Preparation method of degradable nanocellulose sustained-release drug-loaded film

Abstract

This invention discloses a biodegradable cellulose nanoparticle sustained-release drug-loaded film and its preparation method, belonging to the field of pharmaceutical functional materials technology. The invention involves mixing and stirring microcrystalline cellulose and a 64 wt% sulfuric acid solution, then centrifuging, dialyzing to neutral, and freeze-drying to obtain CNCs (cell nanoparticles). The CNCs, NaIO4, and water are mixed and subjected to a light-protected reaction, followed by ethanol precipitation, dialyzing purification, and freeze-drying to obtain aldehyde-modified CNCs. The aldehyde-modified CNCs, sericin, polyvinyl alcohol, water, and the target drug are mixed and stirred to obtain a core layer solution. Polylactic acid-glycolic acid copolymer is dissolved in a mixture of chloroform and DMF to obtain a shell layer solution. The core layer solution and shell layer solution are coaxially electrospun to form drug-loaded fibers. The drug-loaded fibers are then subjected to biomimetic mineralization surface modification to obtain a biodegradable cellulose nanoparticle sustained-release drug-loaded film, which improves the drug loading rate, enhances the mechanical properties of the drug-loaded film, and exhibits sustained-release and controllable release effects.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical functional materials technology, specifically relating to a method for preparing a biodegradable nanocellulose sustained-release drug-loaded film. Background Technology

[0002] Nanocellulose-based drug delivery systems have become a research hotspot in the field of biomedical materials, demonstrating great potential in drug controlled release, wound repair, and tissue engineering in recent years. However, traditional drug-loaded films generally suffer from technical bottlenecks such as drug burst release, insufficient mechanical properties, and uncontrollable release behavior. Analysis of existing technologies reveals that: nanocellulose / chitosan composite membranes, which are simply physically mixed, exhibit burst release rates as high as 40-60% in the initial stages of drug release, severely impacting therapeutic efficacy; monolayer fiber membranes prepared by traditional electrospinning struggle to achieve synergistic loading of hydrophilic / hydrophobic drugs, limiting their application; and conventional drug delivery systems lack sufficient sensitivity to external environmental stimuli (such as pH, temperature, and light), making precise drug controlled release difficult. For example, chitosan (CS) nanofiber membranes are widely used in drug-loaded dressings due to their biocompatibility, antibacterial properties, and wound-healing properties. However, pure CS nanofibers have significant drawbacks: poor mechanical properties (tensile strength approximately 27 MPa, Young's modulus 0.24 GPa), requiring toxic cross-linking agents such as glutaraldehyde for reinforcement, which poses a risk of cytotoxicity. Drug burst release is severe, and the swelling property of CS leads to unstable drug release in the later stages. Cellulose nanoparticles (CNC / CNF) hydrogels possess high specific surface area, biodegradability, and an extracellular matrix-like structure, but have the following limitations: short sustained-release period, making them unsuitable for chronic disease treatment; strong hydrophilicity leads to excessively rapid drug diffusion and a high burst release rate. Polylactic acid (PLA), polybutylene terephthalate adipate (PBAT), etc., are commonly used in blown film or casting processes to prepare barrier films, but have inherent defects: uncontrollable degradation period, mismatch with drug release curves. Hydrophobic surfaces result in low drug loading, and drug release is mainly passive diffusion, lacking environmental responsiveness.

[0003] Therefore, there is an urgent need to develop a novel biodegradable nanocellulose sustained-release drug delivery film to solve the above-mentioned technical challenges. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for preparing a biodegradable nanocellulose sustained-release drug-loaded film. This invention improves the drug loading rate, enhances the mechanical properties of the drug-loaded film, and has a sustained-release and controllable release effect.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing a biodegradable cellulose nanoparticle sustained-release drug-loaded film, comprising the following preparation steps:

[0007] S1. Microcrystalline cellulose and 64 wt% sulfuric acid solution were mixed and stirred, then centrifuged, dialyzed to neutral, and freeze-dried to obtain CNCs;

[0008] S2. CNCs, NaIO4, and water were mixed and reacted in the dark. Ethanol was added to precipitate the mixture, followed by dialysis purification and freeze-drying to obtain aldehyde-modified CNCs.

[0009] S3. Aldehyde-modified CNCs, sericin, polyvinyl alcohol, water, and target drug are mixed and stirred to obtain a core layer solution;

[0010] S4. Dissolve the polylactic acid-glycolic acid copolymer in a mixture of chloroform and DMF to obtain a shell solution;

[0011] S5. The core layer solution and shell layer solution are coaxially electrospun to form drug-loaded fibers, and then the drug-loaded fibers are modified with biomimetic mineralization surface to obtain a biodegradable nanocellulose sustained-release drug-loaded film.

[0012] Preferably, the mass ratio of microcrystalline cellulose to 64w% sulfuric acid solution in S1 is 10:(100-150).

[0013] Preferably, the microcrystalline cellulose has a particle size of 50-100 μm.

[0014] Preferably, the stirring temperature in S1 is 45-55℃ and the stirring time is 45-60 min.

[0015] By adopting the above scheme, sulfuric acid selectively hydrolyzes the amorphous region of cellulose while retaining the crystalline region (the directional arrangement of β-1,4-glycosidic bonds), forming rod-shaped nanocrystals.

[0016] Preferably, the mass ratio of CNCs, NaIO4, and water in S2 is (1-10):(1-10):100.

[0017] Preferably, the temperature of the light-protected reaction in S2 is 45-55℃ and the time is 30-40 min.

[0018] By adopting the above scheme, sodium periodate (NaIO4) oxidizes the hydroxyl groups at C2-C3 positions, opens the ring to generate aldehyde groups, and introduces aldehyde groups as drug bonding sites, thereby increasing drug loading. Therefore, aldehyde-modified cellulose nanocrystals (DACNCs) are used as the core carrier. The aldehyde groups on their surface can form dynamic Schiff base bonds with drug molecules, which significantly increases drug loading and delays drug release.

[0019] Preferably, the mass ratio of aldehyde-modified CNCs, sericin, polyvinyl alcohol, water, and target drug in S3 is (5-10):25:(50-100):(1-15).

[0020] Preferably, the target drug includes, but is not limited to, tetracycline hydrochloride, vancomycin, doxorubicin, and paclitaxel.

[0021] Preferably, the mixing temperature in step S3 is 30-50℃ and the time is 4-8h.

[0022] By employing the above technical solution, aldehyde groups form Schiff base bonds with amino-containing drugs, reducing burst release; sericin (SS) self-assembles into a gel network at body temperature, and PVA enhances mechanical strength (hydrogen bond crosslinking); therefore, a temperature-sensitive hydrogel composed of sericin (SS) and polyvinyl alcohol (PVA) is formed, encapsulating the DACNCs. This layer can rapidly form a stable gel network at body temperature, providing pH-responsive release function. In the slightly acidic environment of the wound (pH 5.5-6.5), the gel swelling degree increases by 40%, accelerating drug release; while maintaining a stable structure in a neutral environment.

[0023] Preferably, the polylactic acid-glycolic acid copolymer in S4 has an LA:GA ratio of 75:25 and a MW of 100 kDa.

[0024] Preferably, the concentration of the shell solution in S4 is 50-150 g / L.

[0025] By employing the above technical solution, chloroform dissolves the hydrophobic segments of PLGA, and DMF increases the solution conductivity, forming a biodegradable drug-controlled release barrier. Polylactic acid-glycolic acid copolymer is used as the hydrophobic barrier layer, precisely coated onto the outer layer of the core using coaxial electrospinning technology. The tunable degradation characteristics of PLGA can control the drug release rate, and its hydrophobic properties effectively prevent excessively rapid penetration of body fluids.

[0026] Preferably, the coaxial electrospinning parameters in S5 are as follows:

[0027] Core layer flow rate: 0.25 mL / h;

[0028] Shell flow rate: 0.4 mL / h;

[0029] Voltage: 25kV;

[0030] Reception distance: 18cm;

[0031] Ambient temperature and humidity: 25℃ / 50% RH.

[0032] Preferably, the biomimetic mineralization surface modification method in S5 is as follows:

[0033] The drug-loaded fiber was immersed in a saturated Ca(OH)2 solution, then filtered and immersed in a mineralization solution for shaking culture. After washing and vacuum drying, the biomimetic mineralization surface modification was completed.

[0034] Preferably, the mineralizing solution comprises NaCl 100-150mM, CaCl2 2.5-5mM, Na2HPO4 1-3mM, and NaHCO3 4-6mM.

[0035] By employing the above technical solution, Ca(OH)₂ pretreatment activates carboxyl / hydroxyl groups on the fiber surface, inducing nHA nucleation. 2+ With PO4 3- Nano-hydroxyapatite is co-precipitated on the fiber surface. A biomimetic mineralization coating is constructed on the fiber membrane surface, depositing nano-hydroxyapatite (nHA) through a simulated biomineralization process. This coating not only improves the osseointegration capacity of the membrane material but also generates a localized microthermal effect under near-infrared light irradiation, triggering pulsed drug release.

[0036] It contains at least the following beneficial technical effects:

[0037] High drug loading and sustained release performance: Using aldehyde-modified cellulose nanofibers (DACNCs) as the core carrier, the aldehyde groups on its surface form dynamic Schiff base bonds with amino-containing drugs (such as tetracycline hydrochloride, vancomycin, etc.), which significantly increases the drug loading and effectively reduces drug burst release, achieving long-term sustained release.

[0038] Environmentally responsive release: The nuclear layer sericin (SS) / polyvinyl alcohol (PVA) hydrogel forms a gel network at body temperature and its swelling degree increases in the slightly acidic environment of the wound (pH 5.5), accelerating drug release; at the same time, the biomimetic mineralized coating generates a microthermal effect under near-infrared light irradiation, triggering pulsed drug release.

[0039] Enhanced mechanical properties: The three-layer composite structure (DACNCs core layer, PLGA shell layer, and nHA mineralization layer) significantly improves the mechanical strength of the film, with a tensile strength of 41.0 MPa and a Young's modulus of 0.58 GPa, while maintaining a moderate elongation at break, meeting the application requirements of biomaterials.

[0040] Multifunctional synergy: The hydrophobic shell of PLGA precisely controls the drug diffusion rate, the biomimetic mineralization layer enhances bone integration, and combined with the pH / NIR dual response mechanism, the drug release behavior can be programmably controlled, making it suitable for precision medicine scenarios such as wound repair and bone tissue engineering. Detailed Implementation

[0041] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0042] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0043] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0044] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0045] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0046] Unless otherwise specified, "room temperature" and "normal temperature" in this invention refer to 25±2℃.

[0047] Unless otherwise specified, all raw materials or instruments used in the following embodiments of the present invention are commercially available.

[0048] Example 1

[0049] This embodiment provides a method for preparing a biodegradable cellulose nanoparticle sustained-release drug-loaded film, the steps of which are as follows:

[0050] S1. Microcrystalline cellulose with a particle size of 80 μm and 64 wt% sulfuric acid solution were mixed at a mass ratio of 10:120 and magnetically stirred at 50 °C for 50 min, then centrifuged (10,000 rpm × 15 min), dialyzed to neutral, and freeze-dried to obtain CNCs;

[0051] S2. CNCs, NaIO4, and water were mixed in a mass ratio of 5:5:100 and reacted at 50°C in the dark for 35 min. Ethanol was added to precipitate the mixture, followed by dialysis purification and freeze-drying to obtain aldehyde-modified CNCs.

[0052] S3. Aldehyde-modified CNCs, sericin, polyvinyl alcohol, water, and tetracycline hydrochloride were mixed and stirred at 40°C for 6 hours in a mass ratio of 8:25:80:8 to obtain a core layer solution.

[0053] S4. Dissolve the polylactic acid-glycolic acid copolymer in a mixture of chloroform and DMF (chloroform:DMF = 5:1) to obtain a shell solution with a concentration of 100 g / L;

[0054] S5. The core solution and shell solution are coaxially electrospinned to obtain drug-loaded fibers; the coaxial electrospinning parameters are:

[0055] Core layer flow rate: 0.25 mL / h;

[0056] Shell flow rate: 0.4 mL / h;

[0057] Voltage: 25kV;

[0058] Reception distance: 18cm;

[0059] Ambient temperature and humidity: 25℃ / 50% RH.

[0060] The drug-loaded fibers were then immersed in a saturated Ca(OH)2 solution, filtered, and then immersed in a mineralization solution. The solution was then immersed in the solution and cultured at 37°C with shaking for 24 hours. After washing and vacuum drying, the biomimetic mineralization surface modification was completed to obtain a biodegradable nanocellulose sustained-release drug-loaded film. The mineralization solution contained 125 mM NaCl, 3 mM CaCl2, 2 mM Na2HPO4, and 5 mM NaHCO3.

[0061] Example 2

[0062] This embodiment provides a method for preparing a biodegradable cellulose nanoparticle sustained-release drug-loaded film, the steps of which are as follows:

[0063] S1. Microcrystalline cellulose with a particle size of 50 μm and 64 wt% sulfuric acid solution were mixed at a mass ratio of 10:100 and magnetically stirred at 45 °C for 45 min, then centrifuged (10,000 rpm × 15 min), dialyzed to neutral, and freeze-dried to obtain CNCs;

[0064] S2. CNCs, NaIO4, and water were mixed in a mass ratio of 1:1:100 and reacted at 45°C in the dark for 30 min. Ethanol was added to precipitate the mixture, followed by dialysis purification and freeze-drying to obtain aldehyde-modified CNCs.

[0065] S3. Aldehyde-modified CNCs, sericin, polyvinyl alcohol, water, and tetracycline hydrochloride were mixed and stirred at 30°C for 4 hours in a mass ratio of 5:25:50:1 to obtain a core layer solution.

[0066] S4. Dissolve the polylactic acid-glycolic acid copolymer in a mixture of chloroform and DMF (chloroform:DMF = 5:1) to obtain a shell solution with a concentration of 50 g / L;

[0067] S5. The core solution and shell solution are coaxially electrospinned to obtain drug-loaded fibers; the coaxial electrospinning parameters are:

[0068] Core layer flow rate: 0.25 mL / h;

[0069] Shell flow rate: 0.4 mL / h;

[0070] Voltage: 25kV;

[0071] Reception distance: 18cm;

[0072] Ambient temperature and humidity: 25℃ / 50% RH.

[0073] The drug-loaded fibers were then immersed in a saturated Ca(OH)2 solution, filtered, and then immersed in a mineralization solution. The solution was then immersed in the solution and cultured at 37°C with shaking for 24 hours. After washing and vacuum drying, the biomimetic mineralization surface modification was completed to obtain a biodegradable nanocellulose sustained-release drug-loaded film. The mineralization solution contained 100 mM NaCl, 2.5 mM CaCl2, 1 mM Na2HPO4, and 4 mM NaHCO3.

[0074] Example 3

[0075] This embodiment provides a method for preparing a biodegradable cellulose nanoparticle sustained-release drug-loaded film, the steps of which are as follows:

[0076] S1. Microcrystalline cellulose with a particle size of 100 μm and 64 wt% sulfuric acid solution were mixed at a mass ratio of 10:150 and magnetically stirred at 55 °C for 60 min, then centrifuged (10,000 rpm × 15 min), dialyzed to neutral, and freeze-dried to obtain CNCs;

[0077] S2. CNCs, NaIO4, and water were mixed in a mass ratio of 10:10:100 and reacted at 55°C in the dark for 40 min. Ethanol was added to precipitate the mixture, and the mixture was purified by dialysis and freeze-dried to obtain aldehyde-modified CNCs.

[0078] S3. Aldehyde-modified CNCs, sericin, polyvinyl alcohol, water, and tetracycline hydrochloride were mixed and stirred at 50°C for 8 hours in a mass ratio of 10:25:100:15 to obtain a core layer solution.

[0079] S4. Dissolve the polylactic acid-glycolic acid copolymer in a mixture of chloroform and DMF (chloroform:DMF = 5:1) to obtain a shell solution with a concentration of 150 g / L;

[0080] S5. The core solution and shell solution are coaxially electrospinned to obtain drug-loaded fibers; the coaxial electrospinning parameters are:

[0081] Core layer flow rate: 0.25 mL / h;

[0082] Shell flow rate: 0.4 mL / h;

[0083] Voltage: 25kV;

[0084] Reception distance: 18cm;

[0085] Ambient temperature and humidity: 25℃ / 50% RH.

[0086] The drug-loaded fibers were then immersed in a saturated Ca(OH)2 solution, filtered, and then immersed in a mineralization solution at 37°C with shaking for 24 hours. After washing and vacuum drying, the biomimetic mineralization surface modification was completed to obtain a biodegradable nanocellulose sustained-release drug-loaded film. The mineralization solution contained 150 mM NaCl, 5 mM CaCl2, 3 mM Na2HPO4, and 6 mM NaHCO3.

[0087] Comparative Example 1

[0088] The comparative example is prepared in the same way as Example 1, except that it does not contain the CNCs aldehyde modification step in S2, and CNCs are directly used in S3.

[0089] Experimental Example 1

[0090] The target drug tetracycline hydrochloride in Example 1 was replaced with vancomycin, doxorubicin, and paclitaxel, respectively, and the drug loading was calculated as shown in Table 1.

[0091] Table 1

[0092] Target drug Drug loading (μg / mg) Tetracycline hydrochloride 413 Vancomycin 327 Doxorubicin 386 Paclitaxel 276

[0093] Comparative Example 1 showed that the drug loading of tetracycline hydrochloride was 106 μg / mg.

[0094] Therefore, it can be seen that the carrier film of the present invention has a high drug loading capacity for a variety of drugs. Prior art document 1 shows that aldehyde-modified CNCs can significantly improve the drug loading capacity.

[0095] Experimental Example 2

[0096] Mechanical property testing (ASTM D638)

[0097] Table 2

[0098] Performance parameters Experimental Example 1 Pure chitosan film PLA cast film Tensile strength (MPa) 41.0±0.30 27.2±0.25 35.8±0.40 Elongation at break (%) 18.5±0.8 45.3±1.2 5.2±0.3 Young's modulus (GPa) 0.58±0.02 0.24±0.01 1.05±0.05 Swelling rate (pH 5.5) 38±2％ 210±10％ <5% (no response)

[0099] It is evident that the preparation method of the present invention can effectively improve the mechanical properties of the drug-loaded film and reduce the swelling rate.

[0100] Experimental Example 3

[0101] Drug sustained-release performance verification

[0102] The biodegradable cellulose nanoparticle sustained-release drug-loaded film prepared in Example 1 was placed in a medium: PBS (pH 7.4) and shaken at 37°C (100 rpm); the release rate at different times was detected, as shown in Table 3.

[0103] Table 3

[0104]

[0105]

[0106] Experiment Example 4

[0107] Environmentally responsive release

[0108]

[0109] It is evident that the biodegradable cellulose nanoparticle sustained-release drug-loaded film prepared in this application has a sustained-release effect; moreover, the release rate is controllable under specific conditions.

[0110] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a biodegradable cellulose nanoparticle sustained-release drug-loaded film, characterized in that, The preparation steps include the following: S1. Microcrystalline cellulose and 64 wt% sulfuric acid solution were mixed and stirred, then centrifuged, dialyzed to neutral, and freeze-dried to obtain CNCs; S2. CNCs, NaIO4, and water were mixed and reacted in the dark. Ethanol was added to precipitate the mixture, followed by dialysis purification and freeze-drying to obtain aldehyde-modified CNCs. S3. Aldehyde-modified CNCs, sericin, polyvinyl alcohol, water, and target drug are mixed and stirred to obtain a core layer solution; The target drugs include, but are not limited to, tetracycline hydrochloride, vancomycin, doxorubicin, and paclitaxel; S4. Dissolve the polylactic acid-glycolic acid copolymer in a mixture of chloroform and DMF to obtain a shell solution; S5. The core layer solution and shell layer solution are coaxially electrospun to form drug-loaded fibers, and then the drug-loaded fibers are modified with biomimetic mineralization surface to obtain a biodegradable nanocellulose sustained-release drug-loaded film. The coaxial electrospinning parameters in S5 are as follows: Core layer flow rate: 0.25 mL / h; Shell flow rate: 0.4 mL / h; Voltage: 25 kV; Reception distance: 18 cm; Ambient temperature and humidity: 25℃ / 50% RH; The biomimetic mineralized surface modification method in S5 is as follows: The drug-loaded fiber was immersed in a saturated Ca(OH)2 solution, then filtered and immersed in a mineralization solution for shaking culture, washed, and vacuum dried to complete the biomimetic mineralization surface modification. The mineralization solution comprises NaCl 100-150mM, CaCl2 2.5-5mM, Na2HPO4 1-3mM, and NaHCO3 4-6mM.

2. The preparation method according to claim 1, characterized in that, The mass ratio of microcrystalline cellulose to 64 wt% sulfuric acid solution in S1 is 10:(100-150).

3. The preparation method according to claim 1, characterized in that, The mass ratio of CNCs, NaIO4, and water in S2 is (1-10):(1-10):

100.

4. The preparation method according to claim 1, characterized in that, The polylactic acid-glycolic acid copolymer in S4 has an LA:GA ratio of 75:25 and a MW of 100 kDa.

5. The preparation method according to claim 1, characterized in that, The concentration of the shell solution in S4 is 50-150 g / L.

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