Uniformly dispersed chopped bacterial cellulose nanofiber as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of nano biomedical materials, and particularly relates to a uniformly dispersed chopped bacterial cellulose nanofiber as well as a preparation method and application thereof. The preparation method comprises the following steps: carrying out alkali liquor purification treatment, gradient freeze drying, cracking pretreatment and ultrasonic-assisted-high-speed homogenization shearing treatment on bacterial cellulose nanofiber hydrogel, and then freeze drying to obtain uniformly dispersed chopped bacterial cellulose nanofibers. The preparation method has the advantages of wide source, simplicity in operation, low cost and the like, not only has large specific surface area and surface chemical activity, but also has excellent mechanical properties, can realize efficient loading of bioactive molecules and enhance the mechanical properties of high polymer materials and hydrogel materials, and has wide application prospects in the field of biological medicines.

Description

Technical Field

[0001] The invention belongs to the technical field of nano-biomedical materials, and more specifically relates to uniformly dispersed short-cut bacterial cellulose nanofibers and a preparation method and application thereof. Background Art

[0002] Nanofibers have a high specific surface area and specific volume ratio, a structure similar to that of the extracellular matrix, excellent mechanical properties and unique biological functions, and are widely studied and applied in the biomedical field. Loading drugs (proteins, peptides, antibodies and small molecule drugs) inside or on the surface of nanofibers to achieve controllable drug delivery has broad application development prospects (Zhou et al. Chem Eng J, 2024: 152105).

[0003] Bacterial cellulose (BC) is a high-purity cellulose nanofiber with excellent hydrophilicity and biocompatibility. Compared with electrospun nanofibers, it has the advantages of wide sources, low cost, and simple preparation (Zhou et al. Bioact. Mater., 2022, 13: 212-222). However, the network structure of the original bacterial cellulose nanofiber is too dense, and the pore size is only 0.02 to 10 μm, which makes it impossible to fully utilize the huge specific surface area of ​​the nanofibers to achieve efficient drug loading. In addition, the surface chemistry of bacterial cellulose nanofibers is inert, and the loaded drugs are mostly physically adsorbed and adhered (Badshahet al. Int. J. Bio. Macromol., 2018, 113: 526-533). The above problems seriously limit the wide application of drug-loaded bacterial cellulose nanofibers.

[0004] High-speed shearing technology has been used to break bulk bacterial cellulose materials into nanofiber bundles to improve their drug loading efficiency (Li et al. Bioact. Mater., 2025, 47: 136-151). However, the prior art is unstable and cannot controllably prepare uniform highly dispersed nanofibers, resulting in limited use. Therefore, how to make bacterial cellulose nanofibers into highly dispersed short nanofibers and simultaneously improve their surface chemical activity to enhance the drug-loaded properties of bacterial cellulose nanofibers and expand their wide application in the biomedical field is a technical problem that those skilled in the art urgently need to solve. Summary of the invention

[0005] The purpose of the present invention is to provide a uniformly dispersed short-cut bacterial cellulose nanofiber and a preparation method and application thereof, and more specifically to provide a short-cut bacterial cellulose nanofiber with rich active chemical groups on the surface and uniform dispersion, which can be loaded with drugs and bioactive molecules for use in the biomedical field, so as to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is to provide a method for preparing uniformly dispersed short-cut bacterial cellulose nanofibers, the steps comprising:

[0008] The bacterial cellulose nanofiber hydrogel is purified by alkaline solution and gradient freeze-dried to obtain the bacterial cellulose aerogel.

[0009] The bacterial cellulose aerogel is added into a TEMPO oxidation system for pyrolysis pretreatment to obtain pyrolysis bacterial cellulose;

[0010] The lysed bacterial cellulose is dispersed in a solvent, subjected to shearing treatment by ultrasonic-assisted high-speed homogenization, and then freeze-dried to obtain uniformly dispersed short-cut bacterial cellulose nanofibers.

[0011] The present invention makes high-purity bacterial cellulose nanofibers into uniformly dispersed short-cut nanofibers, breaking the inherent limitations of the original bacterial cellulose structure such as being too dense; by improving the alkali solution purification method and lysis pretreatment operations, it not only helps the lysis of bacterial cellulose nanofibers, but also improves the chemical activity of the nanofiber surface, expanding the wide application of bacterial cellulose in the biomedical field.

[0012] Furthermore, the dosage ratio of the bacterial cellulose nanofiber hydrogel to the alkali solution is 1-5 g: 50-250 mL.

[0013] Furthermore, the alkaline solution purification treatment includes: boiling the bacterial cellulose nanofiber hydrogel in a sodium hydroxide solution.

[0014] Optionally, the concentration of the sodium hydroxide solution is 1 to 1.5 mol / L.

[0015] Optionally, the boiling temperature is 60-100° C. and the boiling time is 0.5-1 h.

[0016] High-concentration alkali solution treatment can not only shorten the purification time of bacterial fibers, but also soften the nanofibers, laying the foundation for subsequent pretreatment and shearing treatment.

[0017] Furthermore, the gradient freeze-drying is performed by pre-freezing at three temperature stages and then freeze-drying at -40°C for 48 hours.

[0018] Optionally, the three-stage pre-freezing is pre-freezing at 4°C, -20°C and -80°C for 4 to 12 hours respectively.

[0019] Gradient pre-freezing can ensure that the bacterial cellulose nanofiber hydrogel is fully cooled and can effectively avoid the collapse of the nanofiber structure during the freeze-drying process.

[0020] Furthermore, the dosage ratio of the bacterial cellulose aerogel to the TEMPO oxidation system is 0.1-0.5 g: 10-50 mL.

[0021] Furthermore, the TEMPO oxidation system includes 2,2,6,6-tetramethylpiperidinyloxy free radical (TEMPO), sodium hypochlorite (NaClO) and sodium bromide (NaBr).

[0022] Optionally, the concentration of the 2,2,6,6-tetramethylpiperidinyloxy free radical (TEMPO) in the TEMPO oxidation system is 0.01 to 0.1 mol / L; the concentration of the sodium hypochlorite (NaClO) in the TEMPO oxidation system is 0.1 to 1 mol / L; and the concentration of the sodium bromide (NaBr) in the TEMPO oxidation system is 1.5 to 2.5 mol / L.

[0023] Furthermore, the lysis pretreatment is a shaking treatment at 50-300 rpm for 3-24 hours.

[0024] The pyrolysis pretreatment can not only pyrolyze the amorphous regions of bacterial cellulose nanofibers, but also oxidize their surface hydroxyl groups into aldehyde groups, thus giving the surface of bacterial cellulose nanofibers chemical activity.

[0025] Furthermore, the usage ratio of the lysed bacterial cellulose and the solvent is 0.01-0.1 g: 10-100 mL.

[0026] Furthermore, the solvent includes water and / or butanol.

[0027] Optionally, when the solvent is water and butanol, the volume ratio of water to butanol is 0-1:0-1, and is not 0, preferably 4:1, 1:1 or 3:7.

[0028] Optionally, the butanol is at least one of tert-butanol, n-butanol, sec-butanol and isobutanol.

[0029] Furthermore, the ultrasonic-assisted homogenization is to place the homogenizing device in an ultrasonic atmosphere.

[0030] Optionally, the power of the ultrasound is 500-1000W.

[0031] Optionally, the rotation speed of the high-speed homogenizer is 10000-15000 rpm.

[0032] Furthermore, the shearing treatment time is 20 to 40 minutes.

[0033] Furthermore, the freeze-drying temperature is -80 to -40°C, and the time is 24 to 72 hours.

[0034] The invention adopts an ultrasound-assisted high-speed homogenization method to significantly improve the uniformity and dispersion of bacterial cellulose short-cut nanofibers.

[0035] The second technical solution of the present invention is to provide a uniformly dispersed short-cut bacterial cellulose nanofiber, wherein the uniformly dispersed short-cut bacterial cellulose nanofiber is prepared by the above-mentioned preparation method.

[0036] Furthermore, the uniformly dispersed short-cut bacterial cellulose nanofibers have a diameter of 30 to 90 nm, a length of 5 to 10 μm, and have abundant aldehyde groups on the surface.

[0037] The uniformly dispersed short-cut bacterial cellulose nanofibers prepared by the present invention have a moderate length and can be used as a reinforcing phase to improve the mechanical properties of polymer materials; the abundant active groups on the surface can be used to load drugs and bioactive molecules, showing great application prospects in the biomedical field.

[0038] The third technical solution of the present invention is to provide an application of the above-mentioned uniformly dispersed short-cut bacterial cellulose nanofibers as a carrier in drug preparation.

[0039] Optionally, the drug preparation is for the preparation of a drug for bone and cartilage tissue regeneration, skin repair or artificial blood vessel construction.

[0040] The fourth technical solution of the present invention is to provide a method for improving drug release performance, the steps comprising: using the above-mentioned uniformly dispersed short-cut bacterial cellulose nanofibers as a carrier, and loading the active ingredient of the drug through grafting and / or adsorption reaction.

[0041] Optionally, the pharmaceutically active ingredient includes a drug for bone and cartilage tissue regeneration, skin repair or artificial blood vessel construction.

[0042] The present invention discloses the following technical effects:

[0043] The ultrasonic-assisted high-speed homogenization treatment method used in the present invention allows the bacterial cellulose block material to be efficiently dispersed into single fibers, thereby solving the problem that the prior art can only disperse it into nanofiber fragments.

[0044] Compared with other electrospun nanofibers, the chopped bacterial cellulose nanofibers prepared by the present invention have the advantages of wide sources, simple operation, and low cost. They not only have a large specific surface area and surface chemical activity, but also have excellent mechanical properties. They can achieve efficient loading of bioactive molecules and enhance the mechanical properties of polymer materials and hydrogel materials, and have broad application prospects in the field of biomedicine.

[0045] The uniformly dispersed short-cut bacterial cellulose nanofibers provided in the present invention have a diameter of 30 to 90 nm and a length of 5 to 10 μm, and have a good specific surface area and specific volume ratio. The present invention uses a TEMPO oxidation system to pretreat bacterial cellulose, which is not only non-toxic and harmless, but also can improve the surface chemical activity of the nanofibers, giving the short-cut bacterial cellulose nanofibers excellent surface chemical activity. The above method gives bacterial cellulose nanofibers a huge advantage in drug delivery, laying the foundation for their application in the biomedical field. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0047] Figure 1 The SEM images of BC, cracked BC and short-cut BC in Example 1, wherein a is BC, b is cracked BC, and c is short-cut BC;

[0048] Figure 2 is a size distribution diagram of BC, cracked BC and short-cut BC in Example 1, wherein a is BC, b is cracked BC, and c is short-cut BC;

[0049] Figure 3 SEM images of short-cut BC-1, short-cut BC-2, short-cut BC-3 and short-cut BC-4, where a is short-cut BC-1, b is short-cut BC-2, c is short-cut BC-3, and d is short-cut BC-4;

[0050] Figure 4 FTIR and XRD spectra of BC, cracked BC and short-cut BC in Example 1, wherein a is FTIR and b is XRD;

[0051] Figure 5 The FTIR spectra of short-cut BC before and after loading with small molecule proteins and the fluorescence photos after loading, where a is the FTIR spectrum and b is the fluorescence photo;

[0052] Figure 6 The TGF-β release curves of the drug-loaded fibers prepared from the products of Example 1 and Comparative Examples 1 to 4;

[0053] Figure 7 The biocompatibility of BC, uncleaved short-cut BC and short-cut BC. DETAILED DESCRIPTION

[0054] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0055] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0056] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0057] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0058] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0059] The source of the bacterial cellulose nanofiber hydrogel in the present invention is not limited, and can be commercially available or prepared by oneself. An exemplary preparation method is provided below, and the steps include:

[0060] Acetobacter xylinum was used as a biogenerator and the bacterial cellulose hydrogel was obtained by culturing in a bacterial cellulose growth medium at 30°C for 7 days using a static culture method.

[0061] The steps of preparing the bacterial cellulose growth medium include: weighing 25 g of glucose, 7.5 g of yeast powder, 10 g of peptone and 10 g of Na2PO4, dissolving them in 1 L of deionized water, and stirring until completely dissolved; adding glacial acetic acid to adjust the pH value of the medium to 4-5; and sterilizing at 115°C for 30 minutes and then taking out to obtain the bacterial cellulose growth medium.

[0062] In some specific embodiments, optionally, the lysed bacterial cellulose is cut into small pieces with a size of 2-5 mm×2-5 mm×1-3 mm.

[0063] The bacterial cellulose nanofiber hydrogels in the following examples and comparative examples are prepared using the above exemplary preparation method, but this does not limit the method of the present invention.

[0064] Unless otherwise specified, the "room temperature" in the specific embodiments of the present invention refers to 20-30°C.

[0065] Example 1

[0066] The preparation steps of uniformly dispersed short-cut bacterial cellulose nanofibers are as follows:

[0067] S1, 10 g of the bacterial cellulose nanofiber hydrogel was immersed in a 1 M sodium hydroxide solution (500 mL) and boiled at 60 ° C for 0.5 h, then rinsed with deionized water until neutral, and then pre-frozen (gradient pre-cooling) in 4 ° C (4 h), -20 ° C (4 h), and -80 ° C (4 h) environments in sequence, and then freeze-dried at -40 ° C for 48 h to obtain bacterial cellulose aerogel, recorded as BC;

[0068] S2, 0.1 g of bacterial cellulose aerogel was added to a mixed solution (10 mL) of TEMPO (concentration of 0.01 M), NaClO (concentration of 0.1 M) and NaBr (concentration of 1.5 M), and the mixture was shaken at 100 rpm at room temperature for 8 h, then rinsed three times with deionized water, and freeze-dried to obtain lysed bacterial cellulose, which was recorded as lysed BC;

[0069] S3, take 0.15g of lysed bacterial cellulose and cut it into small pieces of 5mm×5mm×5mm with scissors, then add it into a mixed solution of 30mL of tert-butyl alcohol and water (volume ratio 4:1) and disperse it evenly, place the dispersed dispersion in an ultrasonic processor, and then place the blade of a high-speed homogenizer in the dispersion, the ultrasonic power is 500W, the homogenization speed is 13000rpm, and the treatment is carried out at room temperature for 0.8h to obtain a chopped bacterial cellulose nanofiber dispersion;

[0070] S4. Freeze-dry the chopped bacterial cellulose nanofiber dispersion at -60°C for 24 hours to obtain uniformly dispersed chopped bacterial cellulose nanofibers, which are referred to as chopped BC.

[0071] Comparative Example 1

[0072] Compared with Example 1, the only difference is that after the alkaline solution purification treatment in step S1, it is directly freeze-dried at -40°C for 48 hours, that is, the gradient pre-cooling process is reduced, wherein the bacterial cellulose aerogel prepared in step S1 is recorded as BC-1, and the final product is recorded as short-cut BC-1.

[0073] Comparative Example 2

[0074] Compared with Example 1, the only difference is that the ultrasonic assistance is reduced in step S3, and the final product is recorded as short-cut BC-2.

[0075] Comparative Example 3

[0076] Compared with Example 1, the only difference is that step S2 is omitted, that is, the bacterial cellulose aerogel prepared in step S1 is directly subjected to step S3, and the final product is recorded as short-cut BC-3.

[0077] Comparative Example 4

[0078] Compared with Example 1, the only difference is that the alkali solution purification step is omitted in step S1, and the bacterial cellulose aerogel is obtained directly by gradient freeze drying. The final product is recorded as short-cut BC-4.

[0079] Test Example 1: Characterization of Physical and Chemical Properties

[0080] The BC, cracked BC and short-cut BC in Example 1 were characterized as follows:

[0081] Scanning electron microscopy (SEM) was used to observe the microscopic morphology of the material and to calculate the fiber size distribution. Figure 1-2 shown.

[0082] Figure 1 The SEM images of BC, cracked BC and short-cut BC in Example 1, wherein a is BC, b is cracked BC, and c is short-cut BC; Figure 2 This is the size distribution diagram of BC, cracked BC and short-cut BC in Example 1, wherein a is BC, b is cracked BC, and c is short-cut BC.

[0083] Depend on Figure 1-2 It can be seen that BC has a natural nanofiber porous network structure; although the cracked BC retains the BC porous network structure, the nanofiber diameter is reduced from the original 49.8±15.1nm to 29.8±9.6nm; unlike BC and cracked BC, short-cut BC presents uniformly dispersed short nanofibers, there is no entanglement between the nanofibers, the dispersion effect is good, and the length is 7.15±2.32μm.

[0084] Figure 3 These are SEM images of short-chopped BC-1, short-chopped BC-2, short-chopped BC-3 and short-chopped BC-4, where a is short-chopped BC-1, b is short-chopped BC-2, c is short-chopped BC-3, and d is short-chopped BC-4.

[0085] Depend on Figure 3It can be seen that gradient freeze-drying was not performed when BC-1 was prepared, which resulted in the collapse of the three-dimensional structure during the freeze-drying process. The nanofibers were stacked and entangled together, and it was difficult to shear them into single short fibers even with the use of ultrasound-assisted homogenization technology; at the same time, without the use of ultrasound assistance, although the fibers were sheared during the homogenization shearing process, they still existed in the form of bundles; the fibers were not cracked and chopped, and although the fibers were well dispersed, the fiber length was too long; and if the bacterial cellulose was directly freeze-dried, cracked and sheared without purification, it would be difficult to disperse and shear the fibers, and a large number of bacterial corpses would remain.

[0086] The physicochemical properties of chopped BC nanofibers were characterized by infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Figure 4 shown.

[0087] Figure 4 The FTIR and XRD spectra of BC, cracked BC and short-cut BC in Example 1, where a is FTIR and b is XRD. As shown in the figure, the FTIR spectrum shows that after the cracking treatment, the surface groups of the nanofibers are changed from the original hydroxyl groups to carboxyl / aldehyde groups; the XRD spectrum shows that the short BC nanofibers have a lower crystallinity than the original BC, but still retain the diffraction peaks of BC, and have the original physical and chemical properties of BC.

[0088] Test Example 2: Drug loading and drug release performance test

[0089] Drug loading method: Weigh 10 mg of fluorescently labeled bovine serum albumin (BSA) and dissolve it in 2 mL of MES buffer, add 0.006 g of short-cut BC nanofibers and stir the reaction at 37°C overnight. The aldehyde groups on the surface of the short-cut BC nanofibers react with the amino groups of BSA to produce a Schiff base reaction, thereby using the short-cut BC nanofibers to load BSA. After the reaction is completed, dialyze is performed and the drug-loaded short-cut BC nanofibers are obtained after freeze-drying.

[0090] Infrared spectroscopy (FTIR) was used to characterize the occurrence of the grafting reaction, and an inverted fluorescence microscope was used to observe the distribution of fluorescently labeled BSA on the surface of the nanofibers. Figure 5 shown.

[0091] Figure 5 The FTIR spectra of short-cut BC before and after loading growth factors and the fluorescence photos after loading, where a is the FTIR spectrum and b is the fluorescence photo. As shown in the figure, the infrared spectrum shows that compared with short-cut BC, the drug-loaded short-cut BC has a high concentration of 1656cm -1 A strong absorption peak appears at the surface of the short-cut BC, which proves that the amino group of BSA undergoes a Schiff base reaction with the aldehyde group on the surface of the short-cut BC, achieving successful drug loading; the fluorescence photograph shows that BSA is evenly dispersed on the surface of the short-cut BC nanofibers.

[0092] The product prepared in Comparative Example 3 was subjected to drug loading treatment using the above-mentioned drug loading method. The drug-loaded products of Example 1 and Comparative Example 3 are collectively referred to as drug-loaded fibers.

[0093] The drug-loaded fibers were dispersed in a test tube containing 5 mL of PBS and incubated at 37°C in a shaking bath at 30 rpm. The supernatant was collected at 4 h, 8 h, 12 h, 16 h, 20 h, 24 h, 36 h, 48 h, and 72 h and replaced with an equal volume of fresh PBS. The cumulative release of BSA was detected using an enzyme-linked immunosorbent assay (ELISA) kit. The release curve is shown in Figure 2. Figure 6 shown.

[0094] Figure 6 The BSA release curves of the drug-loaded fibers prepared from the products of Example 1 and Comparative Example 3 show that the short-cut BC nanofibers loaded with BSA in Example 1 can achieve a slow and sustained release of BSA, with a release rate of 84.9% after 72 hours; while the drug-loaded fibers prepared in Comparative Example 3 not only have a low drug loading amount, but also have a burst release phenomenon, and reach release equilibrium only within 8 hours, with a drug loading rate of only 22.2%, and cannot achieve efficient drug loading and sustained release.

[0095] The biocompatibility of the material was tested using a CCK-8 kit. The material was dispersed in a culture medium and rBMSCs (bone marrow mesenchymal stem cells) were cultured using the culture medium at a cell density of 2.0×10 4 The culture medium was renewed every two days. At 1, 3 and 5 days. At each time point, fresh culture medium (300 μL) and CCK-8 solution (30 μL) were added after rinsing with PBS, and incubated at 37°C for 1.5 h. 100 μL of the supernatant was transferred to a 96-well plate and the absorbance was measured using an ELISA reader.

[0096] Figure 7 The figure shows the biocompatibility of the original BC, comparative example 3 and example 1. It can be seen from the figure that at different time points, the number of cells in comparative example 3 and example 1 is greater than that of the original BC. On the fifth day, the number of cells in example 1 gradually widened the gap with comparative example 3 and was greater than that in comparative example 3. The results show that the short-cut BC nanofibers prepared by the present invention have more excellent biocompatibility and are more suitable for use in the biomedical field.

[0097] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0098] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing uniformly dispersed short-cut bacterial cellulose nanofibers, characterized in that the steps include: The bacterial cellulose nanofiber hydrogel is purified by alkaline solution and gradient freeze-dried to obtain the bacterial cellulose aerogel. The bacterial cellulose aerogel is added into a TEMPO oxidation system for pyrolysis pretreatment to obtain pyrolysis bacterial cellulose; The lysed bacterial cellulose is dispersed in a solvent, subjected to shearing treatment by ultrasonic-assisted high-speed homogenization, and then freeze-dried to obtain uniformly dispersed short-cut bacterial cellulose nanofibers.

2. The preparation method according to claim 1, characterized in that The ratio of the bacterial cellulose nanofiber hydrogel to the alkali solution is 1-5 g: 50-250 mL; and / or, The dosage ratio of the bacterial cellulose aerogel to the TEMPO oxidation system is 0.1-0.5 g: 10-50 mL; and / or, The usage ratio of the lysed bacterial cellulose and the solvent is 0.01-0.1 g: 10-100 mL.

3. The preparation method according to claim 1, characterized in that: The alkaline solution purification treatment comprises: boiling the bacterial cellulose nanofiber hydrogel in a sodium hydroxide solution.

4. The preparation method according to claim 3, characterized in that: The sodium hydroxide solution has a concentration of 1 to 1.5 mol / L; and / or, The boiling temperature is 60-100° C. and the boiling time is 0.5-1 h.

5. The preparation method according to claim 1, characterized in that: The gradient freeze drying is pre-freezing at three temperature stages and then freeze drying at -40°C for 48 hours; and / or, The TEMPO oxidation system comprises 2,2,6,6-tetramethylpiperidinyloxy free radical, sodium hypochlorite and sodium bromide; and / or, The lysis pretreatment is performed by shaking at 50 to 300 rpm for 3 to 24 hours; and / or, The solvent comprises water and / or butanol; and / or, The ultrasonic-assisted homogenization is to place the homogenization device in an ultrasonic atmosphere; and / or, The shearing treatment time is 20 to 40 minutes; and / or, The freeze-drying temperature is -80 to -40°C and the time is 24 to 72 hours.

6. The preparation method according to claim 5, characterized in that: The three-stage pre-freezing is pre-freezing at 4°C, -20°C and -80°C for 4 to 12 hours respectively; and / or, The concentration of the 2,2,6,6-tetramethylpiperidinyloxy free radical in the TEMPO oxidation system is 0.01-0.1 mol / L; and / or, The concentration of sodium hypochlorite in the TEMPO oxidation system is 0.1-1 mol / L; and / or, The concentration of sodium bromide in the TEMPO oxidation system is 1.5-2.5 mol / L; and / or, When the solvent is water and butanol, the volume ratio of water to butanol is 0-1:0-1, and is not 0; and / or, The butanol is at least one of tert-butanol, n-butanol, sec-butanol and isobutanol; and / or, The power of the ultrasound is 500-1000W; and / or, The rotation speed of the high-speed homogenizer is 10000-15000 rpm.

7. A uniformly dispersed short-cut bacterial cellulose nanofiber, characterized in that: The uniformly dispersed short-cut bacterial cellulose nanofibers are prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the uniformly dispersed short-cut bacterial cellulose nanofibers according to claim 7 as a carrier in drug preparation.

9. A method for improving drug release performance, characterized in that the steps include: The uniformly dispersed short-cut bacterial cellulose nanofibers as claimed in claim 7 are used as carriers to load the active pharmaceutical ingredient through grafting and / or adsorption reaction.

10. The method according to claim 9, characterized in that The pharmaceutical active ingredients include drugs for bone and cartilage tissue regeneration, skin repair or artificial blood vessel construction.

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