Modified bacterial cellulose composite material as well as preparation method and application thereof

Abstract

The invention discloses a modified bacterial cellulose composite material as well as a preparation method and application thereof. The preparation method comprises the following steps: inoculating a seed solution for producing bacterial cellulose into a culture medium containing soybean oil, and performing in-situ culture to obtain the bacterial cellulose composite material. According to the method, the seed solution for producing the bacterial cellulose is inoculated into the culture medium containing the soybean oil for in-situ culture, chemical modification or post-treatment is not needed, the process is simplified, and no pollution risk exists. The sustainable and renewable soybean oil is adopted to replace a chemical modifier in a traditional method, so that the hydrogel has excellent biocompatibility, chemical pollution is reduced, the cost of raw materials is reduced, and the hydrogel is suitable for large-scale production. The performance of the prepared modified bacterial cellulose composite material is synergistically optimized, the crystallinity and the water absorption rate are synchronously reduced, and the modified bacterial cellulose composite material has hydrophobicity, flexibility and degradability and breaks through the limitation of traditional single performance modification.

Description

Technical Field

[0001] The present invention relates to the field of preparing compounds or compositions using microorganisms or enzymes, and in particular to a modified bacterial cellulose composite material and a preparation method and application thereof. Background Art

[0002] Bacterial cellulose composites are natural polymer materials synthesized by microorganisms. They have unique structures and excellent properties and have broad application prospects in many fields. However, the strong hydrophilicity and high crystallinity of traditional bacterial cellulose composites limit their application in some scenarios. Soybean oil is rich in fatty acids, is a natural renewable resource, and has good biocompatibility. At present, traditional technology uses soybean oil to modify the fermented product, and the modified bond strength of the obtained composite material is not high, and the modification effect is not good. Therefore, it is crucial to develop a culture medium containing soybean oil, use microbial metabolic processes to achieve the composite of soybean oil and bacterial cellulose, and obtain soybean oil-modified bacterial cellulose composites to promote the high added value of bacterial cellulose.

[0003] Chinese invention patent application CN114753153A discloses a bacterial cellulose textile and its preparation method. The textile is prepared by compounding acrylated epoxidized soybean oil with bacterial cellulose. This process requires multiple chemical treatments (emulsification, polymerization, redox reaction) and a dehydration process lasting up to 7 days. The preparation process is complex and cumbersome, with high energy consumption and high chemical residues. Chinese invention patent CN105031722B discloses a modified bacterial cellulose for bone repair scaffolds and its preparation method. Hydroxyapatite forms a chelate bond with carboxylated bacterial cellulose and is in situ compounded on the carboxylated bacterial cellulose through the chelate bond to form modified bacterial cellulose, reducing the crystallinity of the carboxylated bacterial cellulose. However, the bacterial cellulose must first be chemically oxidized and then compounded through complex titration and alkaline conditions, resulting in a cumbersome process. Chinese invention patent application CN103980526A discloses a method for preparing an acetylated-modified bacterial cellulose aerogel oil-absorbing material. The bacterial cellulose is post-treated and hydrophobically modified by chemical acetylation (pyridine / DMF and acetic anhydride), thereby avoiding strong water absorption. However, the prepared oil-absorbing material has a single function and is difficult to adapt to flexible hydrophobic scenarios. Summary of the Invention

[0004] The strong hydrophilicity and high crystallinity of traditional bacterial cellulose composite materials limit their application in some scenarios. In the field of medical dressings, high water absorption can lead to excessive wetting of wounds; in waterproof textiles or food packaging, the lack of hydrophobicity and flexibility makes it difficult to meet actual needs. Existing bacterial cellulose composite materials are hydrophobically modified by chemical methods, which has complex process steps, chemical residues, and cannot coordinate crystallinity and hydrophobicity. In order to solve the above problems, the first aspect of the present invention provides a method for preparing a modified bacterial cellulose composite material, comprising inoculating a seed liquid for producing bacterial cellulose into a culture medium containing soybean oil for in situ cultivation to obtain a bacterial cellulose composite material.

[0005] As an embodiment, the concentration of soybean oil in the soybean oil-containing culture medium is 3 to 30 g / L.

[0006] As an embodiment, the concentration of soybean oil in the soybean oil-containing culture medium is 3 to 20 g / L.

[0007] As an embodiment, the concentration of soybean oil in the culture medium containing soybean oil is 3 g / L, 5 g / L, 10 g / L, 15 g / L, or 20 g / L.

[0008] As an embodiment, the concentration of soybean oil in the culture medium containing soybean oil is 15 g / L.

[0009] As an embodiment, the components of the culture medium include 20-60 g / L glucose, 15-45 g / L peptone, 2-7 g / L dipotassium hydrogen phosphate, 0.5-2 g / L magnesium sulfate and 1-3 g / L acetic acid.

[0010] As an embodiment, the components of the culture medium include 30-55 g / L glucose, 20-40 g / L peptone, 4-6 g / L dipotassium hydrogen phosphate, 0.8-1.5 g / L magnesium sulfate and 1.5-2.5 g / L acetic acid.

[0011] As an embodiment, the components of the culture medium include 50 g / L glucose, 30 g / L peptone, 5 g / L dipotassium hydrogen phosphate, 1 g / L magnesium sulfate and 2 g / L acetic acid.

[0012] As an embodiment, the seed liquid for producing bacterial cellulose includes Acetobacter xylinum seed liquid.

[0013] As an embodiment, the volume percentage concentration of the inoculation of the Acetobacter xylinum seed solution is 2-10%.

[0014] As an embodiment, the volume percentage concentration of the inoculated Acetobacter xylinum seed solution is 2-8%.

[0015] As an embodiment, the volume percentage concentration of the inoculation of the Acetobacter xylinum seed solution is 4%.

[0016] As an embodiment, the Acetobacter xylinum seed liquid is a secondary Acetobacter xylinum seed liquid.

[0017] As an embodiment, the preparation method further comprises purifying and drying the bacterial cellulose composite material to obtain a hydrophobic bacterial cellulose composite material; the purification comprises alkali boiling purification in an alkaline solution.

[0018] As an embodiment, the alkaline solution is an aqueous solution of sodium hydroxide.

[0019] As an embodiment, the concentration of the sodium hydroxide aqueous solution is 0.1-0.5 mol / L.

[0020] As an embodiment, the concentration of the sodium hydroxide aqueous solution is 0.1 mol / L.

[0021] As an embodiment, the alkali boiling purification is alkali boiling at 70-90° C. until transparent.

[0022] As an embodiment, the alkali boiling purification is alkali boiling at 80° C. until transparent.

[0023] In one embodiment, the drying comprises freeze-drying.

[0024] As an embodiment, the freeze-drying comprises pre-freezing the bacterial cellulose composite material at -80°C and then freeze-drying it to a constant weight.

[0025] As an embodiment, the culture temperature in the culture medium is 25 to 35° C., and the culture time is 5 to 7 days.

[0026] As an embodiment, the culture temperature in the culture medium is 30° C. and the culture time is 6 days.

[0027] The second aspect of the present invention provides a modified bacterial cellulose composite material prepared by the above-mentioned method for preparing the modified bacterial cellulose composite material.

[0028] As an embodiment, the surface morphology of the modified bacterial cellulose composite material is a network structure with low porosity, and the infrared spectrum is at 1741cm -1 The characteristic peak of ester bond is shown at , and the XRD (X-ray diffraction) spectrum has a characteristic diffraction peak at around 29.5°.

[0029] A third aspect of the present invention provides an application of the modified bacterial cellulose composite material, wherein the modified bacterial cellulose composite material is used to prepare medical wound dressings, food packaging, and textile coatings.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The method for preparing the modified bacterial cellulose composite material of the present invention is to inoculate the seed liquid for producing bacterial cellulose into a culture medium containing soybean oil for in situ cultivation, without the need for chemical modification or post-treatment, thus simplifying the process and eliminating the risk of pollution.

[0032] (2) The preparation method of the modified bacterial cellulose composite material described in the present invention uses sustainably regenerated soybean oil to replace the chemical modifiers used in traditional methods, has excellent biocompatibility, reduces chemical pollution, and reduces raw material costs, making it suitable for large-scale production.

[0033] (3) The preparation method of the modified bacterial cellulose composite material described in the present invention is to add 3 to 30 g / L of soybean oil to the culture medium to prepare the modified bacterial cellulose composite material. The performance of the prepared modified bacterial cellulose composite material is synergistically optimized, the crystallinity and water absorption rate are simultaneously reduced, and the modified bacterial cellulose composite material has hydrophobicity, flexibility and degradability, breaking through the limitations of traditional single performance modification.

[0034] (4) The modified bacterial cellulose composite material prepared by the preparation method of the modified bacterial cellulose composite material of the present invention solves the problem of excessive hydrophilicity and excessive rigidity of traditional bacterial cellulose.

[0035] (5) The modified bacterial cellulose composite material prepared by the preparation method of the modified bacterial cellulose composite material described in the present invention has excellent biocompatibility and expanded application scenarios, which can be extended to high value-added fields such as medical wound dressings, food packaging and waterproof textiles. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a bar chart showing the yield test results of the modified bacterial cellulose composite material prepared by the methods of Examples 1 to 5 and Comparative Example 1.

[0037] Figure 2 This is a bar chart showing the test results of relative water absorption of the modified bacterial cellulose composite materials prepared by the methods of Examples 1 to 5 and Comparative Example 1.

[0038] Figure 3 These are SEM morphologies of modified bacterial cellulose composite materials prepared by the methods of Examples 1 to 4; in the figures: A: Example 1; B: Example 2; C: Example 3; D: Example 4; E: Comparative Example 1.

[0039] Figure 4The XRD patterns of the modified bacterial cellulose composite materials prepared by the methods of Examples 1 to 4 are as follows: A: Example 1; B: Example 2; C: Example 3; D: Example 4; and E: Comparative Example 1.

[0040] Figure 5 The infrared spectra of the modified bacterial cellulose composite materials prepared by the methods of Examples 1 to 4 and Comparative Example 1 are as follows: A: Example 1; B: Example 2; C: Example 3; D: Example 4; E: Comparative Example 1. DETAILED DESCRIPTION

[0041] Example 1

[0042] A method for preparing a modified bacterial cellulose composite material comprises the following steps:

[0043] The bacterial cellulose-producing seed liquid is inoculated into a culture medium containing soybean oil for in-situ culture to obtain a bacterial cellulose composite material;

[0044] The bacterial cellulose composite material is purified and dried to obtain a hydrophobic bacterial cellulose composite material.

[0045] The concentration of soybean oil in the soybean oil-containing culture medium is 3 g / L.

[0046] The culture medium comprises 50 g / L glucose, 30 g / L peptone, 5 g / L potassium dihydrogen phosphate, 1 g / L magnesium sulfate, and 2 g / L acetic acid. The peptone is tryptone, BR grade, purchased from Oxoid, UK.

[0047] The seed liquid for producing bacterial cellulose is the secondary seed liquid of Acetobacter xylinum.

[0048] The volume percentage concentration of the inoculated Acetobacter xylinum seed solution is 4%.

[0049] The culture temperature in the culture medium is 30° C., and the culture time is 6 days.

[0050] The purification step is to boil the mixture in a sodium hydroxide aqueous solution at 80° C. until the mixture becomes transparent, followed by rinsing with deionized water. The concentration of the sodium hydroxide aqueous solution is 0.1 mol / L.

[0051] The drying step is to pre-freeze the bacterial cellulose composite material at -80°C and then freeze-dry it to a constant weight.

[0052] Example 2

[0053] A method for preparing a modified bacterial cellulose composite material, the specific implementation manner is the same as that of Example 1, except that the concentration of soybean oil in the soybean oil-containing culture medium is 5 g / L.

[0054] Example 3

[0055] A method for preparing a modified bacterial cellulose composite material, the specific implementation manner is the same as that of Example 1, except that the concentration of soybean oil in the soybean oil-containing culture medium is 10 g / L.

[0056] Example 4

[0057] A method for preparing a modified bacterial cellulose composite material, the specific implementation manner is the same as that of Example 1, except that the concentration of soybean oil in the soybean oil-containing culture medium is 15 g / L.

[0058] Example 5

[0059] A method for preparing a modified bacterial cellulose composite material, the specific implementation manner is the same as that of Example 1, except that the concentration of soybean oil in the soybean oil-containing culture medium is 20 g / L.

[0060] Comparative Example 1

[0061] A method for preparing a modified bacterial cellulose composite material comprises the following steps:

[0062] Inoculating the bacterial cellulose production seed solution into the culture medium for in-situ cultivation to obtain the bacterial cellulose composite material;

[0063] The bacterial cellulose composite material is purified and dried to obtain a hydrophobic bacterial cellulose composite material.

[0064] The components of the culture medium are 50 g / L glucose, 30 g / L peptone, 5 g / L dipotassium hydrogen phosphate, 1 g / L magnesium sulfate and 2 g / L acetic acid.

[0065] The seed liquid for producing bacterial cellulose is the secondary seed liquid of Acetobacter xylinum.

[0066] The volume percentage concentration of the inoculated Acetobacter xylinum seed solution is 4%.

[0067] The culture temperature in the culture medium is 30° C., and the culture time is 6 days.

[0068] The purification step is to boil the mixture in a sodium hydroxide aqueous solution at 80° C. until the mixture becomes transparent, followed by rinsing with deionized water. The concentration of the sodium hydroxide aqueous solution is 0.1 mol / L.

[0069] The drying step is to pre-freeze the bacterial cellulose composite material at -80°C and then freeze-dry it to a constant weight.

[0070] Performance Testing

[0071] 1. Yield test: The purified bacterial cellulose composite materials prepared in the examples and comparative examples were freeze-dried to a constant weight and then tested for dry weight. The test results are shown in Table 1. Figure 1 .

[0072] 2. Water Absorption Test: Place the bacterial cellulose composite materials prepared in the Examples and Comparative Examples in deionized water and absorb water until saturated. Remove the composite materials after water absorption and hang them in the air to drain for 1 minute before measuring the wet weight. Substitute the dry weight and wet weight into the formula to calculate the water absorption rate. The water absorption rate calculation formula is as follows:

[0073] Water absorption rate = (wet weight - dry weight) / dry weight × 100%.

[0074] Note: Since the general method of measuring wet weight is to remove the bacterial cellulose film after absorbing water and wipe the surface moisture to measure the wet weight, the general method of "wiping off the surface moisture" is too subjective. To ensure the comparability of the data, the method of draining for 1 minute is adopted. Because the results of different wet weight measurements are different, the results of water absorption are different. Therefore, the water absorption rate of soybean oil modified bacterial cellulose composite material relative to pure bacterial cellulose is calculated and expressed. The relative water absorption rate formula is:

[0075] Relative water absorption = (water absorption of Examples 1-5) / water absorption of Comparative Example 1.

[0076] The test results are shown in Table 1. Figure 2 .

[0077] 3. Morphology test: The surface morphology of the composite materials of Examples 1-4 and Comparative Example 1 was observed using SEM (field emission scanning electron microscope). Platinum was sprayed on the surface using an ion sputtering coating device and observed under a thermal field emission scanning electron microscope at a voltage of 3.0 kV and a magnification of 25.0 k times. The test results are shown in Figure 3 .

[0078] 4. Crystallinity test: XRD (X-ray diffractometer) was used to detect the crystallinity of the sample. The diffraction angle 2θ scan range was 10° to 35°, and a scan was performed every 0.02° at a scanning speed of 10° / min.

[0079] The formula for calculating crystallinity is: CrI (%) = (I 020 -I am ) / I 020 ×100%

[0080] I 020 is the maximum intensity of lattice diffraction, and I am The corresponding intensity is the diffraction peak corresponding to 2θ of about 16.8°. The test results are shown in Table 1. Figure 4 .

[0081] 5. Infrared detection: Qualitative testing of the composite materials of Examples 1-4 and Comparative Example 1 was performed using FTIR (Fourier Transform Infrared Spectroscopy). The test results are shown in Figure 5 .

[0082] Table 1

[0083]

[0084]

[0085] The test results show that: Comparative Example 1 has a lower yield and a higher water absorption rate. The surface morphology observed by SEM has a more obvious three-dimensional network structure and more pores than other examples. There are three absorption peaks in the XRD graph, which are around 14.7°, 16.8°, and 22.8°, indicating that it is type I cellulose. The FTIR graph has a peak at 2894 cm -1 There is an absorption peak at 2923cm -1 and 2853cm -1 There is no absorption peak.

[0086] The yield of Example 1 increased by 29.2% compared with that of Comparative Example 1, the relative water absorption rate decreased by 51.2% compared with that of Comparative Example 1, and the crystallinity decreased by 17.3% compared with that of Comparative Example 1. The surface morphology observed by SEM showed fewer and smaller pores than that of Comparative Example 1, which may be due to the components in soybean oil (such as fatty acids) forming a coating on the fiber surface, making the fibers adhere more closely; there are four absorption peaks in the XRD graph, which are around 14.7°, 16.8°, 22.8°, and 29.3°, respectively. The diffraction peak at 29.3° may correspond to the composite structure formed by the interaction between soybean oil components and cellulose molecules; in the FTIR graph, there is a peak at 2894cm -1 The absorption peak at 2923 cm -1 、2853cm -1 and 1741cm -1 The absorption peak appears at 1741cm, indicating that triglycerides or fatty acid esters in soybean oil exist in the composite material. -1 The appearance of the ester bond peak and 2894 cm -1 The disappearance of the peak indicates that there is an intermolecular interaction between soybean oil and bacterial cellulose (such as hydrogen bonding or van der Waals force). Combined with the appearance of new diffraction peaks in XRD, it shows that a soybean oil-bacterial cellulose composite material was obtained by in situ modification of bacterial cellulose by adding 3 g / L soybean oil to the culture medium.

[0087] In Example 2, the yield was increased by 35% compared to Comparative Example 1, the relative water absorption was reduced by 52.2%, and the crystallinity was reduced by 14.1% compared to Comparative Example 1. The XRD pattern showed four absorption peaks, located at approximately 14.7°, 16.8°, 22.8°, and 29.6°, respectively. The diffraction peak at 29.6° likely corresponds to a composite structure formed by interactions between soybean oil components and cellulose molecules. SEM and FTIR analysis were similar to those in Example 1. Combined with the FTIR and XRD results, it is speculated that a soybean oil-bacterial cellulose composite material was obtained by in situ modification of bacterial cellulose by adding 5 g / L soybean oil to the culture medium.

[0088] In Example 3, the yield was increased by 33.7% compared to Comparative Example 1, the relative water absorption was reduced by 58.1%, and the crystallinity was reduced by 19.5% compared to Comparative Example 1. The XRD pattern showed four absorption peaks, located at approximately 14.7°, 16.8°, 22.8°, and 29.5°, respectively. The diffraction peak at 29.5° likely corresponds to a composite structure formed by the interaction between soybean oil components and cellulose molecules. SEM and FTIR analysis were similar to those in Example 1. Combined with the FTIR and XRD results, it is speculated that a soybean oil-bacterial cellulose composite material was obtained by in situ modification of bacterial cellulose by adding 10 g / L soybean oil to the culture medium.

[0089] In Example 4, the yield increased by 61.3% compared to Comparative Example 1, the relative water absorption decreased by 64.6%, and the crystallinity decreased by 34.4%. SEM images showed that the surface was almost completely free of pores, and the fibers were coarser than those in Comparative Example 1. Other conditions were the same as in Example 4. Based on the FTIR and XRD results, it is speculated that the addition of 15 g / L soybean oil to the culture medium resulted in the in situ modification of bacterial cellulose to produce a soybean oil-bacterial cellulose composite.

[0090] In Example 5, the yield increased by 25.8% compared to Comparative Example 1, the relative water absorption decreased by 65.2%, and the crystallinity decreased by 34.4% compared to Comparative Example 1. XRD results were similar to those of Example 4. Crystallinity testing was not performed. Since the yield decreased compared to Example 5 and the water absorption rate barely decreased, material characterization and crystallinity testing were not performed.

Claims

1. A method for preparing a modified bacterial cellulose composite material, characterized in that: The method comprises inoculating seed liquid for producing bacterial cellulose into a culture medium containing soybean oil for in-situ cultivation to obtain a bacterial cellulose composite material.

2. The method for preparing the modified bacterial cellulose composite material according to claim 1, characterized in that: The concentration of soybean oil in the soybean oil-containing culture medium is 3 to 30 g / L.

3. The method for preparing the modified bacterial cellulose composite material according to claim 1, characterized in that: The components of the culture medium include 20-60 g / L glucose, 15-45 g / L peptone, 2-7 g / L dipotassium hydrogen phosphate, 0.5-2 g / L magnesium sulfate and 1-3 g / L acetic acid.

4. The method for preparing the modified bacterial cellulose composite material according to claim 1, characterized in that: The seed liquid for producing bacterial cellulose includes Acetobacter xylinum seed liquid.

5. The method for preparing the modified bacterial cellulose composite material according to claim 4, characterized in that: The volume percentage concentration of the inoculated Acetobacter xylinum seed solution is 2-10%.

6. The method for preparing the modified bacterial cellulose composite material according to claim 4, characterized in that: The Acetobacter xylinum seed liquid is a secondary Acetobacter xylinum seed liquid.

7. The method for preparing the modified bacterial cellulose composite material according to claim 1, characterized in that: The method also includes purifying and drying the bacterial cellulose composite material to obtain a hydrophobic bacterial cellulose composite material; the purification includes alkali boiling purification in an alkaline solution.

8. The method for preparing the modified bacterial cellulose composite material according to claim 1, characterized in that: The culture temperature in the culture medium is 25-35° C., and the culture time is 5-7 days.

9. A modified bacterial cellulose composite material prepared according to the method for preparing a modified bacterial cellulose composite material according to any one of claims 1 to 8.

10. An application of the modified bacterial cellulose composite material according to claim 9, characterized in that: The modified bacterial cellulose composite material is used to prepare medical wound dressings, food packaging and textile coatings.

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