A carrier material with light response controlled release function, a preparation method thereof and application thereof in bio-based active packaging

Abstract

The application discloses a carrier material with a light response controlled release function, a preparation method of the carrier material and application of the carrier material in bio-based active packaging. The carrier material with the light response controlled release function is obtained by modifying a photoisomerization group, azobenzene, on IRMOF-3 through functional modification, and taking the IRMOF-3 as a base body. After the carrier material is used to load carvacrol and is added into a sodium alginate base film, a bio-based active packaging film with a light response controlled carvacrol release performance is prepared, and the prepared packaging film has good tensile performance, hydrophobic performance and barrier performance.

Description

Technical Field

[0001] This invention relates to the field of controlled-release technology in active packaging, and in particular to a carrier material with photoresponsive controlled-release function, its preparation method, and its application in bio-based active packaging. Background Technology

[0002] The concept of controlled-release packaging was first proposed by Lacoste et al. in 2005. Packaging acts as a delivery system for active substances, controlling their diffusion or release rate to prolong the duration of action of the active substances. In the early research and development of controlled-release packaging, its essence was mostly slow release, slowing down the diffusion or release rate of active substances to varying degrees, while research on precise control of release was still lacking.

[0003] In 2016, Brockgreitens and Abbas first proposed the definition of smart controlled-release packaging. They stated that smart controlled-release packaging is a type of packaging that relies on stimuli to trigger the release of active compounds by reacting materials (shrinkage, expansion, dissolution, chemical functional changes, or self-assembly). The stimuli can be characteristics of the headspace inside the packaging or food (e.g., pH, water activity, gas composition, microorganisms, and contaminants) or storage conditions (e.g., temperature, relative humidity, light). When exposed to environmental stimuli, the packaging system releases the active agent and controls its release rate to maintain or improve food safety and quality. Wu et al. prepared an aerogel of nanocellulose-reinforced pectin with water as the stimuli. This aerogel can rapidly absorb moisture within the packaging, leading to pore expansion and partial structural decomposition, allowing the release of loaded thymol. Heras-Mozos et al. prepared a chitosan-based film containing imine bonds for packaging blackberries. The acidic conditions created in the headspace microenvironment during blackberry respiration stimulated the hydrolysis of imine bonds, releasing antimicrobial volatiles. For the above-mentioned stimulus-responsive packaging, it is difficult to precisely control the material's moisture absorption and the pH range of the headspace microenvironment. Therefore, the intensity of stimulation from such stimuli is difficult to accurately grasp. However, light, as a non-contact stimulus, can have its intensity, wavelength, and duration precisely set using current technology and methods. It possesses unique characteristics in both time and space that other stimuli lack, making it an ideal, clean stimulus source. Currently, photoresponsive materials have expanded from traditional fields such as printing and packaging, and wood processing to high-tech fields such as electronics, communications, optical instruments, and medical materials. However, there are relatively few reports on photoresponsive materials in the field of active food packaging.

[0004] Photostimulation response allows for the controlled release of active substances shielded within a carrier material by irradiating it with different light sources. Ultraviolet radiation is widely used to initiate the release process by inducing carrier degradation or structural changes. The configurational changes of the double bond structure in azobenzene materials during photoresponsiveness offer advantages such as low energy barriers, low energy consumption, no emissions, and good reproducibility. Due to the presence of the N=N double bond, azobenzene has both trans and cis configurations. Under ultraviolet light irradiation, the azobenzene molecule can rapidly transform from the trans configuration to the cis configuration, exhibiting fast photoisomerization speed and high efficiency. The trans structure of the azophenyl group is more stable; under thermal effects or visible light irradiation, it can transform from the cis configuration to the trans configuration, and this photoinduced cis-trans isomerization exhibits excellent reversibility. During the molecular configurational transformation process, the differences in material properties are reflected in changes in molecular size, ultraviolet-visible absorption spectrum, and refractive index. Due to its unique photoisomerization properties, azobenzene materials have wide applications in fields such as light-controlled actuators, solar thermal fuels, and drug sustained release, but there are few reports on their use in the field of active food packaging.

[0005] In recent years, post-synthetic functionalization modification of MOFs, as excellent carrier materials, has become an important means to develop and expand the unique properties of MOFs. In 2011, Stock et al. first modified the side chain of the MOF backbone with azobenzene molecules, constructing a photoresponsive MOF material based on azobenzene molecules. The presence of free amino groups on the organic ligands of IRMOF-3 provides base sites, making post-synthetic functionalization possible. Through functionalization modification of IRMOF-3, the properties of IRMOF-3 can be designed or improved. In the post-synthetic modification reactions of IRMOF-3, amidation reactions of carboxylic acids, anhydrides, etc., with amino groups are common reaction types. Liu modified IRMOF-3 by condensing the amino group in the IRMOF-3 backbone with the carboxyl group of lactic acid to anchor Au. 3+ Therefore, it can be used as a catalyst; Yang Baochun used folic acid to functionalize IRMOF-3 and then used it as a carrier for anti-tumor drugs, utilizing the tumor cell targeting properties of folic acid to achieve targeted delivery of anti-tumor drugs; this provides a reference for the functionalization modification of IRMOF-3. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a carrier material with photoresponsive controlled-release function, its preparation method, and its application in bio-based active packaging. This invention obtains a carrier material with photoisomerization group azobenzene on IRMOF-3 through functionalization modification; carvacrol is loaded onto this carrier material and then added to a sodium alginate-based membrane to prepare a bio-based active packaging film with photoresponsive controlled-release properties of carvacrol. The prepared packaging film also exhibits good tensile properties, hydrophobic properties, and barrier properties.

[0007] The technical solution of the present invention is as follows:

[0008] A carrier material with photoresponsive controlled release function, characterized in that it comprises the following structure:

[0009]

[0010] PBA is azobenzene-4-benzoic acid with an azobenzene photoisomerization group, and PBA-IRMOF-3 is formed by modifying the amino group of IRMOF-3 with PBA.

[0011] Furthermore, the carrier material with photoresponsive controlled release function is characterized in that,

[0012]

[0013] Where UV stands for ultraviolet light, and Vis / heat stands for visible light / heating.

[0014] Furthermore, the carrier material with photoresponsive controlled release function is characterized by being prepared from the following components: isomorphous metal-organic framework material-3 (IRMOF-3), azobenzene-4-benzoic acid (PBA), 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCl), 1-hydroxybenzotriazole (HOBt), and acetonitrile (C2H2N).

[0015] Furthermore, the method for preparing the carrier material with photoresponsive controlled release function is characterized by comprising the following steps:

[0016] (1) PBA and EDCl were ultrasonically dispersed into C2H2N and stirred with a magnetic stirrer to obtain mixed solution A.

[0017] (2) Disperse HOBt in C2H2N by ultrasonication, add it to mixed solution A and continue stirring to obtain mixed solution B.

[0018] (3) Add IRMOF-3 to mixed solution B to obtain mixed suspension C, and stir at room temperature to obtain mixed suspension D.

[0019] (4) Centrifuge the mixed suspension D to obtain the precipitate, wash it several times with C2H2N and then vacuum dry it to obtain PBA-IRMOF-3.

[0020] Further, in step (1), the concentration of PBA is 0.04 to 0.12 mmol / mL; the concentration of EDCl is 0.048 to 0.144 mmol / mL; the magnetic stirring speed is 200 to 400 r / min; and the magnetic stirring time is 30 to 50 min.

[0021] Further, in step (2), the concentration of HOBt is 0.034 to 0.103 mmol / mL; the magnetic stirring speed is 200 to 400 r / min; and the magnetic stirring time is 40 to 80 min.

[0022] Further, in step (3), the concentration of IRMOF-3 in the mixed suspension C is 2.67 to 8.00 mg / mL; the magnetic stirring speed is 200 to 400 r / min; and the magnetic stirring time is 12 to 36 h.

[0023] Further, in step (4), the precipitate is washed with C2H2N 5 to 8 times; the vacuum drying temperature is 30 to 50°C; and the vacuum drying time is 12 to 36 hours.

[0024] Furthermore, the amino modification rate of the PBA-IRMOF-3 is 25.12% to 33.33%.

[0025] The application of the aforementioned carrier material with photoresponsive controlled-release function in bio-based active packaging, namely the preparation of a bio-based photoresponsive controlled-release active film, is characterized by the following specific preparation method: PBA-IRMOF-3 / carvacrol is dissolved and dispersed in water, then the bio-based material is added, and water is added to a fixed volume to obtain a fixed solution. The bio-based material is sodium alginate, a natural polysaccharide. The PBA-IRMOF-3 / carvacrol is formed by loading carvacrol onto PBA-IRMOF-3. The mass ratio of PBA-IRMOF-3 / carvacrol to sodium alginate in the fixed solution is 0.2–1.0:2.5. The carvacrol concentration was 2.10–10.53 mg / mL. A mixed solution A was obtained by heating and stirring. A plasticizer, glycerol, was added to mixed solution A and stirring continued. The volume ratio of the plasticizer to mixed solution A was 1:19. After vacuuming, a film-forming base solution B was obtained. Film-forming base solution B was poured into a mold and cast into a film. The film was dried at 30–60°C for 10–12 h to obtain a sodium alginate-based photoresponsive controlled-release active film. A crosslinking agent was added to the prepared photoresponsive controlled-release active film for crosslinking for 50–70 s. The crosslinking agent used was a 5 wt% calcium chloride solution, and the amount of the crosslinking agent was 0.080–0.112 mL / cm³. 2 The sodium alginate-based photoresponsive controlled-release active packaging film with added PBA-IRMOF-3 / carvacrol was dried for 10-12 hours at a relative humidity of 50%-60% and a temperature of 21-25℃ to obtain the film.

[0026] The beneficial technical effects of this invention are as follows:

[0027] (1) The amino modification rate of the carrier material PBA-IRMOF-3 with photoresponsive controlled release function prepared by the present invention is 25.12% to 33.33%, which realizes the successful modification of the azobenzene photosensitive group on IRMOF-3.

[0028] (2) The photosensitive group of the carrier material PBA-IRMOF-3 with photoresponsive controlled release function prepared in this invention achieves reversible changes in cis-trans structure under alternating UV and Vis irradiation.

[0029] (3) The PBA-IRMOF-3 / carvacrol prepared by the present invention has the property of controlling the release of carvacrol by light response.

[0030] (4) The sodium alginate-based active membrane with added PBA-IRMOF-3 / carvacrol prepared in this invention has the property of controlling the release of carvacrol in response to light.

[0031] (5) The sodium alginate-based active membrane prepared by the present invention with added PBA-IRMOF-3 / carvacrol has a smooth surface without pores and cracks; it improves the tensile properties of the sodium alginate-based composite membrane, and also improves the barrier properties and hydrophobic properties of the composite membrane.

[0032] (6) By adding PBA-IRMOF-3 / carvacrol, the tensile strength of this invention can reach 40.98±1.19~41.77±1.05MPa, the elongation at break is 58.85%±2.93%~59.24%±1.58%, and the water vapor transmission rate is 559.68±5.99~561.52±5.57g / (d·m) 2 The water contact angle is 69.67±1.21°~70.60±1.64°.

[0033] (7) The sodium alginate-based photoresponsive controlled-release active film with added PBA-IRMOF-3 / carvacrol prepared by the present invention has a smooth surface, good tensile properties and barrier properties, and can be made into films of different thicknesses and mechanical properties as needed; the sodium alginate-based photoresponsive controlled-release active film with added PBA-IRMOF-3 / carvacrol has the property of photoresponsive control of carvacrol release, and can be used as a response controlled-release packaging, suitable for packaging of chilled fresh meat and other foods, and can control the release of active substances in the packaging according to changes in food quality, effectively extending the shelf life of food. Attached Figure Description

[0034] Figure 1 The Fourier transform infrared spectrum of PBA-IRMOF-3 prepared in Example 1 of this invention is shown.

[0035] Figure 2 The image shows the X-ray photoelectron spectrum of PBA-IRMOF-3 prepared in Example 1 of this invention.

[0036] Figure 3 The nuclear magnetic resonance spectrum of PBA-IRMOF-3 prepared in Example 1 of this invention.

[0037] Figure 4 The UV / Vis spectra of PBA-IRMOF-3 prepared in Example 1 of this invention after different irradiation treatments.

[0038] Figure 5 The absorbance value of PBA-IRMOF-3 prepared in Example 1 of the present invention at 323 nm varies with irradiation time under different power UV irradiation.

[0039] Figure 6 The absorbance value of PBA-IRMOF-3 prepared in Example 1 of the present invention after being fully irradiated with UV was shown to change with the irradiation time at different temperatures at 323 nm.

[0040] Figure 7 The photoresponse-controlled release curve of PBA-IRMOF-3 / carvacrol prepared in Example 2 of this invention.

[0041] Figure 8 This is a schematic diagram illustrating the photoresponsive controlled release principle of PBA-IRMOF-3 / carvacrol prepared in Example 2 of the present invention.

[0042] Figure 9 The CA release rate of the photoresponsive active film prepared in Example 3 of the present invention within 24 hours after UV irradiation for different times.

[0043] Figure 10 The photoresponse controlled release curve of the photoresponse controlled release active membrane prepared in Example 3 of the present invention.

[0044] Figure 11 The transmittance curves are for the composite films prepared in Examples 2-3 and Comparative Examples 3-4 of this invention. Detailed Implementation

[0045] The claims of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made within the scope of protection of the claims of the present invention shall still be within the scope of protection of the claims of the present invention.

[0046] This invention aims to functionalize prepared IRMof-3 to obtain a carrier material PBA-IRMOF-3 with photoresponsive controlled release function. After encapsulating the plant essential oil carvacrol, it is added to the bio-based biodegradable material sodium alginate. This protects the active ingredient from degradation under adverse environmental conditions while enabling its controlled release, thereby developing an active packaging film with photoresponsive controlled release performance.

[0047] First, a method for preparing the aforementioned photoresponsive controlled-release carrier material PBA-IRMOF-3 is protected, comprising the following steps:

[0048] (1) PBA and EDCl were ultrasonically dispersed into C2H2N and stirred with a magnetic stirrer to obtain mixed solution A.

[0049] (2) Disperse HOBt in C2H2N by ultrasonication, add it to mixed solution A and continue stirring to obtain mixed solution B.

[0050] (3) Add IRMOF-3 to mixed solution B to obtain mixed suspension C, and stir at room temperature to obtain mixed suspension D.

[0051] (4) Centrifuge the mixed suspension D to obtain the precipitate, wash it several times with C2H2N and then vacuum dry it to obtain PBA-IRMOF-3.

[0052] Further, in step (1), the concentration of PBA is 0.04 to 0.12 mmol / mL; the concentration of EDCl is 0.048 to 0.144 mmol / mL; the magnetic stirring speed is 200 to 400 r / min; and the magnetic stirring time is 30 to 50 min.

[0053] Further, in step (2), the concentration of HOBt is 0.034 to 0.103 mmol / mL; the magnetic stirring speed is 200 to 400 r / min; and the magnetic stirring time is 40 to 80 min.

[0054] Further, in step (3), the concentration of IRMOF-3 in the mixed suspension C is 2.67 to 8.00 mg / mL; the magnetic stirring speed is 200 to 400 r / min; and the magnetic stirring time is 12 to 36 h.

[0055] Further, in step (4), the precipitate is washed with C2H2N 5 to 8 times; the vacuum drying temperature is 30 to 50°C; and the vacuum drying time is 12 to 36 hours.

[0056] Furthermore, the amino modification rate of the PBA-IRMOF-3 is 25.12% to 33.33%.

[0057] The second objective of this invention is to protect the application of a carrier material with photoresponsive controlled-release function in bio-based active packaging, namely, a bio-based photoresponsive controlled-release active film. The photoresponsive controlled-release carrier material PBA-IRMOF-3 is obtained by functionalizing IRMOF-3. The application of this carrier material in bio-based active packaging involves using sodium alginate as the main film-forming material, adding PBA-IRMOF-3 / carvacrol and a plasticizer, followed by casting, drying, and crosslinking to obtain a composite film. The PBA-IRMOF-3 / carvacrol is formed by loading carvacrol onto PBA-IRMOF-3.

[0058] Furthermore, the sodium alginate is a natural polysaccharide sodium alginate; the plasticizer is glycerol; and the crosslinking agent used for crosslinking is a 5% (w / w) calcium chloride solution.

[0059] Further, the preparation method of PBA-IRMOF-3 / carvacrol is as follows: PBA-IRMOF-3 is added to carvacrol and dispersed, then placed under vacuum for 10-30 min, and then restored to normal pressure and allowed to stand for 5-20 min. The above operation of placing under vacuum and standing under normal pressure is repeated 2-5 times to obtain a suspension. After centrifugation, the precipitate is collected and washed 1-3 times with anhydrous ethanol. The solid precipitate is collected and dried to obtain PBA-IRMOF-3 / carvacrol.

[0060] The third objective of this invention is to protect the application of a carrier material with photoresponsive controlled-release function in bio-based active packaging, namely, a method for preparing a bio-based photoresponsive controlled-release active film, comprising the following steps:

[0061] (1) PBA-IRMOF-3 / carvacrol was dissolved in water and dispersed, then sodium alginate was added, and water was added to make up to a fixed volume to obtain a fixed solution. The mass ratio of PBA-IRMOF-3 / carvacrol to sodium alginate in the fixed solution was 0.2-1.0:2.5, and the mass concentration of PBA-IRMOF-3 / carvacrol in the fixed solution was 2.10-10.53 mg / mL. The solution was heated and stirred to obtain mixed solution A.

[0062] (2) Add plasticizer to mixed solution A and continue stirring. The volume ratio of plasticizer to mixed solution A is 1:19. After vacuuming, film-forming base liquid B is obtained.

[0063] (3) Pour the film-forming base solution B into the mold, cast the film, and dry it at 30-60℃ for 10-12h to obtain a sodium alginate-based photoresponsive controlled-release active film.

[0064] (4) Add a crosslinking agent to the prepared photoresponsive controlled-release active membrane and crosslink for 50–70 s. The amount of the crosslinking agent is 0.080–0.112 mL / cm³. 2 ;

[0065] (5) Drying at a relative humidity of 50% to 60% and a temperature of 21 to 25°C for 10 to 12 hours yields a sodium alginate-based photoresponsive controlled-release active membrane with added PBA-IRMOF-3 / carvacrol.

[0066] In the photoresponsive controlled-release active membrane of this invention, after ultraviolet irradiation, the azophenyl groups on PBA-IRMOF-3 undergo "ultraviolet light response," i.e., trans-to-cis structural isomerization. During subsequent storage, the azophenyl groups undergo "cis-trans relaxation" under visible light irradiation, gradually recovering from the cis structure to the trans structure. During this process, the azophenyl groups act as "impeller stirring," promoting the release of carboxylic acid (CA) from PBA-IRMOF-3. After a period of time, the azophenyl groups undergo "complete relaxation," i.e., completely recovering from the cis structure to the trans structure. After this, the "impeller stirring" effect disappears, and the release of CA begins to slow down relatively. The PBA-IRMOF-3 / carvacrol system possesses photoresponsive controlled-release potential, enabling the regulated release of CA under ultraviolet light stimulation. This property allows the sodium alginate-based photoresponsive controlled-release active membrane with added PBA-IRMOF-3 / carvacrol to exhibit photoresponsive control of carvacrol release.

[0067] In the photoresponsive controlled-release active membrane of the present invention, ultraviolet light emitted by the UVP CL-1000 UV crosslinker (UV lamp wavelength 365nm, power adjustable from 8 to 40W) is used as the ultraviolet irradiation treatment stimulus source (UV irradiation), and LED lighting of the temperature-adjustable ZQLY-300 shaking incubator is used to simulate the visible light irradiation treatment stimulus source (Vis irradiation).

[0068] The photoresponse performance study of this invention was conducted by measuring the UV / Vis spectrum of the sample in the wavelength range of 200–600 nm and the absorbance value of the sample at 323 nm using a UV / Vis spectrophotometer.

[0069] The mechanical properties of this invention were determined using a 4.104 type microcomputer-controlled electronic universal testing machine manufactured by MITES Industrial Systems (China) Co., Ltd.; the water vapor transmission rate was determined using gravimetric analysis according to ASTM-E96 / E96M (2016); the water contact angle was determined using a JC2000D contact angle measuring instrument manufactured by Shanghai Zhongchen Digital Technology Equipment Co., Ltd.; and the light transmittance was determined using a UV-1800 ultraviolet-visible spectrophotometer manufactured by Shimadzu Corporation of Japan.

[0070] The sodium alginate-based photoresponsive controlled-release active membrane of the present invention, with reference to specific embodiments, will be further explained below.

[0071] Example 1

[0072] A photoresponsive controlled-release carrier material, PBA-IRMOF-3, is prepared as follows: PBA and EDCl are ultrasonically dispersed in C2H2N to obtain an acetonitrile solution of 0.08 mmol / mL PBA and an acetonitrile solution of 0.096 mmol / mL EDCl. The mixture is stirred at 300 r / min for 40 min to obtain mixed solution A. HOBt is ultrasonically dispersed in C2H2N to obtain an acetonitrile solution of 0.069 mmol / mL HOBt, which is added to mixed solution A and stirred for another 60 min to obtain mixed solution B. IRMOF-3 is added to mixed solution B to obtain mixed suspension C, with an IRMOF-3 concentration of 5.33 mg / mL. The mixture is stirred at room temperature to obtain mixed suspension D. Mixed suspension D is centrifuged to obtain a precipitate, which is washed 6 times with C2H2N and then vacuum dried at 40℃ for 24 h to obtain PBA-IRMOF-3. The amino modification rate of PBA-IRMOF-3 is 33.33%. Figure 1 The Fourier transform infrared spectrum of PBA-IRMOF-3 prepared in Example 1. Figure 2 The image shows the X-ray photoelectron spectrum of PBA-IRMOF-3 prepared in Example 1. Figure 3 The nuclear magnetic resonance spectrum of PBA-IRMOF-3 prepared in Example 1 is shown.

[0073] Example 2

[0074] The application of a carrier material with photoresponsive controlled-release function in bio-based active packaging, namely the preparation of a bio-based photoresponsive controlled-release active film, wherein the active film is prepared by adding sodium alginate as the main film-forming material, along with PBA-IRMOF-3 / carvacrol and a plasticizer, followed by casting, drying, and crosslinking to obtain a composite film; wherein PBA-IRMOF-3 / carvacrol is formed by loading carvacrol onto IRMOF-3. The sodium alginate is a natural polysaccharide sodium alginate; the plasticizer is glycerol; and the crosslinking agent used is a 5% (w / w) calcium chloride solution.

[0075] The preparation method of PBA-IRMOF-3 / carvacrol is as follows: PBA-IRMOF-3 is added to carvacrol at a mass-to-volume ratio of 0.1g:1mL, and dispersed at 40KHZ for 30min; then, it is placed under vacuum (vacuum degree <0MP) for 20min, and then restored to normal pressure and allowed to stand for 10min. The above operation of placing under vacuum and standing under normal pressure is repeated 3 times to obtain a suspension. The suspension is centrifuged at 3000r / min for 15min, the precipitate is collected and washed twice with anhydrous ethanol, the solid precipitate is collected and dried at 40℃ for 24h to obtain PBA-IRMOF-3 / carvacrol.

[0076] A method for preparing the above-mentioned photoresponsive controlled-release active membrane: 0.4 g of PBA-IRMOF-3 / carvacrol was dissolved in 80 mL of water and dispersed. 2.5 g of sodium alginate was added, and water was added to make up to 95 mL to obtain a constant solution. The solution was stirred at 1000 r / min for 40 min at 50 °C to obtain mixed solution A. Plasticizer was added to mixed solution A at a volume ratio of 1:19, and stirring was continued for 40 min. After vacuuming for 30 min to remove air bubbles, film-forming base solution B was obtained. Film-forming base solution B was poured into a horizontal glass mold for casting and dried at 50 °C for 12 h to obtain sodium alginate-based photoresponsive controlled-release active membrane. The membrane was prepared at 0.080 mL / cm³. 2 Add a crosslinking agent to the active membrane prepared in step (3) and crosslink for 60s. Dry at 23°C for 12h at a relative humidity (RH) of 50%. Peel the dried membrane off the mold to obtain the sodium alginate-based photoresponsive controlled-release active membrane PMC@SA with added PBA-IRMOF-3 / carvacrol. The thickness of the active membrane is 55±5μm.

[0077] The active membrane PMC@SA is not treated with ultraviolet light irradiation.

[0078] The performance of the sodium alginate-based photoresponsive controlled-release active membrane with added PBA-IRMOF-3 / carvacrol in this embodiment is shown in Appendix Table 1 and Appendix Table 2. Figure 11 .

[0079] Example 3

[0080] The application of a carrier material with photoresponsive controlled-release function in bio-based active packaging, namely the preparation of a bio-based photoresponsive controlled-release active film, wherein the active film is prepared by adding sodium alginate as the main film-forming material, along with PBA-IRMOF-3 / carvacrol and a plasticizer, followed by casting, drying, and crosslinking to obtain a composite film; wherein PBA-IRMOF-3 / carvacrol is formed by loading carvacrol onto IRMOF-3. The sodium alginate is a natural polysaccharide sodium alginate; the plasticizer is glycerol; and the crosslinking agent used is a 5% (w / w) calcium chloride solution.

[0081] The preparation method of PBA-IRMOF-3 / carvacrol is as follows: PBA-IRMOF-3 is added to carvacrol at a mass-to-volume ratio of 0.1g:1mL, and dispersed at 40KHZ for 30min; then, it is placed under vacuum (vacuum degree <0MP) for 20min, and then restored to normal pressure and allowed to stand for 10min. The above operation of placing under vacuum and standing under normal pressure is repeated 3 times to obtain a suspension. The suspension is centrifuged at 3000r / min for 15min, the precipitate is collected and washed twice with anhydrous ethanol, the solid precipitate is collected and dried at 40℃ for 24h to obtain PBA-IRMOF-3 / carvacrol.

[0082] A method for preparing the above-mentioned photoresponsive controlled-release active membrane: 0.4 g of PBA-IRMOF-3 / carvacrol was dissolved in 80 mL of water and dispersed. 2.5 g of sodium alginate was added, and water was added to make up to 95 mL to obtain a constant solution. The solution was stirred at 1000 r / min for 40 min at 50 °C to obtain mixed solution A. Plasticizer was added to mixed solution A at a volume ratio of 1:19, and stirring was continued for 40 min. After vacuuming for 30 min to remove air bubbles, film-forming base solution B was obtained. Film-forming base solution B was poured into a horizontal glass mold for casting and dried at 50 °C for 12 h to obtain sodium alginate-based photoresponsive controlled-release active membrane. The membrane was prepared at 0.080 mL / cm³. 2 Add a crosslinking agent to the active membrane prepared in step (3) and crosslink for 60s. Dry at 23°C for 12h at a relative humidity (RH) of 50%. Peel the dried membrane off the mold to obtain the sodium alginate-based photoresponsive controlled-release active membrane PMC@SA with added PBA-IRMOF-3 / carvacrol. The thickness of the active membrane is 55±5μm.

[0083] The active film PMC@SA was irradiated with 40W ultraviolet light for 150s and named PMC@SA-UV.

[0084] The performance of the sodium alginate-based photoresponsive controlled-release active membrane with added PBA-IRMOF-3 / carvacrol in this embodiment after 40W UV irradiation for 150s is shown in Appendix Table 1 and Appendix 2. Figure 11 .

[0085] Comparative Example 1

[0086] A photoresponsive controlled-release carrier material, PBA-IRMOF-3, is prepared as follows: PBA and EDCl are ultrasonically dispersed in C2H2N to obtain an acetonitrile solution of 0.04 mmol / mL PBA and an acetonitrile solution of 0.048 mmol / mL EDCl. The mixture is stirred at 300 r / min for 40 min to obtain mixed solution A. HOBt is ultrasonically dispersed in C2H2N to obtain an acetonitrile solution of 0.034 mmol / mL HOBt, which is added to mixed solution A and stirred for another 60 min to obtain mixed solution B. IRMOF-3 is added to mixed solution B to obtain mixed suspension C, with an IRMOF-3 concentration of 5.33 mg / mL. The mixture is stirred at room temperature to obtain mixed suspension D. Mixed suspension D is centrifuged to obtain a precipitate, which is washed 6 times with C2H2N and then vacuum dried at 40℃ for 24 h to obtain PBA-IRMOF-3. The amino modification rate of PBA-IRMOF-3 is 28.57%.

[0087] Comparative Example 2

[0088] A photoresponsive controlled-release carrier material, PBA-IRMOF-3, is prepared as follows: PBA and EDCl are ultrasonically dispersed in C2H2N to obtain an acetonitrile solution of 0.12 mmol / mL PBA and an acetonitrile solution of 0.144 mmol / mL EDCl. The mixture is stirred at 300 r / min for 40 min to obtain mixed solution A. HOBt is ultrasonically dispersed in C2H2N to obtain an acetonitrile solution of 0.103 mmol / mL HOBt, which is added to mixed solution A and stirred for another 60 min to obtain mixed solution B. IRMOF-3 is added to mixed solution B to obtain mixed suspension C, with an IRMOF-3 concentration of 5.33 mg / mL. The mixture is stirred at room temperature to obtain mixed suspension D. Mixed suspension D is centrifuged to obtain a precipitate, which is washed 6 times with C2H2N and then vacuum dried at 40℃ for 24 h to obtain PBA-IRMOF-3. The amino modification rate of PBA-IRMOF-3 is 25.12%.

[0089] Comparative Example 3 (without PBA-IRMOF-3 / carvacrol)

[0090] The application of a carrier material with photoresponsive controlled-release function in bio-based active packaging, namely a bio-based photoresponsive controlled-release active membrane, is disclosed. Specifically, this involves the preparation of a sodium alginate-based composite membrane without the addition of PBA-IRMOF-3 / carvacrol. The composite membrane is prepared by crosslinking sodium alginate as the main film-forming material, adding a plasticizer, and then casting, drying, and crosslinking. The sodium alginate is a natural polysaccharide sodium alginate; the plasticizer is glycerol; and the crosslinking agent used is a 5% (w / w) calcium chloride solution.

[0091] A method for preparing the above-mentioned composite membrane: 2.5g of sodium alginate is added to 80mL of deionized water and brought to a final volume of 95mL to obtain a fixed volume solution. The solution is stirred at 1000r / min for 40min at 50℃ to obtain mixed solution A. Plasticizer is added to mixed solution A at a volume ratio of 1:19, and stirring continues for 40min. After vacuuming for 30min to remove air bubbles, film-forming base solution B is obtained. Film-forming base solution B is poured into a horizontal glass mold for casting and drying at 50℃ for 12h to obtain the sodium alginate composite membrane. The membrane is prepared at 0.080mL / cm². 2 Add a crosslinking agent to the sodium alginate-based composite membrane prepared in step (3) and crosslink for 60 seconds. Dry at 23°C for 12 hours at a relative humidity (RH) of 50%. Peel the dried membrane off the mold to obtain Pure SA sodium alginate composite membrane without IRMOF-3 / carvacrol. The thickness of the sodium alginate-based composite membrane is 55±5μm.

[0092] The performance of the sodium alginate-based composite membrane without PBA-IRMOF-3 / carvacrol in this comparative example is shown in Appendix 1 and Appendix 2. Figure 11 .

[0093] Comparative Example 4 (with added IRMof-3 / carvacrol)

[0094] The application of a carrier material with photoresponsive controlled-release function in bio-based active packaging, namely a bio-based photoresponsive controlled-release active membrane, is disclosed. Specifically, this involves the preparation of a sodium alginate-based active membrane with added IRMOF-3 / carvacrol. The active membrane is prepared by crosslinking sodium alginate as the main film-forming material, adding carvacrol and a plasticizer, followed by casting, drying, and crosslinking. The sodium alginate is a natural polysaccharide sodium alginate; the plasticizer is glycerol; and the crosslinking agent used is a 5% (w / w) calcium chloride solution.

[0095] The preparation method of IRMOF-3 / carvacrol is as follows: IRMOF-3 is added to carvacrol at a mass-to-volume ratio of 0.1 g: 1 mL, and dispersed at 40 kHz for 30 min. Then, it is placed under vacuum (vacuum degree < 0 MPa) for 20 min, and then restored to normal pressure and allowed to stand for 10 min. The above operation of placing under vacuum and standing under normal pressure is repeated 3 times to obtain a suspension. The suspension is centrifuged at 3000 r / min for 15 min, the precipitate is collected and washed twice with anhydrous ethanol, the solid precipitate is collected and dried at 40 ℃ for 24 h to obtain IRMOF-3 / carvacrol.

[0096] A method for preparing the above-mentioned active membrane: 2.5g of sodium alginate and 400mg of IRMOF-3 / carvacrol are added to 80mL of deionized water and the volume is adjusted to 95mL to obtain a fixed volume solution. The solution is stirred at 1000r / min for 40min at 50℃ to obtain mixed solution A. Plasticizer is added to mixed solution A at a volume ratio of 1:19, and stirring is continued for 40min. After vacuuming for 30min to remove air bubbles, film-forming base solution B is obtained. Film-forming base solution B is poured into a horizontal glass mold for casting and drying at 50℃ for 12h to obtain the sodium alginate composite membrane. The membrane is prepared at 0.080mL / cm². 2 Add a crosslinking agent to the sodium alginate-based composite membrane prepared in step (3) and crosslink for 60 seconds. Dry at 23°C for 12 hours at a relative humidity (RH) of 50%. Peel the dried membrane off the mold to obtain the sodium alginate-based active membrane MC2@SA with added IRMOF-3 / carvacrol. The thickness of the sodium alginate-based active membrane is 55±5μm.

[0097] The performance of the sodium alginate-based active membrane with added IRMOF-3 / carvacrol in this comparative example is shown in Appendix 1 and Appendix 2. Figure 11 .

[0098] Test example:

[0099] (1) Test of PBA-IRMOF-3 modification rate:

[0100] The effect of different reactant ratios on the modification rate of PBA-IRMOF-3 was compared.

[0101] Experimental groups S1-S3: Azobenzene-4-benzoic acid (PBA) and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCl) were ultrasonically dispersed in acetonitrile (C2H2N) to obtain an acetonitrile solution of 0.08 mmol / mL PBA and an acetonitrile solution of 0.096 mmol / mL EDCl. The mixture was stirred at 300 rpm for 40 min with a magnetic stirrer to obtain mixed solution A. 1-hydroxybenzotriazole (HOBt) was ultrasonically dispersed in C2H2N to obtain an acetonitrile solution of 0.069 mmol / mL HOBt, which was added to mixed solution A and the mixture was stirred for another 60 min to obtain mixed solution B. IRMof-3 was added to mixed solution B to obtain mixed suspension C (the concentration of IRMof-3 at 2.67 mg / mL was designated S1; the concentration at 5.33 mg / mL was designated S2; and the concentration at 8.00 mg / mL was designated S3). The mixture was stirred at room temperature to obtain mixed suspension D. Mixed suspension D was centrifuged to obtain a precipitate, which was washed six times with C2H2N and then dried under vacuum at 40℃ for 24 h to obtain PBA-IRMOF-3.

[0102] Testing: Since PBA-IRMOF-3 is poorly soluble in a single solvent, the sample was digested and appropriately diluted using a digestion solution (5 mL DMSO + 0.35 mL HCl + 0.65 mL H2O). The absorption curves of the solution in the range of 200–800 nm were measured using a Shimadzu UV-1800 UV / Vis spectrophotometer to obtain UV / Vis spectra and analyze the positions of characteristic peaks for different samples.

[0103] PBA Standard Curve Construction: A series of PBA solutions of different concentrations were prepared, and the absorbance of PBA solutions of different concentrations at 440 nm was measured using a UV / Vis spectrophotometer, with the digestion solution as a blank reference. Based on the obtained data, a PBA standard curve was plotted with PBA solution concentration as the x-axis and absorbance value as the y-axis. Within the range of 0.08–0.32 mg / mL, the fitted linear regression equation was y = 3.01036x + 0.00489 (R²). 2 =0.9994).

[0104] Calculation of the functional group modification rate of IRMOF-3: After digestion, the PBA-IRMOF-3 sample was diluted to an appropriate concentration, and the absorbance value at 440 nm was measured. The absorbance value was then substituted into the PBA standard curve to calculate the PBA content in the PBA-IRMOF-3 sample, thereby estimating the functional group modification rate in PBA-IRMOF-3. The amino modification rates of PBA-IRMOF-3 in experimental groups S1-3 were 28.65%, 33.33%, and 25.12%, respectively. It can be seen that the relative concentration of IRMOF-3 and reactants affects the amino modification rate of PBA-IRMOF-3 during the preparation of PBA-IRMOF-3.

[0105] (2) Photoresponse performance test of PBA-IRMOF-3:

[0106] 1) Photoresponse performance of PBA-IRMOF-3

[0107] PBA-IRMOF-3 was dispersed in anhydrous ethanol and subjected to UV irradiation under 40W ultraviolet light. The UV / Vis spectra of the test samples were scanned at 0, 60, and 120 s of irradiation. The samples that had been UV irradiated for 120 s were then subjected to Vis irradiation, and the UV / Vis spectra of the test samples were scanned at 10 min and 60 min.

[0108] Figure 4 In the study, after PBA-IRMOF-3 was treated with UV and Vis irradiation for different durations, the absorption peak at 323 nm significantly weakened with increasing UV irradiation time, while the absorption at 440 nm strengthened. This indicates that the azophenyl group on PBA-IRMOF-3 gradually underwent trans-cis structural isomerization under UV irradiation, i.e., a "UV-responsive" effect. When PBA-IRMOF-3 treated with UV irradiation for 120 s was further irradiated with Vis for 10 min and 60 min, the characteristic absorption peak at 325 nm gradually strengthened again, while the absorption peak at 440 nm weakened. This indicates that PBA-IRMOF-3 underwent cis-trans structural isomerization again under Vis irradiation after UV irradiation, i.e., a "cis-trans relaxation" effect. This demonstrates that PBA-IRMOF-3 can achieve structural isomerization under alternating UV and Vis irradiation treatments, exhibiting "photoresponsive" characteristics.

[0109] 2) UV response performance of PBA-IRMOF-3 under different power UV irradiation

[0110] PBA-IRMOF-3 was dispersed in anhydrous ethanol, and the samples were subjected to UV irradiation at 8, 24, and 40 W. The UV absorbance at 323 nm was measured at irradiation times of 0, 15, 30, 45, 60, 90, 120, 150, 180, 210, 240, 300, 360, 420, 480, 540, and 600 s. As the UV irradiation time increased, the absorbance gradually decreased and then stabilized. The UV irradiation time corresponding to the point where the absorbance no longer decreased significantly was defined as the "complete response time" of the sample under different power UV irradiation conditions.

[0111] Figure 5 In this study, PBA-IRMOF-3 samples were irradiated with 365nm ultraviolet light of different powers (8, 24, and 40W) for different durations, and the absorbance at 323nm showed different changes. Under the same UV irradiation power, the absorbance at 323nm gradually decreased with increasing irradiation time, indicating that the azophenyl group of PBA-IRMOF-3 exhibits a "UV light response" under UV irradiation. After a certain period of UV irradiation, the absorbance at 323nm of PBA-IRMOF-3 began to stabilize, indicating that the azophenyl group had completely converted from the trans structure to the cis structure, exhibiting a "complete response." This UV irradiation time is referred to as the "complete response time" of PBA-IRMOF-3 at this irradiation power. Based on the absorbance values ​​in the figure, it can be seen that when the UV irradiation power is 8, 24, and 40 W, the "complete response time" of PBA-IRMOF-3 is 480, 150, and 90 s, respectively. It was found that increasing the UV irradiation power can shorten the "complete response time". The UV irradiation power affects the "ultraviolet light response" rate of PBA-IRMOF-3, that is, it affects the trans-cis isomerization rate of the azophenyl group in PBA-IRMOF-3.

[0112] 3) Analysis of the "cis-reverse relaxation" performance of PBA-IRMOF-3

[0113] PBA-IRMOF-3 was dispersed in anhydrous ethanol and irradiated under 40W UV light for 90s to obtain PBA-IRMOF-3 with cis-structured azophenyl groups. The samples were then divided into three aliquots and placed in shaking incubators at 4, 25, and 50℃, respectively, with UV irradiation performed. The absorbance at 323nm was measured at irradiation times of 0, 10, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 360, 420, 480, 540, and 600 min. With increasing UV irradiation time, the absorbance gradually increased and then stabilized. The time corresponding to the point where the absorbance no longer increased significantly was defined as the "complete relaxation time" of the sample under different temperature conditions.

[0114] Figure 6 In this study, cis-PBA-IRMOF-3 samples obtained after UV treatment were subjected to Vis irradiation at 4, 25, and 50 °C. The absorbance at 323 nm of the PBA-IRMOF-3 samples changed differently at different temperatures under Vis irradiation. At the same temperature, the absorbance at 323 nm gradually increased with prolonged Vis irradiation time, indicating that the azophenyl group on PBA-IRMOF-3 underwent "cis-trans relaxation" under Vis irradiation. After a certain period of Vis irradiation, the absorbance at 323 nm of PBA-IRMOF-3 began to stabilize, indicating that the azophenyl group had completely converted from the cis structure to the trans structure. This Vis irradiation time was termed the "complete relaxation time" of PBA-IRMOF-3 at that temperature. Based on the absorbance changes, the "complete relaxation times" of PBA-IRMOF-3 under Vis irradiation at 4, 25, and 50 °C were 480, 210, and 90 min, respectively. The "complete relaxation time" of PBA-IRMOF-3 is temperature-dependent, with a longer "complete relaxation time" at lower temperatures. Increasing the temperature can accelerate the relaxation rate of the azophenyl group.

[0115] Comprehensive analysis of the UV response and cis-trans relaxation properties of PBA-IRMOF-3 revealed that its complete response time is significantly shorter than its complete relaxation time. Under UV irradiation of a certain power, the azophenyl group on PBA-IRMOF-3 rapidly undergoes a transformation from a trans to a cis configuration. During subsequent storage under UV exposure, the azophenyl group gradually reverts from the cis to the trans configuration, indicating that PBA-IRMOF-3 can undergo structural isomerization under alternating UV and UV irradiation, exhibiting photoresponsive characteristics.

[0116] (3) Photoresponsive controlled-release performance test of PBA-IRMOF-3 / carvacrol:

[0117] Construction of the CA standard curve: A series of anhydrous ethanol solutions of CA were prepared, and the absorbance of the anhydrous ethanol solutions with different CA concentrations at a wavelength of 276 nm was measured using a UV-1800 ultraviolet spectrophotometer, with anhydrous ethanol as a blank reference. Based on the obtained data, a standard curve of CA was plotted with CA concentration on the x-axis and absorbance value on the y-axis. Within the range of 0.01–0.08 μL / mL, the fitted linear regression equation was y = 15.02545x + 0.00916(R²). 2 =0.9998).

[0118] 100 mg of PBA-IRMOF-3 / CA sample was weighed and dispersed into sealed transparent glass bottles containing 50 mL of anhydrous ethanol. At the start of the release experiment, Group A received no treatment; Group B was irradiated under 365 nm, 40 W UV light for 90 s; and Group C received no treatment. All samples were placed in a shaking incubator at 25 °C and 200 rpm, and the illumination was turned on for UV irradiation to begin the release experiment. At 0, 2, 4, 6, 8, and 10 h, the glass bottles were shaken to homogenize the mixture, and a certain amount of the mixture was aspirated. After sampling at 10 h, Group C samples were irradiated under 365 nm, 40 W UV light for 90 s, and then placed in the shaking incubator to continue the release experiment. At 12, 14, 16, 18, 20, 22, and 24 h, the glass bottles were shaken to homogenize the mixture, and a certain amount of the mixture was aspirated. The extracted mixed solutions were centrifuged, and the supernatant was diluted before its UV absorbance at 276 nm was measured. Three parallel samples were prepared for each group. The arithmetic mean of the UV absorbance values ​​of each group was substituted into the regression equation of the CA standard curve to calculate the final CA release amount. Then, a CA release rate curve was plotted with release time (h) on the x-axis and the ratio of CA release amount to the theoretical total amount (CA loading) at different times (CA release rate, %) on the y-axis.

[0119] Figure 7In the study, the untreated sample exhibited continuous CA release. Upon initial UV irradiation, the sample underwent CA release. Initially, the release rate of the irradiated sample was higher than that of the untreated sample, then leveled off. After UV irradiation, the azophenyl group on PBA-IRMOF-3 underwent "UV light response," i.e., a trans-to-cis structural isomerization. During subsequent storage, the azophenyl group underwent "cis-trans relaxation," gradually reverting from the cis to the trans structure. During this process, the azophenyl group acted as a "stirring wheel," promoting CA release from PBA-IRMOF-3. After a period of time, the azophenyl group underwent "complete relaxation," i.e., completely reverting from the cis to the trans structure. After this, the "stirring wheel" effect disappeared, and CA release began to slow down relatively. Ten hours after the start of release, UV irradiation of the sample resulted in a sudden increase in the CA release rate, which then gradually leveled off. This was also a result of the "UV light response" and "cis-trans relaxation" of the azophenyl group. The results show that the PBA-IRMOF-3 / CA system has the potential for photoresponsive controlled release, and can achieve the regulated release of CA under ultraviolet light stimulation. Figure 8 This is a schematic diagram illustrating the photoresponse-controlled release of the PBA-IRMOF-3 / CA system.

[0120] (4) Test of the photoresponsive controlled-release performance of the photoresponsive controlled-release active membrane:

[0121] 1) Determination of the "complete response time" of the photoresponsive membrane

[0122] The prepared PMC@SA film samples were cut into 5cm × 5cm samples and placed in sealed transparent glass bottles containing 100mL of anhydrous ethanol. They were then subjected to UV irradiation at 365nm, 40W for 0, 30, 60, 90, 120, 150, 180, 210, 240, 270, and 300s, respectively. Afterward, all samples were placed in a 25℃ shaking incubator with illumination turned on for UV irradiation. After 24 hours, the supernatant was collected, diluted with anhydrous ethanol, and the absorbance at 276nm was measured. Three parallel samples were set up for each sample. The arithmetic mean of the UV absorbance values ​​was substituted into the regression equation of the CA standard curve obtained in Section 2.3.7 to calculate the final CA release rate. The UV irradiation time corresponding to the experimental group where the CA release rate no longer changed significantly within 24 hours with the extension of UV irradiation time was defined as the "complete response time" of the photoresponsive controlled-release active membrane.

[0123] Figure 9In the study, compared with the untreated active membrane, the CA release rate of the UV-irradiated active membrane increased within 24 hours, and the release initially increased and then stabilized with prolonged treatment time. Different UV irradiation times caused the azophenyl groups of the PBA-IRMOF-3 / CA added to the membrane to undergo varying degrees of "UV light response," i.e., varying degrees of trans-to-cis isomerization. In the subsequent 24-hour release experiment, the azophenyl groups underwent varying degrees of "cis-trans relaxation," which increased the CA release rate of the active membrane to varying degrees. After the UV irradiation time was extended beyond 150 seconds, the CA release rate no longer increased significantly. It can be inferred that when the photoresponsive active membrane was irradiated with UV light for 150 seconds, the azophenyl groups on PBA-IRMOF-3 in the active membrane had already undergone maximum trans-to-cis isomerization, and further extending the UV irradiation time would not significantly change the degree of isomerization. Therefore, the "complete response time" of the prepared photoresponsive controlled-release active membrane under "40W, 365nm" UV irradiation is about 150s. The "40W, 365nm, 150s" UV irradiation conditions can be used as the response stimulus conditions for the photoresponsive controlled-release active membrane PMC@SA for the controlled release of CA.

[0124] 2) Study on the release behavior of CA in photoresponsive membranes

[0125] The PMC@SA film samples were cut into 5cm×5cm pieces and placed in sealed transparent glass bottles containing 100mL of anhydrous ethanol. At the start of the release experiment, Group A: no treatment was given; Group B: irradiated with "365nm, 40W" UV for 150s (the "complete response time" determined in 6.2.3.6(1)); Group C: no treatment was given. All samples were placed in a shaking incubator at 25℃ and 200rpm, and the illumination was turned on for Vis irradiation treatment to start the release experiment. The supernatant was collected at 0, 2, 4, 6, 8, and 10h. After the sampling test was completed at 10h, the samples of Group C were treated with "365nm, 40W" UV irradiation for 150s, and then placed in a shaking incubator to continue the release experiment. The supernatant was collected at 12, 14, 16, 18, 20, 22, and 24h. After each sampling, an equal volume of anhydrous ethanol was added to maintain a constant volume. The supernatant was diluted with anhydrous ethanol, and the absorbance at 276 nm was measured. Three parallel samples were set up for each sample. The arithmetic mean of the UV absorbance values ​​was substituted into the regression equation of the CA standard curve to calibrate the obtained concentration. After eliminating the influence of sampling on the concentration, the final CA release amount was calculated. Then, a CA release rate curve was plotted with release time (h) as the x-axis and the ratio of CA release amount at different times to the theoretical total amount (CA content in the membrane) (CA release rate, %) as the y-axis.

[0126] Figure 10 In the study, the active membrane without UV irradiation exhibited continuous CA release. When the active membrane was irradiated with UV at the beginning of the release experiment, the CA release behavior of the UV-irradiated active membrane was similar to that of the unirradiated membrane throughout the entire release experiment. However, the CA release of the UV-irradiated active membrane accelerated after irradiation and then gradually slowed down. When the active membrane was irradiated with UV at the 10th hour after the start of the release experiment, the CA release rate suddenly accelerated after the 10th hour and then gradually slowed down. These results are similar to the CA release behavior of PBA-IRMOF-3 / CA after UV irradiation, which is a result of the isomerization of the azophenyl group of PBA-IRMOF-3, indicating that the prepared photoresponsive controlled-release active membrane can achieve controlled CA release under certain UV light stimulation conditions.

[0127] (5) Composite membrane performance testing:

[0128] The composite films prepared in Examples 1-2 and Comparative Examples 1-2 were subjected to mechanical and physical property tests. The tensile strength and elongation at break of the film samples were measured using a computer-controlled electronic universal testing machine (E43-104). The water vapor transmission rate was determined by gravimetric analysis, and the water contact angle of the film surface was measured using a WCA analyzer (POWEREACH, JC2000C). The transmittance of different films was measured using a UV-Vis spectrophotometer in the wavelength range of 200–800 nm. The test results are shown in Table 1 and [Table data missing]. Figure 11 As shown.

[0129] Table 1 Physical property values ​​of different thin films

[0130]

[0131] Note: Different lowercase letters in the same column indicate significant differences (p<0.05).

[0132] Table 1 shows that the photoresponsive controlled-release active membrane with added PBA-IRMOF-3 / carvacrol exhibits more significant water vapor barrier and hydrophobic properties. Furthermore, while pure sodium alginate membranes have high light transmittance, the photoresponsive controlled-release active membrane with added PBA-IRMOF-3 / carvacrol has almost zero light transmittance in the 250–380 nm wavelength range, demonstrating excellent light barrier properties. Figure 11 ).

[0133] The photoresponsive controlled-release carrier material PBA-IRMOF-3 prepared in this invention can achieve reversible cis-trans structural changes under alternating UV and Vis irradiation. Under UV irradiation, a "UV photoresponse" occurs, i.e., the azophenyl group undergoes trans-cis isomerization; under Vis irradiation, a "cis-trans relaxation" occurs, i.e., the azophenyl group undergoes cis-trans isomerization. Furthermore, the UV irradiation power affects the "UV photoresponse" rate of PBA-IRMOF-3. When the UV irradiation power is 8, 24, and 40 W, the "complete response time" of PBA-IRMOF-3 is 480, 150, and 90 s, respectively. Increasing the UV irradiation power can shorten the "complete response time." Temperature affects the cis-trans relaxation properties of PBA-IRMOF-3 under Vis irradiation. Under Vis irradiation at 4, 25, and 50 °C, the complete relaxation time of PBA-IRMOF-3 is 480, 210, and 90 min, respectively. Increasing the temperature shortens the complete relaxation time. PBA-IRMOF-3, a carrier material with photoresponsive controlled release function, can be loaded with carvacrol. Alternating UV and Vis irradiation induces structural isomerization of the azophenyl group. During this process, the azophenyl group acts as a "stirring wheel," accelerating the release of carvacrol, thus achieving photoresponsive controlled release of carvacrol. In bio-based active packaging applications, PBA-IRMOF-3 can be used to prepare sodium alginate-based photoresponsive controlled release active films containing PBA-IRMOF-3 / carvacrol. Due to the photoresponsive controlled release performance of PBA-IRMOF-3 for carvacrol, the active film exhibits similar regulated release properties. Furthermore, the main raw materials and additives used in the preparation of the active film are all non-toxic, harmless, and biodegradable materials. Sodium alginate is widely available and inexpensive, the metal-organic framework material IRMof-3 derivative PBA-IRMOF-3 exhibits good biodegradability and biocompatibility, and carvacrol is harmless to humans and the environment. Therefore, the prepared composite film is an environmentally friendly material. The production method of this invention is safe, the process is simple, and the production cost is low, making it widely applicable in the market with promising prospects.

[0134] 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 carrier material with photoresponsive controlled release function, characterized in that, It includes the following PBA-IRMOF-3 structure: PBA is azobenzene-4-benzoic acid with an azobenzene photoisomerization group, and PBA-IRMOF-3 is formed by modifying the amino group of IRMOF-3 with PBA.

2. The carrier material with photoresponsive controlled release function according to claim 1, characterized in that, Where UV stands for ultraviolet light, and Vis / heat stands for visible light / heating.

3. The carrier material with photoresponsive controlled release function according to claim 1, characterized in that, It is prepared from the following components: isomorphous metal-organic framework material-3 (IRMOF-3), azobenzene-4-benzoic acid (PBA), 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCl), 1-hydroxybenzotriazole (HOBt), and acetonitrile (C2H3N).

4. The carrier material with photoresponsive controlled release function according to any one of claims 1-3, characterized in that, The photoisomerization group modification rate of PBA-IRMOF-3 ranged from 25.12% to 33.33%.

5. A method for preparing a carrier material with photoresponsive controlled release function as described in any one of claims 1 to 4, characterized in that, Includes the following steps: (1) PBA and EDCl were ultrasonically dispersed in C2H3N and stirred with a magnetic stirrer to obtain mixed solution A; (2) Disperse HOBt in C2H3N by ultrasonication, add it to mixed solution A and continue stirring to obtain mixed solution B; (3) Add IRMOF-3 to mixed solution B to obtain mixed suspension C, and stir at room temperature to obtain mixed suspension D; (4) Centrifuge the mixed suspension D to obtain the precipitate, wash it several times with C2H3N and then vacuum dry it to obtain PBA-IRMOF-3; In step (1), the concentration of PBA is 0.04–0.12 mmol / mL; the concentration of EDCl is 0.048–0.144 mmol / mL; In step (2), the concentration of HOBt is 0.034–0.103 mmol / mL; In step (3), the concentration of IRMOF-3 in the mixed suspension C is 2.67 to 8.00 mg / mL.

6. The preparation method according to claim 5, characterized in that, In step (1), the magnetic stirring speed is 200-400 r / min; the magnetic stirring time is 30-50 min.

7. The preparation method according to claim 5, characterized in that, In step (2), the magnetic stirring speed is 200-400 r / min; the magnetic stirring time is 40-80 min.

8. The preparation method according to claim 5, characterized in that, In step (3), the magnetic stirring speed is 200-400 r / min; the magnetic stirring time is 12-36 h.

9. The preparation method according to claim 5, characterized in that, In step (4), the precipitate is washed with C2H3N 5 to 8 times; the vacuum drying temperature is 30 to 50°C; and the vacuum drying time is 12 to 36 hours.

10. The application of the carrier material with photoresponsive controlled release function as described in any one of claims 1-4 or the carrier material with photoresponsive controlled release function prepared by the preparation method described in any one of claims 5-9 in bio-based active packaging films, characterized in that, The specific preparation method is as follows: PBA-IRMOF-3 / carvacrol is dissolved and dispersed in water, then added to the bio-based material, and water is added to make up to a constant volume to obtain a constant solution. The bio-based material is sodium alginate, a natural polysaccharide. The PBA-IRMOF-3 / carvacrol is formed by loading carvacrol onto PBA-IRMOF-3. The mass ratio of PBA-IRMOF-3 / carvacrol to sodium alginate in the constant solution is 0.2-1.0:2.5, and the mass concentration of PBA-IRMOF-3 / carvacrol in the constant solution is 2.10-10.53 mg / mL. A mixed solution A is obtained by hot stirring; a plasticizer, glycerol, is added to mixed solution A and stirring continues. The volume ratio of the plasticizer to mixed solution A is 1:

19. After vacuuming, a film-forming base solution B is obtained. The film-forming base solution B is poured into a mold, cast into a film, and dried at 30–60°C for 10–12 h to obtain a sodium alginate-based photoresponsive controlled-release active film. A crosslinking agent is added to the prepared photoresponsive controlled-release active film for crosslinking for 50–70 s. The crosslinking agent used is a 5 wt% calcium chloride solution, and the amount of the crosslinking agent is 0.080–0.112 mL / cm³. 2 The sodium alginate-based photoresponsive controlled-release active packaging film with added PBA-IRMOF-3 / carvacrol was dried for 10-12 hours at a relative humidity of 50%-60% and a temperature of 21-25℃ to obtain the film.

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