Preparation method of anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel
By loading anthocyanins into oxidized nanocellulose/chitosan composite aerogels, the problem of easy degradation of anthocyanins was solved, and a composite aerogel with high stability and multifunctionality was prepared, expanding its application range.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- KUNMING UNIV OF SCI & TECH
- Filing Date
- 2026-01-16
- Publication Date
- 2026-05-26
AI Technical Summary
Anthocyanins are sensitive to environmental factors such as light, heat, and pH, and are easily degraded, which limits their application and performance in the food, cosmetics, and pharmaceutical fields.
Anthocyanins were loaded into oxidized nanocellulose/chitosan elastic composite aerogels, and epichlorohydrin and KH570 silane coupling agents were used as crosslinking agents. The anthocyanin-loaded oxidized nanocellulose/chitosan elastic composite aerogels were prepared by two crosslinking processes and freeze drying, which enhanced their stability and functionality.
The prepared composite aerogel material exhibits good mechanical stability, resilience, and antibacterial properties, significantly improving the loading efficiency and stability of anthocyanins, expanding its application areas, and making it suitable for smart packaging, biomedical dressings, and sustained-release formulations.
Smart Images
Figure FT_1 
Figure FT_2 
Figure FT_3
Abstract
Description
Technical Field
[0001] This invention relates to the field of composite aerogels, specifically to a method for preparing an anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel. Background Technology
[0002] Composite aerogels are high-performance porous materials developed through material composite design to overcome the performance limitations of single-component aerogels. There are many types of composite aerogels, including silicon-reinforced composite aerogels, organic polymer composite aerogels, carbon-functionalized composite aerogels, and organic-inorganic hybrid composite aerogels. Composite aerogels have a wide range of applications. For example, in the energy and catalysis field, they can serve as catalyst supports; in the field of smart responses and devices, flexible conductive aerogels can be used as strain sensors; and in the field of environmental remediation, their high specific surface area and functionalizable surfaces can be used for oil-water separation and the adsorption of harmful substances. Considering economic factors, designing recyclable and multifunctional aerogels is currently a key focus of aerogel development.
[0003] Anthocyanins are water-soluble flavonoid pigments widely found in plants, possessing excellent anti-inflammatory, antioxidant, and antibacterial properties, and are widely used in the food, cosmetic, and pharmaceutical industries. However, their sensitivity to environmental factors such as light, heat, and pH, and their susceptibility to degradation, limit their applications and performance. Therefore, this invention loads anthocyanins into an oxidized nanocellulose / chitosan elastic composite aerogel. This combination improves the stability of anthocyanins, allowing them to better exert their advantages, while also integrating bio-based materials with the composite aerogel, broadening the performance characteristics and application areas of the composite aerogel. Summary of the Invention
[0004] Based on the problems existing in the prior art, the present invention provides a method for preparing anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel (MPCA / TOCNF / CS-gel), using epichlorohydrin and KH570 silane coupling agent as crosslinking agents and loaded with anthocyanins, which has good water absorption, mechanical stability and resilience, as well as good antibacterial properties.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing anthocyanin-loaded oxidized cellulose nanoparticles / chitosan elastic composite aerogel, the specific steps of which are as follows: The oxidized cellulose nanoparticle dispersion and chitosan solution were mixed in a certain proportion, stirred evenly, and the pH value was adjusted to 10-11 to obtain a mixed solution. Epichlorohydrin was added to the mixed solution in step (1) for one cross-linking. After the first cross-linking was completed, dialysis was performed to remove excess unreacted epichlorohydrin. After freeze-drying, oxidized nanocellulose / chitosan composite aerogel (TOCNF / CS-gel) was obtained. The TOCNF / CS-gel obtained in step (2) was immersed in KH570 silane coupling agent solution for secondary crosslinking. After the secondary crosslinking was completed, excess KH570 silane coupling agent on the surface was rinsed off with ethanol and then placed in an oven to dry. The aerogel dried in step (3) was placed in anthocyanin solution and soaked for 20-30 hours to load anthocyanins. After loading, the anthocyanins physically attached to the surface were washed off with ultrapure water and then freeze-dried to obtain anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel MPCA / TOCNF / CS-gel.
[0006] In step (1), the volume ratio of the oxidized nanocellulose dispersion and the chitosan solution is 1~3:3~1, the solid content of the oxidized nanocellulose dispersion is 0.5%, and the mass concentration of the chitosan solution is 1~3%.
[0007] The stirring time for step (1) is 4 to 12 hours.
[0008] In step (2), the molar ratio of epichlorohydrin to the amino groups in the chitosan solution is 5:1, the crosslinking time is 1-4 hours, and the crosslinking temperature is 55-65℃. The silane coupling agent KH570 solution in step (3) is a 5% KH570 ethanol solution with a secondary crosslinking time of 2-6 hours.
[0009] The drying time in step (3) is 2~6 hours and the drying temperature is 40~80℃.
[0010] The concentration of the anthocyanin solution in step (4) is 5~40 mg / mL.
[0011] The preparation method of anthocyanins used in this invention includes the following specific steps: Add 1g of purple corn powder to a beaker containing 30mL of 60% ethanol solution. Sonicate for 10min at 100W and extract at 20-60℃ for 120-360min. Remove the filter residue by vacuum filtration. Concentrate the filtrate under reduced pressure at 50℃ on a rotary evaporator to remove excess ethanol. After freeze-drying, anthocyanin powder is obtained. Dissolve the anthocyanin powder in water to obtain anthocyanin solutions of different concentrations.
[0012] The beneficial effects of this invention are: The composite aerogel materials prepared by this invention are all derived from natural polymer materials, are non-toxic and biodegradable, and conform to the development trend of green materials.
[0013] This invention presents a composite aerogel with a three-dimensional porous network structure, providing numerous adsorption sites for anthocyanins and significantly improving loading efficiency. Anthocyanins are efficiently loaded into a highly elastic and stable oxidized nanocellulose / chitosan composite aerogel. The anthocyanin-loaded composite aerogel not only exhibits excellent mechanical stability, resilience, and water absorption, but also possesses sensing (anthocyanin pH color change indication), antibacterial, and antioxidant functions, expanding its application areas. Simultaneously, it enhances the stability of anthocyanins, allowing them to better exert their superior properties and slowing down their natural degradation. The prepared anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel (MPCA / TOCNF / CS-gel) can be applied to smart packaging, biomedical dressings, sustained-release formulations, and other fields. This invention provides a sound theoretical basis for the subsequent applications of composite aerogels. Attached Figure Description
[0014] Figure 1 Cyclic compression diagram of anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel MPCA / TOCNF / CS-gel; Figure 2 The water absorption curve of anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel MPCA / TOCNF / CS-gel; Figure 3 The antibacterial properties of anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel MPCA / TOCNF / CS-gel. Detailed Implementation
[0015] The present invention will be further described below with reference to specific embodiments.
[0016] The oxidized cellulose nanoparticle dispersion used in this invention is commercially available TEMPO-oxidized carboxyl-modified cellulose nanoparticles with a solid content of 0.5%; the chitosan solution is prepared by dissolving chitosan powder in glacial acetic acid.
[0017] Example 1 1 g of purple corn powder was added to a beaker containing a 60% ethanol solution at a material-to-liquid ratio of 1:30 (w / v). The mixture was ultrasonicated for 10 min at 100 W and extracted at 60 °C for 120 min. The residue was removed by vacuum filtration. The filtrate was concentrated under reduced pressure at 50 °C on a rotary evaporator to remove excess ethanol. After freeze-drying, anthocyanin powder was obtained.
[0018] Example 2 1 g of purple corn powder was added to a beaker containing a 40% ethanol solution at a material-to-liquid ratio of 1:30 (w / v). The mixture was ultrasonicated for 10 min at a power of 100 W and extracted at 40 °C for 240 min. The residue was removed by vacuum filtration. The filtrate was concentrated under reduced pressure at 50 °C on a rotary evaporator to remove excess ethanol. After freeze-drying, anthocyanin powder was obtained.
[0019] Example 3 1 g of purple corn powder was added to a beaker containing a 20% ethanol solution at a material-to-liquid ratio of 1:30 (w / v). The mixture was ultrasonicated for 10 min at 100 W and extracted at 20 °C for 360 min. The residue was removed by vacuum filtration. The filtrate was concentrated under reduced pressure at 50 °C on a rotary evaporator to remove excess ethanol. After freeze-drying, anthocyanin powder was obtained.
[0020] Example 4 Take an oxidized nanocellulose dispersion with a solid content of 0.5%; add glacial acetic acid to ultrapure water to prepare an acetic acid solution with a mass concentration of 1%, then add chitosan to prepare a chitosan solution with a mass concentration of 1%. Oxidized cellulose nanoparticle dispersion and chitosan solution were mixed at a ratio of 1:3 and stirred for 6 hours. The pH was adjusted to 11 with 1M NaOH solution. Epichlorohydrin was added to the mixed solution and mixed thoroughly. The molar ratio of epichlorohydrin to amino groups in chitosan solution was 5:1. Crosslinking was performed once at 65°C water bath temperature for 1 hour. After the first crosslinking was completed, the mixed solution was dialyzed through a 500Da dialysis bag for 48 hours to remove excess unreacted epichlorohydrin. Then, it was freeze-dried to obtain TOCNF / CS-gel. TOCNF / CS-gel was immersed in a 5% (w / w) ethanol solution of silane coupling agent KH570 for 2 hours to perform secondary crosslinking. After the secondary crosslinking was completed, excess silane coupling agent adhering to the surface of TOCNF / CS-gel was washed off with ethanol and then dried in an oven at 55°C for 6 hours. The anthocyanins prepared in Example 1 were mixed with water to prepare an anthocyanin solution with a concentration of 5 mg / mL. The TOCNF / CS-gel, which was cross-linked twice and then washed and dried, was immersed in the 5 mg / mL anthocyanin solution for 22 h to load anthocyanins. After completion, the anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel MPCA / TOCNF / CS-gel was obtained by freeze drying.
[0021] Example 5 Take an oxidized nanocellulose dispersion with a solid content of 0.5%; add glacial acetic acid to ultrapure water to prepare an acetic acid solution with a mass concentration of 1%, then add chitosan to prepare a chitosan solution with a mass concentration of 1%. Oxidized cellulose nanoparticle dispersion and chitosan solution were mixed in a 1:1 ratio and stirred for 4 hours. The pH was adjusted to 10 with 1M NaOH solution. Epichlorohydrin was added to the mixed solution and mixed thoroughly. The molar ratio of epichlorohydrin to amino groups in chitosan solution was 5:1. Crosslinking was performed once at 55℃ water bath temperature for 4 hours. After the first crosslinking was completed, the mixed solution was dialyzed through a 500Da dialysis bag for 48 hours to remove excess unreacted epichlorohydrin. Then, it was freeze-dried to obtain TOCNF / CS-gel. TOCNF / CS-gel was immersed in a 5% (w / w) ethanol solution of silane coupling agent KH570 for 3 hours to perform secondary crosslinking. After the secondary crosslinking was completed, excess silane coupling agent adhering to the surface of TOCNF / CS-gel was washed off with ethanol and then dried in an oven at 60°C for 6 hours. The anthocyanins prepared in Example 1 were mixed with water to prepare an anthocyanin solution with a concentration of 15 mg / mL. The TOCNF / CS-gel, which was cross-linked twice and then washed and dried, was immersed in the 15 mg / mL anthocyanin solution for 20 h to load anthocyanins. After completion, the anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel MPCA / TOCNF / CS-gel was obtained by freeze drying.
[0022] Example 6 Take an oxidized nanocellulose dispersion with a solid content of 0.5%; add glacial acetic acid to ultrapure water to prepare an acetic acid solution with a mass concentration of 1%, then add chitosan to prepare a chitosan solution with a mass concentration of 2%. Oxidized cellulose nanoparticle dispersion and chitosan solution were mixed at a ratio of 2:1 and stirred for 8 hours. The pH was adjusted to 11 with 1M NaOH solution. Epichlorohydrin was added to the mixed solution and mixed thoroughly. The molar ratio of epichlorohydrin to amino groups in chitosan solution was 5:1. Crosslinking was carried out once at 60℃ water bath temperature for 3 hours. After the first crosslinking, the mixed solution was dialyzed through a 500Da dialysis bag for 48 hours to remove excess unreacted epichlorohydrin. Then, it was freeze-dried to obtain TOCNF / CS-gel. TOCNF / CS-gel was immersed in a 5% (w / w) ethanol solution of silane coupling agent KH570 for 4 hours to perform secondary crosslinking. After the secondary crosslinking was completed, excess silane coupling agent adhering to the surface of TOCNF / CS-gel was washed off with ethanol and then dried in an oven at 60°C for 2 hours. The anthocyanins prepared in Example 1 were mixed with water to prepare an anthocyanin solution with a concentration of 10 mg / mL. The TOCNF / CS-gel, which was cross-linked twice and then washed and dried, was immersed in the 10 mg / mL anthocyanin solution for 24 h to load anthocyanins. After completion, the anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel MPCA / TOCNF / CS-gel was obtained by freeze drying.
[0023] Test Example 1 The method for determining the compressive resilience of anthocyanin-loaded oxidized cellulose nanoparticles / chitosan elastic composite aerogels MPCA / TOCNF / CS-gel is as follows: The anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel MPCA / TOCNF / CS-gel prepared in Example 6 was placed on a universal testing machine and subjected to five consecutive cyclic compression tests with a compression amount of 50%.
[0024] Stress-strain curves and stress attenuation are as follows: Figure 1 As shown, the maximum compressive stress of the sample is 110 kPa, and the stress retention rate after 5 cycles of compression is 90%, which shows good mechanical stability and fatigue resistance. The maximum compressive stress only decreases slightly after 5 cycles of compression, indicating that the MPCA / TOCNF / CS-gel has a uniform stress distribution and a three-dimensional network structure that can effectively resist cyclic loads.
[0025] Test Example 2 The method for determining the water absorption rate of anthocyanin-loaded oxidized cellulose nanoparticles / chitosan elastic composite aerogel MPCA / TOCNF / CS-gel is as follows: The anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel MPCA / TOCNF / CS-gel prepared in Example 6 was immersed in 0.01M hydrochloric acid, 0.01M NaOH solution and ultrapure water, respectively. The aerogel was weighed at 1, 2, 4, 6, 12, 24, 48 and 72 h and the water absorption rate was calculated.
[0026] Figure 2 The water absorption curves of MPCA / TOCNF / CS-gel under three solution environments show that MPCA / TOCNF / CS-gel has a relatively high water absorption rate in acidic, alkaline, and neutral environments, with an equilibrium water absorption rate of over 1600%. Furthermore, the structure remains intact after soaking for 72 hours without any edge breakage, demonstrating high water absorption and good chemical stability.
[0027] Test Example 3 The method for determining the antibacterial properties of anthocyanin-loaded oxidized cellulose nanoparticles / chitosan elastic composite aerogel MPCA / TOCNF / CS-gel, with specific steps as follows: The anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel MPCA / TOCNF / CS-gel prepared in Example 6 was soaked in ultrapure water for 7 days. The supernatant was used as the experimental group, and a blank control group was set up. Antibacterial analysis of Staphylococcus aureus and Escherichia coli was performed to study the antibacterial properties of MPCA / TOCNF / CS-gel.
[0028] Figure 3 The study investigated the inhibitory effects of anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel MPCA / TOCNF / CS-gel on Staphylococcus aureus and Escherichia coli. The results showed that MPCA / TOCNF / CS-gel had a good inhibitory effect on the growth of both Staphylococcus aureus and Escherichia coli, indicating that the prepared MPCA / TOCNF / CS-gel has good antibacterial properties.
[0029] Example 7 Take an oxidized nanocellulose dispersion with a solid content of 0.5%; add glacial acetic acid to ultrapure water to prepare an acetic acid solution with a mass concentration of 1%, and then add chitosan to prepare a chitosan solution with a mass concentration of 3%. Oxidized nanocellulose dispersion and chitosan solution were mixed at a ratio of 3:1 and stirred for 12 h. The pH was adjusted to 10 with 1 M NaOH solution. Epichlorohydrin was added to the mixed solution and mixed well. The molar ratio of epichlorohydrin to amino groups in chitosan solution was 5:1. Crosslinking was carried out once at 60 °C water bath temperature for 2 h. After the first crosslinking was completed, the mixed solution was dialyzed through a 500 Da dialysis bag for 48 h to remove excess unreacted epichlorohydrin. Then, it was freeze-dried to obtain TOCNF / CS-gel. TOCNF / CS-gel was immersed in a 5% (w / w) ethanol solution of silane coupling agent KH570 for 6 hours to perform secondary crosslinking. After the secondary crosslinking was completed, excess silane coupling agent adhering to the surface of TOCNF / CS-gel was washed off with ethanol and then dried in an oven at 65°C for 2 hours. The anthocyanins prepared in Example 1 were mixed with water to prepare an anthocyanin solution with a concentration of 25 mg / mL. The TOCNF / CS-gel, which was cross-linked twice and then washed and dried, was immersed in the 25 mg / mL anthocyanin solution for 30 h to load anthocyanins. After completion, the anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel MPCA / TOCNF / CS-gel was obtained by freeze drying.
[0030] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.
Claims
1. A method for preparing anthocyanin-loaded oxidized cellulose nanoparticles / chitosan elastic composite aerogel, characterized in that, The specific steps are as follows: Oxidized nanocellulose dispersion and chitosan solution were mixed and stirred. The pH was adjusted to 10-11, and epichlorohydrin was added for primary cross-linking. After removing excess unreacted epichlorohydrin by dialysis, the mixture was freeze-dried and then soaked in silane coupling agent KH570 solution for secondary cross-linking. After washing and drying, the mixture was placed in anthocyanin solution and soaked for 20-30 hours for anthocyanin loading. After washing, the mixture was freeze-dried to obtain anthocyanin-loaded oxidized nanocellulose / chitosan elastic composite aerogel.
2. The method for preparing anthocyanin-loaded oxidized cellulose nanoparticles / chitosan elastic composite aerogel according to claim 1, characterized in that, The volume ratio of the oxidized nanocellulose dispersion to the chitosan solution is 1~3:3~1, the solid content of the oxidized nanocellulose dispersion is 0.5%, and the mass concentration of the chitosan solution is 1~3%.
3. The method for preparing anthocyanin-loaded oxidized cellulose nanoparticles / chitosan elastic composite aerogel according to claim 1, characterized in that, The stirring time is 4~12 hours.
4. The method for preparing anthocyanin-loaded oxidized cellulose nanoparticles / chitosan elastic composite aerogel according to claim 1, characterized in that, The molar ratio of epichlorohydrin to amino groups in the chitosan solution is 5:1, the cross-linking time is 1-4 hours, and the cross-linking temperature is 55-65℃.
5. The method for preparing anthocyanin-loaded oxidized cellulose nanoparticles / chitosan elastic composite aerogel according to claim 1, characterized in that, The silane coupling agent KH570 solution is a 5% (w / w) silane coupling agent KH570 ethanol solution, and the secondary crosslinking time is 2-6 h.
6. The method for preparing anthocyanin-loaded oxidized cellulose nanoparticles / chitosan elastic composite aerogel according to claim 1, characterized in that, The drying time is 2-6 hours, and the drying temperature is 40-80℃.
7. The method for preparing anthocyanin-loaded oxidized cellulose nanoparticles / chitosan elastic composite aerogel according to claim 1, characterized in that, The concentration of the anthocyanin solution is 5~40 mg / mL.