Carrier material with photoresponse controlled release function, preparation method of carrier material and application of carrier material in bio-based active packaging

Abstract

The invention discloses a carrier material with a photoresponse controlled release function, a preparation method of the carrier material and application of the carrier material in bio-based active packaging. According to the carrier material with the photoresponse controlled release function, an equal-net-shaped metal organic framework material-3 (IRMOF-3) is used as a matrix, and a photoisomerization group azobenzene is modified on the IRMOF-3 through functional modification, so that the carrier material with the photoresponse controlled release function is obtained; the carrier material is used for loading carvacrol and then is added into a sodium alginate-based film to prepare the bio-based active packaging film with photoresponse carvacrol release control performance, and meanwhile, the prepared packaging film has good tensile property, hydrophobic property and barrier property.

Description

Technical Field

[0001] The present invention relates to the field of active packaging controlled release technology, and in particular to a carrier material with light-responsive controlled release function, a preparation method thereof, and application thereof in bio-based active packaging. Background Art

[0002] The concept of controlled-release packaging was first proposed by Lacoste et al. in 2005. Packaging is used as a delivery system for active substances to control their diffusion or release rate in order to prolong the duration of action of the active substances. In the early research and development of controlled-release packaging, its essence was mostly sustained release, which slowed down the diffusion or release rate of active substances to varying degrees, but 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 pointed out that smart controlled-release packaging is a packaging that relies on stimulus-responsive materials (contraction, expansion, dissolution, chemical functional changes or self-assembly) to trigger the release of active compounds. The stimulus can be the characteristics of the headspace inside the package or food (such as pH, water activity, gas composition, microorganisms and contaminants) or storage conditions (such as temperature, relative humidity, light), etc. 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 a nanocellulose-reinforced pectin aerogel with moisture as the stimulus source. The aerogel can quickly absorb moisture in the package, resulting in the expansion of pores and the decomposition of some structures, allowing the loaded thymol to be released. Heras-Mozos et al. prepared a chitosan-based film containing imine bonds for packaging blackberries. Acidic conditions were formed in the headspace microenvironment under the respiration of blackberries, stimulating the hydrolysis of imine bonds and releasing antimicrobial volatiles. For the above stimulus-responsive packaging, it is difficult to precisely control the amount of water absorbed by the material and the range of changes in the pH value of the headspace microenvironment. Therefore, it is difficult to accurately grasp the degree of stimulation of similar stimulus sources. However, as a non-contact stimulus, light can be precisely set in terms of intensity, wavelength, duration and other parameters based on existing technology and means. It has good properties in time and space that other stimuli do not have, and is an ideal clean stimulus source. At present, light stimulus-responsive 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, in the field of food active packaging, there are few reports on light-responsive stimulus materials.

[0004] Photostimulation response allows the controlled release of active substances that are shielded in the carrier material by irradiation with different light sources. Ultraviolet radiation is widely used to initiate the release process by inducing degradation of the carrier or structural changes. The configuration change of the double bond structure of azobenzene materials during the photoresponse process has the advantages of low energy barrier, low energy consumption, no emission, and good repeatability. Due to the presence of the N=N double bond, azobenzene has two configurations, trans and cis. Under the irradiation of ultraviolet light, azobenzene molecules can quickly transform from trans to cis, with fast photoisomerization speed and high photoisomerization efficiency; the trans structure of the azobenzene group is more stable. Under the thermal effect or irradiation of visible light, it can be converted from cis to trans, and this photoinduced cis-trans isomerization has very good reversibility. During the molecular configuration conversion process, the difference in the properties of the material is reflected in the changes in molecular size, UV-visible absorption spectrum, refractive index, etc. Due to the unique photoisomerization properties of azobenzene, azobenzene materials have wide applications in light-controlled actuators, solar thermal fuels and drug sustained release, but there are few reports in the field of food active packaging.

[0005] In recent years, post-synthetic functional modification of MOFs, which are excellent carrier materials, has become an important means to develop and expand the unique properties of MOFs. In 2011, Stock et al. modified azobenzene molecules onto the side chains of the MOFs skeleton for the first time and constructed a photoresponsive MOF material based on azobenzene molecules. The presence of free amino groups on the organic ligands of IRMOF-3 provides it with base sites, making it possible to modify it after functionalization. Through the functional modification of IRMOF-3, the properties of IRMOF-3 can be designed or improved. In the post-synthetic modification reaction of IRMOF-3, the amidation reaction of carboxylic acids, acid anhydrides, etc. with amino groups is a common reaction type. Liu modified lactic acid onto IRMOF-3 through the condensation reaction of the amino groups in the IRMOF-3 skeleton and the carboxyl groups of lactic acid to modify it for anchoring Au. 3+ Thus, it can be used as a catalyst; Yang Baochun used folic acid to functionally modify IRMOF-3 and used it as a carrier of anti-tumor drugs, taking advantage of the tumor cell targeting properties of folic acid to achieve targeted transport of anti-tumor drugs; this provides a reference for the functional modification of IRMOF-3. Summary of the invention

[0006] In view of the deficiencies of the prior art, the present invention provides a carrier material with a photoresponsive controlled release function, a preparation method thereof, and an application thereof in bio-based active packaging. The present invention modifies IRMOF-3 with a photoisomerizable group azobenzene through functional modification to obtain a carrier material with a photoresponsive controlled release function; the carrier material is loaded with carvacrol and then added to a sodium alginate-based film to prepare a bio-based active packaging film with a photoresponsive controlled carvacrol release performance, and the prepared packaging film has good tensile properties, hydrophobic properties, and barrier properties.

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

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

[0009]

[0010] Among them, 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 having the light-responsive controlled release function is characterized in that:

[0012]

[0013] Among them, UV is ultraviolet light, and Vis / heat is visible light / heat.

[0014] Furthermore, the carrier material with light-responsive controlled release function is characterized in that it is prepared from the following components: isoreticular 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 light-responsive controlled release function is characterized by comprising the following steps:

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

[0017] (2) HOBt was ultrasonically dispersed in C2H2N, added to mixed solution A and continued to stir to obtain mixed solution B.

[0018] (3) IRMOF-3 was added to the mixed solution B to obtain a mixed suspension C, and the mixed suspension D was obtained by stirring at room temperature.

[0019] (4) The mixed suspension D was centrifuged to obtain a precipitate, which was washed several times with C2H2N and then vacuum dried to obtain PBA-IRMOF-3.

[0020] Furthermore, 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; the magnetic stirring speed is 200-400 r / min; and the magnetic stirring time is 30-50 min.

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

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

[0023] Furthermore, 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] An application of the above-mentioned carrier material with light-responsive controlled-release function in bio-based active packaging, that is, the preparation of a bio-based light-responsive controlled-release active film, characterized in that the specific preparation method is as follows: PBA-IRMOF-3 / carvacrol is dissolved in water and dispersed, then added to the bio-based material, and water is added to the fixed volume to obtain a fixed solution, the bio-based material is a natural polysaccharide sodium alginate, the PBA-IRMOF-3 / carvacrol is formed by loading carvacrol on 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, and the PBA-IRMOF-3 in the fixed solution is 0.2-1.0:2.5. / The mass concentration of carvacrol is 2.10-10.53 mg / mL, and a mixed solution A is obtained by heating and stirring; a plasticizer is added to the mixed solution A and continued to be stirred, wherein the plasticizer is glycerol, and the volume ratio of the plasticizer to the mixed solution A is 1:19, and a film-forming base liquid B is obtained after vacuuming; the film-forming base liquid B is poured into a mold, cast into a film, and dried at a temperature of 30-60°C for 10-12h to obtain a sodium alginate-based light-responsive controlled-release active film; a cross-linking agent is added to the prepared light-responsive controlled-release active film for cross-linking for 50-70s; the cross-linking agent used for the cross-linking is a 5wt% calcium chloride solution, and the amount of the cross-linking agent is 0.080-0.112mL / cm 2 ; Drying for 10 to 12 hours at a relative humidity of 50% to 60% and a temperature of 21 to 25°C to obtain a sodium alginate-based light-responsive controlled-release active packaging film with added PBA-IRMOF-3 / carvacrol.

[0026] The beneficial technical effects of the present invention are:

[0027] (1) The amino modification rate of the carrier material PBA-IRMOF-3 with light-responsive controlled release function prepared by the present invention is 25.12% to 33.33%, achieving the successful modification of azobenzene photosensitizing groups on IRMOF-3.

[0028] (2) The photosensitive group of the carrier material PBA-IRMOF-3 with light-responsive controlled release function prepared by the present invention realizes reversible changes in cis- and trans-structures under alternating treatment of UV and Vis irradiation.

[0029] (3) The PBA-IRMOF-3 / carvacrol prepared in the present invention has the performance of light-responsively controlling the release of carvacrol.

[0030] (4) The sodium alginate-based active film with added PBA-IRMOF-3 / carvacrol prepared by the present invention has the performance of light-responsively controlling the release of carvacrol.

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

[0032] (6) By adding PBA-IRMOF-3 / carvacrol, the tensile strength of the present 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 with different thicknesses and mechanical properties as needed; the sodium alginate-based photoresponsive controlled-release active film with added PBA-IRMOF-3 / carvacrol has the performance of photoresponsively controlling the release of carvacrol, can be used as responsive controlled-release packaging, is suitable for the packaging of foods such as fresh meat, and can control the release of active substances in the packaging according to changes in food quality, thereby effectively extending the shelf life of the food. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the Fourier transform infrared spectrum of PBA-IRMOF-3 prepared in Example 1 of the present invention.

[0035] Figure 2 This is the X-ray photoelectron spectrum of PBA-IRMOF-3 prepared in Example 1 of the present invention.

[0036] Figure 3 This is the nuclear magnetic resonance spectrum of PBA-IRMOF-3 prepared in Example 1 of the present invention.

[0037] Figure 4 UV / Vis spectra of PBA-IRMOF-3 prepared in Example 1 of the present 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 changes with irradiation time under UV irradiation of different powers.

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

[0040] Figure 7 This is the light-responsive controlled release curve of PBA-IRMOF-3 / carvacrol prepared in Example 2 of the present invention.

[0041] Figure 8 Schematic diagram of the light-responsive controlled release principle of PBA-IRMOF-3 / carvacrol prepared in Example 2 of the present invention.

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

[0043] Fig.10 This is the photoresponsive controlled release curve of the photoresponsive controlled release active film prepared in Example 3 of the present invention.

[0044] Fig.11 It is a light transmittance curve diagram of the composite films prepared in Examples 2-3 of the present invention and Comparative Examples 3-4. DETAILED DESCRIPTION

[0045] The following is a further detailed description of the claims of the present invention in conjunction with the accompanying drawings and embodiments, but does not constitute any limitation to the present invention. Any limited modifications made within the scope of protection of the claims of the present invention are still within the scope of protection of the claims of the present invention.

[0046] The present invention aims to obtain a carrier material PBA-IRMOF-3 with light-responsive controlled-release function by functionally modifying the prepared IRMOF-3, encapsulating the plant essential oil carvacrol and then adding it to the bio-based degradable material sodium alginate, thereby protecting the active ingredients from degradation under adverse environmental conditions and achieving controlled release thereof, thereby developing an active packaging film with light-responsive controlled-release performance.

[0047] First, a preparation method of the above-mentioned carrier material PBA-IRMOF-3 with light-responsive controlled release function is provided, comprising the following steps:

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

[0049] (2) HOBt was ultrasonically dispersed in C2H2N, added to mixed solution A and continued to stir to obtain mixed solution B.

[0050] (3) IRMOF-3 was added to the mixed solution B to obtain a mixed suspension C, and the mixed suspension D was obtained by stirring at room temperature.

[0051] (4) The mixed suspension D was centrifuged to obtain a precipitate, which was washed several times with C2H2N and then vacuum dried to obtain PBA-IRMOF-3.

[0052] Furthermore, 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; the magnetic stirring speed is 200-400 r / min; and the magnetic stirring time is 30-50 min.

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

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

[0055] Furthermore, 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 purpose of the present invention is to protect the application of a carrier material with a photoresponsive controlled release function in bio-based active packaging, that is, a bio-based photoresponsive controlled release active film. The carrier material PBA-IRMOF-3 with a photoresponsive controlled release function is obtained by functionally modifying IRMOF-3; the application of the carrier material in the bio-based active packaging is to use sodium alginate as the main film-forming material, add PBA-IRMOF-3 / carvacrol and a plasticizer, and cross-link after cast drying to obtain a composite film; the PBA-IRMOF-3 / carvacrol is formed by PBA-IRMOF-3 loaded with carvacrol.

[0058] Furthermore, the sodium alginate is natural polysaccharide sodium alginate; the plasticizer is glycerol; and the cross-linking agent used for cross-linking is a calcium chloride solution with a mass fraction of 5%.

[0059] Furthermore, the preparation method of the PBA-IRMOF-3 / carvacrol is as follows: after PBA-IRMOF-3 is added to carvacrol and dispersed, it is placed in a vacuum for 10 to 30 minutes, then restored to normal pressure and allowed to stand for 5 to 20 minutes, the above-mentioned vacuum placement-normal pressure standing operation is repeated 2 to 5 times to obtain a suspension, centrifuged, and the precipitate is collected and washed with anhydrous ethanol for 1 to 3 times, and the solid phase precipitate is collected and dried to obtain PBA-IRMOF-3 / carvacrol.

[0060] The third object of the present invention is to protect the use of a carrier material with a light-responsive controlled-release function in a bio-based active packaging, that is, a method for preparing a bio-based light-responsive controlled-release active film, comprising the following steps:

[0061] (1) PBA-IRMOF-3 / carvacrol is dissolved in water and dispersed, and then sodium alginate is added, and water is added to obtain a fixed solution, wherein the mass ratio of PBA-IRMOF-3 / carvacrol to sodium alginate in the fixed solution is 0.2-1.0:2.5, and the mass concentration of PBA-IRMOF-3 / carvacrol in the fixed solution is 2.10-10.53 mg / mL, and heating and stirring are performed to obtain a mixed solution A;

[0062] (2) adding a plasticizer to the mixed solution A and continuing stirring, wherein the volume ratio of the plasticizer to the mixed solution A is 1:19, and obtaining a film-forming base solution B after vacuuming;

[0063] (3) pouring the film-forming base liquid B into a mold, casting it into a film, and drying it at a temperature of 30 to 60° C. for 10 to 12 hours to obtain a sodium alginate-based light-responsive controlled-release active film;

[0064] (4) adding a crosslinking agent to the prepared light-responsive controlled-release active film for crosslinking for 50 to 70 seconds, wherein the amount of the crosslinking agent is 0.080 to 0.112 mL / cm 2 ;

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

[0066] In the light-responsive controlled-release active film of the present invention, after the active film is irradiated with ultraviolet light, the azobenzene group on PBA-IRMOF-3 undergoes "ultraviolet light response", that is, structural isomerization from trans to cis occurs; in the subsequent storage process, the azobenzene group undergoes "cis-trans relaxation" under visible light irradiation, and the azobenzene group gradually recovers from the cis structure to the trans structure. During this period, the azobenzene group plays a "impeller stirring" role, promoting the release of CA in PBA-IRMOF-3. After a period of time, the azobenzene group "completely relaxes", that is, it completely recovers from the cis structure to the trans structure, after which the "impeller stirring" effect disappears, and the release of CA begins to slow down relatively. The PBA-IRMOF-3 / carvacrol system has the potential for light-responsive controlled release, and can achieve the regulated release of CA under ultraviolet light stimulation. This property causes the sodium alginate-based light-responsive controlled-release active film with the addition of PBA-IRMOF-3 / carvacrol to have the performance of light-responsive control of carvacrol release.

[0067] In the light-responsive controlled-release active film of the present invention, ultraviolet light emitted by an American UVP CL-1000 ultraviolet crosslinking instrument (UV lamp wavelength 365nm, power 8-40W adjustable) is used as an ultraviolet light irradiation treatment stimulus source (UV irradiation), and LED lighting of a temperature-adjustable ZQLY-300 oscillating incubator is used to simulate a visible light irradiation treatment stimulus source (Vis irradiation).

[0068] The light response performance research of the present invention is carried out by respectively measuring the UV / Vis spectrum of the sample in the wavelength range of 200-600nm and the absorbance value of the sample at 323nm using an ultraviolet / visible spectrophotometer.

[0069] The mechanical properties of the present invention are measured using a 4.104 microcomputer-controlled electronic universal material testing machine manufactured by Meters Industrial Systems (China) Co., Ltd.; the water vapor transmission rate is measured using a gravimetric method in accordance with ASTM-E96 / E96M (2016); the water contact angle is measured using a JC2000D contact angle meter manufactured by Shanghai Zhongchen Digital Technology Equipment Co., Ltd.; and the transmittance is measured using a UV-1800 ultraviolet-visible spectrophotometer manufactured by Shimadzu Corporation of Japan.

[0070] The sodium alginate-based light-responsive controlled-release active film with added PBA-IRMOF-3 / carvacrol of the present invention will be further described below in conjunction with specific examples.

[0071] Example 1

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

[0073] Example 2

[0074] The invention discloses an application of a carrier material with a light-responsive controlled-release function in a bio-based active packaging, i.e., the preparation of a bio-based light-responsive controlled-release active film, wherein the active film is made of sodium alginate as the main film-forming material, PBA-IRMOF-3 / carvacrol and a plasticizer are added, and the composite film is prepared by cross-linking after casting and drying; the PBA-IRMOF-3 / carvacrol is formed by IRMOF-3 loading carvacrol. The sodium alginate is a natural polysaccharide sodium alginate; the plasticizer is glycerol; and the cross-linking agent used for the cross-linking is a calcium chloride solution with a mass fraction of 5%.

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

[0076] A preparation method of the above-mentioned light-responsive controlled-release active film: 0.4 g PBA-IRMOF-3 / carvacrol is dissolved in 80 mL of water, then 2.5 g of sodium alginate is added, and water is added to make the volume to 95 mL to obtain a fixed solution, which is stirred at 50°C and 1000 r / min for 40 min to obtain a mixed solution A; a plasticizer is added to the mixed solution A at a volume ratio of plasticizer to mixed solution A of 1:19, and stirring is continued for 40 min, and then a film-forming base liquid B is obtained after vacuuming for 30 min to remove bubbles; the film-forming base liquid B is poured into a horizontal glass mold for casting, and dried at 50°C for 12 h to obtain a sodium alginate-based light-responsive controlled-release active film; the film-forming base liquid B is poured into a horizontal glass mold for casting, and dried at 50°C for 12 h to obtain a sodium alginate-based light-responsive controlled-release active film; the film-forming base liquid B is poured into a horizontal glass mold for casting, and the film is dried at 0.080 mL / cm 2 A cross-linking agent was added to the active film prepared in step (3) and cross-linked for 60 seconds. The film was dried at 23°C for 12 hours at a relative humidity (RH) of 50%, and the dried film was peeled off from the mold to obtain a sodium alginate-based light-responsive controlled-release active film PMC@SA with added PBA-IRMOF-3 / carvacrol. The thickness of the active film was 55±5 μm.

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

[0078] It can be seen from the test that the performance of the sodium alginate-based light-responsive controlled-release active membrane with PBA-IRMOF-3 / carvacrol added in this example is shown in Table 1 and Table 2. Fig.11 .

[0079] Example 3

[0080] The invention discloses an application of a carrier material with a light-responsive controlled-release function in a bio-based active packaging, i.e., the preparation of a bio-based light-responsive controlled-release active film, wherein the active film is made of sodium alginate as the main film-forming material, PBA-IRMOF-3 / carvacrol and a plasticizer are added, and the composite film is prepared by cross-linking after casting and drying; the PBA-IRMOF-3 / carvacrol is formed by IRMOF-3 loading carvacrol. The sodium alginate is a natural polysaccharide sodium alginate; the plasticizer is glycerol; and the cross-linking agent used for the cross-linking is a calcium chloride solution with a mass fraction of 5%.

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

[0082] A preparation method of the above-mentioned light-responsive controlled-release active film: 0.4 g PBA-IRMOF-3 / carvacrol is dissolved in 80 mL of water, then 2.5 g of sodium alginate is added, and water is added to make the volume to 95 mL to obtain a fixed solution, which is stirred at 50°C and 1000 r / min for 40 min to obtain a mixed solution A; a plasticizer is added to the mixed solution A at a volume ratio of plasticizer to mixed solution A of 1:19, and stirring is continued for 40 min, and then a film-forming base liquid B is obtained after vacuuming for 30 min to remove bubbles; the film-forming base liquid B is poured into a horizontal glass mold for casting, and dried at 50°C for 12 h to obtain a sodium alginate-based light-responsive controlled-release active film; the film-forming base liquid B is poured into a horizontal glass mold for casting, and dried at 50°C for 12 h to obtain a sodium alginate-based light-responsive controlled-release active film; the film-forming base liquid B is poured into a horizontal glass mold for casting, and the film is dried at 0.080 mL / cm 2 A cross-linking agent was added to the active film prepared in step (3) and cross-linked for 60 seconds. The film was dried at 23°C for 12 hours at a relative humidity (RH) of 50%, and the dried film was peeled off from the mold to obtain a sodium alginate-based light-responsive controlled-release active film PMC@SA with added PBA-IRMOF-3 / carvacrol. The thickness of the active film was 55±5 μm.

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

[0084] Through testing, it can be seen that the performance of the sodium alginate-based light-responsive controlled-release active film with PBA-IRMOF-3 / carvacrol added in this embodiment after being irradiated with 40W ultraviolet light for 150s is shown in Table 1 and Table 2. Fig.11 .

[0085] Comparative Example 1

[0086] A carrier material PBA-IRMOF-3 with a photoresponsive controlled release function, the specific preparation method is: PBA and EDCl are ultrasonically dispersed in C2H2N to obtain a 0.04mmol / mL PBA acetonitrile solution and a 0.048mmol / mL EDCl acetonitrile solution, and a magnetic stirrer is stirred at 300r / min for 40min to obtain a mixed solution A. HOBt is ultrasonically dispersed in C2H2N to obtain a 0.034mmol / mL HOBt acetonitrile solution, which is added to the mixed solution A and stirred for 60min to obtain a mixed solution B. IRMOF-3 is added to the mixed solution B to obtain a mixed suspension C, the concentration of IRMOF-3 is 5.33mg / mL, and a mixed suspension D is obtained by stirring at room temperature. The mixed suspension D is centrifuged to obtain a precipitate, which is washed with C2H2N 6 times and then vacuum dried at 40°C for 24h to obtain PBA-IRMOF-3. The amino modification rate of the PBA-IRMOF-3 is 28.57%.

[0087] Comparative Example 2

[0088] A carrier material PBA-IRMOF-3 with a photoresponsive controlled release function, the specific preparation method is: PBA and EDCl are ultrasonically dispersed in C2H2N to obtain a 0.12mmol / mL PBA acetonitrile solution and a 0.144mmol / mL EDCl acetonitrile solution, and a magnetic stirrer is stirred at 300r / min for 40min to obtain a mixed solution A. HOBt is ultrasonically dispersed in C2H2N to obtain a 0.103mmol / mL HOBt acetonitrile solution, which is added to the mixed solution A and stirred for 60min to obtain a mixed solution B. IRMOF-3 is added to the mixed solution B to obtain a mixed suspension C, the concentration of IRMOF-3 is 5.33mg / mL, and a mixed suspension D is obtained by stirring at room temperature. The mixed suspension D is centrifuged to obtain a precipitate, which is washed with C2H2N 6 times and then vacuum dried at 40°C for 24h to obtain PBA-IRMOF-3. The amino modification rate of the PBA-IRMOF-3 is 25.12%.

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

[0090] The invention discloses an application of a carrier material with a photoresponsive controlled release function in a bio-based active packaging, i.e., a bio-based photoresponsive controlled release active film, and a preparation of a sodium alginate-based composite film without adding PBA-IRMOF-3 / carvacrol. The composite film is prepared by adding a plasticizer to sodium alginate as the main film-forming material, casting and drying, and then cross-linking to obtain the composite film; the sodium alginate is a natural polysaccharide sodium alginate; the plasticizer is glycerol; and the cross-linking agent used for the cross-linking is a calcium chloride solution with a mass fraction of 5%.

[0091] A preparation method of the composite film is as follows: 2.5 g of sodium alginate is added to 80 mL of deionized water, the volume is fixed to 95 mL to obtain a fixed volume solution, and the solution is stirred at 50° C. and 1000 r / min for 40 min to obtain a mixed solution A; a plasticizer is added to the mixed solution A at a volume ratio of 1:19, and the solution is stirred for 40 min, and then the bubbles are removed by vacuuming for 30 min to obtain a film-forming base liquid B; the film-forming base liquid B is poured into a horizontal glass mold for film casting, and dried at 50° C. for 12 h to obtain a sodium alginate composite film; and the mixture is heated at 0.080 mL / cm 2 A cross-linking agent was added to the sodium alginate-based composite film prepared in step (3) for cross-linking for 60 seconds, and the film was dried at 23°C for 12 hours at a relative humidity (RH) of 50%. The dried film was peeled off from the mold to obtain a sodium alginate composite film Pure SA without adding IRMOF-3 / carvacrol. The thickness of the sodium alginate-based composite film was 55±5 μm.

[0092] Through testing, it can be seen that the performance of the sodium alginate-based composite membrane without adding PBA-IRMOF-3 / carvacrol in this comparative example is shown in Table 1 and Table 2. Fig.11 .

[0093] Comparative Example 4 (addition of IRMOF-3 / carvacrol)

[0094] The invention discloses an application of a carrier material with a photoresponsive controlled release function in a bio-based active packaging, i.e., a bio-based photoresponsive controlled release active film, and a preparation of a sodium alginate-based active film with IRMOF-3 / carvacrol added. The active film is a composite film made of sodium alginate as the main film-forming material, carvacrol and a plasticizer are added, and the composite film is cross-linked after casting and drying; the sodium alginate is a natural polysaccharide sodium alginate; the plasticizer is glycerol; and the cross-linking agent used for the cross-linking is a calcium chloride solution with a mass fraction of 5%.

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

[0096] A preparation method of the above active film: 2.5g sodium alginate and 400mg IRMOF-3 / carvacrol are added to 80mL deionized water, and the volume is adjusted to 95mL to obtain a fixed solution, and the solution is stirred at 50°C and 1000r / min for 40min to obtain a mixed solution A; a plasticizer is added to the mixed solution A at a volume ratio of 1:19, and the mixture is stirred for 40min, and then the bubbles are removed by vacuuming for 30min to obtain a film-forming base liquid B; the film-forming base liquid B is poured into a horizontal glass mold for film casting, and dried at 50°C for 12h to obtain a sodium alginate composite film; the mixture is heated at 0.080mL / cm 2 A cross-linking agent was added to the sodium alginate-based composite membrane prepared in step (3) and cross-linked for 60 seconds. The membrane was dried at 23°C for 12 hours at a relative humidity (RH) of 50%, and the dried membrane was peeled off from 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 was 55±5 μm.

[0097] Through testing, it can be seen that the performance of the sodium alginate-based active membrane with IRMOF-3 / carvacrol added in this comparative example is shown in Table 1 and Table 2. Fig.11 .

[0098] Test example:

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

[0100] The effects of different reactant ratios on the preparation method and the modification rate of PBA-IRMOF-3 were 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 0.08 mmol / mL PBA acetonitrile solution and 0.096 mmol / mL EDCl acetonitrile solution, which were stirred at 300 r / min for 40 min using a magnetic stirrer to obtain a mixed solution A. 1-Hydroxybenzotriazole (HOBt) was ultrasonically dispersed in C2H2N to obtain a 0.069 mmol / mL HOBt acetonitrile solution, which was added to mixed solution A and stirred for 60 min to obtain a mixed solution B. IRMOF-3 was added to the mixed solution B to obtain a mixed suspension C (the concentration of IRMOF-3 was 2.67 mg / mL, recorded as S1; the concentration of IRMOF-3 was 5.33 mg / mL, recorded as S2; the concentration of IRMOF-3 was 8.00 mg / mL, recorded as S3.) Stirring at room temperature to obtain a mixed suspension D. The mixed suspension D was centrifuged to obtain a precipitate, which was washed with C2H2N 6 times and then dried in vacuum at 40°C for 24 h to obtain PBA-IRMOF-3.

[0102] Test: Since PBA-IRMOF-3 is poorly soluble in a single solvent, the sample was digested and appropriately diluted with a digestion solution (the digestion solution was: 5 mL DMSO + 0.35 mL HCl + 0.65 mL H2O). The absorption curve of the solution in the range of 200 to 800 nm was measured using a Shimadzu UV-1800 UV / Vis spectrophotometer from Japan to obtain an UV / Vis (UV / Vis) spectrum and analyze the characteristic peak positions of different samples.

[0103] Drawing of PBA standard curve: Prepare a series of PBA solutions with different concentrations, and then use a UV / visible spectrophotometer to measure the absorbance of PBA solutions with different concentrations at 440nm, with the digestion solution as a blank reference. Based on the obtained data, draw a standard curve of PBA with the concentration of PBA solution as the x-axis and the absorbance as the y-axis. In the range of 0.08 to 0.32 mg / mL, the fitted linear regression equation is y=3.01036x+0.00489(R 2 =0.9994).

[0104] Calculation of the modification rate of IRMOF-3 functional groups: 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 substituted into the PBA standard curve to calculate the PBA content in the PBA-IRMOF-3 sample, thereby inferring the modification rate of the functional groups in PBA-IRMOF-3. The amino modification rates of PBA-IRMOF-3 in the experimental groups S1-3 were 28.65%, 33.33% and 25.12%, respectively. It can be seen that during the preparation of PBA-IRMOF-3, the relative concentrations of IRMOF-3 and the reactants affect the amino modification rate of PBA-IRMOF-3.

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

[0106] 1) Photoresponsive properties of PBA-IRMOF-3

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

[0108] Figure 4 In the figure, after PBA-IRMOF-3 was irradiated with UV and Vis for different times, the absorption peak at 323nm was significantly weakened with the extension of UV irradiation time, while the absorption at 440nm was enhanced, indicating that the azobenzene group on PBA-IRMOF-3 gradually underwent trans-cis structural isomerization under UV irradiation, that is, "ultraviolet light response" occurred. PBA-IRMOF-3 that had been irradiated with UV for 120s was irradiated with Vis again for 10min and 60min, and the characteristic absorption peak at 325nm gradually increased, while the absorption peak at 440nm weakened, indicating that PBA-IRMOF-3 after UV irradiation under Vis irradiation underwent cis-trans structural isomerization, that is, "cis-trans relaxation" occurred. This shows that PBA-IRMOF-3 can achieve structural isomerization under alternating treatment of UV irradiation and Vis irradiation, and has the characteristic of "light response".

[0109] 2) “Ultraviolet light response” performance of PBA-IRMOF-3 under UV irradiation of different powers

[0110] PBA-IRMOF-3 was dispersed in anhydrous ethanol, and the samples were placed under 8, 24 and 40W UV light for UV irradiation treatment, and the UV absorbance of the samples at 323nm was measured at 0, 15, 30, 45, 60, 90, 120, 150, 180, 210, 240, 300, 360, 420, 480, 540 and 600s. As the UV irradiation time increases, the absorbance gradually decreases and then tends to stabilize. When the absorbance no longer decreases significantly, the corresponding UV irradiation time is the "complete response time" of the sample under different power UV irradiation conditions.

[0111] Figure 5 In the experiment, the PBA-IRMOF-3 samples were irradiated with 365nm ultraviolet light of different powers (8, 24, and 40W) for different times, and the absorbance values ​​of the samples at 323nm changed differently. Under UV irradiation of the same power, the absorbance value at 323nm gradually decreased with the extension of irradiation time, indicating that the azobenzene group of PBA-IRMOF-3 under UV irradiation had "ultraviolet light response". After a certain period of UV irradiation, the absorbance value of PBA-IRMOF-3 at 323nm began to stabilize, indicating that the azobenzene group had completely converted from the trans structure to the cis structure, and a "complete response" occurred. This UV irradiation time is called the "complete response time" of PBA-IRMOF-3 at this irradiation power. According to the absorbance value change information in the figure, when the UV irradiation power is 8, 24 and 40W respectively, the "complete response time" of PBA-IRMOF-3 is 480, 150 and 90s respectively. It is found that increasing the UV irradiation power can shorten the "complete response time". The UV irradiation power will affect the "ultraviolet light response" rate of PBA-IRMOF-3, that is, it will affect the trans-cis structural isomerization rate of the azobenzene group in PBA-IRMOF-3.

[0112] 3) Analysis of the “cis-trans relaxation” properties of PBA-IRMOF-3

[0113] PBA-IRMOF-3 was dispersed in anhydrous ethanol and irradiated under UV light at 40W for 90s to obtain PBA-IRMOF-3 with cis-structure azobenzene groups. The samples were then divided into three parts and placed in an oscillating incubator at 4, 25, and 50°C, respectively. The lighting was turned on for Vis irradiation. The UV absorbance of the samples at 323nm was measured at 0, 10, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 360, 420, 480, 540, and 600min. As the Vis irradiation time increases, the absorbance gradually increases and then stabilizes. When the absorbance no longer increases significantly, the corresponding time is the "complete relaxation time" of the sample under different temperature conditions.

[0114] Figure 6 In the present study, the cis-PBA-IRMOF-3 samples obtained after UV treatment were subjected to Vis irradiation at 4, 25 and 50 °C, respectively. The absorbance values ​​of the PBA-IRMOF-3 samples at 323 nm changed differently during Vis irradiation at different temperatures. At the same temperature, as the Vis irradiation time increased, the absorbance value at 323 nm gradually increased, indicating that the azobenzene group on PBA-IRMOF-3 underwent "cis-trans relaxation" under Vis irradiation. After a certain period of Vis irradiation, the absorbance value of PBA-IRMOF-3 at 323 nm began to stabilize, indicating that the azobenzene group had completely converted from the cis structure to the trans structure at this time. This Vis irradiation time is called the "complete relaxation time" of PBA-IRMOF-3 at this temperature. According to the change information of the absorbance value, the "complete relaxation time" of PBA-IRMOF-3 under Vis irradiation at 4, 25 and 50 °C is 480, 210 and 90 min, respectively. The "complete relaxation time" of PBA-IRMOF-3 is related to temperature. The "complete relaxation time" at lower temperatures is longer. Increasing the temperature can accelerate the relaxation rate of the azobenzene group.

[0115] Comprehensive analysis of the "ultraviolet light response" and "cis-trans relaxation" properties of PBA-IRMOF-3 shows that the "complete response time" of PBA-IRMOF-3 is much shorter than the "complete relaxation time". Under UV irradiation of a certain power, the azobenzene group on PBA-IRMOF-3 rapidly transforms from a trans structure to a cis structure. During the subsequent storage process exposed to Vis, the azobenzene group gradually recovers from a cis structure to a trans structure, indicating that PBA-IRMOF-3 can undergo structural isomerization under alternating UV and Vis irradiation and has light-responsive characteristics.

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

[0117] Drawing of CA standard curve: Prepare a series of CA anhydrous ethanol solutions, and then use UV-1800 ultraviolet spectrophotometer to measure the absorbance of anhydrous ethanol solutions of different CA concentrations at a wavelength of 276nm, with anhydrous ethanol as a blank reference. Based on the obtained data, draw a CA standard curve with CA concentration as the x-axis and absorbance as the y-axis. In the range of 0.01 to 0.08 μL / mL, the fitted linear regression equation is y=15.02545x+0.00916(R 2 =0.9998).

[0118] Weigh 100 mg of PBA-IRMOF-3 / CA sample and disperse them into sealed transparent glass bottles containing 50 mL of anhydrous ethanol. At the beginning of the release experiment, Group A: no treatment; Group B: placed under "365 nm, 40 W" UV light for UV irradiation for 90 s; Group C: no treatment. All samples were placed in an oscillating incubator at 25 ° C and 200 rpm, and the lighting was turned on for Vis irradiation treatment, and the release experiment began. At 0, 2, 4, 6, 8, and 10 hours, shake the glass bottle to make the mixed solution uniform and absorb a certain amount of the mixed solution. After sampling at 10 hours, the samples of Group C were placed under "365 nm, 40 W" UV irradiation for 90 seconds, and then placed in an oscillating incubator to continue the release experiment. At 12, 14, 16, 18, 20, 22, and 24 hours, shake the glass bottle to make the mixed solution uniform and absorb a certain amount of the mixed solution. The mixed solutions were centrifuged respectively, and the ultraviolet absorbance of the supernatant was measured at 276 nm after dilution. Three parallel samples were set for each group of samples, and the arithmetic mean of the ultraviolet absorbance values ​​of each group of samples was substituted into the regression equation of the CA standard curve of the chapter to calculate the final CA release amount. Then, the CA release rate curve was drawn with the release time (h) as the horizontal axis and the ratio of the CA release amount at different times to the theoretical total amount (CA loading amount) (CA release rate, %) as the vertical axis.

[0119] Figure 7In the experiment, the CA of the sample without UV irradiation showed the characteristics of sustained release. The sample was treated with UV irradiation at the beginning of release. In the early stage of release, the CA release rate of the sample treated with UV irradiation was higher than that of the untreated sample, and then it tended to be flat. After UV irradiation, the azobenzene group on PBA-IRMOF-3 underwent "ultraviolet light response", that is, structural isomerization from trans to cis occurred. In the subsequent storage process, the azobenzene group underwent "cis-trans relaxation", and the azobenzene group gradually recovered from the cis structure to the trans structure. During this period, the azobenzene group played a "impeller stirring" role, promoting the release of CA in PBA-IRMOF-3. After a period of time, the azobenzene group "completely relaxed", that is, completely recovered from the cis structure to the trans structure. After that, the "impeller stirring" effect disappeared, and the release of CA began to slow down relatively. After the sample was treated with UV irradiation at 10h after the start of release, the CA release rate suddenly increased, and then gradually tended to be flat, which was also the result of the "ultraviolet light response" and "cis-trans relaxation" of the azobenzene group. The results showed 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 Schematic diagram of light-responsive controlled release of the PBA-IRMOF-3 / CA system.

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

[0121] 1) Determination of the “full response time” of the photoresponsive active film

[0122] The prepared PMC@SA film samples were cut into 5cm×5cm samples and added to sealed transparent glass bottles containing 100mL of anhydrous ethanol. They were placed under "365nm, 40W" UV irradiation for 0, 30, 60, 90, 120, 150, 180, 210, 240, 270, and 300s, respectively. After that, all samples were placed in a 25℃ shaking incubator and turned on for Vis irradiation. After 24h, the supernatant was taken and diluted with anhydrous ethanol to measure the absorbance at 276nm. Three sets of parallel samples were set for each sample, and 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. As the UV irradiation time increases, the UV irradiation time corresponding to the experimental group where the CA release rate no longer changes significantly between the experimental groups within 24h is the "complete response time" of the photoresponsive controlled release active film.

[0123] Fig. 9In the results, compared with the active membranes not treated with UV irradiation, the CA release rate of the active membranes treated with UV irradiation increased within 24 hours, and as the treatment time increased, the release first increased and then stabilized. Different UV irradiation treatment times caused the azobenzene groups of PBA-IRMOF-3 / CA added to the membrane to undergo different degrees of "ultraviolet light response", that is, different degrees of isomerization from trans to cis structure. In the subsequent 24-hour release experiment, the azobenzene groups underwent different degrees of "cis-trans relaxation", which increased the CA release rate of the active membrane within 24 hours to different degrees. After the UV irradiation treatment time was 150s, the CA release rate was no longer significantly increased when the irradiation time was further extended. It can be inferred that when the light-responsive active membrane was irradiated with UV for 150s, the azobenzene groups on PBA-IRMOF-3 in the active membrane had undergone the maximum degree of trans-cis structural isomerization, and further extension of UV irradiation time would not significantly change its isomerization degree. Therefore, the "complete response time" of the prepared photoresponsive controlled-release active membrane under UV irradiation of "40 W, 365 nm" is about 150 s. The UV irradiation conditions of "40 W, 365 nm, 150 s" can be used as the response stimulation conditions of 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 active membranes

[0125] The PMC@SA film samples were cut into 5 cm × 5 cm pieces and added to sealed transparent glass bottles containing 100 mL of anhydrous ethanol. At the beginning of the release experiment, Group A: no treatment; Group B: irradiated with "365 nm, 40 W" UV for 150 s ("full response time" determined in 6.2.3.6 (1)); Group C: no treatment. All samples were placed in an oscillating incubator at 25 ° C and 200 rpm, and the lighting was turned on for Vis irradiation treatment to start the release experiment. The supernatant was taken at 0, 2, 4, 6, 8, and 10 hours. After the sampling test was completed at 10 hours, the samples of Group C were placed under "365 nm, 40 W" UV irradiation for 150 seconds, and then placed in an oscillating incubator to continue the release experiment. The supernatant was taken at 12, 14, 16, 18, 20, 22, and 24 hours. After each sampling, an equal amount of anhydrous ethanol was added to keep the volume constant, and the supernatant was diluted with anhydrous ethanol to measure the absorbance at 276nm. Three sets of parallel samples were set for each sample, and the arithmetic mean of the ultraviolet absorbance value 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, the CA release rate curve was drawn with the release time (h) as the horizontal axis and the ratio of the CA release amount at different times to the theoretical total amount (CA content in the membrane) (CA release rate, %) as the vertical axis.

[0126] Fig.10 In the experiment, CA in the active membrane without UV irradiation treatment showed sustained release characteristics. When the active membrane was treated with UV irradiation at the beginning of the release experiment, the CA release behavior of the active membrane treated with UV irradiation during the entire release experiment was similar to that of the active membrane without UV irradiation, but the CA release of the active membrane treated with UV irradiation accelerated after irradiation and then gradually slowed down. When the active membrane was treated with UV irradiation at 10h after the start of the release experiment, the CA release rate suddenly accelerated after 10h and then gradually slowed down. These results are similar to the CA release behavior of PBA-IRMOF-3 / CA after UV irradiation, which is the result of the isomerization of the azobenzene group of PBA-IRMOF-3, indicating that the prepared light-responsive controlled-release active membrane can achieve controlled release of CA under certain conditions of ultraviolet light stimulation.

[0127] (5) Composite membrane performance test:

[0128] The composite films prepared in Example 1-2 and Comparative Example 1-2 were tested for mechanical and physical properties. The tensile strength and elongation at break of the film samples were measured by a microcomputer-controlled electronic universal material testing machine (E43-104), the water vapor transmission rate was determined by gravimetric analysis, and the water contact angle on the film surface was measured by a WCA analyzer (POWEREACH, JC2000C). The transmittance of different films was measured in the wavelength range of 200 to 800 nm using an ultraviolet-visible spectrophotometer. The test results are shown in Tables 1 and Fig.11 shown.

[0129] Table 1 Physical properties of different films

[0130]

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

[0132] As shown in Table 1, the light-responsive controlled-release active film with PBA-IRMOF-3 / carvacrol has more significant water vapor barrier and hydrophobic properties. In addition, the pure sodium alginate film has a high light transmittance, and the light-responsive controlled-release active film with PBA-IRMOF-3 / carvacrol has a light transmittance of almost zero in the 250-380 nm band, which has excellent light barrier properties ( Fig.11 ).

[0133] The carrier material PBA-IRMOF-3 prepared by the present invention with light-responsive controlled-release function can realize reversible changes in cis-trans structure under alternating UV and Vis irradiation treatments, and "ultraviolet light response" occurs under UV irradiation, that is, the azobenzene group undergoes trans-cis structural isomerization; "cis-trans relaxation" occurs under Vis irradiation, that is, the azobenzene group undergoes cis-trans structural isomerization. In addition, the UV irradiation power affects the "ultraviolet light response" rate of PBA-IRMOF-3. When the UV irradiation power is 8, 24 and 40W, respectively, the "complete response time" of PBA-IRMOF-3 is 480, 150 and 90s, respectively. Increasing the UV irradiation power can shorten the "complete response time". Temperature affects the "cis-trans relaxation" performance of PBA-IRMOF-3 under Vis irradiation. Under Vis irradiation at 4, 25 and 50℃, the "complete relaxation time" of PBA-IRMOF-3 is 480, 210 and 90min respectively. Increasing the temperature can shorten the "complete relaxation time". PBA-IRMOF-3, a carrier material with photoresponsive controlled release function, can load carvacrol. Alternating treatment with UV and Vis irradiation promotes structural isomerization of azobenzene groups. During this process, azobenzene groups play the role of "impeller stirring" to accelerate the release of carvacrol, thereby realizing the photoresponsive controlled release of carvacrol. PBA-IRMOF-3, a carrier material with photoresponsive controlled release function, is used in the application of bio-based active packaging to prepare sodium alginate-based photoresponsive controlled release active membranes with PBA-IRMOF-3 / carvacrol. Due to the photoresponsive controlled release performance of PBA-IRMOF-3 on carvacrol, the active membrane has similar regulated release performance. In addition, the main raw materials and auxiliary agents for preparing the active film are non-toxic, harmless and degradable materials, among which sodium alginate is widely available and inexpensive, the metal organic framework material IRMOF-3 derivative PBA-IRMOF-3 has good biodegradability and biocompatibility, and carvacrol is a substance that is harmless to the human body and the environment, so the prepared composite film is an environmentally friendly material. The production method of the invention is safe, has a simple process flow, and has a low production cost, can be widely promoted in the market, and has a good market prospect.

[0134] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A carrier material with light-responsive controlled release function, characterized in that: Contains the following structure: Among them, 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 light-responsive controlled release function according to claim 1, characterized in that: Among them, UV is ultraviolet light, and Vis / heat is visible light / heat.

3. The carrier material with light-responsive controlled release function according to claim 1, characterized in that: The invention is prepared from the following components: isoreticular 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).

4. A method for preparing a carrier material with light-responsive controlled release function as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: (1) PBA and EDCl were ultrasonically dispersed in C2H2N and stirred with a magnetic stirrer to obtain a mixed solution A. (2) HOBt was ultrasonically dispersed in C2H2N, added to mixed solution A and continued to stir to obtain mixed solution B. (3) IRMOF-3 was added to the mixed solution B to obtain a mixed suspension C, and the mixed suspension D was obtained by stirring at room temperature. (4) The mixed suspension D was centrifuged to obtain a precipitate, which was washed several times with C2H2N and then vacuum dried to obtain PBA-IRMOF-3.

5. The preparation method according to claim 4, characterized in that: 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; the magnetic stirring speed is 200-400 r / min; and the magnetic stirring time is 30-50 min.

6. The preparation method according to claim 4, characterized in that: In step (2), the concentration of HOBt is 0.034-0.103 mmol / mL; the magnetic stirring speed is 200-400 r / min; and the magnetic stirring time is 40-80 min.

7. The preparation method according to claim 4, characterized in that: In step (3), the concentration of IRMOF-3 in the mixed suspension C is 2.67-8.00 mg / mL; the magnetic stirring speed is 200-400 r / min; and the magnetic stirring time is 12-36 h.

8. The preparation method according to claim 4, characterized in that: 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.

9. The carrier material with light-responsive controlled release function according to claim 4, characterized in that: The photoisomerization group modification rate of PBA-IRMOF-3 is 25.12% to 33.33%.

10. Use of a carrier material with light-responsive controlled-release function as claimed in any one of claims 1 to 9 in a bio-based active packaging film, i.e., preparation of a bio-based light-responsive controlled-release active film, characterized in that: The specific preparation method is as follows: PBA-IRMOF-3 / carvacrol is dissolved in water and dispersed, then a bio-based material is added, and water is added to obtain a fixed solution, wherein the bio-based material is a natural polysaccharide sodium alginate, and the PBA-IRMOF-3 / carvacrol is formed by loading carvacrol on 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 mass concentration of PBA-IRMOF-3 / carvacrol in the fixed solution is 2.10-10.53 mg / mL, and the volume of the fixed solution is 100 mL. The method comprises the steps of: hot stirring to obtain a mixed solution A; adding a plasticizer to the mixed solution A and continuing stirring, wherein the plasticizer is glycerol, and the volume ratio of the plasticizer to the mixed solution A is 1:19, and obtaining a film-forming base liquid B after vacuuming; pouring the film-forming base liquid B into a mold, casting the film, and drying the film at a temperature of 30 to 60° C. for 10 to 12 hours to obtain a sodium alginate-based light-responsive controlled-release active film; adding a crosslinking agent to the prepared light-responsive controlled-release active film for crosslinking for 50 to 70 seconds; the crosslinking agent used for the crosslinking is a 5wt% calcium chloride solution, and the amount of the crosslinking agent used is 0.080 to 0.112 mL / cm 2 ; Drying for 10 to 12 hours at a relative humidity of 50% to 60% and a temperature of 21 to 25°C to obtain a sodium alginate-based light-responsive controlled-release active packaging film with added PBA-IRMOF-3 / carvacrol.

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