Intelligent response type anthocyanin oral dissolving film as well as preparation method and application thereof

Abstract

The invention relates to an intelligent response type anthocyanin oral dissolving film as well as a preparation method and application thereof, and belongs to the technical field of medicine / nutrient delivery systems. The intelligent response type anthocyanin oral dissolving film is formed by interweaving nanofibers which are prepared by a coaxial electrostatic spinning technology and have a core-shell structure, the core of the nanofibers comprises polyvinylpyrrolidone, esterified konjac glucomannan and anthocyanin, the shell layer of the nanofibers comprises polyvinyl alcohol, and the shell layer of the nanofibers comprises polyvinyl alcohol. A space interlocking structure is formed between the core and the shell layer of the nanofiber through intermolecular hydrogen-bond interaction. The structure of the obtained oral dissolving film can realize self-supporting without any chemical cross-linking agent, the oral dissolving film has excellent mechanical properties, controlled release characteristics and mucous membrane permeability, and in addition, the preparation method is simple, green and safe, and has very wide application prospects.

Description

Technical Field

[0001] This invention relates to a smart responsive anthocyanin oral dissolving membrane, its preparation method, and its application, belonging to the technical field of drug / nutrient delivery systems. Background Technology

[0002] Anthocyanins (ACNs) are a class of water-soluble natural pigments widely found in plants. Belonging to the flavonoid family, they possess a variety of bioactivities, including potent antioxidant, anti-inflammatory, lipid metabolism-regulating, vision-improving, and immune-enhancing effects. However, anthocyanins exhibit poor stability in the gastrointestinal tract and are easily degraded in alkaline intestinal fluids, resulting in extremely low oral bioavailability (typically below 1%). This severely limits their efficient application in functional and health foods. To overcome this bottleneck, existing technologies have explored encapsulation and delivery strategies such as microencapsulation, liposomes, and nanoparticles. However, these methods still fail to fundamentally solve the problems of poor stability and low bioavailability of anthocyanins in the gastrointestinal tract.

[0003] Oral dissolving films (ODFs), as an emerging dosage form, can be directly absorbed into the bloodstream through the rich capillaries of the oral mucosa, effectively bypassing the first-pass effect of the gastrointestinal tract and hepatic metabolism, thereby significantly improving the bioavailability of active ingredients. Coaxial electrospinning technology is an ideal technique for preparing nanofiber membranes loaded with active ingredients. The core-shell structure of the fibers constructed by this technique can achieve effective protection and controlled release of active ingredients. However, the technology still faces the following key technical bottlenecks in the preparation of oral dissolving membranes: (1) The difficulty in process control makes it difficult to form a stable and regular core-shell structure: The fluids of the core layer and the shell layer are difficult to maintain a stable interfacial dynamic balance in the electric field jet. Due to the mismatch of fluid parameters (such as viscosity and surface tension), the jet is unstable, the core layer is broken or the shell layer is not fully wrapped, resulting in structural defects such as beading, fiber fusion or blurred core-shell interface, which seriously affects the encapsulation rate and release controllability of active ingredients; (2) The structural stability depends on physical or chemical crosslinking: Existing technologies often require post-crosslinking (such as photocrosslinking, genipin crosslinking, glutaraldehyde crosslinking, etc.) to maintain the stable structure of fibers. This process is not only complicated, but may also introduce toxic and harmful chemical reagents, increasing safety risks; (3) Single function: Existing technologies focus more on film formation and mechanical strength, and it is difficult to achieve efficient loading, stable protection and controllable release of active ingredients in a coordinated manner.

[0004] Therefore, developing an oral dissolving membrane that is simple to prepare, structurally stable, requires no chemical cross-linking, and can synergistically achieve efficient encapsulation and intelligent controlled release of active ingredients is of great significance for promoting the efficient application of active ingredients such as anthocyanins in functional foods and oral delivery systems. Summary of the Invention

[0005] This invention provides a smart, responsive anthocyanin oral dissolving membrane, its preparation method, and its applications. Specifically, it provides an oral dissolving membrane that is structurally stable and can efficiently deliver anthocyanins without chemical cross-linking, along with its preparation method and its application in the preparation of functional foods or health products for absorption through the oral mucosa and to improve the bioavailability of anthocyanins. The oral dissolving membrane obtained by this invention achieves self-support without any chemical cross-linking agents, exhibiting excellent mechanical properties, controlled-release characteristics, and mucosal permeability. Furthermore, the preparation method is simple, green, and safe, and has very broad application prospects.

[0006] A smart responsive anthocyanin oral dissolving membrane is provided, wherein the oral dissolving membrane is formed by interwoven nanofibers with a core-shell structure prepared by coaxial electrospinning technology. The core of the nanofibers includes polyvinylpyrrolidone (PVP), esterified konjac glucomannan and anthocyanins, and the shell of the nanofibers includes polyvinyl alcohol (PVA). The core and shell of the nanofibers form a spatially interlocked structure through intermolecular hydrogen bonding.

[0007] Furthermore, the hydroxyl and carboxyl groups on the esterified konjac glucomannan molecular chain in the core, and the carbonyl group of polyvinylpyrrolidone and the hydroxyl group of polyvinyl alcohol in the shell spontaneously form a stable three-dimensional hydrogen bond network during coaxial electrospinning, enabling self-assembly between the core and the shell, thereby forming a core-shell structure with "spatial interlocking" characteristics. This structure effectively inhibits the migration of anthocyanins during spinning and maintains a clear core-shell interface.

[0008] Furthermore, the addition of esterified konjac glucomannan can mildly and reversibly regulate the permeability of the oral mucosa, significantly improving the transmembrane permeation efficiency of hydrophilic anthocyanins without damaging cells. In addition, upon contact with saliva, the oral dissolving membrane exhibits rapid hydration of konjac glucomannan (KGM), forming a viscous gel barrier at the membrane-mucosa interface. This barrier prolongs the membrane's residence time in the oral cavity and acts as a controllable diffusion barrier, enabling the continuous and controlled release of anthocyanins. Esterified KGM undergoes specific degradation under the action of salivary amylase, forming an enzyme-responsive release mechanism; simultaneously, its carboxyl groups ionize in the neutral pH environment of the oral cavity, enhancing hydrophilicity and viscosity, thus achieving responsive release.

[0009] Furthermore, the mass ratio of polyvinylpyrrolidone, esterified konjac glucomannan, and anthocyanins in the core is 10: 2-6: 0.1-0.4.

[0010] Furthermore, the mass ratio of the core to the shell is 1:0.8-1.2.

[0011] Furthermore, the molecular weight of the polyvinylpyrrolidone is 1,000,000 to 1,500,000 Da.

[0012] Furthermore, the molecular weight of the polyvinyl alcohol is 120,000-180,000 Da.

[0013] Further, the esterified konjac glucomannan is prepared by the following method: konjac glucomannan and triethyl citrate are mixed in DMSO; p-toluenesulfonic acid is added as a catalyst, and the mixture is reacted at 60-85℃ for 4-6 h. After cooling, the mixture is poured into ethanol to precipitate, washed, and the product is obtained. The mass-to-volume ratio of konjac glucomannan, triethyl citrate, p-toluenesulfonic acid, and DMSO is 1 g : 0.5-1.0 g : 0.05-0.1 g : 10-20 mL, and the molecular weight of the konjac glucomannan is 200-800 kDa.

[0014] Furthermore, the diameter of the nanofibers is 0.8-1.5 μm.

[0015] Furthermore, the oral dissolving membrane has a tensile strength of 4.0-7.0 MPa, an elongation at break of 15%-25%, a disintegration time of 20-50 s, and a solubility of 70%-95%.

[0016] Another object of the present invention is to provide a method for preparing the above-mentioned oral dissolving membrane, comprising the following steps: adding polyvinylpyrrolidone, esterified konjac glucomannan and anthocyanins to distilled water, stirring and dissolving at room temperature, and allowing to stand at room temperature to remove bubbles, to obtain a core spinning solution; adding polyvinyl alcohol to distilled water, stirring and dissolving, and allowing to stand at room temperature to remove bubbles, to obtain a shell spinning solution; performing coaxial electrospinning of the above spinning solution through an electrospinning device, collecting the solution with aluminum foil, to obtain a uniform nanofiber membrane, which is the anthocyanin oral dissolving membrane.

[0017] In the method of the present invention, the concentration of polyvinylpyrrolidone in the core spinning solution is 8%-12%, the concentration of esterified konjac glucomannan is 2%-6%, and the concentration of anthocyanins is 0.1%-0.4%.

[0018] Preferably, in the core spinning solution, the concentration of polyvinylpyrrolidone is 10%, the concentration of esterified konjac glucomannan is 4%, and the concentration of anthocyanins is 0.2%.

[0019] In the method of the present invention, the concentration of polyvinyl alcohol in the shell spinning solution is 12%-18%.

[0020] Preferably, the concentration of polyvinyl alcohol in the shell spinning solution is 15%.

[0021] In the method of the present invention, the mass ratio of the core layer to the shell layer is 1:0.8-1.2.

[0022] In the method described in this invention, the coaxial electrospinning conditions include: a voltage of 16-20 kV, a shell spinning solution flow rate of 8-12 μL / min, a core spinning solution flow rate of 10-14 μL / min, a spinning temperature of 15-30℃, a humidity of 20%-40%, a collection distance of 8-12 cm, and a collection time of 5-6 h.

[0023] Preferably, the coaxial electrospinning conditions include: a voltage of 18-20 kV, a shell spinning solution flow rate of 10 μL / min, a core spinning solution flow rate of 12 μL / min, and a collection distance of 10 cm.

[0024] During electrospinning, the molecular chains (PVP, KGM, PVA) of the core and shell spinning solutions undergo dynamic self-assembly through hydrogen bond interactions at the interface under the action of a high-voltage electric field and jet stretching, directly forming core-shell nanofibers with a "spatial interlocking structure" and collecting them on aluminum foil. The fiber membrane obtained by this process can achieve a stable structure without any subsequent cross-linking steps.

[0025] In the method described in this invention, the room temperature standing degassing time is 12-24 h.

[0026] Another object of the present invention is to provide the application of the above-mentioned anthocyanin oral dissolving membrane or the anthocyanin oral dissolving membrane prepared by the above method in the preparation of functional foods or health products.

[0027] The oral dissolving membrane described in this invention, through its unique dynamic hydrogen-bonded interlocking structure and the multifunctional synergy of KGM, disintegrates and adheres to the mucosa in the oral cavity, establishing a local high-concentration anthocyanin library, thereby significantly improving the bioavailability of anthocyanins. It is particularly suitable for individuals requiring antioxidant effects, lipid metabolism regulation, or immune function enhancement. This product can be formulated into individually packaged film form for convenient carrying and administration.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) This invention proposes and constructs for the first time a “spatially interlocked” core-shell structure based on dynamic hydrogen bonds, namely, a stable structure in which the core polymer molecular chains and the shell polymer molecular chains are spatially anchored and intertwined through a dense three-dimensional hydrogen bond network formed at the interface. This structure is formed in one step during the spinning process entirely through the interaction (hydrogen bonds) between food-grade material molecules, avoiding the chemical cross-linking steps required by traditional coaxial fibers, which may pose safety risks. The process is simpler and safer, and is especially suitable for applications in the food and pharmaceutical fields.

[0030] (2) This invention achieves a more optimal concentration system that allows the core and shell solutions to have matched rheological properties. Under optimized electrospinning parameters, a stable Taylor cone and a continuous composite jet can be realized. More importantly, the numerous hydroxyl and carboxyl groups on the esterified KGM molecular chain spontaneously assemble with the carbonyl groups of PVP and the hydroxyl groups of PVA through dynamic hydrogen bonding during the jet stretching process, forming a "spatial interlocking" structure. This process does not require any chemical crosslinking agents, effectively suppressing the migration and diffusion of the core material, ensuring the clarity and stability of the core-shell interface, and fundamentally solving the structural defects commonly found in traditional coaxial electrospinning, such as blurred core-shell interfaces, low coaxiality, fiber breakage, or beading.

[0031] (3) This invention innovatively introduces and utilizes the multiple functions of esterified KGM, making it no longer a simple thickener or gelling agent. The introduction of esterified KGM gives the product intelligent responsive release characteristics: it degrades under the action of salivary amylase, forming an enzyme response mechanism; at the same time, the carboxyl group introduced after esterification ionizes in the neutral pH environment of the oral cavity, enhancing hydrophilicity and forming a pH response mechanism. The synergistic effect of the two response mechanisms enables the resulting oral dissolving membrane to rapidly initiate release in the oral environment and achieve continuous and controllable release kinetics under the action of the in-situ gel barrier. Experimental data show that the anthocyanin cumulative release rate of this oral dissolving membrane is as high as 97% within 120 minutes, which is significantly better than the unesterified KGM system (only 53%), achieving almost complete intelligent controlled release.

[0032] (4) The oral dissolving membrane obtained by the present invention has high mechanical strength, rapid disintegration, high load stability, near-complete controlled release and extremely high mucosal permeability, which significantly improves the transmembrane transport efficiency and bioavailability of hydrophilic anthocyanins. It has huge industrialization potential and market value in the fields of functional foods, nutritional supplements and oral delivery drugs. Attached Figure Description

[0033] Figure 1 SEM images (AI) and nanofiber diameter distribution maps (A1-I1) of nanofibers in the oral dissolving membrane obtained during the concentration screening process of various substances in the core spinning solution.

[0034] Figure 2 The images show SEM images (AC), nanofiber diameter distribution maps (A1-C1), and coaxial nanofiber TEM images (DF) of the oral dissolving membranes obtained in Example 1, Comparative Example 1, and Comparative Example 2.

[0035] Figure 3 The FTIR spectrum, XRD pattern, TGA curve, and DTG curve of the oral dissolving membranes obtained in Example 1 and Comparative Example 1 are shown.

[0036] Figure 4The physical properties of the oral dissolving films obtained in Example 1, Comparative Example 1, and Comparative Example 2 are characterized; where (A) is tensile strength (TS), (B) is elongation at break (EAB), (C) is thickness, (D) is disintegration time; (E) is solubility, (F) is apparent viscosity; and (G) is the water contact angle test result. The significance level is marked as... P<0.05, P<0.01, P<0.001 indicates a significant difference, and NS indicates no significant difference.

[0037] Figure 5 The figures show the color change and retention rate of the oral dissolving membranes obtained in Example 1 and Comparative Example 1 after 8 days of light exposure (AB); the ABTS and DPPH free radical scavenging capabilities of the oral dissolving membranes obtained in Example 1 and Comparative Example 1 (CD); and the oral release and permeation simulation results of the oral dissolving membrane obtained in Example 1 (EH). Specifically, (E) is the in vitro release curve of the oral dissolving membrane obtained in Example 1 at 5, 10, 15, 30, 45, 60, 90, and 120 minutes; (F) is the in vitro permeation amount of the oral dissolving membrane obtained in Example 1 at 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5 hours; and (G, H) are the ABTS and DPPH free radical scavenging capabilities of the oral dissolving membrane obtained in Example 1 within 5 hours of permeation, respectively. The figure also includes a schematic diagram of the application, preparation, and absorption process of the oral dissolving membrane obtained in Example 1 (I). The significance level is marked as... P<0.05, P<0.01, P<0.001 indicates a significant difference, and NS indicates no significant difference.

[0038] Figure 6 The graph shows the in vitro release rate of the oral dissolving membrane obtained in Comparative Example 3 in artificial saliva (pH 6.8) without amylase.

[0039] Figure 7 The image shows the cytotoxicity test results (AC) of the oral dissolving membranes obtained in Example 1, Comparative Example 1, and Comparative Example 2 after 24 hours and 48 hours of culture. Detailed Implementation

[0040] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.

[0041] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0042] Example 1 A method for preparing a smart responsive anthocyanin oral dissolving membrane includes the following steps: (1) Preparation of esterified KGM: 5.0 g KGM (Mw: 809,473, Mn: 854,507) and 3.0 g triethyl citrate were mixed in 80 mL DMSO; 0.1 g p-toluenesulfonic acid was added as a catalyst and the mixture was reacted at 85 °C for 6 h to obtain esterified KGM with a purity ≥95%.

[0043] (2) Preparation of core spinning solution: Weigh PVP (Mw: 1,300,000), esterified KGM and ACNs (total anthocyanin content 40%), add them to distilled water to make their concentrations 10% w / v, 4% w / v and 0.2% w / v respectively, stir magnetically for 3 h at room temperature until completely dissolved, and then let stand for 24 h to remove bubbles to obtain core spinning solution.

[0044] (3) Preparation of shell spinning solution: Accurately weigh 15.0 g PVA (Mw: 145,000, degree of alcoholysis 98%-99%) and add it to 85 mL of distilled water. Stir magnetically in a 70℃ water bath for 4 h until completely dissolved to form a transparent viscous solution. Let stand at room temperature for 24 h to remove bubbles and obtain shell spinning solution.

[0045] (4) Coaxial electrospinning: Inject the two spinning solutions mentioned above into 10 mL syringes respectively. Using a coaxial needle (inner core: 18 G, inner diameter 0.35 mm; outer shell: 16 G), set the electrospinning parameters according to the following conditions: shell flow rate 10 μL / min, core flow rate 12 μL / min, voltage 19 kV, spinning temperature 25℃, humidity 30%, receiving distance 10 cm. Collect on aluminum foil for about 4 h to obtain a uniform nanofiber membrane, which is anthocyanin oral dissolution membrane, denoted as PVP / KGM / ACNs@PVA.

[0046] Example 2 The difference between this embodiment and embodiment 1 is that the PVP concentration in the preparation of the core spinning solution in step (2) is 8%, while the rest of the operations are the same as in embodiment 1.

[0047] Example 3 The difference between this embodiment and embodiment 1 is that the PVP concentration in the preparation of the core spinning solution in step (2) is 12%, while the rest of the operations are the same as in embodiment 1.

[0048] Comparative Example 1 The difference between this comparative example and Example 1 is that no esterified KGM was added in the preparation of the core spinning solution in step (2), and the rest of the operations were the same as in Example 1, denoted as PVP / ACNs@PVA.

[0049] Comparative Example 2 The difference between this comparative example and Example 1 is that ACNs were not added in step (2), and the rest of the operations were the same as in Example 1, denoted as PVP / KGM@PVA.

[0050] Comparative Example 3 The difference between this comparative example and Example 1 is that KGM was not esterified in step (2), while the rest of the operations were the same as in Example 1.

[0051] 1. Screening of the concentrations of various substances in the core spinning solution; results are shown below. Figure 1 .

[0052] (1) Weigh PVP and add it to distilled water to make concentrations of 5% w / v, 10% w / v, and 15% w / v. Stir magnetically at room temperature for 3 h until completely dissolved, then let stand for 24 h to remove bubbles and obtain spinning solutions. Perform uniaxial electrospinning to obtain oral dissolving membranes, which are denoted as PVP 5%, PVP 10%, and PVP 15%, respectively. The uniaxial electrospinning conditions are as follows: inject the prepared spinning solution into a 10 mL syringe and set the electrospinning parameters as follows: flow rate 12 μL / min, voltage 19 kV, spinning temperature 25℃, humidity 30%, receiving distance 10 cm. Collect on aluminum foil for about 4 h to obtain nanofiber membranes. The SEM images and average fiber diameter distribution histograms of the nanofibers are shown in the figure. Figure 1 AC and Figure 1 A1-C1 shows that the fiber diameter increases with increasing PVP concentration, with average diameters of 0.16±0.01 μm, 0.78±0.26 μm, and 1.71±0.25 μm, respectively. Figure 1 In A, the increased conductivity leads to an increase in electrostatic force and Coulomb repulsion, the jet elongates along its axis and generates fine nanofibers, making it difficult to load anthocyanins. Figure 1 In C, increased viscosity enhances interchain entanglement, resulting in thicker nanofibers. Based on a comprehensive analysis of fiber morphology and process feasibility, a crosslinking agent concentration of 10% is optimal for PVP.

[0053] (2) Weigh PVP and the esterified KGM obtained in step (1) of Example 1 to prepare a spinning solution, making the PVP concentration 10% w / v and the esterified KGM concentrations 2% w / v, 4% w / v and 6% w / v, respectively. Stir magnetically at room temperature for 3 h until completely dissolved, and then let stand for 24 h to remove bubbles to obtain the spinning solution. Perform uniaxial electrospinning to obtain oral dissolving membranes, which are denoted as PVP-2% KGM, PVP-4% KGM and PVP-6% KGM, respectively. The uniaxial electrospinning conditions are the same as in step (1). The SEM images and average fiber diameter distribution histograms of the nanofibers are shown in the figure. Figure 1 DF and Figure 1 D1-F1 shows that the addition of esterified KGM protects anthocyanins and improves their stability. When PVP / KGM is combined, KGM concentrations of 2% and 6% exhibit a beaded, coarse fiber morphology. This is because excessively high concentrations of esterified KGM during electrospinning alter the morphology of the Taylor cone, affecting the fiber structure and morphology. Figure 1 Smooth and uniform fiber morphology was observed in E. Therefore, the optimal concentration of esterified KGM is 4% w / v.

[0054] (3) Weigh PVP, esterified KGM obtained in step (1) of Example 1, and ACNs to prepare a spinning solution, with PVP concentration of 10% w / v, esterified KGM concentration of 4% w / v, and ACNs concentrations of 0.1% w / v, 0.2% w / v, and 0.4% w / v. Stir magnetically at room temperature for 3 hours until completely dissolved, then let stand for 24 hours to remove bubbles and obtain the spinning solution. Perform uniaxial electrospinning to obtain oral dissolving membranes, which are denoted as PVP / KGM-0.1% ACNs, PVP / KGM-0.2% ACNs, and PVP / KGM-0.4% ACNs, respectively. The uniaxial electrospinning conditions are the same as in step (1). The SEM images and average fiber diameter distribution histograms of the nanofibers are shown in [reference needed]. Figure 1 GI and Figure 1 Figures G1-I1 show that anthocyanin concentrations of 0.1% and 0.4% produced unevenly shaped fibers of varying thickness and texture, indicating that the anthocyanins were not completely encapsulated. This is attributed to migration of the material during electrospinning, which affected the morphology. Furthermore, smooth fibers were observed in Figure H, demonstrating successful incorporation of anthocyanins into the nanofiber matrix. Therefore, the optimal concentration of anthocyanins is 0.2% w / v.

[0055] 2. The morphology of the dissolved films obtained in Example 1 and Comparative Examples 1 and 2 was observed, and the nanofiber structure was characterized. The results are shown in [the table below]. Figures 2-3 .

[0056] (1) SEM images, nanofiber diameter distribution maps, and TEM images of the oral dissolving membranes obtained in Example 1, Comparative Example 1, and Comparative Example 2 are as follows: Figure 2 As shown. From Figure 2 As can be seen from AC and A1-C1, the fiber surface exhibits a smooth and uniform quality, free from pores, beading, cracks, or other defects; the fiber diameter increases with the addition of KGM and nucleoside anthocyanins. The diameter of the coaxial nanofibers in Comparative Example 2 is 0.98 ± 0.13 μm. Figure 2 A1), Comparative Example 1 nanofiber diameter is 1.09 ± 0.12 μm ( Figure 2 B1). The diameter of the fiber in Example 1 was 1.38 ± 0.27 μm ( Figure 2 C1). Figure 2 The DF image shows a transmission electron microscope (TEM) image of the electrospun fibers, revealing a distinct core-shell structure with a black inner layer and a gray outer surface. This indicates that coaxial electrospun fibers were successfully prepared by incorporating anthocyanins into the nanofiber matrix, further validating the SEM results.

[0057] (2) Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) were performed on the dissolved films obtained in Example 1 and Comparative Example 1 to further investigate intermolecular interactions and crystal structures. FTIR spectroscopy ( Figure 3 A) shows that the PVP / KGM / ACNs complex at 3443 cm⁻¹ - The OH stretching vibration peak at position ¹ exhibits a redshift (compared to the single component) and broadens, indicating the formation of a dense hydrogen bond network between the core and shell layers. Characteristic peaks of ACNs (such as 1654 cm⁻¹) - The disappearance of the C=C vibration at position ¹ in the complex indicates that anthocyanins were successfully encapsulated in the fiber matrix. XRD pattern ( Figure 3 (B) shows that the diffraction peak of the PVP / KGM / ACNs complex at 2θ=20° is broadened and weakened, indicating that hydrogen bonding disrupts the crystalline regions of the components, causing the anthocyanins to disperse in an amorphous state and enhancing stability. (TGA curve) Figure 3 C) indicates that the membrane of Example 1 experienced a weight loss of only 6.88% during the main degradation phase at 100–400°C, significantly lower than that of single ACNs (42.09%), demonstrating that the core-shell structure enhances thermal stability. DTG curves show that the temperature corresponding to the main degradation peak increases with the addition of esterified KGM. Figure 3 (D) indicates that the addition of esterified KGM improved the thermal stability of the orally dissolving membrane, further supporting the TGA results.

[0058] 3. The physical properties of the dissolved films obtained in Example 1 and Comparative Examples 1 and 2 were tested, and the results are shown in the figure. Figure 4 .

[0059] The physical properties of the oral dissolution film, such as mechanical strength, disintegration time, and solubility, were evaluated for Example 1, Comparative Example 1, and Comparative Example 2. Figure 4 AB's statistical data shows that the addition of esterified KGM significantly improved the toughness and ductility of the film. Example 1 exhibited a tensile strength of 6.48 MPa and an elongation at break of 17.68%, which was superior to Comparative Example 1 (tensile strength of 4.89 MPa and elongation at break of 15.53%), demonstrating excellent mechanical properties. This is because esterified KGM forms a three-dimensional network structure with PVP and PVA through hydrogen bonds, enhancing the entanglement between molecular chains. Thickness test results ( Figure 4 C) shows that Example 1 exhibits greater thickness characteristics, a phenomenon consistent with the trend observed by SEM of increasing fiber diameter with the addition of polysaccharides and anthocyanins. Disintegration time test ( Figure 4 D) indicates that the membrane of Example 1 disintegrated in artificial saliva (pH 6.8) in 40.08 seconds, meeting the requirements for rapid oral dissolution (20–50 seconds), while Comparative Example 1 only took 23.14 seconds, demonstrating that the gel barrier effect of esterified KGM delayed disintegration. Solubility test ( Figure 4 E) shows that the membrane solubility of Example 1 reached 93.32%, indicating good hydrophilicity, which is conducive to the release of active ingredients. Contact angle test ( Figure 4 G) further confirmed that all membrane contact angles were less than 90°, indicating high hydrophilicity. The introduction of esterified KGM and anthocyanins significantly enhanced membrane hydrophilicity by increasing hydroxyl content and forming a hydrogen bond network (PVP / KGM / ACNs@PVA had the smallest contact angle). Apparent viscosity analysis ( Figure 4 F) indicates that the addition of esterified KGM increases the system viscosity, forming a more stable network structure, which is beneficial to the stability of the spinning process and the uniformity of fiber morphology. In summary, the film agent of this invention has high mechanical strength, controllable disintegration, high hydrophilicity, and suitable rheological properties, fully meeting the physical requirements of oral delivery systems.

[0060] 4. Stability tests were conducted on the dissolved films obtained in Example 1 and Comparative Example 1. The results are shown in [the table below]. Figure 5 AD.

[0061] The chemical stability of anthocyanins was evaluated by a light-accelerated irradiation experiment (8 days) on Example 1 and Comparative Example 1. After 8 days of light irradiation, the membrane of Example 1 retained 81.22% of the anthocyanins, while Comparative Example 1 retained less than 50%. Figure 5AB). The color difference (ΔE value) change curve shows that the ΔE value of the film in Example 1 is only 2.03, significantly lower than that in Comparative Example 1, indicating that the UV shielding effect and hydrogen bond network of esterified KGM effectively inhibit the photodegradation of anthocyanins. To evaluate the effect of long-term light exposure on the stability of functional components in anthocyanin-loaded oral films, day 8 was used as the key time point to compare the antioxidant activity decline patterns of Example 1 and Comparative Example 1. The antioxidant activity of Example 1 was significantly enhanced, while Comparative Example 1 only showed lower antioxidant performance (AB). Figure 5 (CD). In summary, the film-forming agent of this invention significantly improves the photostability and pH stability of anthocyanins through the synergistic effect of the core-shell structure and esterified KGM.

[0062] 5. The in vitro release behavior of the dissolved membranes obtained in Example 1 and Comparative Example 3 was tested, and the results are shown in [the table below]. Figure 5 E and Figure 6 .

[0063] The anthocyanin release kinetics of Example 1 and Comparative Example 3 were tested in a simulated oral environment. The membrane of Example 1 achieved a cumulative anthocyanin release rate of 97% within 120 minutes. Figure 5 E), while the release rate of Comparative Example 3 (unesterified KGM) was only 53% ( Figure 6 This demonstrates that Example 1 possesses excellent controlled-release capability.

[0064] 6. The in vitro permeability performance of the dissolved membrane obtained in Example 1 was tested, and the results are shown in [the table below]. Figure 5 FH.

[0065] In Example 1, a porcine oral mucosa model was used to simulate the osmosis process. Figure 5 The permeation curve of F shows that the permeation rate increases with time, and effective permeation (approximately 10%) can be detected after 0.5 hours. Antioxidant activity testing of the samples after permeation (…) Figure 5 The results (GH) showed that the ABTS and DPPH free radical scavenging rates remained at 55.93% and 63.97%, respectively, within 5 hours, demonstrating that anthocyanins retain their bioactivity after transmembrane transport. This result is attributed to the gel barrier formed by esterified KGM, which prolongs the mucosal retention time and promotes transmembrane transport through the concentration gradient. In summary, the film formulation of this invention can significantly improve the oral penetration efficiency and bioavailability of anthocyanins, and the function of the active ingredients is not impaired after penetration.

[0066] 7. Cytotoxicity evaluation tests were conducted on the lysed membranes obtained in Example 1, Comparative Example 1, and Comparative Example 2. The results are shown in [the table below]. Figure 7 .

[0067] The effect of oral soluble membrane extract on the survival rate of Caco-2 cells was tested using the MTT assay. Figure 7The results showed that after 24 and 48 hours of membrane treatment in Example 1, the cell viability was >90%, with no significant difference compared to the blank control group (P>0.05). Figure 7 In summary, the film-forming agent of this invention is non-cytotoxic, possesses excellent biocompatibility, and meets the safety standards for functional foods and health products.

Claims

1. A smart responsive anthocyanin oral dissolving membrane, characterized in that: The oral dissolving membrane is made of interwoven nanofibers with a core-shell structure obtained by coaxial electrospinning technology. The core of the nanofibers includes polyvinylpyrrolidone, esterified konjac glucomannan and anthocyanins, and the shell of the nanofibers includes polyvinyl alcohol. The core and shell of the nanofibers form a spatially interlocked structure through intermolecular hydrogen bonding.

2. The anthocyanin oral dissolving membrane according to claim 1, characterized in that: The mass ratio of polyvinylpyrrolidone, esterified konjac glucomannan, and anthocyanins in the core is 10:2-6:0.1-0.4; the mass ratio of the core to the shell is 1:0.8-1.

2.

3. The anthocyanin oral dissolving membrane according to claim 1, characterized in that: The molecular weight of the polyvinylpyrrolidone is 1,000,000 to 1,500,000 Da; the molecular weight of the polyvinyl alcohol is 120,000 to 180,000 Da.

4. The anthocyanin oral dissolving membrane according to claim 1, characterized in that: The esterified konjac glucomannan is prepared by the following method: konjac glucomannan and triethyl citrate are mixed in DMSO; p-toluenesulfonic acid is added as a catalyst, and the mixture is reacted at 60-85℃ for 4-6 h. After cooling, the mixture is poured into ethanol to precipitate, washed, and the product is obtained. The mass-to-volume ratio of konjac glucomannan, triethyl citrate, p-toluenesulfonic acid, and DMSO is 1 g : 0.5-1.0 g : 0.05-0.1 g : 10-20 mL, and the molecular weight of the konjac glucomannan is 200-800 kDa.

5. The anthocyanin oral dissolving membrane according to claim 1, characterized in that: The nanofibers have a diameter of 0.8-1.5 μm; the oral dissolving membrane has a tensile strength of 4.0-7.0 MPa, an elongation at break of 15%-25%, a disintegration time of 20-50 s, and a solubility of 70%-95%.

6. The method for preparing the oral dissolving film according to any one of claims 1-5, characterized in that: Polyvinylpyrrolidone, esterified konjac glucomannan, and anthocyanins were added to distilled water, stirred and dissolved at room temperature, and allowed to stand at room temperature to remove bubbles, thus obtaining the core spinning solution. Polyvinyl alcohol was added to distilled water, stirred and dissolved, and allowed to stand at room temperature to remove bubbles, thus obtaining the shell spinning solution. The above spinning solutions were coaxially electrospun using an electrospinning device, and collected using aluminum foil to obtain a uniform nanofiber membrane, which is the anthocyanin oral dissolving membrane.

7. The preparation method according to claim 6, characterized in that: In the core spinning solution, the concentration of polyvinylpyrrolidone is 8%-12%, the concentration of esterified konjac glucomannan is 2%-6%, and the concentration of anthocyanins is 0.1%-0.4%; in the shell spinning solution, the concentration of polyvinyl alcohol is 12%-18%; and the mass ratio of the core layer to the shell layer is 1:0.8-1.

2.

8. The preparation method according to claim 6, characterized in that: The coaxial electrospinning conditions include: a voltage of 16-20 kV, a shell spinning solution flow rate of 8-12 μL / min, a core spinning solution flow rate of 10-14 μL / min, a spinning temperature of 15-30℃, a humidity of 20%-40%, a collection distance of 8-12 cm, and a collection time of 5-6 h.

9. The preparation method according to claim 6, characterized in that: The degassing time at room temperature is 12-24 h.

10. The use of the anthocyanin oral dissolving membrane according to any one of claims 1-5 or the anthocyanin oral dissolving membrane prepared by the method according to any one of claims 6-9 in the preparation of functional foods or health products.

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