Chitosan-sodium carboxymethyl cellulose composite microspheres, and preparation method and application thereof

Abstract

The application belongs to the technical field of medical biomacromolecule materials, and particularly relates to a chitosan-sodium carboxymethyl cellulose composite microsphere as well as a preparation method and application thereof. The application uses sodium carboxymethyl cellulose and chitosan as a microsphere shell material. The carboxyl on the sodium carboxymethyl cellulose is easy to react with the amino on the chitosan, so that the stability of the chitosan in an acidic medium can be improved, and the mechanical strength can be improved. Meanwhile, the hydroxyl and carboxyl on the sodium carboxymethyl cellulose have a strong affinity to cations, and the chitosan contains polar groups such as hydroxyl and amino, which also have a certain adsorption to cations. The obtained composite microsphere can selectively adsorb cationic drugs, has high drug adsorption performance, and can be used as a drug controlled release carrier material, an adsorbent and the like. The application uses electrostatic spraying or dropwise addition, is simple and convenient to operate, is environment-friendly, can be continuously operated, has mild conditions, and is low in cost.

Description

Technical Field

[0001] This invention belongs to the field of medical biopolymer materials technology, specifically relating to a chitosan-sodium carboxymethyl cellulose composite microsphere, its preparation method, and its application. Background Technology

[0002] In recent years, microsphere drug delivery systems, as novel drug carriers, have been widely used in the biomedical field due to their special size and structure, which enable them to deliver drugs to the local lesion and maintain slow drug release, prolong drug half-life, and reduce toxic side effects.

[0003] Traditional methods for preparing microspheres mainly include solvent evaporation, membrane emulsification, and microfluidics. Chitosan is a commonly used outer shell material. Chitosan is one of the few natural products with charge and has many unique physical, chemical, and biological properties, such as good biocompatibility, biodegradability, and non-toxic degradation products. Chitosan microspheres play a key role in pharmaceuticals, sterilization, and microseparators. Chitosan microspheres with different particle sizes and morphologies perform different functions such as drug loading, sterilization, and adsorption separation.

[0004] However, the application of chitosan is greatly limited because it is easily dissolved and lost in aqueous solutions, especially acidic ones. Summary of the Invention

[0005] The purpose of this invention is to provide a chitosan-sodium carboxymethyl cellulose composite microsphere, its preparation method, and its application. The preparation method provided by this invention improves the stability of chitosan in acidic media.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing chitosan-sodium carboxymethyl cellulose composite microspheres, comprising the following steps:

[0008] (1) Inject sodium carboxymethyl cellulose aqueous solution into an aqueous solution of metal ions, and then electrostatically spray or drop it to obtain sodium carboxymethyl cellulose microspheres;

[0009] (2) The sodium carboxymethyl cellulose microspheres were immersed in an aqueous solution of chitosan acetic acid and stirred to assemble, thereby obtaining chitosan-sodium carboxymethyl cellulose composite microspheres.

[0010] Preferably, the aqueous solution of sodium carboxymethyl cellulose has a viscosity of 1000–8000 mPa·s and a concentration of 0.5–2 wt%.

[0011] Preferably, the aqueous solution of metal ions is an aqueous solution of metal chlorides; the metal ions in the aqueous solution include one or more of iron ions, zinc ions, magnesium ions and copper ions; the metal chlorides include one or more of ferric chloride, zinc chloride, magnesium chloride and copper chloride; and the concentration of the aqueous solution of metal ions is 3-9 wt%.

[0012] Preferably, the injection rate is 0.05 to 1 mL / min.

[0013] Preferably, the concentration of chitosan in the chitosan-acetic acid aqueous solution is 0.5–2 wt%.

[0014] Preferably, the volume ratio of the chitosan acetic acid aqueous solution to the sodium carboxymethyl cellulose aqueous solution is 1-3:1-3; and the volume ratio of the sodium carboxymethyl cellulose aqueous solution to the metal ion aqueous solution is 1:2-5.

[0015] The present invention also provides chitosan-sodium carboxymethyl cellulose composite microspheres obtained by the preparation method described above, comprising a sodium carboxymethyl cellulose layer and a chitosan layer coating the outer surface of the sodium carboxymethyl cellulose layer; the chitosan-sodium carboxymethyl cellulose composite microspheres are hollow spheres.

[0016] This invention also provides the application of the chitosan-carboxymethyl cellulose sodium composite microspheres described above in the preparation of cationic drug carriers, tissue fillers, and as strong adsorbents.

[0017] The present invention also provides a chitosan-carboxymethyl cellulose drug-loaded microsphere, comprising chitosan-carboxymethyl cellulose sodium composite microspheres and a cationic drug loaded in the inner cavity of the chitosan-carboxymethyl cellulose sodium composite microspheres;

[0018] The chitosan-carboxymethyl cellulose sodium composite microspheres are the chitosan-carboxymethyl cellulose sodium composite microspheres described in the above scheme.

[0019] The present invention also provides a method for preparing chitosan-carboxymethyl cellulose drug-loaded microspheres as described above, characterized by comprising the following steps:

[0020] Chitosan-carboxymethyl cellulose sodium composite microspheres were mixed with an aqueous solution of a cationic drug and then adsorbed by shaking. The resulting adsorption system was then mixed with a crosslinking agent to crosslink the microspheres, thus obtaining chitosan-carboxymethyl cellulose drug-loaded microspheres.

[0021] This invention provides a method for preparing chitosan-sodium carboxymethyl cellulose composite microspheres. The invention uses sodium carboxymethyl cellulose and chitosan as the shell materials of the microspheres. The carboxyl groups on sodium carboxymethyl cellulose readily react with the amino groups on chitosan, improving the stability of chitosan in acidic media and increasing its mechanical strength. Simultaneously, the hydroxyl and carboxyl groups on sodium carboxymethyl cellulose have a strong affinity for cations, and chitosan, containing polar groups such as hydroxyl and amino groups, also has a certain adsorption capacity for cations. The resulting composite microspheres can selectively adsorb cationic drugs, exhibiting high drug adsorption performance and can be used as drug controlled-release carrier materials and adsorbents. This invention utilizes electrostatic spraying or dropwise addition methods, which are simple to operate, environmentally friendly, allow for continuous operation, operate under mild conditions, and are low in cost.

[0022] This invention uses sodium carboxymethyl cellulose and metal ions to prepare composite microspheres. On the one hand, sodium carboxymethyl cellulose and metal ions react to cause the spheres to shrink; on the other hand, the reaction force on the spheres causes them to expand. When the two opposing forces reach equilibrium, a hollow sphere structure is formed.

[0023] Furthermore, the viscosity of the sodium carboxymethyl cellulose aqueous solution is 1000–8000 mPa·s, and the concentration is 0.5–2 wt%; the concentration of chitosan in the chitosan-acetic acid aqueous solution is 0.5–2 wt%; the volume ratio of the chitosan-acetic acid aqueous solution to the sodium carboxymethyl cellulose aqueous solution is 1–3:1–3; and the volume ratio of the sodium carboxymethyl cellulose aqueous solution to the metal ion aqueous solution is 1:2–5. This invention prepares spherically rounded composite microspheres by using sodium carboxymethyl cellulose and chitosan at specific concentrations and ratios.

[0024] This invention also provides chitosan-sodium carboxymethyl cellulose composite microspheres prepared by the above-described method, comprising a sodium carboxymethyl cellulose layer and a chitosan layer coating the outer surface of the sodium carboxymethyl cellulose layer; the chitosan-sodium carboxymethyl cellulose composite microspheres are hollow spheres. The chitosan-sodium carboxymethyl cellulose composite microspheres provided by this invention have a rounded morphology, regular shape, controllable particle size, uniform size, high purity, are easy to separate, and do not stick together.

[0025] This invention also provides the application of the chitosan-sodium carboxymethyl cellulose composite microspheres described above in the preparation of cationic drug carriers, tissue fillers, and as strong adsorbents. The composite microspheres provided by this invention can be used as strong adsorbents in the preparation of tissue fillers and controlled-release drug carriers, exhibiting good adsorption effects and stable drug release.

[0026] This invention also provides chitosan-carboxymethyl cellulose drug-loaded microspheres. The chitosan-carboxymethyl cellulose drug-loaded microspheres provided by this invention have a rounded morphology, controllable particle size, and stable drug release.

[0027] This invention also provides a method for preparing chitosan-carboxymethyl cellulose drug-loaded microspheres as described above. The preparation method provided by this invention is continuous, operates under mild conditions, is low in cost, and can be industrially produced. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a morphology image of the chitosan-carboxymethyl cellulose sodium composite microspheres before freeze-drying in Example 12 of the present invention.

[0030] Figure 2 This is a morphology image of chitosan-sodium carboxymethyl cellulose composite microspheres after freeze-drying in Example 12 of the present invention.

[0031] Figure 3 This is a morphology image of chitosan-sodium carboxymethyl cellulose composite microspheres after freeze-drying in Example 15 of the present invention.

[0032] Figure 4 The infrared spectra of Fe-CMC microspheres and Fe-CMC-chitosan composite microspheres in Example 4 of this invention are shown below.

[0033] Figure 5 The images show the in vitro dissolution curves of chitosan-carboxymethyl cellulose sodium loaded microspheres in Examples 26, 29, 31 and 32 of this invention. Detailed Implementation

[0034] This invention provides a method for preparing chitosan-sodium carboxymethyl cellulose composite microspheres, comprising the following steps:

[0035] (1) Inject sodium carboxymethyl cellulose aqueous solution into an aqueous solution of metal ions, and then electrostatically spray or drop it to obtain sodium carboxymethyl cellulose microspheres;

[0036] (2) The sodium carboxymethyl cellulose microspheres were immersed in an aqueous solution of chitosan acetic acid and stirred to assemble, thereby obtaining chitosan-sodium carboxymethyl cellulose composite microspheres.

[0037] This invention involves injecting an aqueous solution of sodium carboxymethyl cellulose into an aqueous solution of metal ions, followed by electrostatic spraying or dropwise addition to obtain sodium carboxymethyl cellulose microspheres. In this invention, the viscosity of the sodium carboxymethyl cellulose aqueous solution is preferably 1000–8000 mPa·s, more preferably 3000–7000 mPa·s, and even more preferably 5000–6000 mPa·s; the concentration is preferably 0.5–2 wt%, more preferably 0.75–1.6 wt%, and even more preferably 1.0–1.3 wt%.

[0038] In this invention, the preferred method for preparing the sodium carboxymethyl cellulose aqueous solution is to dissolve sodium carboxymethyl cellulose (CMC) in an aqueous solution and stir at room temperature until completely dissolved to obtain a uniform and transparent sodium carboxymethyl cellulose aqueous solution.

[0039] In this invention, the aqueous solution of metal ions is preferably an aqueous solution of metal chlorides; the metal ions in the aqueous solution of metal ions preferably include one or more of iron ions, zinc ions, magnesium ions and copper ions; the metal chlorides preferably include one or more of ferric chloride, zinc chloride, magnesium chloride and copper chloride, more preferably ferric chloride; the concentration of the aqueous solution of metal ions is preferably 3-9 wt%, more preferably 4-8 wt%, and even more preferably 5-6 wt%.

[0040] In this invention, the preferred method for preparing the metal ion aqueous solution is to dissolve the metal ions in an aqueous solution and stir at room temperature until completely dissolved to obtain the metal ion aqueous solution.

[0041] In this invention, the volume ratio of the sodium carboxymethyl cellulose aqueous solution to the metal ion aqueous solution is preferably 1:2 to 5, more preferably 1:2 to 3, and even more preferably 1:3.

[0042] In this invention, the injection rate is preferably 0.05-1 mL / min, more preferably 0.2-0.8 mL / min, and even more preferably 0.4-0.6 mL / min; the injection device is preferably a syringe.

[0043] In this invention, the injection process preferably further includes a first post-treatment of the resulting system; the first post-treatment preferably includes centrifugal washing and solvent removal.

[0044] In this invention, the needle type for electrostatic spraying is preferably 30G to 21G, more preferably 21G. This invention prepares composite microspheres of different particle sizes by adjusting the needle size and raw material ratio.

[0045] In this invention, the injection speed of the electrostatic spray is preferably 0.2-0.5 mL / min, more preferably 0.3-0.4 mL / min, the injection distance is preferably 15-20 cm, more preferably 17-19 cm, the injection voltage is preferably 8-15 kV, more preferably 10-12 kV, and the temperature is preferably room temperature.

[0046] This invention first adjusts the concentration of an aqueous solution of sodium carboxymethyl cellulose (CMC), then disperses the CMC solution into fine droplets under electrostatic force using electrostatic spraying or dropwise addition. Next, the fine droplets undergo solvent evaporation and contraction in the air to form microspheres, which then fall into an aqueous solution containing metal ions. The reaction between CMC and the metal ions causes the spheres to shrink, while the reaction force on the spheres causes them to expand. When these two opposing forces reach equilibrium, more rounded hollow spheres are formed. The chitosan-sodium carboxymethyl cellulose composite microspheres provided by this invention have a rounded morphology, regular shape, controllable particle size, uniform size, high purity, are easily separated, and do not stick together.

[0047] After obtaining sodium carboxymethyl cellulose microspheres, the present invention soaks the sodium carboxymethyl cellulose microspheres in a chitosan-acetic acid aqueous solution and stirs to assemble them, thereby obtaining chitosan-sodium carboxymethyl cellulose composite microspheres.

[0048] In this invention, the concentration of chitosan in the chitosan-acetic acid aqueous solution is preferably 0.5-2 wt%, more preferably 0.8-1.7 wt%, and even more preferably 1.0-1.4 wt%; the pH value of the chitosan-acetic acid aqueous solution is preferably 3-5.5, more preferably 3.8-4.5.

[0049] In this invention, the preferred method for preparing the chitosan-acetic acid aqueous solution is to dissolve chitosan in an acetic acid aqueous solution and stir at room temperature until completely dissolved to obtain a uniform and transparent chitosan-acetic acid aqueous solution.

[0050] In this invention, the volume ratio of the chitosan acetic acid aqueous solution to the sodium carboxymethyl cellulose aqueous solution is preferably 1-3:1-3, more preferably 1.5-2.5:1.5-2.5, and even more preferably 2:2.

[0051] In this invention, the stirring speed is preferably 50-300 rpm, more preferably 50-150 rpm, and even more preferably 100 rpm; the stirring time is preferably 10-120 min, more preferably 10-60 min, and even more preferably 30 min. This invention, through stirring assembly, uniformly coats chitosan onto the exterior of sodium carboxymethyl cellulose.

[0052] In this invention, the stirring assembly preferably includes a second post-processing of the resulting product system; the second post-processing preferably includes filtration, washing and drying.

[0053] The present invention also provides chitosan-sodium carboxymethyl cellulose composite microspheres obtained by the preparation method described above, comprising a sodium carboxymethyl cellulose layer and a chitosan layer coating the outer surface of the sodium carboxymethyl cellulose layer; the chitosan-sodium carboxymethyl cellulose composite microspheres are hollow spheres.

[0054] In this invention, the diameter of the chitosan-sodium carboxymethyl cellulose composite microspheres is preferably less than 1 mm, more preferably 0.1 to 2 μm, and even more preferably 0.8 to 1.5 μm.

[0055] The chitosan-sodium carboxymethyl cellulose composite microspheres provided by this invention are hollow microspheres. The spheres consist of a sodium carboxymethyl cellulose layer and a chitosan layer from the inside out. The sodium carboxymethyl cellulose layer is prepared by reacting sodium carboxymethyl cellulose with metal ions, and the chitosan layer is prepared by reacting chitosan. The reaction of sodium carboxymethyl cellulose and chitosan yields the composite microspheres with an integral structure.

[0056] This invention also provides the application of the chitosan-carboxymethyl cellulose sodium composite microspheres described above in the preparation of cationic drug carriers, tissue fillers, and as strong adsorbents.

[0057] The composite microspheres provided by this invention can be used as strong adsorbents to prepare tissue fillers and drug controlled-release carriers, exhibiting good adsorption effects and stable drug release.

[0058] The present invention also provides a chitosan-carboxymethyl cellulose drug-loaded microsphere, comprising chitosan-carboxymethyl cellulose sodium composite microspheres and a cationic drug loaded in the inner cavity of the chitosan-carboxymethyl cellulose sodium composite microspheres;

[0059] The chitosan-carboxymethyl cellulose sodium composite microspheres are the chitosan-carboxymethyl cellulose sodium composite microspheres described in the above scheme.

[0060] In this invention, the drug loading rate of the chitosan-carboxymethyl cellulose drug-loaded microspheres is preferably 1 to 10 wt%.

[0061] The present invention also provides a method for preparing chitosan-carboxymethyl cellulose drug-loaded microspheres as described above, characterized by comprising the following steps:

[0062] Chitosan-carboxymethyl cellulose sodium composite microspheres were mixed with an aqueous solution of a cationic drug and then adsorbed by shaking. The resulting adsorption system was then mixed with a crosslinking agent to crosslink the microspheres, thus obtaining chitosan-carboxymethyl cellulose drug-loaded microspheres.

[0063] In this invention, the concentration of the cationic drug aqueous solution is preferably 5-20 μg / L, more preferably 10 μg / L; the cationic drug is preferably an antibiotic; the antibiotic preferably includes one or more of vancomycin, penicillin and ciprofloxacin.

[0064] In this invention, the mass ratio of the chitosan-carboxymethyl cellulose sodium composite microspheres to the cationic drug aqueous solution is preferably 0.05-0.1:5-10, more preferably 0.05-0.1:10.

[0065] In this invention, the preferred rate of the shaking adsorption is 50–150 rpm, more preferably 50–100 rpm, and the preferred time is 1–5 h, more preferably 3 h. During shaking adsorption, the cations in the cationic drug form complexes with the carboxyl groups in sodium carboxymethyl cellulose, thereby causing adsorption.

[0066] In this invention, the crosslinking agent preferably includes one or more of glutaraldehyde and epichlorohydrin.

[0067] In this invention, the crosslinking temperature is preferably 0-10°C, more preferably 0-5°C, and even more preferably 2°C, and the heat preservation time is preferably 1-3 hours, more preferably 2 hours.

[0068] In this invention, the crosslinking process preferably further includes a third post-treatment of the crosslinking product; the third post-treatment preferably includes washing and drying.

[0069] To further illustrate the present invention, the following detailed description of the invention's solutions, in conjunction with the accompanying drawings and embodiments, is provided, but should not be construed as limiting the scope of protection of the present invention.

[0070] Example

[0071] The effects of dropping distance and needle inner diameter on microspheres were investigated; a method for preparing chitosan-sodium carboxymethyl cellulose composite microspheres (dropping method) includes the following steps:

[0072] (1) Dissolve sodium carboxymethyl cellulose (CMC) in an aqueous solution to prepare a 1 wt% CMC aqueous solution. Stir at room temperature until completely dissolved to obtain a uniform and transparent sodium carboxymethyl cellulose aqueous solution for later use.

[0073] (2) Dissolve the metal ions ferric chloride in an aqueous solution to prepare a 3wt% ferric chloride aqueous solution. Stir at room temperature until completely dissolved to obtain an aqueous solution of metal ions for later use.

[0074] (3) Dissolve chitosan in a 1 wt% aqueous acetic acid solution to prepare a 1 wt% chitosan-acetic acid aqueous solution. Stir at room temperature until completely dissolved to obtain a uniform and transparent chitosan-acetic acid aqueous solution for later use.

[0075] (4) At room temperature, take 2 mL of the CMC aqueous solution from step (1) and place it in a syringe. Then slowly add it dropwise to 6 mL of the metal ion aqueous solution from step (2). Then centrifuge and wash to remove the solvent and obtain CMC microspheres for later use.

[0076] (5) The CMC microspheres collected in step (4) were immersed in 4 mL of chitosan acetic acid aqueous solution from step (3) and stirred at 150 rpm for 1 h to make chitosan uniformly coat the outside of CMC. Then, 1 mL of 20 wt% glutaraldehyde solution was added for cross-linking for 2 h. Then, the mixture was filtered, washed with water and dried to obtain chitosan-carboxymethyl cellulose sodium composite microspheres.

[0077] Table 1. Parameters for preparing chitosan-sodium carboxymethyl cellulose composite microspheres in Examples 1-4

[0078]

[0079] As shown in Table 1, with the CMC, ferric chloride, and chitosan formulations remaining unchanged, the drop distance of the solution has little effect on the morphology and diameter of the spheres; the inner diameter of the needle has a greater impact on the diameter of the spheres. The smaller the inner diameter of the needle, the smaller the diameter of the prepared spheres. However, when the inner diameter of the needle is too small, the spheres formed during the droplet infiltration tend to be elliptical. When the drop distance is 15 cm and the needle type is 21G, the prepared spheres are relatively round, with a particle size of 1–5 mm.

[0080] Infrared spectroscopy was performed on the Fe-CMC microspheres and Fe-CMC-chitosan composite microspheres prepared in Example 4, and the results are as follows: Figure 4 As shown. According to Figure 4 It can be seen that the absorption peaks at 2916 and 3308 are enhanced due to the polyhydroxy and polyamino groups of chitosan, as well as the electrostatic interaction between chitosan and CMC, and shift to 2929 and 3325, respectively. A relatively strong absorption peak appears at 581 due to the interaction between some chitosan and iron ions. Furthermore, the amino groups in chitosan react with the carboxyl groups in CMC, resulting in a new carbonyl absorption peak at 1714. Therefore, it can be concluded that metal ions, CMC, and chitosan groups participate in reactions to varying degrees, forming composite microspheres.

[0081] Example

[0082] Based on Examples 1-4, the effect of formulation concentration on microspheres was investigated; a method for preparing chitosan-carboxymethyl cellulose sodium composite microspheres (droplet addition method) includes the following steps:

[0083] (1) Dissolve sodium carboxymethyl cellulose (CMC) in an aqueous solution to prepare a CMC aqueous solution of a certain concentration. Stir at room temperature until completely dissolved to obtain a uniform and transparent sodium carboxymethyl cellulose aqueous solution.

[0084] (2) Dissolve the metal chloride ferric chloride in an aqueous solution to prepare a ferric chloride aqueous solution of a certain concentration. Stir at room temperature until completely dissolved to obtain an aqueous solution of metal ions for later use.

[0085] (3) Dissolve chitosan in 1 wt% acetic acid aqueous solution to prepare a chitosan acetic acid aqueous solution of a certain concentration. Stir at room temperature until completely dissolved to obtain a uniform and transparent chitosan acetic acid aqueous solution.

[0086] (4) At room temperature, take 4 mL of the CMC aqueous solution from step (1) and place it in a syringe. Then slowly add it dropwise to 10 mL of the metal ion aqueous solution from step (2). Then centrifuge and wash to remove the solvent and obtain CMC microspheres for later use.

[0087] (5) The CMC microspheres collected in step (4) were immersed in 12 mL of chitosan acetic acid aqueous solution from step (3) and stirred at 100 rpm for 30 min to make chitosan uniformly coat the outside of CMC. Then, 1 mL of 20 wt% glutaraldehyde solution was added for cross-linking for 2 h. Then, the mixture was filtered, washed with water and dried to obtain chitosan-carboxymethyl cellulose sodium composite microspheres.

[0088] Table 2. Parameters for preparing chitosan-sodium carboxymethyl cellulose composite microspheres in Examples 5-11

[0089]

[0090] As shown in Table 2, the higher the concentration of CMC, the larger the diameter of the spheres and the less round the spheres tend to be; the higher the concentration of chitosan, the smaller the diameter of the prepared spheres and the more round the spheres tend to be; when using 1 wt% CMC, 3 wt% ferric chloride, 1 wt% chitosan and 21G needles, the prepared spheres are relatively round and the diameter of the spheres is small.

[0091] Example

[0092] Based on Examples 5-11, the effects of different metal ions on the microspheres were investigated; a method for preparing chitosan-sodium carboxymethyl cellulose composite microspheres (dropping method) includes the following steps:

[0093] (1) Dissolve sodium carboxymethyl cellulose (CMC) in an aqueous solution to prepare a CMC aqueous solution with a concentration of 1 wt%. Stir at room temperature until completely dissolved to obtain a uniform and transparent sodium carboxymethyl cellulose aqueous solution.

[0094] (2) Dissolve different metal chlorides in aqueous solution to prepare a 3wt% chloride aqueous solution. Stir at room temperature until completely dissolved to obtain a metal ion aqueous solution for later use.

[0095] (3) Dissolve chitosan in a 1 wt% aqueous acetic acid solution to prepare a 1 wt% chitosan-acetic acid aqueous solution. Stir at room temperature until completely dissolved to obtain a uniform and transparent chitosan-acetic acid aqueous solution.

[0096] (4) At room temperature, take 2 mL of the CMC aqueous solution from step (1) and place it in a syringe. Then slowly add it dropwise to 6 mL of the metal ion aqueous solution from step (2). Then centrifuge and wash to remove the solvent and obtain CMC microspheres for later use.

[0097] (5) The CMC microspheres collected in step (4) were immersed in 4 mL of chitosan acetic acid aqueous solution from step (3) and stirred at 100 rpm for 30 min to make chitosan uniformly coat the outside of CMC. Then, 1 mL of 20 wt% glutaraldehyde solution was added for cross-linking for 2 h. Then, the mixture was filtered, washed with water and dried to obtain chitosan-carboxymethyl cellulose sodium composite microspheres.

[0098] Table 3. Parameters for preparing chitosan-sodium carboxymethyl cellulose composite microspheres in Examples 12-15

[0099]

[0100] As can be seen from Table 3, when ferric chloride, zinc chloride, and copper chloride are used, round spheres can be prepared, but when calcium chloride is used, spheres cannot be formed.

[0101] When zinc chloride is used, the prepared spheres are transparent; when ferric chloride is used, the prepared spheres are brown; and when copper chloride is used, the prepared spheres are light green. The type of metal ion can be selected according to the needs.

[0102] The morphology of chitosan-sodium carboxymethyl cellulose composite microspheres before and after freeze-drying was observed, and the results are as follows: Figures 1-3 As shown. According to Figures 1-3 It can be seen that the spheres prepared by the conventional dropwise method of the present invention have a relatively large diameter, with the diameter of the spheres concentrated in the range of 1 to 3 mm.

[0103] Example

[0104] Based on Examples 12-15, the effect of electrostatic spraying on microspheres was investigated; a method for preparing chitosan-carboxymethyl cellulose sodium composite microspheres (electrostatic spraying method) includes the following steps:

[0105] (1) Dissolve sodium carboxymethyl cellulose (CMC) in an aqueous solution to prepare a 1 wt% CMC aqueous solution. Stir at room temperature until completely dissolved to obtain a uniform and transparent sodium carboxymethyl cellulose aqueous solution.

[0106] (2) Dissolve the metal chloride ferric chloride in an aqueous solution to prepare a 3 wt% ferric chloride aqueous solution. Stir at room temperature until completely dissolved to obtain an aqueous solution of metal ions for later use.

[0107] (3) Dissolve chitosan in a 1 wt% aqueous acetic acid solution to prepare a 1 wt% chitosan-acetic acid aqueous solution. Stir at room temperature until completely dissolved to obtain a uniform and transparent chitosan-acetic acid aqueous solution.

[0108] (4) At room temperature, electrostatic spraying process is used, the injection distance is set to 15cm, the injection voltage is 10kV, and different injection speeds are set. Take 4mL of CMC aqueous solution from step (1) and place it in a syringe, then inject it into 10mL of metal ion aqueous solution from step (2), then centrifuge and wash to remove the solvent, and obtain CMC microspheres for later use.

[0109] (5) The CMC microspheres collected in step (4) were immersed in 12 mL of chitosan acetic acid aqueous solution from step (3) and stirred at 100 rpm for 30 min to make chitosan uniformly coat the outside of CMC. Then, 1 mL of 20 wt% glutaraldehyde solution was added for cross-linking for 2 h. Then, the mixture was filtered, washed with water and dried to obtain chitosan-carboxymethyl cellulose sodium composite microspheres.

[0110] Table 4. Parameters for preparing chitosan-sodium carboxymethyl cellulose composite microspheres in Examples 16-19

[0111]

[0112]

[0113] As shown in Table 4, the injection speed is related to the morphology and diameter of the spheres. When the injection speed is low, the prepared spheres are rounder and smaller in diameter. As the injection speed increases, the particle size of the spheres gradually increases. When the injection speed increases again, the spheres become less round, have poor morphology, or are not formed.

[0114] When using 1 wt% CMC, 3 wt% FeCl3, 1 wt% chitosan, and an injection rate of 0.05–0.2 mL / min, the prepared microspheres have a rounded morphology.

[0115] Example

[0116] Based on Examples 16-19, the effect of the ratio of CMC to chitosan on morphology was investigated; a method for preparing chitosan-carboxymethyl cellulose sodium composite microspheres (electrostatic spraying method) includes the following steps:

[0117] (1) Dissolve sodium carboxymethyl cellulose (CMC) in an aqueous solution to prepare a 1 wt% CMC aqueous solution. Stir at room temperature until completely dissolved to obtain a uniform and transparent sodium carboxymethyl cellulose aqueous solution.

[0118] (2) Dissolve ferric chloride in an aqueous solution to prepare a 3 wt% ferric chloride aqueous solution. Stir at room temperature until completely dissolved to obtain an aqueous solution of metal ions for later use.

[0119] (3) Dissolve chitosan in a 1 wt% aqueous acetic acid solution to prepare a 1 wt% chitosan-acetic acid aqueous solution. Stir at room temperature until completely dissolved to obtain a uniform and transparent chitosan-acetic acid aqueous solution.

[0120] (4) At room temperature, an electrostatic spraying process was used, with the injection speed set to 0.2 mL / min, the injection distance to 15 cm, and the injection voltage to 10 kV. A certain volume of the CMC aqueous solution from step (1) was placed in a syringe and then injected into 10 mL of the metal ion aqueous solution from step (2). The solution was then centrifuged and washed to remove the solvent, and CMC microspheres were obtained for later use.

[0121] (5) The CMC microspheres collected in step (4) are immersed in a certain volume of chitosan acetic acid aqueous solution from step (3) and stirred at 50 rpm for 1 h to make chitosan uniformly coat the outside of CMC. Then, 1 mL of 20 wt% glutaraldehyde solution is added for cross-linking for 2 h. Then, the mixture is filtered, washed with water and dried to obtain chitosan-carboxymethyl cellulose sodium composite microspheres.

[0122] Table 5. Parameters for the preparation of chitosan-sodium carboxymethyl cellulose composite microspheres in Examples 20-23

[0123]

[0124]

[0125] As can be seen from Table 5, when the concentrations of CMC and chitosan are constant, changing the ratio of CMC solution to chitosan has little effect on the morphology of the spheres.

[0126] Example

[0127] Based on Examples 20-23, the effect of raw material concentration on drug loading rate was investigated; a method for preparing chitosan-carboxymethyl cellulose sodium composite microspheres includes the following steps:

[0128] (1) Dissolve sodium carboxymethyl cellulose (CMC) in an aqueous solution to prepare a 1 wt% CMC aqueous solution. Stir at room temperature until completely dissolved to obtain a uniform and transparent sodium carboxymethyl cellulose aqueous solution.

[0129] (2) Dissolve different metal chlorides in aqueous solution to prepare a certain concentration of chloride aqueous solution, stir at room temperature until completely dissolved to obtain metal ion aqueous solution for later use;

[0130] (3) Dissolve chitosan in an aqueous acetic acid solution to prepare a 1 wt% chitosan-acetic acid aqueous solution. Stir at room temperature until completely dissolved to obtain a uniform and transparent chitosan-acetic acid aqueous solution.

[0131] (4) At room temperature, take 2 mL of the CMC aqueous solution from step (1) and place it in a syringe. Then slowly add it dropwise to 6 mL of the metal ion aqueous solution from step (2). Then centrifuge and wash to remove the solvent and obtain CMC microspheres for later use.

[0132] (5) The CMC microspheres collected in step (4) were immersed in 4 mL of chitosan acetic acid aqueous solution from step (3) and stirred at 100 rpm for 30 min to make chitosan uniformly coat the outside of CMC. Then, 1 mL of 20 wt% glutaraldehyde solution was added for cross-linking for 2 h. Then, the mixture was filtered, washed with water and dried to obtain chitosan-carboxymethyl cellulose sodium composite microspheres.

[0133] (6) Add the chitosan-carboxymethyl cellulose sodium composite microspheres prepared in step (5) to vancomycin aqueous solution, shake and adsorb for 3 h, add crosslinking agent for crosslinking, wash and dry to obtain chitosan-carboxymethyl cellulose drug-loaded microspheres.

[0134] Table 6. Parameters for the preparation of chitosan-carboxymethyl cellulose drug-loaded microspheres in Examples 24-32.

[0135]

[0136]

[0137] As shown in Table 6, under the condition that other factors remain unchanged, the drug loading rate of vancomycin gradually decreases with the increase of chitosan concentration; when the chitosan concentration is 0.5 wt%, the drug loading rate of the prepared spheres is 4.5%; when CMC and chitosan are constant, the drug loading rate of the prepared spheres first increases and then decreases with the increase of ferric chloride concentration.

[0138] When using 3 mL of 1 wt% CMC, 15 mL of 3 wt% ferric chloride, and 9 mL of 0.5 wt% chitosan, the prepared spheres have a moderate drug loading rate and are relatively round.

[0139] Test case

[0140] The chitosan-carboxymethyl cellulose drug-loaded microspheres prepared in Examples 16-32 were subjected to the following tests:

[0141] (1) Morphological inspection: natural observation method;

[0142] (2) Particle size detection: ruler test; spread the freeze-dried spheres flat on the table and use a ruler with a range of 20cm to test their particle size. Take an average of 3 measurements and take the average value of the results.

[0143] (3) Drug loading rate detection: A UV spectrophotometer was used for testing. 50 mg of drug-loaded microspheres were accurately weighed, dissolved in 20 mL of acetonitrile, and diluted to 100 mL with a 0.1 wt% acetic acid aqueous solution. The supernatant was filtered and then tested using a UV spectrophotometer.

[0144] Drug loading rate = (Drug content in microspheres / Total weight of microspheres) × 100%;

[0145] Encapsulation efficiency = (actual drug loading rate / theoretical drug loading rate) × 100%;

[0146] (4) In vitro release test: 0.025 g microspheres were added to 15 mL of phosphate buffer solution at 37 °C and pH 7.4. Samples were taken at regular intervals and the drug concentration was tested by ultraviolet light.

[0147] The cumulative dissolution rate (%) after each time point = 100% × (C1 + C2 + ... Cn) × V / L, where Cn is the drug concentration after extraction at each time point, V is the fixed sampling volume at each time point (because all samples are extracted and then replenished with the same volume of medium, the sampling volume is equal to the dissolution medium volume), and L is the total drug content added; the test results are shown in Table 7.

[0148] Table 7 Performance tests of chitosan-carboxymethyl cellulose drug-loaded microspheres in Examples 26, 29, and 31-32

[0149]

[0150] As shown in Table 7, different concentrations of metal ions have a certain impact on the drug loading rate of microspheres. Taking iron ions as an example, as the concentration of metal ions increases, the drug loading rate of the prepared microspheres first increases and then decreases. When the concentration of ferric chloride is 3 wt%, the drug loading rate of the prepared microspheres is moderate, with a drug loading rate of 4.5%.

[0151] When using 3 mL of 1 wt% CMC, 15 mL of different concentrations of metal ions, and 9 mL of 0.5 wt% chitosan, the dissolution rate of microspheres prepared with different metal ions varies. When copper ions are used, the microspheres have a larger burst release, and the drug is basically completely released after 1 day. When iron ions are used, the drug release is more stable, and the higher the concentration of iron ions, the faster the drug release.

[0152] When using 3 mL of 1 wt% CMC, 15 mL of 3 wt% ferric chloride, and 9 mL of 0.5 wt% chitosan, the prepared spheres have a moderate drug loading rate, are relatively round, and release the drug stably.

[0153] As can be seen from the above embodiments, the preparation method provided by the present invention improves the stability of chitosan in acidic media. The resulting chitosan-carboxymethyl cellulose sodium composite microspheres have a rounded morphology, regular shape, controllable particle size, uniform size, high purity, are easy to separate, do not stick together, can selectively adsorb cationic drugs, have high drug adsorption performance, and can be used as a drug controlled release carrier material.

[0154] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A chitosan-carboxymethyl cellulose drug-loaded microsphere, characterized in that, The invention comprises chitosan-sodium carboxymethyl cellulose composite microspheres and a cationic drug loaded in the inner cavity of the chitosan-sodium carboxymethyl cellulose composite microspheres; the chitosan-sodium carboxymethyl cellulose composite microspheres include a sodium carboxymethyl cellulose layer and a chitosan layer covering the outer surface of the sodium carboxymethyl cellulose layer; the chitosan-sodium carboxymethyl cellulose composite microspheres are hollow spheres; The preparation method of the chitosan-carboxymethyl cellulose sodium composite microspheres includes the following steps: (1) injecting an aqueous solution of carboxymethyl cellulose sodium into an aqueous solution of metal ions, and then electrostatically spraying or dripping to obtain carboxymethyl cellulose sodium microspheres; the injection rate is 0.05~0.2 mL / min; (2) The sodium carboxymethyl cellulose microspheres were immersed in a chitosan acetic acid aqueous solution and stirred to assemble, thereby obtaining chitosan-sodium carboxymethyl cellulose composite microspheres; The preparation method of the chitosan-carboxymethyl cellulose drug-loaded microspheres includes the following steps: mixing chitosan-carboxymethyl cellulose sodium composite microspheres and cationic drug aqueous solution, followed by shaking adsorption, and then mixing the resulting adsorption system with a crosslinking agent for crosslinking to obtain chitosan-carboxymethyl cellulose drug-loaded microspheres.

2. The chitosan-carboxymethyl cellulose drug-loaded microspheres according to claim 1, characterized in that, The aqueous solution of sodium carboxymethyl cellulose has a viscosity of 1000~8000 mPa·s and a concentration of 0.5~2 wt%.

3. The chitosan-carboxymethyl cellulose drug-loaded microspheres according to claim 1, characterized in that, The aqueous solution of metal ions is an aqueous solution of metal chloride; the metal ions in the aqueous solution include one of iron ions, zinc ions, magnesium ions, and copper ions. One or more; the metal chloride includes one or more of ferric chloride, zinc chloride, magnesium chloride, and copper chloride; the concentration of the aqueous solution of the metal ions is 3-9 wt%.

4. The chitosan-carboxymethyl cellulose drug-loaded microspheres according to claim 1, characterized in that, The concentration of chitosan in the chitosan-acetic acid aqueous solution is 0.5~2wt%.

5. The chitosan-carboxymethyl cellulose drug-loaded microspheres according to claim 1, 2, 3 or 4, characterized in that, The volume ratio of the chitosan acetic acid aqueous solution to the sodium carboxymethyl cellulose aqueous solution is 1~3:1~3; the volume ratio of the sodium carboxymethyl cellulose aqueous solution to the metal ion aqueous solution is 1:2~5.

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