CN-119592085-B - Self-assembled Thy@ZIF-8 nanoparticle, self-enhanced multifunctional fresh-keeping composite film and preparation method and application thereof

Abstract

The invention belongs to the field of functional films, and relates to a self-assembled Thy@ZIF-8 nanoparticle, a self-reinforced multifunctional fresh-keeping composite film, and a preparation method and application thereof. The self-assembled Thy@ZIF-8 nanoparticle is a nanoparticle formed by encapsulating thymol Thy with a metal organic framework material ZIF-8. The self-assembled Thy@ZIF-8 nano particles are prepared and optimized, and are used as a material component for preparing the postharvest preservative film for the first time. The active material Thy is encapsulated by utilizing the characteristics of the self porous structure and the high specific surface area of the ZIF-8 nano-particles, so that the Thy@ZIF-8 nano-particles are prepared. The structure of the Thy@ZIF-8 nano particles is damaged by the change of the pH of the microenvironment of the fruits in the storage process after the fruits are picked, so that the Thy is released, and the purposes of slow release and prolonged bacteriostasis and aging are achieved.

Inventors

• Han Dianpeng
• GAO ZHIXIAN
• ZHOU HUANYING
• CHEN QI
• PENG YUAN
• LI SHUANG
• QIN KANG
• REN SHUYUE
• WANG YU

Assignees

• 中国人民解放军军事科学院军事医学研究院

Dates

Publication Date

20260505

Application Date

20241021

Claims (8)

1. 1. The self-reinforced multifunctional fresh-keeping composite film is characterized in that chitosan is used as a substrate, procyanidins are grafted on at least part of chitosan, and the film comprises self-assembled Thy@ZIF-8 nano particles; The self-assembled Thy@ZIF-8 nanoparticles are nanoparticles formed by encapsulating thymol Thy with a metal organic framework material ZIF-8; The film is prepared by the method comprising the following steps of respectively dissolving chitosan-procyanidine conjugate CS-PA and Thy@ZIF-8 nano particles in distilled water, rapidly stirring at room temperature to prepare CS-PA dispersion and Thy@ZIF-8 dispersion, adding the CS-PA dispersion and the Thy@ZIF-8 dispersion into chitosan film forming solution for blending reaction, and preparing a film from the blend solution after reaction and drying to obtain the CS-PA/Thy@ZIF-8 composite film; The preparation method of the self-assembled Thy@ZIF-8 nano particles comprises the following steps of dissolving 2-methylimidazole and thymol in a first organic solvent, uniformly mixing the solution with Zn 2+ precursor solution after ultrasonic treatment, stirring, reacting and centrifuging to obtain the Thy@ZIF-8 nano particles.
2. 2. The self-reinforced multifunctional fresh-keeping composite film according to claim 1, wherein the self-assembled thy@zif-8 nanoparticles have a ZIF-8 content of 70-85 wt% and a Thy content of 15-30 wt%.
3. 3. The self-reinforced multifunctional fresh-keeping composite film according to claim 1, wherein the first organic solvent is anhydrous methanol; The Zn 2+ precursor is Zn (NO 3 ) 2 ·6H 2 O; the molar ratio of the 2-methylimidazole to the Zn 2+ precursor is 2-12:1; the mass ratio of the 2-methylimidazole to the thymol is 200-300:1.
4. 4. The self-reinforced multifunctional fresh-keeping composite film according to claim 1, wherein the stirring reaction condition comprises a temperature of 10-30 ℃ and a time of 16-36 h; the stirring reaction also comprises the steps of washing and vacuum drying.
5. 5. The self-reinforced multifunctional fresh-keeping composite film according to claim 1, wherein, The self-assembled Thy@ZIF-8 nano particles in the self-reinforced multifunctional fresh-keeping composite film accounts for 25-35 wt%, and the procyanidine accounts for 15-25 wt%.
6. 6. The method for preparing the self-reinforced multifunctional fresh-keeping composite film according to claim 1, which comprises the following steps: Respectively dissolving chitosan-procyanidine conjugate CS-PA and Thy@ZIF-8 nano particles in distilled water, rapidly stirring at room temperature to obtain CS-PA dispersion and Thy@ZIF-8 dispersion, adding the CS-PA dispersion and the Thy@ZIF-8 dispersion into chitosan film forming solution for blending reaction, and preparing a film from the reacted blend solution and drying to obtain the CS-PA/Thy@ZIF-8 composite film.
7. 7. The preparation method according to claim 6, wherein the solution is stirred rapidly until the solution is uniform and free of particles; The preparation method of the chitosan-procyanidine conjugate CS-PA comprises adding hydrogen peroxide solution containing ascorbic acid into acetic acid solution of chitosan, reacting for a period of time, adding procyanidine, reacting at room temperature, adjusting reaction solution to neutrality after reaction, centrifuging, collecting precipitate, washing, and lyophilizing to obtain the chitosan-procyanidine conjugate CS-PA; the preparation method of the chitosan film-forming solution comprises the steps of dissolving chitosan in glacial acetic acid to prepare a chitosan solution, and adding glycerol as a plasticizer to obtain the chitosan film-forming solution; the film making method comprises the steps of pouring the blending solution on a plastic plate.
8. 8. Use of the self-reinforced multifunctional fresh-keeping composite film according to any one of claims 1 to 5 in post-harvest storage of fruits and vegetables.

Description

Self-assembled Thy@ZIF-8 nanoparticle, self-enhanced multifunctional fresh-keeping composite film and preparation method and application thereof Technical Field The invention belongs to the field of functional films, and particularly relates to a self-assembled Thy@ZIF-8 nanoparticle, a self-reinforced multifunctional fresh-keeping composite film, and a preparation method and application thereof. Background Fresh fruit is critical to healthy diet and is one of the most popular foods in the world. Unfortunately, more than one third of the fruits per year are already rotted and spoiled before eating, resulting in serious food wastage and economic loss. Therefore, it is important to prolong the fresh-keeping period of fruits. However, the freshness of fruit is affected by a number of factors, including oxygen, respiration and microorganisms. On the one hand, oxygen and respiration can accelerate oxidative deterioration, water loss and skin shrinkage of the fruit. On the other hand, the nutrition is rich, and the growth and the propagation of microorganisms are promoted, so that the mildew and the decay of fruits are aggravated. Among many preservation techniques, food packaging materials play a vital role in preventing deterioration of foods and in extending the shelf life of foods. At present, most of the most commonly used food fresh-keeping packaging materials in the market are high-molecular plastic packaging fresh-keeping films, and are generally made of petroleum-based polymers such as polyvinylidene chloride, polyethylene and the like. Despite its cost effectiveness and ease of use, it presents challenges in recycling and degradation, resulting in serious environmental pollution. In recent years, with the development of biotechnology, the transition from traditional fresh-keeping packaging materials to degradable environment-friendly packaging materials has become a necessary trend of the development of modern food packaging. The existing degradable green food packaging materials can be mainly divided into biopolymers such as starch, protein, polysaccharide, lipid and the like, and have the excellent characteristics of reproducibility, biodegradability, good biocompatibility, environmental friendliness and the like. Polysaccharide-based films are most attractive due to their excellent gas barrier properties and mechanical properties compared to films made of lipids or proteins. Among them, chitosan (CS) is a relatively common natural polymer, which has been attracting attention for many years due to its excellent properties, however, CS films have low antioxidant activity due to their linear structure and the presence of a large number of hydrogen bonds, and can only be dissolved in an acidic environment, further limiting their application. The invention aims to develop the self-enhanced multifunctional fresh-keeping active packaging material with good antioxidation and antibacterial properties by doping the active natural compound into the CS film, which not only has the advantages of inhibiting the growth of pathogenic bacteria and prolonging the fresh-keeping period of fresh food, but also can realize biodegradation and protect the environmental health. Among the numerous active natural compounds, procyanidins (PA), also known as condensed tannins, are natural bioflavonoids condensed from flavan-3-ols, widely present in fruits, vegetables, seeds and flowers, which can further improve their solubility and oxidation resistance by grafting PA to CS films. In addition, thymol (Thy) is also favored for its remarkable antibacterial and antioxidant properties and good biosafety. However, thy is poor in heat stability, volatility and water solubility, limiting its bioactivity to some extent, while the unique flavor of Thy also affects the original organoleptic properties of the packaged food. By encapsulating Thy in a nanocarrier is one of the effective strategies to solve the above problems, the addition of the nanocarrier allows for better control of the release of the active agent than by encapsulating Thy directly in a biopolymer matrix, thereby providing more durable antimicrobial and antioxidant properties to the composite film. In the aspect of nano-carriers, metal organic framework Materials (MOFs) represented by ZIF-8 have been widely applied to drug delivery and slow release in biomedicine due to the advantages of porous structure, high specific surface area, structural diversity and the like, and in addition, the ZIF-8 can release unsaturated Zn 2+ under an acidic condition to damage a bacterial structure, so that an active material can enter bacterial cells more easily, and synergistic antibacterial effect is realized. Based on the method, the Thy@ZIF-8 nano particles are prepared by encapsulating the Thy into the ZIF-8 nano particles, and meanwhile, the Thy@ZIF-8 nano particles are introduced into a CS-PA matrix to prepare the self-reinforced multifunctional fresh-keeping CS-PA/Thy@ZIF-8 composi