanical property characterization of CBM3-modified CMC films

[0059]

[0060] Example 7

[0061] The breaking length was determined according to the ISO 1924-2:2008 standard using a tensile machine (Qingtong Instruments Co., Ltd., Hangzhou, China). CBM-g-CMC / CNF films were cut into strips of 15 mm width and at least 150 mm length. The tensile force at the time of tensile failure was recorded and the breaking length was calculated. The resistance to break, tear, and fold of CBM-g-CMC / CNF films was tested according to the ISO 2758:2001, ISO 1974:1990, and ISO 5626:1978 standards, respectively.

[0062] The results of the breaking strength test of CMC-based films are shown in Figure 4 a, the breaking strength of pure CMC film is relatively low, about 25 kPa, the addition of CNF leads to significant improvement, the breaking strength increases to about 32 kPa, indicating that the reinforcement provided by CNF enhances the structural integrity of CMC film, which may be due to the formation of a more cohesive network, more effectively distributing stress. The grafting of CBM on CMC and the combination of CNF further improve the resistance to break, the resistance to break of CBM-g-CMC + CNF film is about 55 kPa, which is the highest among all samples. This indicates that CBM not only strengthens the film through physical reinforcement, but also helps to form stronger covalent bonds, thereby improving the overall mechanical break resistance of the film. It indicates that the incorporation of CNF and CBM significantly improves the tear resistance of the film.

[0063] The tear index of CMC-based films was evaluated to assess their tear resistance under stress, and the results are shown in Figure 4 b, the tear index of pure CMC is the lowest, about 4.0 mN·m 2 / g, when CNFs are introduced into CMC, the tear index increases to about 6.8 mN·m 2 / g, the combination of CBM and CNF further improves the tear resistance of the film, the tear index of CBM-g-CMC-+CNF film is about 9.6 mN·m 2 / g. The addition of CNF and CBM improves the tear resistance of the film.

[0064] Pure CMC film showed the lowest folding durability, as shown in the following table. Figure 4 c, about 5 times, when CNF was added, the folding endurance increased to about 12 times, the CBM+CMC+CNF film showed a durability of nearly 20 cycles, and the CBM-g-CMC+CNF film showed the highest folding endurance of 22 times. This shows that the combination of CBM and CNF significantly improves the folding durability, indicating that the synergistic effect of CBM conjugation and CNF reinforcement enhances the robustness of the film.

[0065] Example 8

[0066] The thermal stability and degradation behavior of CMC-based films were evaluated using thermogravimetric analysis (TGA) and derivative thermogravimetric analysis (DTG). A 10 mg sample was measured using a thermogravimetric analyzer (TGA209F1, NETZSCH, Germany) between 30°C and 600°C, at a heating rate of 10°C / min. Nitrogen was used throughout the heating process at a flow rate of 40 mL / min.

[0067] The results are as follows Figure 5 a. The pure CMC film shows significant mass loss at around 300°C, and the mass loss of CMC at 400°C is about 85%. The thermal stability of CMC+CNF, CMC+CBM+CNF, and CBM-g-CMC-+CNF samples are slightly improved, with lower mass loss rates at higher temperatures. This indicates that the incorporation of CNF and CBM into the CMC matrix may be due to the reinforcement provided by CNF and the chemical cross-linking introduced by CBM, resulting in a more stable thermal degradation curve. Figure 5 b. The CMC film exhibits a degradation peak at 285°C, while the degradation peaks of the CMC+CNF, CMC+CBM+CNF, and CBM-g-CMC-+CNF films shift slightly to 271°C, 288°C, and 299°C, respectively. These shifts indicate that the incorporation of CNF and CBM affects the thermal degradation temperature of the films, likely due to changes in molecular structure and the introduction of additional interactions that may alter degradation pathways. The improved thermal stability observed in the CMC-based composites suggests that the incorporation of CBM not only improves mechanical properties but also increases thermal resistance. This enhanced thermal stability is particularly valuable for applications involving high-temperature exposure, such as biomedical or packaging applications.

[0068] Example 9

[0069] The in vitro antibacterial activity of CBM-G-CMC / CNF solution was determined by surface contact method. Gram-positive bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) were used as representative bacteria for the antibacterial test.

[0070] The results are as follows Figure 6 The left panel shows bacterial growth on an agar plate immediately after inoculation, serving as a control before incubation. The absence of zones of inhibition in these images confirms uniform bacterial distribution and that the films exhibited no spontaneous antimicrobial activity prior to incubation. The right panel shows the results after incubation, demonstrating the formation of distinct zones of inhibition around the membrane disks, providing insight into the antimicrobial efficacy of each membrane.

[0071] Figure a shows the results of the E. coli antibacterial test: No. 1 is the control group: no inhibition zone was observed. The control sample (without CTAB) had no antibacterial effect on E. coli. No. 2 is pure CMC: no inhibition zone was observed, indicating that the pure CMC film does not exhibit any inherent antibacterial activity against E. coli. 3 (CMC+CTAB): A moderate inhibition zone was observed around the CMC+CTAB film, indicating that CTAB successfully imparted antibacterial properties to the CMC film against E. coli. 4 (CBM-g-CMC-+CTAB): A larger inhibition zone was observed around the CBM-g-CMC+CTAB film. 5 (CBM-g-CMC+CNF+CTAB): A moderate inhibition zone was observed around the CBM-g-CMC+CNF+CTAB film, indicating that CTAB successfully imparted antibacterial properties to the CMC film against E. coli.

[0072] Figure b (Staphylococcus aureus): Similar to the results for E. coli, a larger and clearer zone of inhibition was observed against S. aureus, confirming a stronger antibacterial effect against Gram-positive bacteria. 1 (Control): No inhibition was observed, indicating that the control sample had no effect. 2 (CMC): No zone of inhibition was observed, indicating that the pure CMC film did not exhibit any inherent antibacterial activity against E. coli. 3 (CMC + CTAB): A moderate zone of inhibition was observed around the CMC + CTAB film, indicating that CTAB successfully imparted antibacterial properties to the CMC film against E. coli. 4 (CBM-g-CMC + CTAB): A larger zone of inhibition was observed around the CBM-g-CMC + CNF + CTAB + CTAB film. 5 (CBM-g-CMC + CNF + CTAB - CNF - CTAB): A moderate zone of inhibition was observed around the CBM-g-CMC + CNF + CTAB film, indicating that CTAB successfully imparted antibacterial properties to the CMC film against E. coli. The results showed that the incorporation of CTAB into CMC membranes significantly enhanced the antibacterial activity against Escherichia coli and Staphylococcus aureus. Furthermore, the addition of CBM and CNF in combination with CTAB enhanced the antibacterial effect, especially against Staphylococcus aureus.

[0073] Example 10

[0074] The water vapor barrier properties of the film were measured using the PERME-W3 / 060 water vapor transmission test system using the weight loss method. The film test area was 33.18 cm 2 , the test humidity is 70%, and the test temperature is 38℃.

[0075] like Figure 7 a is the moisture permeability diagram of CMC-based films. Pure CMC film has the highest moisture permeability, which is about 2250g / m 2 The addition of CNF reduces the moisture permeability to about 1250g / m 2 This may be due to the enhanced network structure provided by CNF, which reduces the gaps available for water vapor to pass through. The moisture permeability of CBM+CMC+CNF or CBM-g-CMC+CNF films is very low (~500g / m 2 ·days), which is less than 1 / 4 of the control sample, indicating that the co-introduction of CNF and CBM, especially the introduction of CBM, significantly improves the water vapor barrier properties of CMC-based film.

[0076] Figure 7 Figure b shows the water contact angles of the membranes. The pure CMC membrane has a water contact angle of approximately 50°, while the incorporation of CNF increases the water contact angle to approximately 60°, indicating enhanced surface hydrophobicity. The CMC+CBM+CNF composite membrane has an even higher contact angle (~70°), while the CBM-g-CMC-+CNF membrane exhibits the highest water contact angle (~110°), indicating that the combined modification of CNF and CBM imparts stronger hydrophobicity to the CMC-based membrane.

[0077] The present invention provides a high-strength CBM-g-CMC+CNF antibacterial composite film and its preparation method and application. The above shows and describes the basic principles, main features and advantages of the present invention. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the present invention. Those skilled in the art should understand that the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments and descriptions in the specification are only for further illustrating the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the invention to be protected. The scope of protection claimed by the present invention is defined by the claims and their equivalents.

Claims

1. A method for preparing a high-strength CBM-g-CMC+CNF antibacterial composite film, characterized in that: The following steps are involved: S1 grafting: 1-Ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC) was added to the CMC solution and magnetically stirred at 60°C for 1 hour. N-hydroxysuccinimide (NHS) and a carbohydrate binding module (CBM) were then added. The mixture was stirred at 22°C under a nitrogen atmosphere for 24 hours, and unreacted EDC, NHS, and other small molecule reagents were removed by dialysis to obtain a CBM-g-CMC composite material. S2 blending: CBM-g - CMC material and CNF solution were mixed in a certain proportion and magnetically stirred for 6 hours to ensure uniform dispersion to prepare CBM-g-CMC+CNF mixed solution; S3 antibacterial modification: The antibacterial agent was added to the CBM-g-CMC+CNF solution and treated at 25°C and a vibration rate of 100 rpm for 1 hour to form a co-deposition reaction solution. S4 Film Formation: The co-deposition reaction solution was ultrasonically treated and vacuumed to remove air bubbles. The solution was then filtered through a hydrophilic filter membrane and dried to produce a CBM-g-CMC+CNF composite film.

2. The method for preparing a high-strength CBM-g-CMC+CNF antibacterial composite film according to claim 1, characterized in that: The concentration of the carbohydrate binding module in step S1 is 0.9 mg / ml, and the amount of the carbohydrate binding module added is 0.5%-2%.

3. A high-strength CBM-g according to claim 1 - The method for preparing CMC+CNF antibacterial composite film is characterized in that: In the grafting step S1, the carbohydrate binding module CBM is one or more of CBM1, CBM2, and CBM3.

4. The method for preparing a high-strength CBM-g-CMC+CNF antibacterial composite film according to claim 1, characterized in that: The solid content of CNF in step S2 is 0.5%-5%.

5. The method for preparing a high-strength CBM-g-CMC+CNF antibacterial composite film according to claim 1, characterized in that: In step S2, the volume ratio of CBM-g-CMC to CNF is 1:1-1:

10.

6. The method for preparing a high-strength CBM-g-CMC+CNF antibacterial composite film according to claim 1, characterized in that: The antibacterial agent in step S3 is one or more of cetyltrimethylammonium bromide (CTAB), penicillin, nano silver ions, and chitosan.

7. The CBM-g-CMC+CNF antibacterial composite membrane prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the CBM-g-CMC+CNF antibacterial composite film prepared by the preparation method according to any one of claims 1 to 6 in medical dressings and packaging.

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